We describe the structural and kinematic properties of the first compact stellar systems discovered by the AIMSS project. These spectroscopically confirmed objects have sizes (∼6 < R e [pc] < 500) and masses (∼2×10 6 < M * /M < 6×10 9 ) spanning the range of massive globular clusters (GCs), ultra compact dwarfs (UCDs) and compact elliptical galaxies (cEs), completely filling the gap between star clusters and galaxies.Several objects are close analogues to the prototypical cE, M32. These objects, which are more massive than previously discovered UCDs of the same size, further call into question the existence of a tight mass-size trend for compact stellar systems, while simultaneously strengthening the case for a universal "zone of avoidance" for dynamically hot stellar systems in the mass-size plane.Overall, we argue that there are two classes of compact stellar systems: 1) massive star clusters and 2) a population closely related to galaxies. Our data provide indications for a further division of the galaxy-type UCD/cE population into two groups, one population that we associate with objects formed by the stripping of nucleated dwarf galaxies, and a second population that formed through the stripping of bulged galaxies or are lower-mass analogues of classical ellipticals. We find compact stellar systems around galaxies in low to high density environments, demonstrating that the physical processes responsible for forming them do not only operate in the densest clusters.

We present a spectroscopic and photometric determination of the distance to the young Galactic open cluster Westerlund 2 using WFPC2 imaging from the Hubble Space Telescope and ground-based optical spectroscopy. HST imaging in the F336W, F439W, F555W, and F814W filters resolved many sources previously undetected in ground-based observations and yielded photometry for 1136 stars. We identified fifteen new O-type stars, along with two probable binary systems, including MSP 188 (O3 + O5.5). We fit reddened SEDs based on the Padova isochrones to the photometric data to determine individual reddening parameters R V and A V for O-type stars in Wd2. We find average values R V = 3.77 ± 0.09 and A V = 6.51 ± 0.38 mag, which result in a smaller distance than most other spectroscopic and photometric studies. After a statistical distance correction accounting for close unresolved binaries (factor of 1.08), our spectroscopic and photometric data on 29 O-type stars yield that Westerlund 2 has a distance d = 4.16 ± 0.07 (random) +0.26 (systematic) kpc. The cluster's age remains poorly constrained, with an upper limit of 3 Myr. Finally, we report evidence of a faint mid-IR PAH ring surrounding the well-known binary candidate MSP 18, which appears to lie at the center of a secondary stellar grouping within Westerlund 2.

The CORCON-Mod3 computercode was developed to mechanistically model the importantcore-concrete interactionphenomena, including those phenomena relevant to the assessment of containmentfailure and radionuelide release. The code can be applied to a wide range of severe accident scenarios and reactorplants. The code represents the current state of the art for simulating core debris interactions with concrete. This document comprises the user's manual and gives a brief description of the models and the assumptions and limitations in the code. Also discussed are the input parametersand the code output. Two sample problems are also given.

Lancaster University has recently begun research into construction robotics and initial concentration is on excavation plant. This paper describes the building of computer and small-scale models to facilitate research and development into hardware and control strategies. The emphasis is on maintaining flexibility to allow the research the widest possible scope. For this reason a modular system for the models was devised so that compatible components can built-up in various ways. A selection of these modules is described.

Plate circuit calculations suggest that motion of thePacifi c plate relative to the North American plate changed from W to NW at ca. 7-8 Ma (Atwater and Stock, 1998). This observation is in good agreement with regional geologic constraints, which indicate that motion of the Sierra Nevada block relative to stable North America also changed from W to NW at ca. 8-10 Ma (Wernicke and Snow, 1998; Snow and Wernicke, 2000). A recent tectonic reconstruction of southwestern North America shows that a portion of plate boundary dextral shear jumped into the continent at 10-12 Ma (McQuarrie and Wernicke, 2005). On the basis of geologic studies, the rate of dextral shear within the Eastern California Shear Zone-Walker Lane Belt north of the Garlock fault has been ~15 mm/yr since ca. 7-8 Ma (Wernicke and Snow, 1998), accounting for ~30% of the relative plate motion (Atwater and Stock, 1998). Today, geodetic data indicate that dextral shear, at a rate of ~10-13 mm/yr, still dominates within the Eastern California Shear Zone-Walker Lane Belt, accounting for 20%-25% of the total relative plate motion (