1,346 research outputs found

    Method and Meaning: Selections from the Gettysburg College Collection

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    What is art historical study and how it should be carried out are fundamental questions the exhibition Method and Meaning: Selections from the Gettysburg College Collection intends to answer. This student-curated exhibition is an exciting academic endeavor of seven students of art history majors and minors in the Art History Methods course. The seven student curators are Shannon Callahan, Ashlie Cantele, Maura D’Amico, Xiyang Duan, Devin Garnick, Allison Gross and Emily Zbehlik. As part of the class assignment, this exhibition allows the students to explore various art history methods on individual case studies. The selection of the works in the exhibition reflects a wide array of student research interests including an example of 18th century Chinese jade chime stone, jade and bronze replicas of ancient Chinese bronze vessels, a piece of early 20th century Chinese porcelain, oil paintings by Pennsylvania Impressionist painter Fern Coppedge, prints by Salvador DalĂ­ and by German artist KĂ€the Kollwitz, and an early 20th century wood block print by Japanese artist Kawase Hasui. [excerpt]https://cupola.gettysburg.edu/artcatalogs/1014/thumbnail.jp

    Analysis for Science Librarians of the 2018 Nobel Prize in Physiology or Medicine: The Life and Work of James P. Allison and Tasuku Honjo

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    On October 1, 2018, James P. Allison and Tasuku Honjo were awarded the 2018 Physiology or Medicine Nobel for their work leading to Immune Checkpoint Inhibition (ICI). ICI is the fourth pillar of cancer treatment and has been used to treat previously un-treatable cancers. Allison discovered that the protein CTLA-4 acts as a T cell brake while Honjo discovered another T cell brake, PD-1. Releasing these brakes allows the immune system to attack tumors, sometimes leading to complete elimination. While there is still more research to be done, Allison’s and Honjo’s work is a breakthrough in cancer immunotherapy

    Bidirectional lipid droplet velocities are controlled by differential binding strengths of HCV Core DII protein

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    Host cell lipid droplets (LD) are essential in the hepatitis C virus (HCV) life cycle and are targeted by the viral capsid core protein. Core-coated LDs accumulate in the perinuclear region and facilitate viral particle assembly, but it is unclear how mobility of these LDs is directed by core. Herein we used two-photon fluorescence, differential interference contrast imaging, and coherent anti-Stokes Raman scattering microscopies, to reveal novel core-mediated changes to LD dynamics. Expression of core protein’s lipid binding domain II (DII-core) induced slower LD speeds, but did not affect directionality of movement on microtubules. Modulating the LD binding strength of DII-core further impacted LD mobility, revealing the temporal effects of LD-bound DII-core. These results for DII-core coated LDs support a model for core-mediated LD localization that involves core slowing down the rate of movement of LDs until localization at the perinuclear region is accomplished where LD movement ceases. The guided localization of LDs by HCV core protein not only is essential to the viral life cycle but also poses an interesting target for the development of antiviral strategies against HCV

    Measurement of the hadronic photon structure function F_{2}^{Îł} at LEP2

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    The hadronic structure function of the photon F_{2}^{Îł} (x, QÂČ) is measured as a function of Bjorken x and of the photon virtuality QÂČ using deep-inelastic scattering data taken by the OPAL detector at LEP at eâșe⁻ centre-of-mass energies from 183 to 209 GeV. Previous OPAL measurements of the x dependence of F_{2}^{Îł} are extended to an average QÂČ of 〈QÂČ〉=780 GeVÂČ using data in the kinematic range 0.15<x<0.98. The QÂČ evolution of F_{2}^{Îł} is studied for 12.1<〈QÂČ〉<780 GeVÂČ using three ranges of x. As predicted by QCD, the data show positive scaling violations in F_{2}^{Îł} with F_{2}^{Îł} (QÂČ)/α = (0.08±0.02âș⁰·⁰⁔_₀.₀₃) + (0.13±0.01âș⁰·⁰Âč_₀.₀₁) lnQÂČ, where QÂČ is in GeVÂČ, for the central x region 0.10–0.60. Several parameterisations of F_{2}^{Îł} are in qualitative agreement with the measurements whereas the quark-parton model prediction fails to describe the data

    Measurement of the charm structure function F_{2,c)^{Îł} of the photon at LEP

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    The production of charm quarks is studied in deep-inelastic electron–photon scattering using data recorded by the OPAL detector at LEP at nominal eâșe⁻ centre-of-mass energies from 183 to 209 GeV. The charm quarks have been identified by full reconstruction of charged D* mesons using their decays into D⁰π with the D⁰ observed in two decay modes with charged particle final states, Kπ and Kπππ. The cross-section σ^{D*} for production of charged D* in the reaction eâșe⁻→eâșe⁻D*Χ is measured in a restricted kinematical region using two bins in Bjorken x, 0.00140.1 the perturbative QCD calculation at next-to-leading order agrees perfectly with the measured cross-section. For x<0.1 the measured cross-section is 43.8±14.3±6.3±2.8 pb with a next-to-leading order prediction of 17.0âșÂČ·âč_₂.₃ pb

