A Hamiltonian Monte Carlo method for Bayesian Inference of Supermassive Black Hole Binaries

We investigate the use of a Hamiltonian Monte Carlo to map out the posterior density function for supermassive black hole binaries. While previous Markov Chain Monte Carlo (MCMC) methods, such as Metropolis-Hastings MCMC, have been successfully employed for a number of different gravitational wave sources, these methods are essentially random walk algorithms. The Hamiltonian Monte Carlo treats the inverse likelihood surface as a "gravitational potential" and by introducing canonical positions and momenta, dynamically evolves the Markov chain by solving Hamilton's equations of motion. We present an implementation of the Hamiltonian Markov Chain that is faster, and more efficient by a factor of approximately the dimension of the parameter space, than the standard MCMC.Comment: 16 pages, 8 figure

Non-Newtonian thin films with normal stresses: dynamics and spreading

The dynamics of thin films on a horizontal solid substrate is investigated in the case of non-Newtonian fluids exhibiting normal stress differences, the rheology of which is strongly non-linear. Two coupled equations of evolution for the thickness of the film and the shear rate are proposed within the lubrication approximation. This framework is applied to the motion of an advancing contact line. The apparent dynamic contact angle is found to depend logarithmically on a lengthscale determined solely by the rheological properties of the fluid and the velocity of the contact line

Finding the Right Fit: How Alternative Staffing Affects Worker Outcomes

Evaluates implementation and activities at four worker-centered, social-purpose alternative staffing organizations, including worker profiles, jobs secured, experience with the ASO, earnings, and subsequent job status, and business clients' experience

Alternative Staffing Organizations and Skills: Linking Temporary Work with Training

This paper provides a brief research background on the field of alternative staffing and what we have learned about connecting job brokering activities with training and education opportunities. This includes drawing on recent research by the Center for Social Policy on the Alternative Staffing Demonstration II, 2008 to 2011, funded by the Charles Stewart (C. S.) Mott Foundation. The paper also offers several points for consideration in connecting temporary help workers to training opportunities. Specifically, it puts the role of alternative staffing in the context of the entry-level job market and discusses the value of staffing services from the perspective of job seekers, customer businesses, and the workforce development field. A number of examples are provided of training programs and partnerships that combine skills development with job brokering. Overall, we address two questions: 1) What do we know about connecting staffing services with training opportunities?, and 2) What are some promising examples of connecting ASO workers to skills training

Understanding the effect of seams on the aerodynamics of an association football

The aerodynamic properties of an association football were measured using a wind tunnel arrangement. A third scale model of a generic football (with seams) was used in addition to a 'mini-football'. As the wind speed was increased, the drag coefficient decreased from 0.5 to 0.2, suggesting a transition from laminar to turbulent behaviour in the boundary layer. For spinning footballs, the Magnus effect was observed and it was found that reverse Magnus effects were possible at low Reynolds numbers. Measurements on spinning smooth spheres found that laminar behaviour led to a high drag coefficient for a large range of Reynolds numbers, and Magnus effects were inconsistent, but generally showed reverse Magnus behaviour at high Reynolds number and spin parameter. Trajectory simulations of free kicks demonstrated that a football that is struck in the centre will follow a near straight trajectory, dipping slightly before reaching the goal, whereas a football that is struck off centre will bend before reaching the goal, but will have a significantly longer flight time. The curving kick simulation was repeated for a smooth ball, which resulted in a longer flight time, due to increased drag, and the ball curving in the opposite direction, due to reverse Magnus effects. The presence of seams was found to encourage turbulent behaviour, resulting in reduced drag and more predictable Magnus behaviour for a conventional football, compared with a smooth ball. © IMechE 2005

Why Use the Services of Alternative Staffing Organizations: Perspectives from Customer Businesses

