4,211 research outputs found

    Solid state microelectronics tolerant to radiation and high temperature

    Get PDF
    The 300 C electronics technology based on JFET thick film hybrids was tested up to 10 to the 9th power rad gamma (Si) and 10 to the 15th power neutrons/sq cm. Circuits and individual components from this technology all survived this total dose although some devices required 1 hour of annealing at 200 or 300 C to regain functionality. This technology used with real time annealing should function to levels greater than 10 to the 10th power rad gamma and 10 to the 16th power n/sq cm

    Decuplet Baryon Structure from Lattice QCD

    Full text link
    The electromagnetic properties of the SU(3)-flavor baryon decuplet are examined within a lattice simulation of quenched QCD. Electric charge radii, magnetic moments, and magnetic radii are extracted from the E0 and M1 form factors. Preliminary results for the E2 and M3 moments are presented giving the first model independent insight to the shape of the quark distribution in the baryon ground state. As in our octet baryon analysis, the lattice results give evidence of spin-dependent forces and mass effects in the electromagnetic properties. The quark charge distribution radii indicate these effects act in opposing directions. Some baryon dependence of the effective quark magnetic moments is seen. However, this dependence in decuplet baryons is more subtle than that for octet baryons. Of particular interest are the lattice predictions for the magnetic moments of Ω\Omega^- and Δ++\Delta^{++} for which new recent experimental measurements are available. The lattice prediction of the Δ++/p\Delta^{++}/p ratio appears larger than the experimental ratio, while the lattice prediction for the Ω/p\Omega^-/p magnetic moment ratio is in good agreement with the experimental ratio.Comment: RevTeX manuscript, 34 pages plus 21 figures (available upon request

    Baryon Octet to Decuplet Electromagnetic Transitions

    Full text link
    The electromagnetic transition moments of the SU(3)SU(3)-flavor baryon octet to decuplet are examined within a lattice simulation of quenched QCD. The magnetic transition moment for the N  γΔN \; \gamma \to \Delta channel is found to be in agreement with recent experimental analyses. The lattice results indicate μpΔ/μp=0.88(15)\mu_{p \Delta} / \mu_p = 0.88(15). In terms of the Particle Data Group convention, fM1=0.231(41)f_{M1} = 0.231(41) GeV1/2{}^{-1/2} for p  γΔ+p \; \gamma \to \Delta^+ transitions. Lattice predictions for the hyperon M1M1 transition moments agree with those of a simple quark model. However the manner in which the quarks contribute to the transition moments in the lattice simulation is different from that anticipated by quark model calculations. The scalar quadrupole form factor exhibits a behavior consistent with previous multipole analyses. The E2/M1E2/M1 multipole transition moment ratios are also determined. The lattice results suggest REMGE2/GM1=+3±8R_{EM} \equiv -{\cal G}_{E2}/{\cal G}_{M1} = +3\pm 8 \% for p  γΔ+p \; \gamma \to \Delta^+ transitions. Of particular interest are significant nonvanishing signals for the E2/M1E2/M1 ratio in Ξ\Xi^- and Σ\Sigma^- electromagnetic transitions.Comment: PostScript file, 37 pages including figures. U. MD PP #93-085, U. KY PP #UK/92-09, TRIUMF PP #TRI-PP-92-12

    On the Effect of Quantum Interaction Distance on Quantum Addition Circuits

    Full text link
    We investigate the theoretical limits of the effect of the quantum interaction distance on the speed of exact quantum addition circuits. For this study, we exploit graph embedding for quantum circuit analysis. We study a logical mapping of qubits and gates of any Ω(logn)\Omega(\log n)-depth quantum adder circuit for two nn-qubit registers onto a practical architecture, which limits interaction distance to the nearest neighbors only and supports only one- and two-qubit logical gates. Unfortunately, on the chosen kk-dimensional practical architecture, we prove that the depth lower bound of any exact quantum addition circuits is no longer Ω(logn)\Omega(\log {n}), but Ω(nk)\Omega(\sqrt[k]{n}). This result, the first application of graph embedding to quantum circuits and devices, provides a new tool for compiler development, emphasizes the impact of quantum computer architecture on performance, and acts as a cautionary note when evaluating the time performance of quantum algorithms.Comment: accepted for ACM Journal on Emerging Technologies in Computing System

    Nucleon Axial Form Factor from Lattice QCD

    Full text link
    Results for the isovector axial form factors of the proton from a lattice QCD calculation are presented for both point-split and local currents. They are obtained on a quenched 163×2416^{3} \times 24 lattice at β=6.0\beta= 6.0 with Wilson fermions for a range of quark masses from strange to charm. We determine the finite lattice renormalization for both the local and point-split currents of heavy quarks. Results extrapolated to the chiral limit show that the q2q^2 dependence of the axial form factor agrees reasonably well with experiment. The axial coupling constant gAg_A calculated for the local and the point-split currents is about 6\% and 12\% smaller than the experimental value respectively.Comment: 8 pages, 5 figures (included in part 2), UK/93-0

