Acoustic observations of suspended participate matter in the ocean
CLOUDS of suspended particulate matter in the ocean have been observed by satellite1, sensed by nephelometers2, and sampled by water bottles. We present here evidence that it may be possible to observe oceanic suspended particulate matter acoustically. The particulate matter discussed is thought to have arisen from a dredging operation. It is also thought that the suspended matter is present at lower concentrations than any in any other case recorded acoustically3. Certain questions, as yet unresolved, regarding acoustic scattering strengths are also discussed.
A Microprocessor Based Echo Integration System for Fisheries Research
Acoustic techniques are now widely used in fisheries research and management. One method used to estimate the total biomass in a specific area is the integration of echo sounder signals. A portable, microprocessor-based digital echo integrator has been developed that greatly simplifies real-time analysis of echo sounder data. Up to 30 depth intervals may be entered, along with TVG correction factors. Bottom tracking prevents the integration of bottom signals, and an operator-selected threshold reduces noise sensitivity. Constants may be entered to compensate for unique system parameters (source level, beam pattern, etc.). A bottom-locked mode of operation is also possible. The system is also designed to operate as a data logger with two channel capability. Raw data are digitized at a 7.45 kHz data rate for storage on digital magnetic tape. This system should be very useful in fisheries or oceanographic problems which require "real-time" data analysis.
Communicative Competence: Theory and Classroom Practice
ABSTRACT Within the framework of viewing communicative competence as a prerequisite to linguistic competence, rather than vice versa, this paper considers the following: (1) the nature of communicative competence; (2) the implications of communicative competence for second language teaching; and (3) ways in which the teacher can begin to make a foreign language program more meaningful. Communicative competeuce is defined as what native speakers know which enables them to interact effectively with each other. Implications for the language teacher include: (T) the need for tests which measure the ability to use language; (2) the irrelevancy of sequencing surface features; (3) the need for emphasis on non-lizguistic aspects of communication; and (4) the need to re-examiLe attitudes toward students and language teaching. Practical suggestins for implementing communicative competence in the classroom include the use of spontaneous role-playing, discussions, games, radio, and the telephone. (AM)