Organizations that aim to improve the experiences and employment chances of job seekers who face barriers to employment have, over the years, had to contend directly with potential employers and their requirements. This is particularly true for community-based job brokers that use a temporary staffing model, offering job access and immediate work to their service population.Alternative staffing organizations (ASOs) are worker-centered, social purpose businesses that place job seekers in temporary and "temp-to-perm" assignments with customer businesses, and charge their customers a markup on the wage of the position. These fee-for-service organizations can help job seekers who face labor market barriers gain work experience and access potential employers. Created by community-based organizations and national nonprofits, ASOs are often embedded within larger organizations that provide other employment, training, and human services to their community. The parent organizations may also be operating other social enterprise ventures. Businesses that contract ASOs for staffing services are customers that expect a service, but also represent an opportunity for employment and work experience for job seekers. Thus ASOs must operate with a dual agenda to serve both sides of the equation. In related publications, we have explored how ASOs operate as social enterprises and how the model fits within the goals of the parent organization. With detailed information from five well-established ASOs, and as part of two waves of a demonstration initiated by the Charles Stewart Mott Foundation, we have documented the employment experiences of workers placed in assignments and their employment status after leaving the ASO. In this paper, we address engagement with businesses and their perspectives on ASO services. This is a major issue for ASOs as well as for other workforce development organizations. ASOs engage with businesses while selling staffing services and monitoring worker performance. By the very nature of temporary staffing, they receive rapid feedback on worker performance and their services from customer businesses. As such, ASOs provide a window into how to connect to potential employers in order to access opportunities. Also, activities of ASOs shed light on how hiring takes place for entry-level jobs, and how customer businesses use ASOs to solve their entry-level hiring problems.This paper demonstrates what can be learned from customers of established ASOs about their reasons for using these services. Specifically, it explores how customer businesses use temporary staffing by ASOs, and for what purposes. What business needs do they meet with ASO services? What are their reasons for using an ASO over conventional staffing agencies? And finally, what causes customer businesses to use an ASO and retain the service over time?These concerns are salient for those organizations considering the creation of an ASO. They also are important for workforce development programs that need to become more active in engaging potential employers and that seek solutions for job seekers who need to connect to employment and need immediate income

Subsidizing low-skilled jobs in a dual labor market

A large exclusion from the labor market or an important unemployment of low-skilled workers is observed in some developed economies in which a minimum wage has been introduced. In such circumstances, governments may adopt two kinds of policies. They may pay unemployment benefits or they may try to increase demand for low-skilled labor by subsidizing low-skilled jobs. In this paper, we propose a matching model which allows to analyze the effects of these policies on the labor market. In our framework, the government budget is balanced through taxes on occupied workers and classical and frictional unemployment simultaneously exist. The labor market is dual featuring low-skilled and high-skilled workers. Low-skilled jobs pay the minimum wage, while high-skilled wages result from bargaining. Moreover, high-skilled unemployed can apply for both types of jobs thereby accepting to be downgraded, while opportunities for low-skilled workers are limited to low-skilled jobs. We first give conditions for the existence and uniqueness of a steady- state equilibrium and we analyze the effects of several fiscal instruments. In this set-up, increasing low-skilled job subsidies does not necessarily reduce low-skilled unemployment or unemployment spells. We provided empirical evidence by calibrating our model on French labor market data, it is found that for five low-skilled workers leaving classical unemployment, two high-skilled workers are downgraded (although they might have been previously unemployed).Crowding-out, Matching, On-the-job search, Taxation

An Alternative to Temporary Staffing: Considerations for Workforce Practitioners

The temporary staffing industry has become a fixture of the US economy in recent decades, and workforce practitioners are increasingly noting the prevalence of temporary jobs in the low-skilled labor market. To ensure that these jobs are a stepping stone for job seekers -- and to tap into additional sources of revenue -- a growing number of social service organizations have launched their own staffing businesses, known as alternative staffing organizations (ASOs)

Compressive Pattern Matching on Multispectral Data

We introduce a new constrained minimization problem that performs template and pattern detection on a multispectral image in a compressive sensing context. We use an original minimization problem from Guo and Osher that uses $L_1$ minimization techniques to perform template detection in a multispectral image. We first adapt this minimization problem to work with compressive sensing data. Then we extend it to perform pattern detection using a formal transform called the spectralization along a pattern. That extension brings out the problem of measurement reconstruction. We introduce shifted measurements that allow us to reconstruct all the measurement with a small overhead and we give an optimality constraint for simple patterns. We present numerical results showing the performances of the original minimization problem and the compressed ones with different measurement rates and applied on remotely sensed data.Comment: Published in IEEE Transactions on Geoscience and Remote Sensin