Langevin-equation simulation is used to study the dynamics of a simple model of homopolymer collapse at infinite dilution for polymers of lengths N=100, 200, 300, 500, and 1024 units. Lennard-Jones potentials are chosen to represent the bead–bead interactions and a harmonic potential bonds nearest-neighbor beads. The Flory coil-to-collapsed globule transition is brought about by an adjustment of the Lennard-Jones potential interactions. The average cluster size and distribution, along with the radius of gyration are used to characterize the collapse dynamics. Our results indicate that there are several kinetic mechanisms that lead to a collapsed polymer. At early times the dominant mechanisms involve cluster creation and growth by adsorption of slack polymer, whereas for later times the mechanism involves cluster coarsening. For this latter mechanism we find that the average cluster size 〈s〉 grows as 〈s〉=Atz, where z is dependent on u3, the third virial coefficient. Depending on the value of u3 we determine two values for z, first, z=0.60±0.02 for u3 not equal to zero and second z=0.66±0.03 for u3 equal to zero, both representing a departure from Lifshitz–Slyozov theory.

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This study is a review of the psychiatric and neurological effects of solvent inhalation on a group of 22 patients with chronic histories of solvent abuse, primarily toluene-based solvents. The findings suggest that the chronic inhalation of toluene-based adhesives can produce a paranoid psychosis which may persist. Other findings were a high incidence of temporal lobe epilepsy and decrease in IQ. We suggest that the psychiatric and neurological sequelae of chronic solvent abuse are serious and potentially irreversible. Toluene is felt to be a major factor in the morbidity associated with chronic solvent abuse, and attention is drawn to the necessity for educational programs in this area. The burden caused by the resulting psychiatric problems resulting from solvent abuse may have implications for health care budgets.

Background Injury incidence in soccer players has received wide attention, but there is a lack of information dealing with match offi cials. Objective To examine the profi le and incidence of injury in soccer match offi cials. Design A 12 month prospective cohort injury surveillance programme. Setting Elite soccer referees and assistant referees who were part of the Football Association of Ireland referee database. Participants 31 participants (27 males and 4 females), mean age 33.2 (6.2) years old (69% of the available cohort). Assessment of risk factors Weekly web based survey, followed up by a telephone interview in those cases who reported injury. Main outcome measurements Details of training and match offi ciating. New injuries in terms of site of the body, type of injury, where, when and how it took place.