    Measurement of triple gauge boson couplings from WâșW⁻ production at LEP energies up to 189 GeV

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    A measurement of triple gauge boson couplings is presented, based on W-pair data recorded by the OPAL detector at LEP during 1998 at a centre-of-mass energy of 189 GeV with an integrated luminosity of 183 pb⁻Âč. After combining with our previous measurements at centre-of-mass energies of 161–183 GeV we obtain Îș = 0.97_{-0.16}^{+0.20}, g_{1}^{z} = 0.991_{-0.057}^{+0.060} and λ = -0.110_{-0.055}^{+0.058}, where the errors include both statistical and systematic uncertainties and each coupling is determined by setting the other two couplings to their Standard Model values. These results are consistent with the Standard Model expectations

    Search for Yukawa Production of a Light Neutral Higgs Boson at LEP

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    Within a Two-Higgs-Doublet Model (2HDM) a search for a light Higgs boson in the mass range of 4-12 GeV has been performed in the Yukawa process e+e- -> b bbar A/h -> b bbar tau+tau-, using the data collected by the OPAL detector at LEP between 1992 and 1995 in e+e- collisions at about 91 GeV centre-of-mass energy. A likelihood selection is applied to separate background and signal. The number of observed events is in good agreement with the expected background. Within a CP-conserving 2HDM type II model the cross-section for Yukawa production depends on xiAd = |tan beta| and xihd = |sin alpha/cos beta| for the production of the CP-odd A and the CP-even h, respectively, where tan beta is the ratio of the vacuum expectation values of the Higgs doublets and alpha is the mixing angle between the neutral CP-even Higgs bosons. From our data 95% C.L. upper limits are derived for xiAd within the range of 8.5 to 13.6 and for xihd between 8.2 to 13.7, depending on the mass of the Higgs boson, assuming a branching fraction into tau+tau- of 100%. An interpretation of the limits within a 2HDM type II model with Standard Model particle content is given. These results impose constraints on several models that have been proposed to explain the recent BNL measurement of the muon anomalous magnetic moment.Comment: 24 pages, 9 figures, Submitted to Euro. Phys. J.

    Tests of model of color reconnection and a search for glueballs using gluon jets with a rapidity gap

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    Gluon jets with a mean energy of 22 GeV and purity of 95% are selected from hadronic Z0 decay events produced in e+e- annihilations. A subsample of these jets is identified which exhibits a large gap in the rapidity distribution of particles within the jet. After imposing the requirement of a rapidity gap, the gluon jet purity is 86%. These jets are observed to demonstrate a high degree of sensitivity to the presence of color reconnection, i.e. higher order QCD processes affecting the underlying color structure. We use our data to test three QCD models which include a simulation of color reconnection: one in the Ariadne Monte Carlo, one in the Herwig Monte Carlo, and the other by Rathsman in the Pythia Monte Carlo. We find the Rathsman and Ariadne color reconnection models can describe our gluon jet measurements only if very large values are used for the cutoff parameters which serve to terminate the parton showers, and that the description of inclusive Z0 data is significantly degraded in this case. We conclude that color reconnection as implemented by these two models is disfavored. The signal from the Herwig color reconnection model is less clear and we do not obtain a definite conclusion concerning this model. In a separate study, we follow recent theoretical suggestions and search for glueball-like objects in the leading part of the gluon jets. No clear evidence is observed for these objects.Comment: 42 pages, 18 figure

    Scaling violations of quark and gluon jet fragmentation functions in e+e- annihilations at sqrt(s) = 91.2 and 183-209 GeV

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    Flavour inclusive, udsc and b fragmentation functions in unbiased jets, and flavour inclusive, udsc, b and gluon fragmentation functions in biased jets are measured in e+e- annihilations from data collected at centre-of-mass energies of 91.2, and 183-209 GeV with the OPAL detector at LEP. The unbiased jets are defined by hemispheres of inclusive hadronic events, while the biased jet measurements are based on three-jet events selected with jet algorithms. Several methods are employed to extract the fragmentation functions over a wide range of scales. Possible biases are studied in the results are obtained. The fragmentation functions are compared to results from lower energy e+e- experiments and with earlier LEP measurements and are found to be consistent. Scaling violations are observed and are found to be stronger for the fragmentation functions of gluon jets than for those of quarks. The measured fragmentation functions are compared to three recent theoretical next-to-leading order calculations and to the predictions of three Monte Carlo event generators. While the Monte Carlo models are in good agreement with the data, the theoretical predictions fail to describe the full set of results, in particular the b and gluon jet measurements.Comment: 46 pages, 17 figures, Submitted to Eur. Phys J.
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