    A Lattice Study of Quark and Glue Momenta and Angular Momenta in the Nucleon

    Get PDF
    We report a complete calculation of the quark and glue momenta and angular momenta in the proton. These include the quark contributions from both the connected and disconnected insertions. The quark disconnected insertion loops are computed with Z4Z_4 noise, and the signal-to-noise is improved with unbiased subtractions. The glue operator is comprised of gauge-field tensors constructed from the overlap operator. The calculation is carried out on a 163×2416^3 \times 24 quenched lattice at β=6.0\beta = 6.0 for Wilson fermions with κ=0.154,0.155\kappa=0.154, 0.155, and 0.15550.1555 which correspond to pion masses at 650,538650, 538, and 478478~MeV, respectively. The chirally extrapolated uu and dd quark momentum/angular momentum fraction is found to be 0.64(5)/0.70(5)0.64(5)/0.70(5), the strange momentum/angular momentum fraction is 0.024(6)/0.023(7)0.024(6)/0.023(7), and that of the glue is 0.33(6)/0.28(8)0.33(6)/0.28(8). The previous study of quark spin on the same lattice revealed that it carries a fraction of 0.25(12)0.25(12) of proton spin. The orbital angular momenta of the quarks are then obtained from subtracting the spin from their corresponding angular momentum components. We find that the quark orbital angular momentum constitutes 0.47(13)0.47(13) of the proton spin with almost all of it coming from the disconnected insertions.Comment: Renormalization section is expanded to include more details. There are slight changes in the final numbers. A few modification and corrections are made in the rest of the tex

    Detection of Trichomonas vaginalis Using the Polymerase Chain Reaction in Pregnant and Non-Pregnant Women

    Get PDF
    Objective: Trichomonas vaginalis vaginal infections are often both asymptomatic and difficult to detect by current methods. We evaluated the ability of a newly developed polymerase chain reaction (PCR) assay to identify T. vaginalis in vaginal samples from pregnant and non-pregnant women

    Simulating chemistry efficiently on fault-tolerant quantum computers

    Get PDF
    Quantum computers can in principle simulate quantum physics exponentially faster than their classical counterparts, but some technical hurdles remain. Here we consider methods to make proposed chemical simulation algorithms computationally fast on fault-tolerant quantum computers in the circuit model. Fault tolerance constrains the choice of available gates, so that arbitrary gates required for a simulation algorithm must be constructed from sequences of fundamental operations. We examine techniques for constructing arbitrary gates which perform substantially faster than circuits based on the conventional Solovay-Kitaev algorithm [C.M. Dawson and M.A. Nielsen, \emph{Quantum Inf. Comput.}, \textbf{6}:81, 2006]. For a given approximation error ϵ\epsilon, arbitrary single-qubit gates can be produced fault-tolerantly and using a limited set of gates in time which is O(logϵ)O(\log \epsilon) or O(loglogϵ)O(\log \log \epsilon); with sufficient parallel preparation of ancillas, constant average depth is possible using a method we call programmable ancilla rotations. Moreover, we construct and analyze efficient implementations of first- and second-quantized simulation algorithms using the fault-tolerant arbitrary gates and other techniques, such as implementing various subroutines in constant time. A specific example we analyze is the ground-state energy calculation for Lithium hydride.Comment: 33 pages, 18 figure

    Naturally-acquired and vaccine-induced human monoclonal antibodies to plasmodium vivax Duffy binding protein inhibit invasion of Plasmodium knowlesi (pvdbpor) transgenic parasites

    Get PDF
    The Duffy antigen receptor for chemokines (DARC) expressed on erythrocytes is central to Plasmodium vivax (Pv) invasion of reticulocytes. Pv expresses a Duffy binding protein (PvDBP) on merozoites, a DARC ligand, and their protein-protein interaction is central to vivax blood stage malaria. Here we compared the functional activity of humAbs derived from naturally exposed and vaccinated individuals for the first time using easily cultured P. knowlesi (Pk) that had been genetically modified to replace its endogenous PkDBP orthologue with PvDBP to create a transgenic parasite, PkPvDBPOR. This transgenic parasite requires DARC to invade human erythrocytes but is not reticulocyte restricted. Using this model, we evaluated the invasion inhibition potential of 12 humAbs (9 naturally acquired; 3 vaccine-induced) targeting PvDBP individually and in combinations using growth inhibition assays (GIAs). The PvDBP-specific humAbs demonstrated 70-100% inhibition of PkPvDBPOR invasion with the IC50 values ranging from 51 to 338 μg/mL for the 9 naturally acquired (NA) humAbs and 33 to 99 μg/ml for the 3 vaccine-induced (VI) humAbs. To evaluate antagonistic, additive, or synergistic effects, six pairwise combinations were performed using select humAbs. Of these combinations tested, one NA/NA (099100/094083) combination demonstrated relatively strong additive inhibition between 10-100 μg/mL; all combinations of NA and VI humAbs showed additive inhibition at concentrations below 25 μg/mL and antagonism at higher concentrations. None of the humAb combinations showed synergy. This PkPvDBPOR model system enables efficient assessment of NA and VI humAbs individually and in combination

    A Spitzer Space Telescope Study of SN 2003gd: Still No Direct Evidence that Core-Collapse Supernovae are Major Dust Factories

    Get PDF
    We present a new, detailed analysis of late-time mid-infrared (IR) observations of the Type II-P supernova (SN) 2003gd. At about 16 months after the explosion, the mid-IR flux is consistent with emission from 4 x 10^(-5) M(solar) of newly condensed dust in the ejecta. At 22 months emission from point-like sources close to the SN position was detected at 8 microns and 24 microns. By 42 months the 24 micron flux had faded. Considerations of luminosity and source size rule out the ejecta of SN 2003gd as the main origin of the emission at 22 months. A possible alternative explanation for the emission at this later epoch is an IR echo from pre-existing circumstellar or interstellar dust. We conclude that, contrary to the claim of Sugerman et al. (2006, Science, 313, 196), the mid-IR emission from SN 2003gd does not support the presence of 0.02 M(solar) of newly formed dust in the ejecta. There is, as yet, no direct evidence that core-collapse supernovae are major dust factories.Comment: 26 pages, 2 figures, 2 tables, accepted for publication in Astrophysical Journa
    corecore