Organic Glasses: A New Class of Photorefractive Materials

The performance of amorphous organic photorefractive (PR) materials in applications such as optical data storage is generally limited by the concentration of active molecules (chromophores) that can be incorporated into the host without forming a crystalline material with poor optical quality. In polymeric PR systems described previously, performance has been limited by the necessity of devoting a large fraction of the material to inert polymer and plasticizing components in order to ensure compositional stability. A new class of organic PR materials composed of multifunctional glass-forming organic chromophores is described that have long-term stability and greatly improved PR properties.     

The Origin of the Great Bend of the Nile from SIR-C/X-SAR Imagery

The course of the Nile in northern Sudan follows a contorted path through Precambrian bedrock. Radar imagery shows that basement structures control the river's course in this region. Northward-flowing segments follow Precambrian fabrics, whereas east-west segments follow faults of much younger age. These faults may reflect recent uplift of the Nubian Swell and deflection of the river to the southwest to form the great bend of the Nile.     

RELATIONSHIPS BETWEEN NET REDISTRIBUTION OF Al AND Fe AND EXTRACTABLE LEVELS IN PODZOLIC SOILS DERIVED FROM LOWER PALAEOZOIC SEDIMENTARY ROCKS

Examination of the translocation and net redistribution of Al and Fe in podzolic soils on Lower Palaeozoic sedimentary rocks has shown marked differences in behaviour between the two elements. Iron exhibits the classical pattern of eluviation and illuviation, the consequences of which are closely correlated with amounts of ‘active’ Fe extracted with pyrophosphate. On the other hand Al rarely accumulates in B horizons enriched in Fe. In addition pyrophosphate-extractable Al is unrelated to its net redistribution pattern. Stagnopodzols on Lower Palaeozoic sediments are strongly acidic throughout and show a characteristic trend in oxidation/reduction conditions with depth. It is the differential response of Al and Fe to the combination of these properties, particularly in relation to their effect on illuviation, which accounts for the observations.     

Relationships between electrocardiographic findings, racing performance and training in Standardbred horses

SUMMARY The presence of abnormal T waves in three or more electrocardiographic leads has been used to diagnose the cause of poor race performance in horses. This study investigated the relationship between previous racing performance in Standardbred horses and T waves, and the effect of training on the T wave. Thirty-two horses were electrocardiographed in two Sydney racing stables. Sixteen horses (50%) had ECGs with three or more leads with abnormal T waves, and these horses had won more races, had a greater ratio of wins per start and a greater number of dollars earned per start than horses with less than three abnormal T waves (P < 0.05). Horses with abnormal T waves also had significantly faster racing times (P < 0.01). There were significant (P < 0.01) correlations between the number of abnormal T waves and both number of wins (R = 0.47) and dollars earned per start (R = 0.45). Fastest winning mile rate was also negatively correlated with number of leads with abnormal T waves (R =?0.52, P < 0.01). Twenty two horses were also electrocardiographed within seven days of good racing performance. The mean number of abnormal T waves was 2.7 ± 0.41, and the mean T wave amplitude in the four chest leads (CV, CR, CL, CF) was 0.9 ± 0.15 mV. Thirteen horses (59%) had abnormal T waves in three or more leads. The effect of training on the T wave was also investigated in nine previously untrained and unraced Standardbred racehorses. There were significant effects of training (P < 0.01) on the number of abnormal T waves and mean chest lead T wave amplitude. These increases occurred in the second phase of training during which faster exercise, race trials and racing were conducted. We concluded that abnormal T waves are a common finding in the race-fit Standardbred horse, and can be found in more than 50% of horses currently performing well in races. In addition, chest lead T waves become more positive after training.