4,018 research outputs found

    P12-15. Replication enhancement of an alphaviral-lentiviral replicating chimeric particle (RCP) vaccine

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    We have developed a novel, acutely replicating VEE-SHIV chimeric particle (RCP) as a vaccine against HIV that combines the superior and long-lived immunity of a live-attenuated virus with the safety of non-replicating particulate antigens. These chimeric particles contain a replicating VEE-SHIV genome and are capable of infecting susceptible cells bearing hCD4/hCCR5, undergoing cytoplasmic replication, genomic RNA encapsidation, assembly and particle release. Due to the replicative nature of the RCPs, lentiviral proteins will be expressed for an extended period of time in vaccinated individuals thus inducing a more comprehensive immune response compared to nonreplicating antigens but without the safety issues associated with integrating, live-attenuated lentiviruses

    Meron-Cluster Solution of Fermion and Other Sign Problems

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    Numerical simulations of numerous quantum systems suffer from the notorious sign problem. Important examples include QCD and other field theories at non-zero chemical potential, at non-zero vacuum angle, or with an odd number of flavors, as well as the Hubbard model for high-temperature superconductivity and quantum antiferromagnets in an external magnetic field. In all these cases standard simulation algorithms require an exponentially large statistics in large space-time volumes and are thus impossible to use in practice. Meron-cluster algorithms realize a general strategy to solve severe sign problems but must be constructed for each individual case. They lead to a complete solution of the sign problem in several of the above cases.Comment: 15 pages,LATTICE9

    Design concepts for bioreactors in space

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    Microbial food sources are becoming viable and more efficient alternatives to conventional food sources, especially in the context of closed ecological life support systems (CELSS) in space habitats. Two bioreactor design concepts presented represent two dissimilar approaches to grappling with the absence of gravity in space habitats and deserve to be tested for adoption as important components of the life support function aboard spacecraft, space stations and other extra-terrestrial habitats

    Smart Metering Enables Effective Demand Management Design

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    The water demand and water use practices of each community are different. Designing cost-effective demand management programs requires investigating and responding directly to the unique water issues and opportunities of each community (Turner et al., 2010). As presented in this paper, a `mixed method baseline analysis' has proven to be valuable in developing a demand management program tailored to the distinctive community context. A mixed method baseline analysis is comprised of two interlinked components: (i) quantitative smart meter data analysis to create a detailed understanding of the water demand pro¬file; and (ii) qualitative social research to understand the social, cultural and institutional influences that drive existing water patterns. This paper shares the mixed method baseline analysis and resulting implications for a demand management program implemented in the remote Indigenous community of Gunbalanya, Northern Territory, in 2013

    Protocol for a national monthly survey of alcohol use in England with 6-month follow-up: 'The Alcohol Toolkit Study'.

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    Timely tracking of national patterns of alcohol consumption is needed to inform and evaluate strategies and policies aimed at reducing alcohol-related harm. Between 2014 until at least 2017, the Alcohol Toolkit Study (ATS) will provide such tracking data and link these with policy changes and campaigns. By virtue of its connection with the 'Smoking Toolkit Study' (STS), links will also be examined between alcohol and smoking-related behaviour

    The Two-Dimensional S=1 Quantum Heisenberg Antiferromagnet at Finite Temperatures

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    The temperature dependence of the correlation length, susceptibilities and the magnetic structure factor of the two-dimensional spin-1 square lattice quantum Heisenberg antiferromagnet are computed by the quantum Monte Carlo loop algorithm (QMC). In the experimentally relevant temperature regime the theoretically predicted asymptotic low temperature behavior is found to be not valid. The QMC results however, agree reasonably well with the experimental measurements of La2NiO4 even without considering anisotropies in the exchange interactions.Comment: 4 Pages, 1 table, 4 figure

    Protocol for the United Kingdom Rotator Cuff Study (UKUFF) : a randomised controlled trial of open and arthroscopic rotator cuff repair

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    This project was funded by the NIHR Health Technology Assessment programme (project number 05/47/02). J. L. Rees has received a grant from Oxford University which is related to this paper. J. Dawson reports that Oxford University has received a grant from HTA which is related to this paper, as well as a study grant.Peer reviewedPublisher PD

    Supersymmetry in models with strong on-site Coulomb repulsion - application to t-J model

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    A supersymmetric way of imposing the constraint of no double occupancy in models with strong on-site Coulomb repulsion is presented in this paper. In this formulation the physical operators in the constrainted Hilbert space are invariant under local unitary transformations mixing boson and fermion representations. As an illustration the formulation is applied to the tJt-J model. The model is studied in the mean-field level in the J=0 limit where we show how both the slave-boson and slave-fermion formulations are included naturally in the present approach and how further results beyond both approaches are obtained.Comment: 12 pages, Latex file, 1 figur

    Thermodynamics of the one-dimensional SU(4) symmetric spin-orbital model

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    The ground state properties and the thermodynamics of the one-dimensional SU(4) symmetric spin system with orbital degeneracy are investigated using the quantum Monte Carlo loop algorithm. The spin-spin correlation functions exhibit a 4-site periodicity, and their low temperature behavior is controlled by two correlation lengths that diverge like the inverse temperature, while the entropy is linear in temperature and its slope is consistent with three gapless modes of velocity π/2\pi/2. The physical implications of these results are discussed.Comment: 4 pages, 4 figures, RevTe

    Evidence for equilibrium iron isotope fractionation by nitrate-reducing iron(II)-oxidizing bacteria

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    Iron isotope fractionations produced during chemical and biological Fe(II) oxidation are sensitive to the proportions and nature of dissolved and solid-phase Fe species present, as well as the extent of isotopic exchange between precipitates and aqueous Fe. Iron isotopes therefore potentially constrain the mechanisms and pathways of Fe redox transformations in modern and ancient environments. In the present study, we followed in batch experiments Fe isotope fractionations between Fe(II)_(aq) and Fe(III) oxide/hydroxide precipitates produced by the Fe(III) mineral encrusting, nitrate-reducing, Fe(II)-oxidizing Acidovorax sp. strain BoFeN1. Isotopic fractionation in ^(56)Fe/^(54)Fe approached that expected for equilibrium conditions, assuming an equilibrium Δ^(56)Fe_(Fe(OH)3–Fe(II)aq) fractionation factor of +3.0‰. Previous studies have shown that Fe(II) oxidation by this Acidovorax strain occurs in the periplasm, and we propose that Fe isotope equilibrium is maintained through redox cycling via coupled electron and atom exchange between Fe(II)_(aq) and Fe(III) precipitates in the contained environment of the periplasm. In addition to the apparent equilibrium isotopic fractionation, these experiments also record the kinetic effects of initial rapid oxidation, and possible phase transformations of the Fe(III) precipitates. Attainment of Fe isotope equilibrium between Fe(III) oxide/hydroxide precipitates and Fe(II)_(aq) by neutrophilic, Fe(II)-oxidizing bacteria or through abiologic Fe(II)_(aq) oxidation is generally not expected or observed, because the poor solubility of their metabolic product, i.e. Fe(III), usually leads to rapid precipitation of Fe(III) minerals, and hence expression of a kinetic fractionation upon precipitation; in the absence of redox cycling between Fe(II)_(aq) and precipitate, kinetic isotope fractionations are likely to be retained. These results highlight the distinct Fe isotope fractionations that are produced by different pathways of biological and abiological Fe(II) oxidation
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