135 research outputs found

    From Merchants to Merchandisers

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    Hadron Structure on the Lattice

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    A few chosen nucleon properties are described from a lattice QCD perspective: the nucleon sigma term and the scalar strangeness in the nucleon; the vector form factors in the nucleon, including the vector strangeness contribution, as well as parity breaking effects like the anapole and electric dipole moment; and finally the axial and tensor charges of the nucleon. The status of the lattice calculations is presented and their potential impact on phenomenology is discussed.Comment: 17 pages, 9 figures; proceedings of the Conclusive Symposium of the Collaborative Research Center 443 "Many-body structure of strongly interacting systems", Mainz, February 23-25, 201

    Atypical genomic cortical patterning in autism with poor early language outcome.

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    Cortical regionalization develops via genomic patterning along anterior-posterior (A-P) and dorsal-ventral (D-V) gradients. Here, we find that normative A-P and D-V genomic patterning of cortical surface area (SA) and thickness (CT), present in typically developing and autistic toddlers with good early language outcome, is absent in autistic toddlers with poor early language outcome. Autistic toddlers with poor early language outcome are instead specifically characterized by a secondary and independent genomic patterning effect on CT. Genes involved in these effects can be traced back to midgestational A-P and D-V gene expression gradients and different prenatal cell types (e.g., progenitor cells and excitatory neurons), are functionally important for vocal learning and human-specific evolution, and are prominent in prenatal coexpression networks enriched for high-penetrance autism risk genes. Autism with poor early language outcome may be explained by atypical genomic cortical patterning starting in prenatal development, which may detrimentally affect later regional functional specialization and circuit formation

    Nuclear Physics from Lattice QCD

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    We review recent progress toward establishing lattice Quantum Chromodynamics as a predictive calculational framework for nuclear physics. A survey of the current techniques that are used to extract low-energy hadronic scattering amplitudes and interactions is followed by a review of recent two-body and few-body calculations by the NPLQCD collaboration and others. An outline of the nuclear physics that is expected to be accomplished with Lattice QCD in the next decade, along with estimates of the required computational resources, is presented.Comment: 56 pages, 39 pdf figures. Final published versio

    Quark transverse charge densities in the Δ(1232)\Delta(1232) from lattice QCD

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    We extend the formalism relating electromagnetic form factors to transverse quark charge densities in the light-front frame to the case of a spin-3/2 baryon and calculate these transverse densities for the Δ(1232)\Delta(1232) isobar using lattice QCD. The transverse charge densities for a transversely polarized spin-3/2 particle are characterized by monopole, dipole, quadrupole, and octupole patterns representing the structure beyond that of a pure point-like spin-3/2 particle. We present lattice QCD results for the Δ\Delta-isobar electromagnetic form factors for pion masses down to approximatively 350 MeV for three cases: quenched QCD, two-degenerate flavors of dynamical Wilson quarks, and three flavors of quarks using a mixed action that combines domain wall valence quarks and dynamical staggered sea quarks. We extract transverse quark charge densities from these lattice results and find that the Δ\Delta is prolately deformed, as indicated by the fact that the quadrupole moment GE2(0G_{E2}(0) is larger than the value -3 characterizing a point particle and the fact that the transverse charge density in a Δ+\Delta^+ of maximal transverse spin projection is elongated along the axis of the spin.Comment: 35 pages, 10 figure

    Broad-line region in NGC 4151 monitored by two decades of reverberation mapping campaigns. I. Evolution of structure and kinematics

