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Food insecurity, or self-reports of inadequate food access due to limited financial resources, remains prevalent among people living with HIV (PLHIV). We examined the impact of food insecurity on combination antiretroviral therapy (cART) adherence within an integrated care programme that provides services to PLHIV, including two meals per day.
Adjusted OR (aOR) were estimated by generalized estimating equations, quantifying the relationship between food insecurity (exposure) and cART adherence (outcome) with multivariable logistic regression.
We drew on survey data collected between February 2014 and March 2016 from the Dr. Peter Centre Study based in Vancouver, Canada.
The study included 116 PLHIV at baseline, with ninety-nine participants completing a 12-month follow-up interview. The median (quartile 1–quartile 3) age was 46 (39–52) years at baseline and 87 % (n 101) were biologically male at birth.
At baseline, 74 % (n 86) of participants were food insecure (≥2 affirmative responses on Health Canada’s Household Food Security Survey Module) and 67 % (n 78) were adherent to cART ≥95 % of the time. In the adjusted regression analysis, food insecurity was associated with suboptimal cART adherence (aOR = 0·47, 95 % CI 0·24, 0·93).
While food provision may reduce some health-related harms, there remains a relationship between this prevalent experience and suboptimal cART adherence in this integrated care programme. Future studies that elucidate strategies to mitigate food insecurity and its effects on cART adherence among PLHIV in this setting and in other similar environments are necessary.
The interaction of gravitationally driven, free-surface flows of viscous fluid with topographic features is investigated theoretically. The motion is studied in the regime where the depth of the flow is much smaller than the streamwise extent of the topography. A lubrication model of the motion is developed, integrated numerically and analysed asymptotically. For small mounds, it is shown that the flow surmounts the obstacles, but for larger mounds the flow is deflected around it and can form dry zones in its wake into which fluid does not flow, as well as forming deeper ponded regions upstream. Which of these phenomena prevails is shown to depend upon the amplitude of the mound height and the thickness of the oncoming flow relative to the streamwise length scale over which the topography varies. By using numerical and asymptotic results, we demonstrate that relatively wide mounds lead to the development of deep ponds of material upstream, which may lead to flow overtopping if the mound is not sufficiently high. These insights can be used to inform the design of barriers that defend built infrastructures from lava flows, and it is shown how this model can also provide an upper bound on the force exerted by the flow on them.
Surface mass balance (SMB) is the net input of mass on a glacier's upper surface, composed of snow deposition, melt and erosion processes, and is a major contributor to the overall mass balance. Pine Island Glacier (PIG) in West Antarctica has been dynamically imbalanced since the early 1990s, indicating that discharge of solid ice into the oceans exceeds snow deposition. However, observations of the SMB pattern on the fast flowing regions are scarce, and are potentially affected by the firn's strain history. Here, we present new observations from radar-derived stratigraphy and a relatively dense network of firn cores, collected along a ~900 km traverse of PIG. Between 1986 and 2014, the SMB along the traverse was 0.505 m w.e. a−1 on average with a gradient of higher snow deposition in the South-West compared with the North-East of the catchment. We show that along ~80% of the traverse the strain history amounts to a misestimation of SMB below the nominal uncertainty, but can exceed it by a factor 5 in places, making it a significant correction to the SMB estimate locally. We find that the strain correction changes the basin-wide SMB by ~0.7 Gt a−1 and thus forms a negligible (1%) correction to the glacier's total SMB.
