Neglecting safety precautions may lead to trenching fatalities.

Background: Trench collapses ranked as the seventh leading cause of the possible twenty-nine causes of OSHA-inspected fatal construction events during the period 1991-2001. This study aims to examine why these fatalities occurred.

Methods: Forty-four case files from OSHA inspections of fatal trench collapses were reviewed.

Unusual behavior of the surface-induced tilted layers in free-standing films of a non-layer-shrinkage liquid crystal compound.

Null-transmission ellipsometry has been conducted to study the molecular arrangements in free-standing films of one chiral compound above the bulk smectic-A-smectic-C* transition temperature. Upon cooling under a proper electric field, a nonplanar-anticlinic-synclinic or a nonplanar-synclinic transition has been observed. The nonplanar structure continuously evolves into the anticlinic or synclinic structures.

Double reentrance of surface arrangements in freestanding liquid crystal films.

The molecular arrangement of tilted surface layers on freestanding films above the bulk smectic-A-smectic-C(*) transition has been studied by null transmission ellipsometry. In the presence of an applied in-plane electric field, a synclinic-anticlinic-synclinic-anticlinic double reentrance has been observed. Furthermore, we have characterized a novel transition from the synclinic arrangement to a structure in which the interior layers tilt in the same orientation and the outermost surface layers tilt oppositely with the interior layers.

Enzyme potentiated desensitisation in treatment of seasonal allergic rhinitis: double blind randomised controlled study.

Objective: To assess the efficacy of enzyme potentiated desensitisation in the treatment of severe summer hay fever poorly controlled by pharmacotherapy.

Design: Double blind randomised placebo controlled parallel group study.

Setting: Hospital in Hampshire.

Antiferroelectric liquid-crystal mixture without smectic layer shrinkage at the direct Sm-A*-Sm-C(*)(a) transition.

We report results of x-ray, optic, electro-optic, and dielectric investigations on an antiferroelectric liquid-crystal mixture exhibiting a direct second-order phase transition between the Sm-A* and Sm-C(*)(a) phases with virtually no shrinkage in the smectic layer spacing. The birefringence measurements and texture observations suggest that the phase transition follows the diffuse cone model of Adrian de Vries, which explains the constant layer spacing. The antiferroelectric nature of the tilted phase is verified by the presence of twin polarization reversal peaks in the current response and by the absence of strong absorptions in the dielectric spectrum.