1980 Preface * 1999 Preface * 1999 Acknowledgements * Introduction * 1 Circular Logic * 2 Phase Singularities (Screwy Results of Circular Logic) * 3 The Rules of the Ring * 4 Ring Populations * 5 Getting Off the Ring * 6 Attracting Cycles and Isochrons * 7 Measuring the Trajectories of a Circadian Clock * 8 Populations of Attractor Cycle Oscillators * 9 Excitable Kinetics and Excitable Media * 10 The Varieties of Phaseless Experience: In Which the Geometrical Orderliness of Rhythmic Organization Breaks Down in Diverse Ways * 11 The Firefly Machine 12 Energy Metabolism in Cells * 13 The Malonic Acid Reagent ('Sodium Geometrate') * 14 Electrical Rhythmicity and Excitability in Cell Membranes * 15 The Aggregation of Slime Mold Amoebae * 16 Numerical Organizing Centers * 17 Electrical Singular Filaments in the Heart Wall * 18 Pattern Formation in the Fungi * 19 Circadian Rhythms in General * 20 The Circadian Clocks of Insect Eclosion * 21 The Flower of Kalanchoe * 22 The Cell Mitotic Cycle * 23 The Female Cycle * References * Index of Names * Index of Subjects

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/596B270197FE27DE5FABB598B6210622/S0025557200150892a.pdf/div-class-title-span-class-italic-the-geometry-of-biological-time-span-by-a-t-winfree-pp-544-dm68-corrected-second-printing-1990-isbn-3-540-52528-9-springer-div.pdf

The geometry of biological time , by A. T. Winfree. Pp 544. DM68. Corrected Second Printing 1990. ISBN 3-540-52528-9 (Springer)

https://users.dimi.uniud.it/~antonio.dangelo/Robotica/2012/helper/leggedRobot/Ijspeert08NN.pdf

2008 Special Issue: Central pattern generators for locomotion control in animals and robots: A review

The goal of this paper is to review in brief the basic physics of single-election devices, as well as their-current and prospective applications. These devices based on the controllable transfer of single electrons between small conducting "islands", have already enabled several important scientific experiments. Several other applications of analog single-election devices in unique scientific instrumentation and metrology seem quite feasible. On the other hand, the prospect of silicon transistors being replaced by single-electron devices in integrated digital circuits faces tough challenges and remains uncertain. Nevertheless, even if this replacement does not happen, single electronics will continue to play an important role by shedding light on the fundamental size limitations of new electronic devices. Moreover, recent research in this field has generated some by-product ideas which may revolutionize random-access-memory and digital-data-storage technologies.

Single-electron devices and their applications

The electronic properties of inorganic devices such as memristors can be used to simulate neurological behaviour. In particular, ionic and electronic effects in a silver sulphide device are now shown to mimic short- and long-term synaptic functions. Memory is believed to occur in the human brain as a result of two types of synaptic plasticity: short-term plasticity (STP) and long-term potentiation (LTP; refs 1, 2, 3, 4). In neuromorphic engineering5,6, emulation of known neural behaviour has proven to be difficult to implement in software because of the highly complex interconnected nature of thought processes. Here we report the discovery of a Ag2S inorganic synapse, which emulates the synaptic functions of both STP and LTP characteristics through the use of input pulse repetition time. The structure known as an atomic switch7,8, operating at critical voltages, stores information as STP with a spontaneous decay of conductance level in response to intermittent input stimuli, whereas frequent stimulation results in a transition to LTP. The Ag2S inorganic synapse has interesting characteristics with analogies to an individual biological synapse, and achieves dynamic memorization in a single device without the need of external preprogramming. A psychological model related to the process of memorizing and forgetting is also demonstrated using the inorganic synapses. Our Ag2S element indicates a breakthrough in mimicking synaptic behaviour essential for the further creation of artificial neural systems that emulate characteristics of human memory.

