Pattern-recognition properties of r.a.m./r.o.m. arrays

Arrays of r.a.m.s may be used as trainable logic devices in arrays whose object is to recognise patterns. The way in which such a system is organised is presented and some of the characteristics of the nature of the recognition are discussed     

A purinergic component of the excitatory postsynaptic current mediated by P2X receptors in the CA1 neurons of the rat hippocampus

The pyramidal neurons in the CA1 area of hippocampal slices from 17- to 19-day-old rats have been investigated by means of patch clamp. Excitatory postsynaptic currents (EPSCs) were elicited by stimulating the Schaffer collateral at a frequency below 0.2 Hz. It was found that inhibition of glutamatergic transmission by 20 microM 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) and 100 microM 2-amino-5-phosphonovaleric acid (D-APV) left a small component of the EPSC uninhibited. The amplitude of this residual EPSC (rEPSC) comprised 25 +/- 11% of the total EPSC when measured at a holding potential of -50 mV. The rEPSC was blocked by selective P2 blocker pyridoxal phosphate-6-azophenyl-2'-4'-disulphonic acid (PPADS) 10 microM and bath incubation with non-hydrolysable ATP analogues, ATP-gamma-S and alpha, beta-methylene-ATP at 50 and 20 microM, respectively. The rEPSC was dramatically potentiated by external Zn2+ (10 microM). In another series of experiments exogenous ATP was applied to the CA1 neurons in situ. An inward current evoked by ATP was inhibited by PPADS to the same extent as the rEPSC. It is concluded that, depending on membrane voltage, about one-fifth to one-quarter of the EPSC generated by the excitatory synaptic input to the hippocampal CA1 neurons of rat is due to the activity of P2X receptors.     

Cross-correlation measurement of the turn-on delay and pulsewidthof a Q-switched two-section semiconductor laser

Cross-correlation techniques were employed for direct optical measurement of output versus electrical bias for a Q-switched two-section semiconductor laser. Since the switching scheme is not limited by external connections to the device, the ultrafast dynamics of the diode laser can be investigated. In particular, a turn-on-delay as small as 70 ps was recorded with picosecond accuracy. The FWHM and peak power of the Q-switched pulse were also measured. A numerical simulation was performed, and good agreement with experimental results was achieved     

Alteration of protein metabolism in individual, identified neurons from Aplysia

A search for control mechanisms governing protein metabolism in neurons from Aplysia californica has uncovered two examples of altered patterns of newly synthesized proteins: (1) The pattern of newly synthesized proteins in the R2 neuron is altered when protein synthesis occurs at elevated temperatures (22-30 degrees C as compared with 13-15 degrees C). (2) The processing of newly synthesized 12,000 dalton (12k) material to 6-9,000 dalton (6-9k) size in the R15 neuron (Strumwasser, F. and Wilson, D.F. [1976], J. Gen. Physiol., in press) can be blocked by certain ion replacements. If acetate replaces chloride in the incubation medium during the synthesis of 12k material, an early step in the processing, prior to the actual breakdown of 12k material, is blocked. Experiments with RNA-synthesis inhibitors indicate that none of the mRNAs which code for abundantly synthesized protein species in the R2 or R15 neurons have short (less than 4 hr) half-lives. This result has implications for an earlier report of regulation of protein synthesis in the R15 neuron.     

The AIS-5000 parallel processor

The AIS-5000 is a commercially available massively parallel processor which was designed to operate in an industrial environment. It has fine-grained parallelism with up to 1024 processing elements arranged in a single-instruction multiple-data (SIMD) architecture. The processing elements are arranged in a one-dimensional chain that, for computer vision applications, can be as wide as the image itself. The overall architecture of the system is described. Various components of the system are discussed, including details of the processing elements, data I/O (input/output) pathways and parallel memory organization. A virtual two-dimensional model for programming image-based algorithms for the system is also presented. Performance benchmarks are given for certain simple and complex functions     

The need for intensification in animal production and the consequent pollution problem

The factors affecting the progress towards intensive livestock production are reviewed with particular reference to milk, beef, lamb, pork, bacon, poultry, meat and egg production. The future trends for the further development of intensive production in each class of livestock are considered and the genetic, managerial and economic constraints are briefly discussed. The different systems of management and housing of the various livestock classes are reviewed and the relevance of each system to the production of effluent is described. The reasons for the trend towards greater control of the animals' environment are listed. Finally, the concept of “stocking density” is considered in respect to the problem of pollution in intensive animal production systems and the possible implications of removing all forms of “animal pollution” are placed within the context of the other requirements for food production involving domesticated animals.     

Examination of grain boundaries in polycrystalline solar cells using a scanning optical microscope

A scanning optical microscope in which the object is scanned mechanically is used to produce images from polycrystalline solar cells using both the reflected-light and photoinduced current modes.