Precise radiocarbon (14C) dating of sedimentary sequences is important for developing robust chronologies of environmental change, but sampling of suitable components can be challenging in highly dynamic landscapes. Here we investigate radiocarbon determinations of different peat size fractions from six peat sites, representing a range of geomorphological contexts on the South Atlantic subantarctic islands of the Falklands and South Georgia. To investigate the most suitable fraction for dating, 112 measurements were obtained from three components within selected horizons: a fine fraction <0.2 mm, a coarse fraction >0.2 mm, and bulk material. We find site selection is critical, with locations surrounded by high-ground and/or relatively slowly accumulating sites more susceptible to the translocation of older carbon. Importantly, in locations with reduced potential for redeposition of material, our results show that there is no significant or systematic difference between ages derived from bulk material, fine or coarse (plant macrofossil) material, providing confidence in the resulting age model. Crucially, in areas comprising complex terrain with extreme relief, we recommend dating macrofossils or bulk carbon rather than a fine fraction, or employing comprehensive dating of multiple sedimentary fractions to determine the most reliable fraction(s) for developing a robust chronological framework.
This research investigates two factors influencing the ability of tree-ring data to provide accurate 14C calibration information: the fitness and rigor of the statistical model used to combine the data into a curve; and the accuracy, precision and reproducibility of the component 14C data sets. It presents a new Bayesian spline method for calibration curve construction and tests it on extant and new Southern Hemisphere (SH) data sets (also examining their dendrochronology and pretreatment) for the post-Little Ice Age (LIA) interval AD 1500–1950. The new method of construction allows calculation of component data offsets, permitting identification of laboratory and geographic biases. Application of the new method to the 10 suitable SH 14C data sets suggests that individual offset ranges for component data sets appear to be in the region of ± 10 yr. Data sets with individual offsets larger than this need to be carefully assessed before selection for calibration purposes. We identify a potential geographical offset associated with the Southern Ocean (high latitude) Campbell Island data. We test the new methodology for wiggle-matching short tree-ring sequences and use an OxCal simulation to assess the likely precision obtainable by wiggle-matching in the post-LIA interval.
When I was asked to give this talk it occurred to me that it might be interesting to think aloud about some of the changes in constitutional law—and in writing about constitutional law—that have occurred since I came to Canada. I am a New Zealander by birth, but I was teaching at the Faculty of Law of Monash University in Melbourne, Australia, when I came to the Osgoode Hall Law School on a one-year visit in the summer of 1970. During that visiting year, the faculty decided to offer me a permanent appointment. This was done over the objection of one of my colleagues, R. J. Gray, who claimed that my lectures would require simultaneous translation, and that I would not meet the height requirements for Canadian citizenship. Anyway I was persuaded to stay (and three years later I became a Canadian citizen).
Simulation-based training has a fundamental role in medical education as it allows the learner to gain experience managing emergencies in a safe, controlled environment.
This 1-day course consisted of eight high-fidelity simulation scenarios, followed by a video-assisted debrief focusing on the technical and non-technical (communication skills, teamwork, leadership and situational awareness) aspects of managing ENT and head and neck emergencies.
Eight courses have run since June 2014. Post-course questionnaires demonstrated that candidates’ confidence scores in managing airway and head and neck emergencies increased following completion of the course (p < 0.0001).
This was the first fully immersive ENT simulation course developed in the region. The learning objectives for each scenario were mapped to the ENT Intercollegiate Surgical Curriculum Programme. Feedback from the course indicated a continued demand for this style of training, leading to its inclusion in the training calendar.
The unsteady ascent of a buoyant, turbulent line plume through a quiescent, uniform environment is modelled in terms of the width-averaged vertical velocity and density deficit. It is demonstrated that for a well-posed, linearly stable model, account must be made for the horizontal variation of the velocity and the density deficit; in particular the variance of the velocity field and the covariance of the density deficit and velocity fields, represented through shape factors, must exceed threshold values, and that models based upon ‘top-hat’ distributions in which the dependent fields are piecewise constant are ill-posed. Numerical solutions of the nonlinear governing equations are computed to reveal that the transient response of the system to an instantaneous change in buoyancy flux at the source may be captured through new similarity solutions, the form of which depend upon both the ratio of the old to new buoyancy fluxes and the shape factors.