/pdf/short-term-plasticity-and-long-term-potentiation-mimicked-in-3c6onjbc0r.pdf

Short-term plasticity and long-term potentiation mimicked in single inorganic synapses

Computational geometry

Introduction We propose an analog CMOS circuit that implements a biologically-inspired locomotion controller for quadruped walking robots. The circuit is designed for emulating a central pattern generator (CPG), which is a biological neural network that can generate rhythmic movements for locomotion of animals [1]. We have fabricated a prototype chip using standard CMOS technology. From the experimental results on the prototype chip, we have confirmed desired performances of the proposed circuit. CPG Circuit The proposed circuit is based on a CPG model constructed from the Wilson-Cowan (WC) neural oscillator that can be easily implemented on a silicon chip [2]. Figure 1 shows the schematic of the WC neural oscillator circuit that consists of excitatory and inhibitory neuron circuits, both of which interact with each other via capacitive couplings. We constructed a network circuit (hereafter call the CPG circuit) from the WC neural oscillator circuits. Depending on coupling configurations (Fig. 2), a CPG circuit can produce various rhythmic patterns that correspond to the typical locomotion patterns of animals, such as walk, trot, and gallop. We have applied such rhythmic patterns to locomotion control in quadruped walking robots. Experimental results The CPG circuit was fabricated on a prototype chip using standard CMOS process (MOSIS AMIS 1.5-um). By changing circuit configurations, we measured voltages on the fabricated chip. Figures 3(a)-(b) show waveforms of the voltages that correspond to the locomotion patterns, such as trot and walk. The results show that the CPG circuit can produce stable rhythmic patterns under noisy environment (SNR:30dB). Conclusions An analog CMOS circuit was proposed for locomotion control in quadruped walking robots. By experiments on a fabricated chip, we have confirmed that the CPG circuit has capability of producing stable rhythmic patterns under an actual (noisy) environment. Such characteristics of the CPG circuit are suitable for robot locomotion control in real situations. In future work, we are going to incorporate our chip into a quadruped walking robot.

/pdf/an-experimental-chip-for-bio-inspired-locomotion-controller-2r8c4kussm.pdf

An Experimental Chip for Bio-Inspired Locomotion Controller based on the Wilson-Cowan Neural Oscillator

In GHz-clock speed LSI, clock skew and phase-lagged stable synchronous patterns called modelock are generated using random process variations and RC delays in the clock line [1]. Once this phenomenon occurs, a system will fail because clock-distribution circuits cannot operate in sync. It takes a long time to simulate the phenomenon because of a large number of calculations for nonlinear partial differential equations. Similar phenomena that produce a variety of orders, rhythms, and self-organizing are often observed in nature. A reactiondiffusion (RD) system is a lively, dynamic system that produces such phenomena [2]. Our purpose was to make a hardware accelerator to calculate the modelock phenomenon at a high speed. We describe an RD chip based on an analog cellular-automaton model, which represents our first step toward this goal.

