Influence of magnetostatic interactions on first-order-reversal-curve (FORC) diagrams: a micromagnetic approach

Accepted versio

Growth dynamics of a Bose-Einstein condensate in a dimple trap without cooling

We study the formation of a Bose-Einstein condensate in a cigar-shaped three-dimensional harmonic trap, induced by the controlled addition of an attractive "dimple" potential along the weak axis. In this manner we are able to induce condensation without cooling due to a localized increase in the phase space density. We perform a quantitative analysis of the thermodynamic transformation in both the sudden and adiabatic regimes for a range of dimple widths and depths. We find good agreement with equilibrium calculations based on self-consistent semiclassical Hartree-Fock theory describing the condensate and thermal cloud. We observe there is an optimal dimple depth that results in a maximum in the condensate fraction. We also study the non-equilibrium dynamics of condensate formation in the sudden turn-on regime, finding good agreement for the observed time dependence of the condensate fraction with calculations based on quantum kinetic theory.Comment: v1: 9 pages, 7 figures, submitted to Phys. Rev. A; v2: 10 pages, 8 figures, fixed typos, added references, additional details on experimental procedure, values of phase-space density, new figure and discussion on effects of three-body loss in Appendix B (replaced with published version

Magnetic signature of daily sampled urban atmospheric particles

Accepted versio

A qualitative study of using nicotine products for smoking cessation after discharge from residential drug and alcohol treatment in Australia

Introduction: Tobacco smoking is highly prevalent among alcohol and other drugs (AOD) service clients and, despite interest in quitting, abstinence is rarely sustained. Nicotine products may assist after discharge from residential treatment services, but little is known about client receptivity to them. This study examined AOD withdrawal service clients' experiences of two types of nicotine products for smoking cessation post-discharge, combination nicotine replacement therapy (cNRT) and nicotine vaping products (NVP). Methods: We held semi-structured telephone interviews with 31 Australian AOD service clients in a clinical trial of a 12-week smoking cessation intervention using Quitline support plus cNRT or NVP delivered post-discharge from a smoke-free residential service. We asked about health and social factors, nicotine cravings, Quitline experience, and barriers and facilitators to cNRT or NVP, then thematically analysed data. Results: cNRT and NVP were described by participants as feasible and acceptable for smoking cessation. For most participants, cost limited cNRT access post study, as did difficulty navigating NVP prescription access. Quitline support was valued, but not consistently used, with participants noting low assistance with NVP-facilitated cessation. Participants considered both cessation methods acceptable and socially supported, and sought information on decreasing nicotine use via NVP. Discussion and Conclusions: AOD service clients highly valued receiving cNRT or NVP with behavioural support for smoking reduction or abstinence. Both interventions were acceptable to service clients. Findings suggest a potential need to examine both whether NVP use should be permitted in this context, and guidance on the individual suitability of cNRT or NVP.</p

Stability of equidimensional pseudo-single-domain magnetite over billion-year timescales

Interpretations of paleomagnetic observations assume that naturally occurring magnetic particles can retain their primary magnetic recording over billions of years. The ability to retain a magnetic recording is inferred from laboratory measurements, where heating causes demagnetization on the order of seconds. The theoretical basis for this inference comes from previous models that assume only the existence of small, uniformly magnetized particles, whereas the carriers of paleomagnetic signals in rocks are usually larger, nonuniformly magnetized particles, for which there is no empirically complete, thermally activated model. This study has developed a thermally activated numerical micromagnetic model that can quantitatively determine the energy barriers between stable states in nonuniform magnetic particles on geological timescales. We examine in detail the thermal stability characteristics of equidimensional cuboctahedral magnetite and find that, contrary to previously published theories, such nonuniformly magnetized particles provide greater magnetic stability than their uniformly magnetized counterparts. Hence, nonuniformly magnetized grains, which are commonly the main remanence carrier in meteorites and rocks, can record and retain high-fidelity magnetic recordings over billions of years

Adherence to sofosbuvir and velpatasvir among people with chronic HCV infection and recent injection drug use:The SIMPLIFY study

BACKGROUND:This study investigated treatment adherence among people with recent injecting drug use in a study of sofosbuvir/velpatasvir therapy for HCV infection. METHODS:SIMPLIFY is an international open-label, single-arm multicentre study that recruited participants with recent injecting drug use (previous six months) and chronic HCV genotype (G) 1-6 infection between March and October 2016 in seven countries (19 sites). Participants received sofosbuvir/velpatasvir once-daily for 12 weeks administered in a one-week electronic blister pack (records the time and date of each dose) for 12 weeks. We evaluated non-adherence (<90% adherent) as measured by electronic blister-pack assessed using logistic regression and generalised estimating equations (continuous) with detailed analyses of dosing dynamics. RESULTS:Among 103 participants, 97% (n = 100) completed treatment. Median adherence to therapy was 94%. Overall, 32% (n = 33) were considered non-adherent (<90% adherence). Adherence significantly decreased over the course of therapy. Recent stimulant injecting (cocaine and/or amphetamines) at treatment initiation and during treatment was independently associated with non-adherence. Inconsistent dose timing (standard deviation of daily dose timing of ≥240 min) was also independently associated with non-adherence to therapy. Factors associated with inconsistent dose timing included lower levels of education and recent stimulant injecting. SVR was similar among adherent and non-adherent populations (94% vs. 94%, P = 0.944). CONCLUSION:This study demonstrated high adherence to once-daily sofosbuvir/velpatasvir therapy among a population of people with recent injecting drug use. Recent stimulant injecting prior to and during DAA therapy and inconsistent dose-timing during treatment was associated with non-adherence. However, there was no impact of non-adherence on response to therapy, suggesting that adherence is not a significant barrier to successful DAA therapy in people with recent injecting drug use.Evan B.Cunningham, Janaki Amin, Jordan J.Feld, Julie Bruneau, Olav Dalgard, Jeff Powis ... et al

Effect of maghemization on the magnetic properties of nonstoichiometric pseudo-single-domain magnetite particles

The effect of maghemization on the magnetic properties of magnetite (Fe3O4) grains in the pseudo-single-domain (PSD) size range is investigated as a function of annealing temperature. X-ray diffraction and transmission electron microscopy confirm the precursor grains as Fe3O4 ranging from ∼150 to ∼250 nm in diameter, whilst Mössbauer spectrometry suggests the grains are initially near-stoichiometric. The Fe3O4 grains are heated to increasing reaction temperatures of 120–220°C to investigate their oxidation to maghemite (γ-Fe2O3). High-angle annular dark field imaging and localized electron-energy loss spectroscopy reveal slightly oxidized Fe3O4 grains, heated to 140°C, exhibit higher oxygen content at the surface. Off-axis electron holography allows for construction of magnetic induction maps of individual Fe3O4 and γ-Fe2O3 grains, revealing their PSD (vortex) nature, which is supported by magnetic hysteresis measurements, including first-order reversal curve analysis. The coercivity of the grains is shown to increase with reaction temperature up to 180°C, but subsequently decreases after heating above 200°C; this magnetic behavior is attributed to the growth of a γ-Fe2O3 shell with magnetic properties distinct from the Fe3O4 core. It is suggested there is exchange coupling between these separate components that results in a vortex state with reduced vorticity. Once fully oxidized to γ-Fe2O3, the domain states revert back to vortices with slightly reduced coercivity. It is argued that due to a core/shell coupling mechanism during maghemization, the directional magnetic information will still be correct; however, the intensity information will not be retained