Skimboarding: a new cause of water sport spinal cord injury.

STUDY DESIGN: Case series. OBJECTIVE: To present three cases of spinal cord injuries associated with skimboarding and to suggest aspects of the sport that may be associated with spinal cord injury. SETTING: Shepherd Center, Atlanta, GA, USA. Spinal cord injury rehabilitation facility. METHODS: Three males, aged 17-23 years, sustained cervical spine fractures resulting in tetraplegia after skimboarding accidents. RESULTS: The patients admitted from Florida hospitals presented with tetraplegia resulting from both incomplete and complete spinal cord injuries. The ASIA Impairment Scale (AIS) neurologic levels ranged from C3 to C5. All were injured by being thrown from the skimboard riding into the waves in shallow water. All patients required surgical stabilization and inpatient rehabilitation. CONCLUSIONS: Previous studies on skimboarding have demonstrated the risk of extremity fractures and soft tissue injuries. Spinal cord injury should be considered an additional risk associated with skimboarding, particularly as the sport has grown in popularity and become more 'extreme' in the maneuvers performed. Increased education and awareness about the potential risk of spinal cord injury are essential.

Seasonal susceptibility of 'Bartlett' pears to codling moth (Lepidoptera: Tortricidae) infestation and notes on diapause induction.

Seasonal susceptibility of 'Bartlett' pear, Pyrus communis L., to codling moth, Cydia pomonella (L.), infestation, successful completion of larval development after infestation, and the induction of C. pomonella diapause was studied from 1992 through 1995. The seasonal variation in C. pomonella infestation and larval survival were effected by changes in fruit maturity. In late May through mid-June, pears were hard and were not as successfully infested by C. pomonella and produced less larvae compared with fruit later in the season. In late June to mid-July, pears became more suitable for infestation and a greater percentage of the larvae completed their development. In late July through mid-August, pears were susceptible to infestation, but the larvae were less likely to successfully complete development than in the late June to mid-July period due to pear tissue breakdown. From mid-August through September, pears are unsuitable for infestation, and few larvae were produced. When fruit were infested with neonate larvae in late May and mature larvae emerged from the fruit in July, a low percentage of the larvae entered diapause. However, when fruit were infested with neonate larvae in early July and mature larvae emerged from the fruit in early August, the majority of the larvae entered diapause. When fruit were infested with neonate larvae in late July through September and mature larvae emerged from the fruit after mid-August, nearly all C. pomonella larvae had entered diapause.

Autoparasitism, interference, and parasitoid-pest population dynamics.

Autoparasitoids ("heteronomous hyperparasitoids") are parasitoids that lay female eggs on homopteran hosts and male eggs on juvenile parasitoids of either the same species or another species. Males develop as hyperparasitoids and eventually kill the juvenile parasitoid. We present a series of stage-structured models that investigate the effects of autoparasitism on population dynamics. Autoparasitism causes density-dependent mortality on juvenile parasitoids and therefore has a stabilizing effect. This also leads to an increase in host population abundance. In most cases an autoparasitoid leads to higher host equilibrium densities than a comparable primary parasitoid (except when the primary parasitoid is arrhenotokous (sexual) and the autoparasitoid has a low preference for attacking parasitized hosts or can attack the parasitized host for only a small portion of its development). When male autoparasitoids are followed explicitly in the models, mate limitation reduces the stabilizing effect of autoparasitism and leads to a further increase in host abundance. Coexistence of an autoparasitoid with a nonprimary parasitoid or second autoparasitoid is possible when the level of conspecific autoparasitism is greater than the level of heterospecific autoparasitism. When an autoparasitoid coexists with a primary parasitoid, the resulting host density is always greater than that with only the primary parasitoid. Therefore, autoparasitoids have the potential to disrupt control achieved by primary parasitoids. When two autoparasitoids coexist, the resulting host density is always lower than that attained by either autoparasitoid alone. The effects of autoparasitism are compared with those of other forms of interference competition.

Duplication diet study on mercury intake by fish consumers in the United Kingdom.

Hair samples were analyzed for mercury in 942 persons living in either one of two coastal areas of the United Kingdom who reported above average fish consumption. A duplicate diet study group was selected from the 942 individual's who had elevated concentrations of mercury in their hair. The study group's fish consumption averaged 0.36 kg/person . wk during the duplicate diet. Concentration of total mercury in the blood of the study group ranged from 1.1 to 42.3 micrograms/L with an arithmetic mean of 8.8 micrograms/L. The linear curve fitted to the data on the concentration of total mercury in blood vs. mercury intake was similar to that observed in a previous study made in the United Kingdom, but different from that observed in other studies. The results from the present study indicate that people in the United Kingdom are unlikely to be adversely affected by the presence of methylmercury in the fish they consume.