Background: In megavoltage radiotherapy rooms, ordinary concrete is usually used due to its low construction costs, although higher density concrete are sometimes used, as well. The use of high-density concrete decreases the required thickness of the concrete barrier hence, its disadvantage is its high cost. In a nuclear reactor, neutron radiation is the most difficult to shield. A method for p...

Aguilarite, Ag4SeS, occurs in a hydrothermal vein deposit associated with sphalerite, chalcopyrite, galena, and native silver. Physical and chemical data agree with descriptions from Guanajuato (type locality). Differential thermal analysis of synthetic material indicates an inversion temperature of i22• T ~ The mineral crystallized late in the paragenetic sequence, probably slightly above 2oo ~

The Bruce Boyd site is an Early Woodland burial area on a sand knoll near Long Point, Lake Erie. Excavation uncovered several burials and offerings with cache blades, Meadowood points, trapezoidal gorgets, galena, copper beads, copper bracelets, iron pyrites and red ochre. The ceramics were cordmarked on both interior and exterior, some of them also showing punctates on the lip and exterior rim.

We present a deenite clause based parsing environment for natural languages, whose operational model is the dynamic interpretation of logical push-down automata. We attempt to brieey explain our design decisions in terms of a set of properties that practical natural language processing systems should incorporate. The aim is to show both the advantages and the drawbacks of our approach.

background: high density concrete is extensively used for efficient radiation attenuation in radiotherapy rooms and nuclear reactors. over the past eight years, some efficient galena-based concrete samples for shielding x or gamma rays was produced. the goal of this study was to produce a novel high density concrete against neutron and photon radiations using tourmaline and galena. materials an...