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    We report the results of long-term reverberation mapping (RM) campaigns of the nearby active galactic nuclei (AGN) NGC 4151, spanning from 1994 to 2022, based on archived observations of the FAST Spectrograph Publicly Archived Programs and our new observations with the 2.3m telescope at the Wyoming Infrared Observatory. We reduce and calibrate all the spectra in a consistent way, and derive light curves of the broad Hβ\beta line and 5100\,{\AA} continuum. Continuum light curves are also constructed using public archival photometric data to increase sampling cadences. We subtract the host galaxy contamination using {\it HST} imaging to correct fluxes of the calibrated light curves. Utilizing the long-term archival photometric data, we complete the absolute flux-calibration of the AGN continuum. We find that the Hβ\beta time delays are correlated with the 5100\,{\AA} luminosities as τHβL51000.46±0.16\tau_{\rm H\beta}\propto L_{5100}^{0.46\pm0.16}. This is remarkably consistent with Bentz et al. (2013)'s global size-luminosity relationship of AGNs. Moreover, the data sets for five of the seasons allow us to obtain the velocity-resolved delays of the Hβ\beta line, showing diverse structures (outflows, inflows and disks). Combining our results with previous independent measurements, we find the measured dynamics of the Hβ\beta broad-line region (BLR) are possibly related to the long-term trend of the luminosity. There is also a possible additional \sim1.86 years time lag between the variation in BLR radius and luminosity. These results suggest that dynamical changes in the BLR may be driven by the effects of radiation pressure.Comment: Accepted for publication in MNRAS; comments welcome

    Bt Crop Effects on Functional Guilds of Non-Target Arthropods: A Meta-Analysis

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    Background: Uncertainty persists over the environmental effects of genetically-engineered crops that produce the insecticidal Cry proteins of Bacillus thuringiensis (Bt). We performed meta-analyses on a modified public database to synthesize current knowledge about the effects of Bt cotton, maize and potato on the abundance and interactions of arthropod non-target functional guilds. Methodology/Principal Findings: We compared the abundance of predators, parasitoids, omnivores, detritivores and herbivores under scenarios in which neither, only the non-Bt crops, or both Bt and non-Bt crops received insecticide treatments. Predators were less abundant in Bt cotton compared to unsprayed non-Bt controls. As expected, fewer specialist parasitoids of the target pest occurred in Bt maize fields compared to unsprayed non-Bt controls, but no significant reduction was detected for other parasitoids. Numbers of predators and herbivores were higher in Bt crops compared to sprayed non-Bt controls, and type of insecticide influenced the magnitude of the difference. Omnivores and detritivores were more abundant in insecticide-treated controls and for the latter guild this was associated with reductions of their predators in sprayed non-Bt maize. No differences in abundance were found when both Bt and non-Bt crops were sprayed. Predator-to-prey ratios were unchanged by either Bt crops or the use of insecticides; ratios were higher in Bt maize relative to the sprayed non-Bt control

    Characterization of Mechanical and Magnetic Properties of Ni-Mn-Ga Shape Memory Thin Films Deposited onto Silicon and Alumina Substrates

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    The mechanical and magnetic properties of off-stoichiometric Ni2MnGa shape memory thin films deposited onto silicon and alumina substrates at different thicknesses are examined. Two sets of films were deposited onto silicon(100) substrates and one set of films were deposited onto polycrystalline alumina. The films deposited onto silicon had a composition of Ni49.5Mn28.0Ga22.5 and Ni51.4Mn28.3Ga20.3. The films deposited onto the alumina substrates had a composition of Ni51.4Mn28.3Ga20.3. Substrate curvature measurements were performed to characterize the martensitic phase transformation temperature, the in-plane film stress change during the phase transformation, and the biaxial modulus of each film. Vibrating sample magnetometry was performed to characterize the Curie temperature and the magnetic anisotropy of each film. The crystallographic texture was characterized for a set of films deposited onto silicon using x-ray diffraction techniques. The martensitic transformation temperature increased with increasing film thickness on the Ni51.4Mn28.3Ga20.3 and decreased with increasing film thickness for the Ni49.5Mn28.0Ga22.5 films. The magnitude of the in-plane stress change during the phase transformation showed an increasing trend with increasing film thickness for the Ni51.4Mn28.3Ga20.3 films and a decreasing trend for the Ni49.5Mn28.0Ga22.5 films. For each set of films, there was a thickness dependence of the biaxial modulus for the films. The Curie temperature was not effected by film thickness. For the films deposited onto alumina substrates, a thickness dependence of the magnetic anisotropy was observed. The mechanical and magnetic properties of the Ni-Mn-Ga films showed both a compositional and thickness dependence
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