Neural systems underlying the suppression of unwanted memories

Over a century ago, Freud proposed that unwanted memories can be excluded from awareness, a process called repression. It is unknown, however, how repression occurs in the brain. We used functional magnetic resonance imaging to identify the neural systems involved in keeping unwanted memories out of awareness. Controlling unwanted memories was associated with increased dorsolateral prefrontal activation, reduced hippocampal activation, and impaired retention of those memories. Both prefrontal cortical and right hippocampal activations predicted the magnitude of forgetting. These results confirm the existence of an active forgetting process and establish a neurobiological model for guiding inquiry into motivated forgetting.     

Multiple-step melting in two-dimensional hexatic liquid-crystal films

An unexpected three-stage melting transition has been observed in two-dimensional (2D) free-standing liquid-crystal films by in situ electron-diffraction and optical-reflectivity measurements. These data suggest the existence of two phases between the 2D solid and liquid: a hexatic phase and, at a higher temperature, an intermediate liquid phase with hexatic-like positional correlations ( approximately 40 angstroms) but no long-range orientational order. Previous high-resolution heat-capacity measurements have revealed a divergent-like anomaly at the hexatic-liquid transition that sharply contradicts the predictions of 2D melting theories. The observation of an intermediate isotropic phase may alter our understanding of 2D melting and lead to reconciliation between current experiments and theories.     

Diethylstilboestrol—clinical pharmacology and alternatives in small animal practice

Diethylstilboestrol is currently only available in Australia for oral use in dogs and cats. As an orally and systemically active non-steroidal oestrogen, DES has been widely used in small animal veterinary medicine for a variety of indications. A review of the literature reveals that many of the recommendations for use are founded on anecdotal or unreported clinical observations. While many of the uses may be valid, accurate determinations of optimum dosing regimens have not been defined. This is especially unfortunate in view of the potential toxicity of DES to small animals. Nevertheless, particularly in cases of low-dose intermittent administration, oral DES appears indicated at least until data on alternative safe and effective interventions become available.     

Incidence rate of musculoskeletal injuries and determinants of time to recovery in young Australian Thoroughbred racehorses

Objective To describe the incidence rate of musculoskeletal (MS) injuries and investigate the factors that influence recovery from MS injury in young Thoroughbred horses in Australia. Methods Training and injury data were collected at fortnightly intervals from 14 trainers in New South Wales. Incidence rates were calculated for initial injuries stratified by age‐class and sex. Survival analysis methods were used to investigate the time to recovery after the first MS injury (measured as a start in a race or barrier trial). Results For the 248 racehorses enrolled, there were 428 injuries recorded; 2‐year‐olds were 2.99‐fold more likely than 3‐year‐olds to sustain an MS injury. The cumulative percentage of horses that had recovered within 6 months was 55%. The time to recovery was longest in horses whose fast gallop speed prior to injury was < 890 m/min. Conclusion This study supports the finding that shin soreness is the most common MS injury in young Australian Thoroughbreds. There was an increased rate of MS injury in 2‐year‐olds compared with 3‐year‐olds. However, it was impossible to determine if the increased risk in 2‐year‐olds was related to age, the start of training or a combination of both. The study also found that horses performing at higher exercise speeds prior to injury were more likely to recover. There was a significant effect of trainer, suggesting that other factors related to trainer may influence the time to the recovery. Additional research is required to understand the determinants of time to recovery.