Extended quantum critical phase in a magnetized spin-1/2 antiferromagnetic chain

Measurements are reported of the magnetic field dependence of excitations in the quantum critical state of the spin S=1/2 linear chain Heisenberg antiferromagnet copper pyrazine dinitrate (CuPzN). The complete spectrum was measured at k_B T/J <= 0.025 for H=0 and H=8.7 Tesla where the system is ~30% magnetized. At H=0, the results are in quantitative agreement with exact calculations of the dynamic spin correlation function for a two-spinon continuum. At high magnetic field, there are multiple overlapping continua with incommensurate soft modes. The boundaries of these continua confirm long-standing predictions, and the intensities are consistent with exact diagonalization and Bethe Ansatz calculations.Comment: 4 pages, 4 figure

Segmentation and tracking individual pseudomonas aeruginosa bacteria in dense populations of motile cells

The dynamics of individual bacteria underlies the manifestation of complex multicellular behaviours such as biofilm development and colony expansion. High resolution movies of expanding bacterial colonies reveal intriguing patterns of cell motions. A quantitative understanding of the observed behaviour in relation to the bacteria's own motile apparatus and to hydrodynamic forces requires that bacteria be identified and tracked over time. This represents a demanding undertaking as their size is close to the diffraction limit; they are very close to each other; and a typical image may contain over a thousand cells. Here, we describe the approach that we have developed to segment individual bacteria and track them in high resolution phase contrast microscopy movies. We report that over 99% of non-overlapping bacteria could be segmented correctly using mathematical morphology, and we present preliminary results that exploit this new capability. © 2009 IEEE

Mutations of the mitochondrial ND1 gene as a cause of MELAS

Copyright © 2004 by the BMJ Publishing Group Ltd. All rights reserved. BMJ JournalsD. M. Kirby, R. McFarland, A. Ohtake, C. Dunning, M. T. Ryan, C. Wilson, D. Ketteridge, D. M. Turnbull, D. R. Thorburn, R. W. Taylo

Neutron scattering from a coordination polymer quantum paramagnet

Inelastic neutron scattering measurements are reported for a powder sample of the spin-1/2 quantum paramagnet $\rm Cu(Quinoxaline)Br_2$. Magnetic neutron scattering is identified above an energy gap of 1.9 meV. Analysis of the sharp spectral maximum at the onset indicates that the material is magnetically quasi-one-dimensional. Consideration of the wave vector dependence of the scattering and polymeric structure further identifies the material as a two-legged spin-1/2 ladder. Detailed comparison of the data to various models of magnetism in this material based on the single mode approximation and the continuous unitary transformation are presented. The latter theory provides an excellent account of the data with leg exchange $J_{\parallel}=2.0$ meV and rung exchange $J_{\perp}=3.3$ meV.Comment: 10 pages, 11 figures, 1 tabl

An advance notification letter increases participation in colorectal cancer screening

© 2007 Royal Society of MedicineObjectives: To determine the impact of novel invitation strategies on population participation in faecal immunochemical test (FIT)-based colorectal cancer (CRC) screening. Setting A community screening programme in Adelaide, South Australia. Methods: In total, 2400 people aged 50–74 years were randomly allocated to one of four CRC screening invitation strategies: (a) Control: standard invitation-to-screen letter explaining risk of CRC and the concept, value and method of screening; (b) Risk: invitation with additional messages related to CRC risk; (c) Advocacy: invitation with additional messages related to advocacy for screening from previous screening programme participants and (d) Advance Notification: first, a letter introducing Control letter messages followed by the standard invitation-to-screen. Invitations included an FIT kit. Programme participation rates were determined for each strategy relative to control. Associations between participation and sociodemographic variables were explored. Results: At 12 weeks after invitation, participation was: Control: 237/600 (39.5%); Risk: 242/600 (40.3%); Advocacy: 216/600 (36.0%) and Advance Notification: 290/600 (48.3%). Participation was significantly greater than Control only in the Advance Notification group (Relative risk [RR] 1.23, 95% confidence interval [CI] 1.06–1.43). This effect was apparent as early as two weeks from date of offer; Advance Notification: 151/600 (25.2%) versus Control: 109/600 (18.2%, RR 1.38, 95% CI 1.11–1.73). Conclusions: Advance notification significantly increased screening participation. The effect may be due to a population shift in readiness to undertake screening, and is consistent with the Transtheoretical Model of behaviour change. Risk or lay advocacy strategies did not improve screening participation. Organized screening programmes should consider using advance notification letters to improve programme participation.S R Cole, A Smith, CWilson, D Turnbull, A Esterman and G P Youn