Background: There is strong evidence to suggest that anxiety is associated with paranoia in clinical and non-clinical samples. However, no research to date has directly manipulated anxiety to investigate if state-anxiety has a causal role in state-paranoia in clinical populations. Aims: To investigate whether an anxious-mood induction leads to greater paranoia than a neutral-mood induction in people experiencing psychosis and paranoia and, if so, whether this is predicted by anxiety over and above other variables. Method: 22 participants with a psychosis-spectrum diagnosis took part in a two condition cross-over experimental design. Participants underwent a neutral-mood and an anxious-mood induction with levels of state-anxiety, state-affect and state-paranoia being measured before and after each condition. Results: State-paranoia was significantly higher after the anxious condition compared with the neutral condition. State-anxiety and negative-affect were significant predictors of levels of state-paranoia after the anxious condition. When both predictors were included in a regression model, only negative-affect was a significant predictor of state-paranoia after the anxious condition. There were a number of methodological limitations. Conclusions: State-anxiety and negative-affect may both be involved in the maintenance of paranoia in clinical populations, as predicted by cognitive models. Negative-affect may be the strongest predictor of state-paranoia in clinical populations. Reasons for this are discussed, as well as the implications. Interventions that seek to reduce negative state-affect may be beneficial in managing state-paranoia. Further research is warranted to explore the suggested clinical and theoretical implications of these findings.
The steady speeds of the front of a gravity current and of an internal jump on a two-layer stratification are often sought in terms of the heights of the relatively dense fluid both up- and downstream from the front or jump, the height of the channel within which they flow, the densities of the two fluids and gravitational acceleration. In this study a unifying framework is presented for calculating the speeds by balancing mass and momentum fluxes across a control volume spanning the front or jump and by ensuring the assumed pressure field is single-valued, which is shown to be equivalent to forming a vorticity balance over the control volume. Previous models have assumed the velocity field is piecewise constant in each layer with a vortex sheet at their interface and invoked explicit or implicit closure assumptions about the dissipative effects to derive the speed. The new formulation yields all of the previously presented expressions and demonstrates that analysing the vorticity balance within the control volume is a useful means of constraining possible closure assumptions, which is arguably more effective than consideration of the flow energetics. However the new approach also reveals that a novel class of models may be developed in which there is shear in the velocity field in the wake downstream of the front or the jump, thus spreading the vorticity over a layer of non-vanishing thickness, rather than concentrating it into a vortex sheet. Mass, momentum and vorticity balances applied over the control volume allow the thickness of the wake and the speed of the front/jump to be evaluated. Results from this vortex-wake model are consistent with published numerical simulations and with data from laboratory experiments, and improve upon predictions from previous formulae. The results may be applied readily to Boussinesq and non-Boussinesq systems and because they arise as simple algebraic expressions, can be straightforwardly incorporated as jump conditions into spatially and temporally varying descriptions of the motion.
Some years back, the English department for which I was Head of Key Stage 3 found that, due to a timetabling issue, Year 7s had an extra hour of English per fortnight. It seemed like a waste of an opportunity to pad this extra hour out with ‘more of the same’, so I made a decision to utilise that hour to teach something different - grammar.
West Antarctic climate and surface mass balance (SMB) records are sparse. To fill this gap, regional atmospheric climate modelling is useful, providing that such models are employed at sufficiently high horizontal resolution and coupled with a snow model. Here we present the results of a high-resolution (5.5 km) regional atmospheric climate model (RACMO2) simulation of coastal West Antarctica for the period 1979–2015. We evaluate the results with available in situ weather observations, remote-sensing estimates of surface melt, and SMB estimates derived from radar and firn cores. Moreover, results are compared with those from a lower-resolution version, to assess the added value of the resolution. The high-resolution model resolves small-scale climate variability invoked by topography, such as the relatively warm conditions over ice-shelf grounding zones, and local wind speed accelerations. Surface melt and SMB are well reproduced by RACMO2. This dataset will prove useful for picking ice core locations, converting elevation changes to mass changes, for driving ocean, ice-sheet and coupled models, and for attributing changes in the West Antarctic Ice Sheet and shelves to changes in atmospheric forcing.
