A cost-benefit analysis of pathways to work for new and repeat incapacity benefits claimants

This latest research forms part of a comprehensive independent evaluation of Pathways to Work. The report is based on a cost-benefit analysis conducted by a consortium of researchers from the Institute for Fiscal Studies, the University of Maryland, Baltimore County and the Policy Studies Institute. It examines whether the financial benefits from Pathways are larger or smaller than its costs and the generalisability of some of the quantitative findings. The estimates of costs and benefits relate to new and repeat incapacity benefits claimants in the seven original Jobcentre Plus districts. The overall findings provide a favourable impression of the financial benefits of the Pathways to Work for new and repeat incapacity benefits claimants, for the Exchequer and hence, for society as a whole

Search for exchange-antisymmetric two-photon states

Atomic two-photon J=0 $\leftrightarrow$J'=1 transitions are forbidden for photons of the same energy. This selection rule is related to the fact that photons obey Bose-Einstein statistics. We have searched for small violations of this selection rule by studying transitions in atomic Ba. We set a limit on the probability $v$ that photons are in exchange-antisymmetric states: $v<1.2\cdot10^{-7}$.Comment: 5 pages, 4 figures, ReVTeX and .eps. Submitted to Phys. Rev. Lett. Revised version 9/25/9

Planetary geology: Impact processes on asteroids

The fundamental geological and geophysical properties of asteroids were studied by theoretical and simulation studies of their collisional evolution. Numerical simulations incorporating realistic physical models were developed to study the collisional evolution of hypothetical asteroid populations over the age of the solar system. Ideas and models are constrained by the observed distributions of sizes, shapes, and spin rates in the asteroid belt, by properties of Hirayama families, and by experimental studies of cratering and collisional phenomena. It is suggested that many asteroids are gravitationally-bound "rubble piles.' Those that rotate rapidly may have nonspherical quasi-equilibrium shapes, such as ellipsoids or binaries. Through comparison of models with astronomical data, physical properties of these asteroids (including bulk density) are determined, and physical processes that have operated in the solar system in primordial and subsequent epochs are studied

Phobos and deimos: Analysis of surface features, ejecta dynamics and a volatile loss mechanism

The question of whether the crater population on Phobos represents a production population or an equilibrium population is considered. The absolute ages of cratered surfaces are interpreted and analyzed. A computer program was developed to study the dynamics of material ejected from Martian satellites and to investigate the hypothesis that at least some of the extensive set of linear features discovered on the surface of Phobos could be the result of secondary cratering from the Stickney impact. The possibility that Deimos was catastrophically disrupted by a large impact but subsequently reaccreted is considered as well as the probability the Phobos had an impact nearly large enough to disrupt it are also discussed

Coronagraph particulate measurements. Skylab flight experiment T025

Major results of the Skylab T025 Coronagraph experiment designed to monitor the particulate contamination about the spacecraft and to study the earth's atmospheric aerosol distribution are presented. A model for comet outbursts based on the properties of amorphous ice and ground based narrow-band and white light photography of comet Kohoutek ten days to perihelion are included. The effect of atmospheric refraction on the analysis of the T025 atmospheric data was also investigated

Entanglement and statistics in Hong-Ou-Mandel interferometry

Hong-Ou-Mandel interferometry allows one to detect the presence of entanglement in two-photon input states. The same result holds for two-particles input states which obey to Fermionic statistics. In the latter case however anti-bouncing introduces qualitative differences in the interferometer response. This effect is analyzed in a Gedankenexperiment where the particles entering the interferometer are assumed to belong to a one-parameter family of quons which continuously interpolate between the Bosonic and Fermionic statistics.Comment: 7 pages, 3 figures; minor editorial changes and new references adde

High-order optical nonlinearity at low light levels

We observe a nonlinear optical process in a gas of cold atoms that simultaneously displays the largest reported fifth-order nonlinear susceptibility \chi^(5) = 1.9x10^{-12} (m/V)^4 and high transparency. The nonlinearity results from the simultaneous cooling and crystallization of the gas, and gives rise to efficient Bragg scattering in the form of six-wave-mixing at low-light-levels. For large atom-photon coupling strengths, the back-action of the scattered fields influences the light-matter dynamics. This system may have important applications in many-body physics, quantum information processing, and multidimensional soliton formation.Comment: 5 pages, 3 figure

An empirical study of the “prototype walkthrough”: a studio-based activity for HCI education

For over a century, studio-based instruction has served as an effective pedagogical model in architecture and fine arts education. Because of its design orientation, human-computer interaction (HCI) education is an excellent venue for studio-based instruction. In an HCI course, we have been exploring a studio-based learning activity called the prototype walkthrough, in which a student project team simulates its evolving user interface prototype while a student audience member acts as a test user. The audience is encouraged to ask questions and provide feedback. We have observed that prototype walkthroughs create excellent conditions for learning about user interface design. In order to better understand the educational value of the activity, we performed a content analysis of a video corpus of 16 prototype walkthroughs held in two HCI courses. We found that the prototype walkthrough discussions were dominated by relevant design issues. Moreover, mirroring the justification behavior of the expert instructor, students justified over 80 percent of their design statements and critiques, with nearly one-quarter of those justifications having a theoretical or empirical basis. Our findings suggest that PWs provide valuable opportunities for students to actively learn HCI design by participating in authentic practice, and provide insight into how such opportunities can be best promoted