282 research outputs found
Framing Engagement that Resonates: Organizing Advocacy for Corporate Social and Environmental Accountability
NURBS modeling and structural shape optimization of cardiovascular stents
Cardiovascular stents have been used since the 1990s to treat atherosclerosis, one of leading causes of death in the western world, and structural optimization has led to significant improvements in stent performance. Much of the potential variation in stent geometry, however, has remained unconsidered. This paper presents a non-uniform rational basis spline (NURBS) parameterization of a stent, the inclusion of structural fatigue resistance as a design consideration, and the results of a design optimization based on response surface techniques. Results show the feasibility and merits of the NURBS approach, which models a much broader range of shapes than was previously possible. Multi-objective optimization produces a range of geometrically diverse Pareto-optimal designs; these can be used to develop future clinical design guides, accounting for the variation observed across patients. We conclude by motivating future work with increasingly complex physical modeling and optimization capabilities
Toxoplasma gondii is not an important contributor to poor reproductive performance of primiparous ewes from southern Australia: A prospective cohort study
Background
Toxoplasma gondii causes reproductive losses in sheep worldwide, including Australia. The reproductive performance of primiparous ewes is typically lower than for mature, multiparous ewes, and younger ewes are more likely to be immunologically naĂŻve and therefore more susceptible to reproductive disease if T. gondii infection occurs during pregnancy. The aim of this study was to assess the impact of infection with T. gondii on the reproductive performance of primiparous ewes in southern Australia using a prospective cohort study. This will inform the need for targeted control strategies for T. gondii in Australian sheep.
Results
Toxoplasma gondii seropositivity using indirect ELISA was detected at 16/28 farms located across southern Australia. Apparent seropositivity to T. gondii was lower in primiparous ewes (1.1, 95% confidence interval (CI) 0.6, 1.8) compared to mature, multiparous ewes (8.1, 95% CI 6.0, 10.5; Pâ<â0.001). Toxoplasma gondii seroconversion during the gestation and lambing period was confirmed for 11/1097 (1.0, 95% CI 0.5, 1.7) of pregnant primiparous ewes that failed to raise a lamb, and 1/161 (0.6, 95% CI 0.1, 2.9) primiparous ewes with confirmed mid-pregnancy abortion.
Conclusions
Low frequency of detection of T. gondii seroconversion during gestation and low frequency of seropositivity to T. gondii suggests that toxoplasmosis was not an important contributor to reproductive losses in primiparous ewes on farms located over a wide geographical area in southern Australia
Abortion and lamb mortality between pregnancy scanning and lamb marking for maiden ewes in southern Australia
The contribution of abortions to the overall mortality of lambs born to maiden (primiparous) ewes in Australia remains unclear. This cohort study aimed to quantify abortion and lamb mortality for ewe lambs and maiden Merino two-tooth ewes. Lamb mortality from pregnancy scanning to marking were determined for 19 ewe lamb and 11 Merino two-tooth ewe flocks across southern Australia. Average lamb mortality from scanning to marking was 35.8% (range 14.3â71.1%) for the ewe lambs and 29.4% (range 19.7â52.7%) for the two-tooth ewes. Mid-pregnancy abortion was detected in 5.7% of ewes (range 0â50%) in the ewe lamb flocks and 0.9% of ewes (range 0â4.4%) in the two-tooth ewe flocks. Mid-pregnancy abortion affecting â„2% of ewes was observed in 6/19 ewe lamb flocks and 2/11 two-tooth ewe flocks. Lamb mortality from birth to marking represented the greatest contributor to foetal and lamb mortality after scanning, but mid-pregnancy abortion was an important contributor to lamb mortality in some ewe lamb flocks. Variability between the flocks indicates scope to improve the overall reproductive performance for maiden ewes by reducing foetal and lamb losses. Addressing mid-pregnancy abortion may improve the reproductive performance in some flocks
Urban policy
The employment relationship â that between employer and employee â is at the heart of capitalism and a core issue for public policy. Governments create rules, policies and institutions within which employees, their representatives, employers and their representatives, operate. The interest to governments when creating policy includes the form that bargaining takes, wage and employment levels, the nature and effects of contracting and the rights of workers â much of this boiling down to issues of power. In recent decades, major policy issues have included the federal Labor governmentâs Prices and Incomes Accords in the 1980s and 1990s, the Coalition governmentâs âWorkChoicesâ legislation, the shift to enterprise bargaining, and developments in such areas as minimum wages and pay equity. In this chapter we outline the matters at stake, the players, the policy processes and some of the key issues
High-pressure spectroscopic investigation of multiferroic Ni3TeO6
We combined diamond anvil cell techniques, infrared and Raman spectroscopies, and lattice dynamics calculations to explore the high pressure properties of multiferroic Ni3TeO6. Using a frequency trend analysis, we trace a subtle decrease in compressibility near 4 GPa to a minimum in the O-Ni2-O bond angle. This unique behavior emanates from the proximity of the Ni2 center in the Ni3-Ni2-Ni1-Te chain to a flexible pocket that is intrinsic to the crystal structure. At the same time, predicted trends in the superexchange pathways are consistent with greater antiferromagnetic character under compression, in line with both phase stability calculations and direct susceptibility measurements. These findings highlight opportunities for local structure control of corundumlike materials
Understanding the preferences and considerations of the public towards riskâstratified screening for colorectal cancer: Insights from thinkâaloud interviews based on a discrete choice experiment
Context
Risk stratification has been suggested as a strategy for improving cancer screening. Any changes to existing programmes must be acceptable to the public.