Background: Recruiting family physicians into primary care research studies requires researchers to continually manage information coming in, going out, and coming in again. In many research groups, Microsoft Excel and Access are the usual data management tools, but they are very basic and do not support any automation, linking, or reminder systems to manage and integrate recruitment information and processes. Objective: We explored whether a commercial customer relationship management (CRM) software program – designed for sales people in businesses to improve customer relations and communications – could be used to make the research recruitment system faster, more effective, and more efficient. Findings: We found that while there was potential for long-term studies, it simply did not adapt effectively enough for our shorter study and recruitment budget. The amount of training required to master the software and our need for ongoing flexible and timely support were greater than the benefit of using CRM software for our study.
A series of laboratory experiments in a 6 m long chute using glass particles of mean diameter 100 μm were performed to investigate the interaction of a supercritical, granular flow with obstacles. It was found that the collision of the flow with a row of mounds led to the formation of a jet, whereby a large fraction of the flow was launched from the top of the mounds and subsequently landed back on the chute. The retarding effect of the mounds was investigated quantitatively by direct measurements of the velocity of the flow, its runout length and the geometry of the jet. The effects of several aspects of the layout of the mounds on their retarding effects were examined. It was observed that a row of steep mounds with an elongated shape in the transverse direction to the flow and with a height several times the flow depth led to dissipation of a large proportion of the kinetic energy of the flow.
Fluidisation is the process by which the weight of a bed of particles is supported by a gas flow passing through it from below. When fluidised materials flow down an incline, the dynamics of the motion differs from their non-fluidised counterparts because the granular agitation is no longer required to support the weight of the flowing layer. Instead, the weight is borne by the imposed gas flow and this leads to a greatly increased flow mobility. In this paper, a framework is developed to model this two-phase motion by incorporating a kinetic theory description for the particulate stresses generated by the flow. In addition to calculating numerical solutions for fully developed flows, it is shown that for sufficiently thick flows there is often a local balance between the production and dissipation of the granular temperature. This phenomenon permits an asymptotic reduction of the full governing equations and the identification of a simple state in which the volume fraction of the flow is uniform. The results of the model are compared with new experimental measurements of the internal velocity profiles of steady granular flows down slopes. The distance covered with time by unsteady granular flows down slopes and along horizontal surfaces and their shapes are also measured and compared with theoretical predictions developed for flows that are thin relative to their streamwise extent. For the horizontal flows, it was found that resistance from the sidewalls was required in addition to basal resistance to capture accurately the unsteady evolution of the front position and the depth of the current and for situations in which sidewall drag dominates, similarity solutions are found for the experimentally measured motion.
Supraglacial lakes (SGLs) affect the dynamics of the Greenland ice sheet by storing runoff and draining episodically. We investigate the evolution of SGLs as reported in three datasets, each based on automated classification of satellite imagery. Although the datasets span the period 2001–10, there are differences in temporal sampling, and only the years 2005–07 are common. By subsampling the most populous dataset, we recommend a sampling frequency of one image per 6.5 days in order to minimize uncertainty associated with poor temporal sampling. When compared with manual classification of satellite imagery, all three datasets are found to omit a sizeable (29, 48 and 41 %) fraction of lakes and are estimated to document the average size of SGLs to within 0.78, 0.48 and 0.95 km2. We combine the datasets using a hierarchical scheme, producing a single, optimized, dataset. This combined record reports up to 67% more lakes than a single dataset. During 2005–07, the rate of SGL growth tends to follow the rate at which runoff increases in each year. In 2007, lakes drain earlier than in 2005 and 2006 and remain absent despite continued runoff. This suggests that lakes continue to act as open surface–bed conduits following drainage.