337 research outputs found

    Nanomaterial structure determination using XUV diffraction

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    Diffraction using coherent XUV radiation is used to study the structure of nanophotonic materials, in this case an ordered array of 196nm spheres. Crystal structure and defects are visible, and the nanomaterial dielectric constant determined

    The Art of Remembering: It Matters how We Tell the Sabbath Story

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    Sabbath is a story without peer. She is ancient, but a constant challenge to the contemporary. She ceases all things but remains unceasing. Her exquisite prestige, her dignified memory, are not indifferent to the sorrow of creation. Cries and tears and wounded bodies find space and embrace in the sacredness of Sabbath. Sabbath cannot be pressed into a doctrinal argument, confined into a rule book, or quarantined within church walls. Sabbath is of spirit matter “never to pass away,” “eternity in disguise,” as Abraham Joshua Heschel so eloquently put it. Freedom is her essence. In this article, I attempt to retell Sabbath’s story with reverberations from the world and language of biblical eras. The commitment is to not ignore the Sabbath’s inner life, to not distort her audacious vision, and not fault her for her vulnerability. Two texts from the book of Exodus will serve as paradigms. The first is from the narrative of Exodus 5, announcing the Sabbath’s subtle but intense destabilizing power of oppressive systems, inasmuch as we will hear her voice coming from an unlikely place, from a tyrant’s mouth. The second text is part of the Covenant Code in Exodus 23:12. Here, God’s compassionate listening to the cries of the oppressed urges us to receive the other, the stranger, the immigrant, the refugee, as one of us. Sabbath disrupts the dehumanizing power structures of this world and demands of us to make room for the defenseless, the weak, and the marginalized

    Bott Periodicity and Realizations of Chiral Symmetry in Arbitrary Dimensions

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    We compute the chiral symmetries of the Lagrangian for confining "vector-like" gauge theories with massless fermions in dd-dimensional Minkowski space and, under a few reasonable assumptions, determine the form of the quadratic fermion condensates which arise through spontaneous breaking of these symmetries. We find that for each type (complex, real, or pseudoreal) of representation of the gauge group carried by the fermions, the chiral symmetries of the Lagrangian, as well as the residual symmetries after dynamical breaking, exactly follow the pattern of Bott periodicity as the dimension changes. The consequences of this for the topological features of the low-energy effective theory are considered.Comment: v2: Small additions and clarifications. To appear in Physics Letters

    The Racing-Game Effect: Why Do Video Racing Games Increase Risk-Taking Inclinations?

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    The present studies investigated why video racing games increase players’ risk-taking inclinations. Four studies reveal that playing video racing games increases risk taking in a subsequent simulated road traffic situation, as well as risk-promoting cognitions and emotions, blood pressure,sensation seeking, and attitudes toward reckless driving. Study 1 ruled out the role of experimental demand in creating such effects. Studies 2 and 3 showed that the effect of playing video racing games on risk taking was partially mediated by changes in selfperceptions as a reckless driver. These effects were evident only when the individual played racing games that reward traffic violations rather than racing games that do not reward traffic violations (Study 3) and when the individual was an active player of such games rather than a passive observer (Study 4). In sum, the results underline the potential negative impact of racing games on traffic safety

    Dimethyl 2-methyl-1,2-dihydro­quinoline-2,4-dicarboxyl­ate

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    In the crystal of the title compound, C14H15NO4, pairs of inter­molecular N—H⋯O hydrogen bonds link the mol­ecules into centrosymmetric R 2 2(10) dimers. These dimers are further connected via inter­molecular C—H⋯O hydrogen bonds, forming a three-dimensional network. The heterocyclic ring adopts a twisted conformation

    Comparison of ICON O+ density profiles with electron density profiles provided by COSMIC-2 and ground-based ionosondes

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    In October 2019, NASA-ICON was launched to observe the low-latitude ionosphere using in-situ and remote sensing instruments, from a LEO circular orbit at about 575 km altitude. The six satellites of the radio-occultation program COSMIC-2 were also successfully launched and currently provide up to 3000 electron density profiles on a daily basis since October 1, 2019. Besides, the network of ground-based ionosondes is constantly growing and allows retrieving very accurate measurements of the electron density profile up to the peak altitude. These three sources of scientific observation of the Earth ionosphere therefore provide a very complementary set of data. We compare O+ density profiles provided during nighttime by the ICON-FUV instrument and during daytime by the ICON-EUV instrument against electron density profiles measured by COSMIC-2 and ionosondes. Co-located and simultaneous observations are compared on statistical grounds, and the differences between the several methods are investigated. Particular attention is given to the most important variables, such as the altitude and the density of the F-peak, hmF2 and NmF2. The time interval considered in this study covers the whole ICON data availability period, which started on November 16, 2019. Manual screening and scaling of ionograms is performed to ensure reliable ionosonde data, while COSMIC-2 data are carefully selected using an automatic quality control algorithm. A particular attention has been brought to the geometry of the observation, because the line-of-sight integration of both airglow and radio-occultation measurements assimilates horizontal and vertical gradients. As a consequence, the local density profiles obtained by inversion of the ICON and COSMIC-2 observation cannot be exactly assimilated to vertical measurements, such as vertical incidence soundings from ionosondes. This slightly limits the reach of the interpretation of the comparison between data of different origin. However, using similar observing geometries, the comparison of ICON and COSMIC-2 data does nevertheless provide very reliable and valuable comparisons.Combining airglow, GNSS and ionosonde data to study ionospheric irregularities over low latitude
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