中国开展数字音频广播（DAB）的前景

文中论述了在我国开展ＤＡＢ广播的意义，总结了国内外ＤＡＢ的发展状况，分析了ＤＡＢ的经济和社会效益及进行ＤＡＢ播出的困难和风险，提出了中国开展了ＤＡＢ广播的重点和目标及应具备的条件，指出了ＤＡＢ在中国未来的主要应用领域。肯定了在现有条件下开展ＤＡＢ广播的可能性。     

Progress towards using the speed of ultrasound for beef leanness classification

Following the observation of a high correlation between the reciprocal of the speed of ultrasound and lean proportion in beef carcasses, commercial equipment (VOSI) was developed and its performance alongside a smaller assembly (Mini G) is reported. The speed of ultrasound was measured through six sites on beef carcasses within 1 h of stunning: three sites with VOSI and three sites with Mini G. Sides were also scored for fatness and conformation using the EAAP system, and subcutaneous fat depth was measured at 25,50 and 75% of the width of M. longissimus thoracis from the midline at the last rib. All sides were dissected into subcutaneous fat, intermuscular fat, muscle and bone. The reciprocal speed averaged over the three VOSI sites (RV346) was the best single predictor of the proportion of lean in the side. Multiple regression analyses, in predicting per cent lean, showed that addition of conformation score improved the precision of fat score and fat depth for a group of 26 sides. It did not provide a significant improvement over RV346. However, in another group of 50 sides showing more variation in side mass and conformation, conformation score did significantly improve RV346. The best prediction of per cent lean, involving RV346 and tissue thicknesses, gave a residual standard deviation of 1·35%, and conformation score did not significantly improve this regression.     

A neuron membrane mesh representation for visualization of electrophysiological simulations

We present a process to automatically generate three-dimensional mesh representations of the complex, arborized cell membrane surface of cortical neurons (the principal information processing cells of the brain) from nonuniform morphological measurements. Starting from manually sampled morphological points (3D points and diameters) from neurons in a brain slice preparation, we construct a polygonal mesh representation that realistically represents the continuous membrane surface, closely matching the original experimental data. A mapping between the original morphological points and the newly generated mesh enables simulations of electrophysiolgical activity to be visualized on this new membrane representation. We compare the new mesh representation with the state of the art and present a series of use cases and applications of this technique to visualize simulations of single neurons and networks of multiple neurons.     

Characterising the energy deposition events produced by trapped protons in low earth orbit

Men and equipment in space vehicles in low earth orbit are exposed to a wide variety of radiations, but the majority of the dose is due to trapped protons, which have energies of the order of 100 MeV and are low LET particles. These high energy particles produce nuclear fragmentation with high LET secondaries that may be responsible for a significant fraction of dose equivalent. In order to understand better the biological effectiveness of this radiation environment, a portable tissue equivalent proportional counter spectrometer has been developed that automatically records the distribution of energy in a small tissue-like site as a function of time. This instrument weighs about 700 g and will be flown on a number of future space shuttle flights.