Stable isotopic characterization of a coastal floodplain forest community: a case study for isotopic reconstruction of Mesozoic vertebrate assemblages.

Stable isotopes are powerful tools for elucidating ecological trends in extant vertebrate communities, though their application to Mesozoic ecosystems is complicated by a lack of extant isotope data from comparable environments/ecosystems (e.g. coastal floodplain forest environments, lacking significant C4 plant components). We sampled 20 taxa across a broad phylogenetic, body size, and physiological scope from the Atchafalaya River Basin of Louisiana as an environmental analogue to the Late Cretaceous coastal floodplains of North America. Samples were analysed for stable carbon, oxygen and nitrogen isotope compositions from bioapatite and keratin tissues to test the degree of ecological resolution that can be determined in a system with similar environmental conditions, and using similar constraints, as those in many Mesozoic assemblages. Isotopic results suggest a broad overlap in resource use among taxa and considerable terrestrial-aquatic interchange, highlighting the challenges of ecological interpretation in C3 systems, particularly when lacking observational data for comparison. We also propose a modified oxygen isotope-temperature equation that uses mean endotherm and mean ectotherm isotope data to more precisely predict temperature when compared with measured Atchafalaya River water data. These results provide a critical isotopic baseline for coastal floodplain forests, and act as a framework for future studies of Mesozoic palaeoecology.

Treated delinquent boys' substance use: onset, pattern, relationship to conduct and mood disorders.

We describe relationships between substance use, conduct disorder (CD), depression, and history of self-injury or suicide attempts, in referred, delinquent, substance involved, adolescent males. Sixty youths (mean age 16.3 years) completed standardized assessments for substance use and other psychiatric disorders, aggressiveness, and social class. All boys met modified criteria for CD. Most had high aggression ratings. Twenty percent had depressive diagnoses. By age 13, 78% had begun regular substance use. Marijuana was the first substance for 42%. The boys had substance dependence on a mean of 3.2 different drugs (usually including alcohol and marijuana), with abuse of an average of one additional drug. CD symptoms began 3.6 years (mean) before regular use. CD symptom count correlated with number of dependence diagnoses, and both of those (but not depression) related significantly to suicide attempt and self-injury histories. Improved understanding of substance involvement in youths with CD may generate more rational prevention and treatment.

An analysis of patient accidents in hospital.

An analysis of patient accidents occurring at St Vincent's Hospital, Sydney in 1990 was undertaken using data obtained from the hospital's computerized accident database. Ward, age and sex specific fall rates were calculated from a total of 800 patient-related accidents and incidents reported. Ninety per cent of all accidents were falls, the majority occurring in patients over the age of 60 years. Female patients experienced a significantly greater rate of accidents than male patients (P < 0.05). No significant difference in the overall fall rates for males and females was found. However males 50 years of age and under were almost twice as likely to fall as females in this age group. More than 50% of patients who fell sustained an injury; 4% of these were serious injuries. The geriatric, neurosciences and HIV wards had the highest rates of patient falls. Nearly 40% of falls involved only 77 patients who fell on multiple occasions. Preventative strategies are discussed. Patient accident data from other Australian hospitals is required for adequate assessment of the incidence of patient accidents.