Pseudomonas aeruginosa is capable of natural transformation in biofilms

Abstract Natural transformation is a mechanism that enables competent bacteria to acquire naked, exogenous DNA from the environment. It is a key process that facilitates the dissemination of antibiotic resistance and virulence determinants throughout bacterial populations. Pseudomonas aeruginosa is an opportunistic Gram-negative pathogen that produces large quantities of extracellular DNA (eDNA) that is required for biofilm formation. P. aeruginosa has a remarkable level of genome plasticity and diversity that suggests a high degree of horizontal gene transfer and recombination but is thought to be incapable of natural transformation. Here we show that P. aeruginosa possesses homologs of all proteins known to be involved in natural transformation in other bacterial species. We found that P. aeruginosa in biofilms is competent for natural transformation of both genomic and plasmid DNA. Furthermore, we demonstrate that type IV pili (T4P) facilitate but are not absolutely essential for natural transformation in P. aeruginosa

WHO SHOULD ASK? Ethical Interviewing in Psychiatric Epidemiology Studies

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72116/1/j.1939-0025.1988.tb01584.x.pd

Patterns of participation over four rounds of annual fecal immunochemical test-based screening for colorectal cancer: what predicts rescreening?

Published online: 01 August 2017Background: Participation at the recommended intervals is critical for screening to be effective in reducing colorectal cancer (CRC) incidence. This study describes patterns of screening participation over four rounds of fecal immunochemical testing (FIT) to identify whether demographic variables and prior screening satisfaction are significantly associated with patterns of re-participation. Methods: Baseline surveys were mailed to 4000 South Australians randomly selected from the electoral-roll. Respondents (n = 1928/48.2%) were offered four annual FIT rounds. Screening participation and satisfaction at each round were recorded. Results: Study participation was 58.5, 66.9, 73.1 and 71.4% respectively over four rounds. Three participation patterns were described: consistent participation (43.1%), consistent non-participation (26.4%) and inconsistent participation (changeable; 30.5%), including intermittent and sustained change patterns. Sustained change described those who changed participatory behavior and then maintained for at least two rounds (n = 375/19.5%). Older people, and those not working were most likely to sustain participation. Younger invitees, especially men, were more likely to change participatory behavior and sustain the change. People with higher disadvantage, less education, not working and with no prior (pre-trial) screening experience were more likely to start participating and drop out. People dissatisfied with a prior screening test, including finding aspects embarrassing or unpleasant, were also more likely not to participate in annual screening or to drop out. Conclusions: The findings identify those at risk of non- or inconsistent participation in rescreening. They should aid targeting of interventions for demographic groups at risk and ensuring screening experiences are not perceived as unpleasant or difficult.Joanne M. Osborne, Carlene Wilson, Amy Duncan, Stephen R. Cole, Ingrid Flight, Deborah Turnbull, Donna L. Hughes and Graeme P. Youn

Single cell induced optical confinement in biological lasers

We acknowledge financial support from the European Research Council (ERC StG ABLASE, 640012), the Scottish Funding Council (via SUPA) and the European Union Marie Curie Career Integration Grant (PCIG12-GA-2012-334407). M.K. acknowledges funding from the EPSRC DTG (EP/M506631/1). M.S. acknowledges funding from the European Commission for a Marie Sklodowska-Curie Individual Fellowship (659213). I.D.W.S. acknowledges funding from a Royal Society Wolfson research merit award.Biological single cell lasers have shown great potential for fundamental research and next generation sensing applications. In this study, the potential of fluorescent biological cells as refractive index landscapes and active optical elements is investigated using a combined Fourier- and hyperspectral imaging technique. We show that the refractive index contrast between cell and surrounding leads to three dimensional confinement of photons inside living cells. The Fourier- and real-space emission characteristics of these biological lasers are closely related and can be predicted from one another. Investigations of the lasing threshold for different energy and momentum position in Fourier-space give insight into the fundamental creation of longitudinal and transverse lasing modes within the cell. These findings corroborate the potential of living biological materials for precision engineering of photonic structures and may pave the way towards low threshold polariton lasing from single cells.Publisher PDFPeer reviewe