In Situ Characterization of Ultraintense Laser Pulses

We present a method for determining the characteristics of an intense laser pulse by probing it with a relativistic electron beam. After an initial burst of very high-energy $\gamma$-radiation the electrons proceed to emit a series of attosecond duration X-ray pulses as they leave the field. These flashes provide detailed information about the interaction, allowing us to determine properties of the laser pulse: something that is currently a challenge for ultra-high intensity laser systems.Comment: 9 pages, 8 figure

Dynamic distributions and changing copulas

A copula models the relationships between variables independently of their marginal distributions. When the variables are time series, the copula may change over time. A statistical framework is suggested for tracking these changes over time. When the marginal distributions change, pre-…ltering is necessary before constructing the indicator variables on which the tracking of the copula is based. This entails solving an even more basic problem, namely estimating time-varying quantiles. The methods are applied to the Hong Kong and Korean stock market indices. Some interesting movements are detected, particularly after the attack on the Hong Kong dollar in 1997

Understanding and Preventing Employee Turnover

Child welfare agencies have identified worker turnover as a particularly problematic organizational issue. In children’s mental health agencies, turnover also seems to be an issue for residential care services. Do people voluntarily leave child welfare and children\u27s mental health organizations because of the work itself, because of the workload, or because they find “success” difficult to experience? These are often given as reasons by departing employees, but to develop a comprehensive understanding why turnover takes place in these organizations, this paper looks at the research on turnover in organizations generally and in child welfare and children\u27s mental health organizations specifically. Research on unwanted employee turnover has produced thousands of articles. We begin by exploring the major themes in this literature and then relate these themes to research done in human services organizations, and child welfare and children\u27s mental health organizations specifically. We conclude with a list of research questions to pursue in our study of workers’ experiences in the workplace

MEASUREMENT OF THE STATE VECTOR

Measurement of the state vecto