This study explored the survival and growth of the marine amphipod Hyaie crassicomis under different conditions of ambient temperature and salinity in the laboratory. In 96-h exposure experiments at a salinity of 30, //. crassicamis tolerated temperatures between 6 and 28 C C>90% survival). The 96-h LT50 value (median lethal temperature) at high temperature range for the amphipod was 32 C. The values at low temperature range for adults and juveniles were 3.2 and 4.2 C, respectiveiy, indicating that adults have a higher tolerance to low temperature than juveniles. At 25 C, the amphipods tolerated salinities between 10 and 50 (with >80% survival in 96 h). The 96-h LS^o values at high and low sahnity ranges were 56 and 2, respectively. Growth of the juveniles ft'om instars 1 to 6 was determined under different combinations of temperature and salinity. Growth rate of juveniles culrured at 25 C and a salinity-of 20 was the highest (0.114 mm day ') among the combinations of 15-25 C and 10-40 salinity. The moult increment of body length was afFected by both temperature and salinity. Yet the intermoult duration ofthe amphipods was affected by temperature only but not by salinity.

In multiband excitation (MBE) vocoders, the excitation spectrum is a series of voicedunvoiced (viuv) bands. This allows each speech segment to be partially voiced and partially unvoiced. It has been found that excitation in low frequency region is mostly voiced whereas in high frequency area, it is usually unvoiced. Although dividing the excitation spectrum into several viuv bands (12 bands are commonly used) provides better output speech quality, its implementation for very low bit rate transmission is very difficult, if not impossible. In this paper, a modified version called dualband excitation LSP vocoder is proposed. The excitation spectrum, in this case, contains either one or two viuv bands. Line spectral pairs (LSP) are used to represent the spectral envelope because of its effectiveness. Speech quality at a transmission rate of 2 kbps has been found to be clear and intelligible.

The excitation parameters of a multiband excitation model for speech production consist of a pitch period and a series of voiced/unvoiced (v/uv) decisions for a number of fixed frequency bands around the harmonics of the fundamental. In this paper, it is shown that, at most, four v/uv variable-length nonoverlapping frequency bands spanning over the telephone bandwidth are adequate to represent the excitation spectrum that provides an improved modeling of mixed voicing and noisy speech. A quad-band excitation (QBE) method is presented which generates excitation source for a linear prediction vocoder for low bit rate transmission of speech signal and the DRT scores validate the potential of the method.

We have developed an efficient method of generating short bursts of picosecond optical pulses. The multiplying stage consists of simple optical elements, including 50/50 beam splitters and a 100% reflecting mirror. Time delay between the pulses can be adjusted by changing the incident angle of the beam or the separation of the splitters. The multiplying scheme has been successfully applied to the output of a cw mode-locked Nd:YAG laser at 82 MHz. Multiplication of beam pulses up to a factor of 8 was demonstrated. This technique promises to increase the repetition rate of laser pulses up to hundreds of gigahertz.