742 research outputs found

    Analytic nuclear forces and molecular properties from full configuration interaction quantum Monte Carlo

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    Unbiased stochastic sampling of the one- and two-body reduced density matrices is achieved in full configuration interaction quantum Monte Carlo with the introduction of a second, "replica" ensemble of walkers, whose population evolves in imaginary time independently from the first, and which entails only modest additional computational overheads. The matrices obtained from this approach are shown to be representative of full configuration-interaction quality, and hence provide a realistic opportunity to achieve high-quality results for a range of properties whose operators do not necessarily commute with the hamiltonian. A density-matrix formulated quasi-variational energy estimator having been already proposed and investigated, the present work extends the scope of the theory to take in studies of analytic nuclear forces, molecular dipole moments and polarisabilities, with extensive comparison to exact results where possible. These new results confirm the suitability of the sampling technique and, where sufficiently large basis sets are available, achieve close agreement with experimental values, expanding the scope of the method to new areas of investigation.Comment: 11 page

    Analysis of clogging in constructed wetlands using magnetic resonance

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    In this work we demonstrate the potential of permanent magnet based magnetic resonance sensors to monitor and assess the extent of pore clogging in water filtration systems. The performance of the sensor was tested on artificially clogged gravel substrates and on gravel bed samples from constructed wetlands used to treat wastewater. Data indicate that the spin lattice relaxation time is linearly related to the hydraulic conductivity in such systems. In addition, within biologically active filters we demonstrate the ability to determine the relative ratio of biomass to abiotic solids, a measurement which is not possible using alternative techniques

    In Vivo Airway Surface Liquid Cl− Analysis with Solid-State Electrodes

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    The pathogenesis of cystic fibrosis (CF) airways disease remains controversial. Hypotheses that link mutations in CFTR and defects in ion transport to CF lung disease predict that alterations in airway surface liquid (ASL) isotonic volume, or ion composition, are critically important. ASL [Cl−] is pivotal in discriminating between these hypotheses, but there is no consensus on this value given the difficulty in measuring [Cl−] in the “thin” ASL (∼30 μm) in vivo. Consequently, a miniaturized solid-state electrode with a shallow depth of immersion was constructed to measure ASL [Cl−] in vivo. In initial experiments, the electrode measured [Cl−] in physiologic salt solutions, small volume (7.6 μl) test solutions, and in in vitro cell culture models, with ≥93% accuracy. Based on discrepancies in reported values and/or absence of data, ASL Cl− measurements were made in the following airway regions and species. First, ASL [Cl−] was measured in normal human nasal cavity and averaged 117.3 ± 11.2 mM (n = 6). Second, ASL [Cl−] measured in large airway (tracheobronchial) regions were as follows: rabbit trachea and bronchus = 114.3 ± 1.8 mM; (n = 6) and 126.9 ± 1.7 mM; (n = 3), respectively; mouse trachea = 112.8 ± 4.2 mM (n = 13); and monkey bronchus = 112.3 ± 10.9 mM (n = 3). Third, Cl− measurements were made in small (1–2 mm) diameter airways of the rabbit (108.3 ± 7.1 mM, n = 5) and monkey (128.5 ± 6.8 mM, n = 3). The measured [Cl−], in excess of 100 mM throughout all airway regions tested in multiple species, is consistent with the isotonic volume hypothesis to describe ASL physiology

    Results Following Three Modalities of Periodontal Therapy

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    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141627/1/jper0522.pd

    Longitudinal Study of Periodontal Therapy

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    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142010/1/jper0066.pd

    Fitness, fatness and active school commuting among Liverpool schoolchildren

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    This study investigated differences in health outcomes between active and passive school commuters, and examined associations between parent perceptions of the neighborhood environment and active school commuting (ASC). One hundred-ninety-four children (107 girls), aged 9–10 years from ten primary schools in Liverpool, England, participated in this cross-sectional study. Measures of stature, body mass, waist circumference and cardiorespiratory fitness (CRF) were taken. School commute mode (active/passive) was self-reported and parents completed the neighborhood environment walkability scale for youth. Fifty-three percent of children commuted to school actively. Schoolchildren who lived in more deprived neighborhoods perceived by parents as being highly connected, unaesthetic and having mixed land-use were more likely to commute to school actively (p < 0.05). These children were at greatest risk of being obese and aerobically unfit(p < 0.01). Our results suggest that deprivation may explain the counterintuitive relationship between obesity, CRF and ASC in Liverpool schoolchildren. These findings encourage researchers and policy makers to be equally mindful of the social determinants of health when advocating behavioral and environmental health interventions. Further research exploring contextual factors to ASC, and examining the concurrent effect of ASC and diet on weight status by deprivation is needed

    Radiographs in Clinical Periodontal Trials

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    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141530/1/jper0381.pd

    Ratification vote on taxonomic proposals to the International Committee on Taxonomy of Viruses (2016)

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    This article lists the changes to virus taxonomy approved and ratified by the International Committee on Taxonomy of Viruses (ICTV) in April 2016. Changes to virus taxonomy (the Universal Scheme of Virus Classification of the International Committee on Taxonomy of Viruses [ICTV]) now take place annually and are the result of a multi-stage process. In accordance with the ICTV Statutes (http://​www.​ictvonline.​org/​statutes.​asp), proposals submitted to the ICTV Executive Committee (EC) undergo a review process that involves input from the ICTV Study Groups (SGs) and Subcommittees (SCs), other interested virologists, and the EC. After final approval by the EC, proposals are then presented for ratification to the full ICTV membership by publication on an ICTV web site (http://​www.​ictvonline.​org/​) followed by an electronic vote. The latest set of proposals approved by the EC was made available on the ICTV website by January 2016 (https://​talk.​ictvonline.​org/​files/​proposals/​). A list of these proposals was then emailed on 28 March 2016 to the 148 members of ICTV, namely the EC Members, Life Members, ICTV Subcommittee Members (including the SG chairs) and ICTV National Representatives. Members were then requested to vote on whether to ratify the taxonomic proposals (voting closed on 29 April 2016)
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