/pdf/reaction-diffusion-chip-implementing-analog-cellular-573typoima.pdf

Reaction-diffusion chip implementing analog cellular-automaton model

We propose a possible circuit structure consisting of single-electron circuits that can extract edges in projected images. Electrical circuits that are designed by mimicking computational structures in living organisms—neuromorphic circuits, would provide an insight in developing even more efficient processors. In this work, based on a well studied model for edge detection in the vertebrate retina [1], we propose a single electron circuit performing the same function, and demonstrate its operation. The vertebrate retina consists of massively interconnected neural cells in a hierarchical structure where edge detection is carried out mainly through three types of cells: (i) photoreceptors which transduce light into electrical signals, (ii) horizontal cells which receive inputs from the superjacent layer of photoreceptors, and produce spatially-averaged outputs in relation to the inputs, and (iii) bipolar cells that produce the difference in amplitudes between the outputs of photoreceptors and horizontal cells [1]. The schematic model is shown in Fig. 1(a). We assume that illuminated (or non-illuminated) photoreceptors produce low (or high) potentials (Fig. 1(b)-P). The outputs are spatially averaged by horizontal cells (Fig. 1(b)-H). The difference in amplitudes between photoreceptors and horizontal cells is obtained by subtracting “H”from their corresponding “P”-values in bipolar cells. Therefore, the non-zero outputs of bipolar cells represent positions of edges in the input image (Fig. 1(b)-B). Based on the retinal model above, we propose a neuromorphic architecture with single-electron oscillators [2]. A single-electron oscillator consists of a tunneling junction Cj, resistance R and a bias voltage source (see insets in Fig. 2). When a positively-biased (or negatively-biased) oscillator is illuminated, photo-induced electron tunneling in Cj occurs [3-4], which leads to voltage drop (or increase) at the node (● in Fig. 2) because of electron tunneling from the ground (or node) to the node (or ground). We refer to this as a firing event. Since the rate of electron tunneling is proportional to the intensity of incident light, the average firing rate of each oscillator would also correspond to the intensity of light input. A unit pixel of the proposed edge extracting circuit is shown in Fig. 2. We implement a retinal photoreceptor (P) with a positively-biased oscillator that is triggered by external light inputs. Horizontal cells (H) are constructed by resistively-coupled single-electron oscillators (negative bias), to emulate extensive gap junctions in retinal cells. Subtractive functions in bipolar cells can qualitatively be imitated by neural excitation and shunting inhibition mechanisms. This is achieved through capacitive coupling between oscillators in the bipolar cell layer (Bx) [5]. An excitatory coupling is achieved by connecting a positively(+) to a negatively(-) biased oscillator. In the absence of an external input, the oscillator node takes a voltage value equivalent to the bias voltage. If tunneling occurs in the positive oscillator, this leads to a drop in the node potential of the coupled negative oscillator below its threshold, thus inducing it to tunnel. Shunting inhibitory coupling is realized by applying the same bias voltage to the two coupled oscillators. For example if the two are positively biased, tunneling in either of them leads to a drop in the node voltage of the other far below the threshold, thus restraining it from tunneling (inhibition) even in the presence of an external trigger input. With these excitatory and inhibitory configurations, we partly imitate subtractive functions of bipolar cells as follows. Let us assume that electron tunneling occurred in P1 (Fig. 2). This induces tunneling in the B1l oscillator to trigger a subsequent tunneling in B1l-B3l branch (excitatory). Simultaneously, tunneling in P1 induces tunneling in H, which in turn induces B2 to tunnel. This activates the inhibitory coupling between B2 and B3l. By so doing, B2 restrains B3l from tunneling, thus reducing its average firing rate. If the B2 cells on both sides of B3l tunnel, they would increase the inhibition effect on it, sufficiently reducing its average tunneling rate. Therefore if adjacent photoreceptors are illuminated, the average firing rates of corresponding output cells (O) would be extremely low in comparison with those at the edges. Through this process, the circuit can detect the edge position, i.e., positions where average firing rates of bipolar cells is high. To confirm the basic operation, we constructed a one-dimensional array circuit consisting of 100 pixel circuits. Light input was incident upon photoreceptors from number 30 to 70. Light input was simulated by applying an external trigger input on photoreceptors. The response of each cell in the photoreceptor, horizontal and bipolar cell layers is shown in Fig. 3. The vertical axis is normalized with the highest average firing rate in the photoreceptor layer. As the figure shows, the average firing rate of the horizontal cells is lower than the corresponding photoreceptors. This is because of the resistive coupling in horizontal layer. The bipolar cells with a high firing rate correspond to the photoreceptors at the edges of the incident image. Thus the proposed single-electron structure can successfully perform as an edge detecting circuit.

/pdf/implementation-of-early-vision-model-for-edge-extraction-40o6bqtv1c.pdf

Implementation of early vision model for edge extraction with single-electron devices

Optimun barrier height and impurity concentration for a power Schottky diode for maximizing rectifying efficiency are theoretically derived. For a low output voltage, 1.5 ~ 2 V as a DC-DC converter, the barrier height has an optimum value of about 17 times the thermal voltage and the impurity concentration has approximately 1 × 1016 cm-3, for n-type silicon. Schottky diodes with some kinds of barrier metals, such as titanium, hafnium and zirconium were fabricated and applied to a forward mode 2 V 50 A DC-DC converter. Power loss and efficiency were investigated in comparison with control molybdenum diodes. Titanium and hafnium diodes reduced the power loss from 49 W to 37 W for main circuit total loss, which improved the efficiency from 67% to 73%, at package surface temperatures below 60°C. These diodes show better efficiency up to 85°C, compared with molybdenum diodes. Smaller heat sinks or cooling fins can be used because of those low loss characteristics.

Schottky Barrier Diode Optimization for a Low Voltage Power Converter

We developed a CMOS integrated-circuit sensor that emulates the change in quality of various perishables. This sensor is attached to perishable goods such as farm and marine products and is carried from producers to consumers along with the goods. During their distribution process, the sensor experiences the surrounding temperature and emulates the deterioration of the goods caused by the surrounding temperatures. By reading the output of the sensor, consumers can determine whether the goods are fresh or not. This sensor consists of subthreshold CMOS circuits with a low-power consumption of 5muW or less

Yoshihito Amemiya

Papers

An Experimental Chip for Bio-Inspired Locomotion Controller based on the Wilson-Cowan Neural Oscillator

Reaction-diffusion chip implementing analog cellular-automaton model

Implementation of early vision model for edge extraction with single-electron devices

Schottky Barrier Diode Optimization for a Low Voltage Power Converter

A Watchdog Sensor for Assuring the Quality of Various Perishables with Subthreshold CMOS Circuits