On the necessary conditions for bursts of convection within the rapidly rotating cylindrical annulus

Zonal flows are often found in rotating convective systems. Not only are these jet-flows driven by the convection, they can also have a profound effect on the nature of the convection. In this work the cylindrical annulus geometry is exploited in order to perform nonlinear simulations seeking to produce strong zonal flows and multiple jets. The parameter regime is extended to Prandtl numbers that are not unity. Multiple jets are found to be spaced according to a Rhines scaling based on the zonal flow speed, not the convective velocity speed. Under certain conditions the nonlinear convection appears in quasi-periodic bursts. A mean field stability analysis is performed around a basic state containing both the zonal flow and the mean temperature gradient found from the nonlinear simulations. The convective growth rates are found to fluctuate with both of these mean quantities suggesting that both are necessary in order for the bursting phenomenon to occur

The dynamics and excitation of torsional waves in geodynamo simulations

The predominant force balance in rapidly rotating planetary cores is between Coriolis, pressure, buoyancy and Lorentz forces. This magnetostrophic balance leads to a Taylor state where the spatially averaged azimuthal Lorentz force is compelled to vanish on cylinders aligned with the rotation axis. Any deviation from this state leads to a torsional oscillation, signatures of which have been observed in the Earth's secular variation and are thought to influence length of day variations via angular momentum conservation. In order to investigate the dynamics of torsional oscillations (TOs), we perform several 3-D dynamo simulations in a spherical shell. We find TOs, identified by their propagation at the correct Alfvén speed, in many of our simulations. We find that the frequency, location and direction of propagation of the waves are influenced by the choice of parameters. Torsional waves are observed within the tangent cylinder and also have the ability to pass through it. Several of our simulations display waves with core traveltimes of 4–6 yr. We calculate the driving terms for these waves and find that both the Reynolds force and ageostrophic convection acting through the Lorentz force are important in driving TOs

Providing True Opportunity for Opportunity Youth: Promising Practices and Principles for Helping Youth Facing Barriers to Employment

Many "opportunity youth" -- youth who are not working or in school -- would benefit substantially from gaining work experience but need help overcoming barriers to employment and accessing the labor market.Those opportunity youth facing the most significant challenges, such as extreme poverty, homelessness, and justice system involvement, often need even more intensive assistance in entering and keeping employment, and are at risk of being left behind even by employment programs that are specifically designed to serve opportunity youth.This paper builds on the research literature with extensive interviews with employment program providers who have had success in helping the most vulnerable opportunity youth succeed in the workforce. Six principles for effectively serving these youth are identified

The Butcher-Oemler Effect in High Redshift X-ray Selected Clusters

We are engaged in a wide-field, multi-colour imaging survey of X-ray selected clusters at intermediate and high redshift. We present blue fractions for the first 8 out of 29 clusters, covering almost a factor of 100 in X-ray luminosity. We find no correlation of blue fraction with redshift or X-ray luminosity. The lack of a correlation with L$_{X}$, places strong constraints on the importance of ram-pressure stripping as a driver of the Butcher-Oemler effect.Comment: 4 pages, 4 figures, to be puplished in the proceedings of the ''Sesto 2001-Tracing Cosmic Evolution with Galaxy Clusters'', Sesto 3-6 July 2001, Italy, eds, Stefano Borgan

A METHOD FOR CALCULATING DYNAMIC BREAST CENTRE OF MASS DURING RUNNING

This study aimed to develop a novel method for calculating breast centre of mass (COM) during running for use in musculoskeletal modelling. Magnetic resonance imaging (MRI) scans and kinematic data were collected from a female participant running at 2.6 m·s-1. A breast surface marker array was used to calculate the COM of 16 segments, based upon tissue composition from the MRI scan. The motion of the surface markers were used to calculate breast COM position during running. Breast COM was more superior, medial and posterior than the nipple marker. Breast COM range of motion was lower (~50%) in all directions during running when compared to the nipple marker. Results suggest that the localised breast deformation is the key factor in calculating breast COM during running

Broadening Responsibilities: Consideration Of The Potential To Broaden The Role Of Uniformed Fire Service Employees

What is this report about? This report, commissioned by the National Joint Council for Local Authority Fire and Rescue Services (NJC), aims to identify what impact, if any, firefighters can have on the delivery of emergency medical response and wider community health interventions in the UK. What are the overall conclusions? Appropriately trained and equipped firefighters co-responding1 to targeted, specific time critical medical events, such as cardiac arrest, can improve patient survival rates. The data also indicate that there is support from fire service staff – and a potential need from members of the public, particularly the elderly, isolated or vulnerable – to expand ‘wider work’. This includes winter warmth assessments, Safe and Well checks, community defibrillator training and client referrals when staff believe someone may have dementia, are vulnerable or even, for example, have substance dependencies such as an alcohol addiction. However, there is currently insufficient data to estimate the net benefit of this work

Rapidly rotating plane layer convection with zonal flow

The onset of convection in a rapidly rotating layer in which a thermal wind is present is studied. Diffusive effects are included. The main motivation is from convection in planetary interiors, where thermal winds are expected due to temperature variations on the core-mantle boundary. The system admits both convective instability and baroclinic instability. We find a smooth transition between the two types of modes, and investigate where the transition region between the two types of instability occurs in parameter space. The thermal wind helps to destabilise the convective modes. Baroclinic instability can occur when the applied vertical temperature gradient is stable, and the critical Rayleigh number is then negative. Long wavelength modes are the first to become unstable. Asymptotic analysis is possible for the transition region and also for long wavelength instabilities, and the results agree well with our numerical solutions. We also investigate how the instabilities in this system relate to the classical baroclinic instability in the Eady problem. We conclude by noting that baroclinic instabilities in the Earth's core arising from heterogeneity in the lower mantle could possibly drive a dynamo even if the Earth's core were stably stratified and so not convecting.Comment: 20 pages, 7 figure