1,255 research outputs found

    John Gower: The Minor Latin Works

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    A translation, with introductions, of the minor Latin works of John Gower

    The Voice of One Crying

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    The first poetic English translation of the entirety of John Gower\u27s Vox Clamanti

    Detection and quantification of poliovirus infection using FTIR spectroscopy and cell culture

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    <p>Abstract</p> <p>Background</p> <p>In a globalized word, prevention of infectious diseases is a major challenge. Rapid detection of viable virus particles in water and other environmental samples is essential to public health risk assessment, homeland security and environmental protection. Current virus detection methods, especially assessing viral infectivity, are complex and time-consuming, making point-of-care detection a challenge. Faster, more sensitive, highly specific methods are needed to quantify potentially hazardous viral pathogens and to determine if suspected materials contain viable viral particles. Fourier transform infrared (FTIR) spectroscopy combined with cellular-based sensing, may offer a precise way to detect specific viruses. This approach utilizes infrared light to monitor changes in molecular components of cells by tracking changes in absorbance patterns produced following virus infection. In this work poliovirus (PV1) was used to evaluate the utility of FTIR spectroscopy with cell culture for rapid detection of infective virus particles.</p> <p>Results</p> <p>Buffalo green monkey kidney (BGMK) cells infected with different virus titers were studied at 1 - 12 hours post-infection (h.p.i.). A partial least squares (PLS) regression method was used to analyze and model cellular responses to different infection titers and times post-infection. The model performs best at 8 h.p.i., resulting in an estimated root mean square error of cross validation (RMSECV) of 17 plaque forming units (PFU)/ml when using low titers of infection of 10 and 100 PFU/ml. Higher titers, from 10<sup>3 </sup>to 10<sup>6 </sup>PFU/ml, could also be reliably detected.</p> <p>Conclusions</p> <p>This approach to poliovirus detection and quantification using FTIR spectroscopy and cell culture could potentially be extended to compare biochemical cell responses to infection with different viruses. This virus detection method could feasibly be adapted to an automated scheme for use in areas such as water safety monitoring and medical diagnostics.</p

    Swept-Wing Ice Accretion Characterization and Aerodynamics

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    NASA, FAA, ONERA, the University of Illinois and Boeing have embarked on a significant, collaborative research effort to address the technical challenges associated with icing on large-scale, three-dimensional swept wings. The overall goal is to improve the fidelity of experimental and computational simulation methods for swept-wing ice accretion formation and resulting aerodynamic effect. A seven-phase research effort has been designed that incorporates ice-accretion and aerodynamic experiments and computational simulations. As the baseline, full-scale, swept-wing-reference geometry, this research will utilize the 65% scale Common Research Model configuration. Ice-accretion testing will be conducted in the NASA Icing Research Tunnel for three hybrid swept-wing models representing the 20%, 64% and 83% semispan stations of the baseline-reference wing. Three-dimensional measurement techniques are being developed and validated to document the experimental ice-accretion geometries. Artificial ice shapes of varying geometric fidelity will be developed for aerodynamic testing over a large Reynolds number range in the ONERA F1 pressurized wind tunnel and in a smaller-scale atmospheric wind tunnel. Concurrent research will be conducted to explore and further develop the use of computational simulation tools for ice accretion and aerodynamics on swept wings. The combined results of this research effort will result in an improved understanding of the ice formation and aerodynamic effects on swept wings. The purpose of this paper is to describe this research effort in more detail and report on the current results and status to date.

    Negative electronic compressibility and tunable spin splitting in WSe2

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    This work was supported by the Engineering and Physical Sciences Research Council, UK (Grant Nos. EP/I031014/1, EP/M023427/1, EP/L505079/1, and EP/G03673X/1), TRF-SUT Grant RSA5680052 and NANOTEC, Thailand through the CoE Network. PDCK acknowledges support from the Royal Society through a University Research Fellowship. MSB was supported by the Grant-in-Aid for Scientific Research (S) (No. 24224009) from the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan.Tunable bandgaps1, extraordinarily large exciton-binding energies2, 3, strong light–matter coupling4 and a locking of the electron spin with layer and valley pseudospins5, 6, 7, 8 have established transition-metal dichalcogenides (TMDs) as a unique class of two-dimensional (2D) semiconductors with wide-ranging practical applications9, 10. Using angle-resolved photoemission (ARPES), we show here that doping electrons at the surface of the prototypical strong spin–orbit TMD WSe2, akin to applying a gate voltage in a transistor-type device, induces a counterintuitive lowering of the surface chemical potential concomitant with the formation of a multivalley 2D electron gas (2DEG). These measurements provide a direct spectroscopic signature of negative electronic compressibility (NEC), a result of electron–electron interactions, which we find persists to carrier densities approximately three orders of magnitude higher than in typical semiconductor 2DEGs that exhibit this effect11, 12. An accompanying tunable spin splitting of the valence bands further reveals a complex interplay between single-particle band-structure evolution and many-body interactions in electrostatically doped TMDs. Understanding and exploiting this will open up new opportunities for advanced electronic and quantum-logic devices.PostprintPeer reviewe

