The STREAM Initiative: support to regional aquatic resources management. Promoting participation, communication, and policies that support the livelihoods of poor aquatic resource users in the Asia-Pacific. Memorandum

Throughout the Asia-Pacific region capture fisheries and certain less intensive forms of aquaculture can and do play a vital role in livelihoods management, food security, and health and nutrition. Knowledge and experience exist that could be more effectively used in policy for poverty alleviation. (PDF contains 89 pages)

The Colorado River; a source of water and power for Los Angeles

The rapid growth and development of Los Angeles City and County has been one of the phenomena of the present age. The growth of a city from 50,600 to 576,000, an increase of over 1000% in thirty years is an unprecedented occurrence. It has given rise to a variety of problems of increasing magnitude.

Chief among these are: supply of food, water and shelter development of industry and markets, prevention and removal of downtown congestion and protection of life and property. These, of course, are the problems that any city must face. But in the case of a community which doubles its population every ten years, radical and heroic measures must often be taken.

The oculomotor system: (1) Vertical-horizontal interaction and signal recognition, (2) Time delays and power spectra

In the first section of this thesis, two-dimensional properties of the human eye movement control system were studied. The vertical - horizontal interaction was investigated by using a two-dimensional target motion consisting of a sinusoid in one of the directions vertical or horizontal, and low-pass filtered Gaussian random motion of variable bandwidth (and hence information content) in the orthogonal direction. It was found that the random motion reduced the efficiency of the sinusoidal tracking. However, the sinusoidal tracking was only slightly dependent on the bandwidth of the random motion. Thus the system should be thought of as consisting of two independent channels with a small amount of mutual cross-talk.

These target motions were then rotated to discover whether or not the system is capable of recognizing the two-component nature of the target motion. That is, the sinusoid was presented along an oblique line (neither vertical nor horizontal) with the random motion orthogonal to it. The system did not simply track the vertical and horizontal components of motion, but rotated its frame of reference so that its two tracking channels coincided with the directions of the two target motion components. This recognition occurred even when the two orthogonal motions were both random, but with different bandwidths.

In the second section, time delays, prediction and power spectra were examined. Time delays were calculated in response to various periodic signals, various bandwidths of narrow-band Gaussian random motions and sinusoids. It was demonstrated that prediction occurred only when the target motion was periodic, and only if the harmonic content was such that the signal was sufficiently narrow-band. It appears as if general periodic motions are split into predictive and non-predictive components.

For unpredictable motions, the relationship between the time delay and the average speed of the retinal image was linear. Based on this I proposed a model explaining the time delays for both random and periodic motions. My experiments did not prove that the system is sampled data, or that it is continuous. However, the model can be interpreted as representative of a sample data system whose sample interval is a function of the target motion.

It was shown that increasing the bandwidth of the low-pass filtered Gaussian random motion resulted in an increase of the eye movement bandwidth. Some properties of the eyeball-muscle dynamics and the extraocular muscle "active state tension" were derived.

Field enhancement and power distribution characteristics of subwavelength-diameter terahertz hollow optical fiber

Fields in subwavelength-diameter terahertz hollow optical fiber (STHOF) can be intensified by large discontinuity of the electric field at high index contrast interfaces. The influences of fiber geometry and refractive index of the dielectric region on the fiber characteristics, such as power distribution, enhancement factor, have been discussed in detail. By appropriate design, the intensity in the central region of STHOF may be enhanced by a factor of greater than 1.5 compared with subwavelength-diameter terahertz fiber without the central hole and the loss can be reduced. For its compact structure and simple fabrication process, the fiber may be very useful in many miniaturized high performance and novel terahertz photonic devices. (c) 2007 Elsevier B.V. All rights reserved.

How can online schedules improve communication and estimation tradeoff?

We consider remote state estimation and investigate the tradeoff between the sensor-to-estimator communication rate and the remote estimation quality. It is well known that if the communication rate is one, e.g., the sensor communicates with the remote estimator at each time, then the remote estimation quality is the best. It degrades when the communication rate drops. We present one optimal offline schedule and two online schedules and show that the two online schedules provide better tradeoff between the communication rate and the estimation quality than the optimal offline schedule. Simulation examples demonstrate that significant communication savings can be achieved under the two online schedules which only introduce small increment of the estimation errors. © 1991-2012 IEEE.