Objective
This study aimed to explore the preferences and considerations of individuals relating to the introduction of different risk-based strategies to determine eligibility for colorectal cancer (CRC) screening.
Study Design
Participants completed a discrete choice experiment (DCE) within online interviews. Nine conjoint-analysis tasks were created, each with two potential CRC screening programmes. The attributes included personal risk of CRC, screening invitation strategy and impact. Participants chose between programmes while thinking aloud and sharing their thoughts. Transcripts were analysed using codebook thematic analysis.
Participants
Twenty participants based in England aged 40â79 years without previous cancer history or medical expertise.
Results
When choosing between programmes, participants first and primarily looked to prioritise saving lives. The harms associated with screening were viewed as a surprise but also felt by most to be inevitable; the benefits frequently outweighed, therefore, harms were considered less important. Risk stratification using individual characteristics was considered a nuanced approach to healthcare, which tended to be preferred over the age-alone model. Detailed personal risk information could be taken more seriously than non-personalised information to motivate behaviour change. Although it had minimal impact on decision-making, not diverting resources for screening from elsewhere was valued. Individuals who chose not to provide health information were considered irresponsible, while it was important that those with no information to provide should not lose out.
Conclusion
Risk-stratified CRC screening is generally aligned with public preferences, with decisions between possible stratification strategies dominated by saving lives. Even if attributes including risk factors, risk stratification strategy and risk communication contributed less to the overall decision to select certain programmes, some levels more clearly fulfilled public values; therefore, all these factors should be taken into consideration when redesigning and communicating CRC screening programmes.
Patient or Public Contribution
The primary data source for this study is interviews with 20 members of the public (current, past or future CRC screening invitees). Two public representatives contributed to planning this study, particularly the DCE
Velocity Amplitudes in Global Convection Simulations: The Role of the Prandtl Number and Near-Surface Driving
Several lines of evidence suggest that the velocity amplitude in global
simulations of solar convection, U, may be systematically over-estimated.
Motivated by these recent results, we explore the factors that determine U and
we consider how these might scale to solar parameter regimes. To this end, we
decrease the thermal diffusivity along two paths in parameter space.
If the kinematic viscosity is decreased proportionally with
(fixing the Prandtl number ), we find that U increases but
asymptotes toward a constant value, as found by Featherstone & Hindman (2016).
However, if is held fixed while decreasing (increasing ),
we find that U systematically decreases. We attribute this to an enhancement of
the thermal content of downflow plumes, which allows them to carry the solar
luminosity with slower flow speeds. We contrast this with the case of
Rayleigh-Benard convection which is not subject to this luminosity constraint.
This dramatic difference in behavior for the two paths in parameter space
(fixed or fixed ) persists whether the heat transport by unresolved,
near-surface convection is modeled as a thermal conduction or as a fixed flux.
The results suggest that if solar convection can operate in a high-
regime, then this might effectively limit the velocity amplitude. Small-scale
magnetism is a possible source of enhanced viscosity that may serve to achieve
this high- regime.Comment: 34 Pages, 8 Figures, submitted to a special issue of "Advances in
Space Research" on "Solar Dynamo Frontiers
Subharmonic bifurcation cascade of pattern oscillations caused by winding number increasing entrainment
Convection structures in binary fluid mixtures are investigated for positive
Soret coupling in the driving regime where solutal and thermal contributions to
the buoyancy forces compete. Bifurcation properties of stable and unstable
stationary square, roll, and crossroll (CR) structures and the oscillatory
competition between rolls and squares are determined numerically as a function
of fluid parameters. A novel type of subharmonic bifurcation cascade (SC) where
the oscillation period grows in integer steps as is found
and elucidated to be an entrainment process.Comment: 7 pages, 4 figure
Influence of through-flow on linear pattern formation properties in binary mixture convection
We investigate how a horizontal plane Poiseuille shear flow changes linear
convection properties in binary fluid layers heated from below. The full linear
field equations are solved with a shooting method for realistic top and bottom
boundary conditions. Through-flow induced changes of the bifurcation thresholds
(stability boundaries) for different types of convective solutions are deter-
mined in the control parameter space spanned by Rayleigh number, Soret coupling
(positive as well as negative), and through-flow Reynolds number. We elucidate
the through-flow induced lifting of the Hopf symmetry degeneracy of left and
right traveling waves in mixtures with negative Soret coupling. Finally we
determine with a saddle point analysis of the complex dispersion relation of
the field equations over the complex wave number plane the borders between
absolute and convective instabilities for different types of perturbations in
comparison with the appropriate Ginzburg-Landau amplitude equation
approximation. PACS:47.20.-k,47.20.Bp, 47.15.-x,47.54.+rComment: 19 pages, 15 Postscript figure
- âŠ