    Measuring and predicting reservoir heterogeneity in complex deposystems: the Late Cambrian Rose Run sandstone of Eastern Ohio and Western Pennsylvania

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    A cooperative two-year multidisciplinary research program, conducted by the Ohio Division of Geological Survey (ODGS) and the Pennsylvania Bureau of Topographic and Geologic Survey (PTGS), designed to measure and predict reservoir heterogeneity in the Upper Cambrian Rose Run sandstone in those two states.257 pages, 125 figures (including numerous maps, cross sections, seismic lines, and photographs of rock thin sections), 6 tables, and five case studies of Rose Run oil and gas fields.Prepared for U.S. Department of Energy, Assistant Secretary for Fossil Energy. Work performed under Contract No. DE-AC22-90BC14657.This two-year investigation of the Upper Cambrian Rose Run sandstone in Eastern Ohio and Western Pennsylvania was conducted by the Ohio and Pennsylvania Geological Surveys in a cost-sharing agreement with the U.S. Department of Energy under the auspices of the Appalachian Oil and Natural Gas Research Consortium, which consists of West Virginia University and the state geological surveys of Kentucky, Ohio, Pennsylvania, and West Virginia

    Electronic bandstructure of in-plane ferroelectric van der Waals β′−In2Se3\beta '-In_{2}Se_{3}

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    Layered indium selenides (In2Se3In_{2}Se_{3}) have recently been discovered to host robust out-of-plane and in-plane ferroelectricity in the α\alpha and β\beta' phases, respectively. In this work, we utilise angle-resolved photoelectron spectroscopy to directly measure the electronic bandstructure of β′−In2Se3\beta '-In_{2}Se_{3}, and compare to hybrid density functional theory (DFT) calculations. In agreement with DFT, we find the band structure is highly two-dimensional, with negligible dispersion along the c-axis. Due to n-type doping we are able to observe the conduction band minima, and directly measure the minimum indirect (0.97 eV) and direct (1.46 eV) bandgaps. We find the Fermi surface in the conduction band is characterized by anisotropic electron pockets with sharp in-plane dispersion about the M‾\overline{M} points, yielding effective masses of 0.21 m0m_{0} along KM‾\overline{KM} and 0.33 m0m_{0} along ΓM‾\overline{\Gamma M}. The measured band structure is well supported by hybrid density functional theory calculations. The highly two-dimensional (2D) bandstructure with moderate bandgap and small effective mass suggest that β′−In2Se3\beta'-In_{2}Se_{3} is a potentially useful new van der Waals semiconductor. This together with its ferroelectricity makes it a viable material for high-mobility ferroelectric-photovoltaic devices, with applications in non-volatile memory switching and renewable energy technologies.Comment: 19 pages, 4 + 1 figures; typos corrected;added references; updated figures & discussion to reflect changes in mode

    Ultrafast band structure control of a two-dimensional heterostructure

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    The electronic structure of two-dimensional (2D) semiconductors can be signicantly altered by screening effects, either from free charge carriers in the material itself, or by environmental screening from the surrounding medium. The physical properties of 2D semiconductors placed in a heterostructure with other 2D materials are therefore governed by a complex interplay of both intra- and inter-layer interactions. Here, using time- and angle-resolved photoemission, we are able to isolate both the layer-resolved band structure and, more importantly, the transient band structure evolution of a model 2D heterostructure formed of a single layer of MoS 2 on graphene. Our results reveal a pronounced renormalization of the quasiparticle gap of the MoS 2 layer. Following optical excitation, the band gap is reduced by up to ∼400 meV on femtosecond timescales due to a persistence of strong electronic interactions despite the environmental screening by the n-doped graphene. This points to a large degree of tuneability of both the electronic structure and electron dynamics for 2D semiconductors embedded in a van der Waals-bonded heterostructure.PostprintPeer reviewe

    Hope in dirt: report of the Fort Apache Workshop on Forensic Sedimentology Applications to Cultural Property Crime, 15—19 October 2018

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    A 2018 workshop on the White Mountain Apache Tribe lands in Arizona examined ways to enhance investigations into cultural property crime (CPC) through applications of rapidly evolving methods from archaeological science. CPC (also looting, graverobbing) refers to unauthorized damage, removal, or trafficking in materials possessing blends of communal, aesthetic, and scientific values. The Fort Apache workshop integrated four generally partitioned domains of CPC expertise: (1) theories of perpetrators’ motivations and methods; (2) recommended practice in sustaining public and community opposition to CPC; (3) tactics and strategies for documenting, investigating, and prosecuting CPC; and (4) forensic sedimentology—uses of biophysical sciences to link sediments from implicated persons and objects to crime scenes. Forensic sedimentology served as the touchstone for dialogues among experts in criminology, archaeological sciences, law enforcement, and heritage stewardship. Field visits to CPC crime scenes and workshop deliberations identified pathways toward integrating CPC theory and practice with forensic sedimentology’s potent battery of analytic methods
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