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.

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

Jump relaxation in solid electrolytes

The applications and interest in thermal analysis and calorimetry have grown enormously during the last half of 20th century. The renaissance in these methods has been fueled by several influences, not least of which has been the revolution in instrumentation resulting from computer automation. Our ingenuity and vision have also expanded to recognize the tremendous versatility of these techniques. They have long been used to characterize materials, decompositions, and transitions. We now appreciate the fact that these techniques have greatly increased their utility in studying many processes such as catalysis, hazards evaluation, etc., or to measuring important physical properties quickly, conveniently, and with markedly improved accuracy. Consequently, thermal analysis and calorimetry have grown in stature and more scientists and engineers have become, at least part time, practitioners. It is very desirable that those who are new to the field can have a source of information describing the basic principles and current state of the art. Examples of the prevailing applications of these methods are also essential to spur recognition of the potential for future uses. The use of these methods is highly interdisciplinary and any adequate description must encompass a range of topics well beyond the interests and capabilities of any single investigator. To this end, a convenient four-volume compendium of such information has been prepared by recognized experts in various aspects of the topic. The editorial team has chosen authors with great care in an effort to produce a readable, informative handbook on this broad topic. The chapters are not intended to be a comprehensive review of the specific subject. The purpose is that they will enable the reader to glean the essence of the subject and form the basis for further critical reading or actual involvement in the topic. The goal of the editorial team is to spur the imagination to recognize the potential application of these methods to specific goals and efforts. In addition it is hoped to anticipate and answer questions, to guide the reader in the selection of appropriate techniques, and to help him perform them in a proper and meaningful manner.

Handbook of thermal analysis and calorimetry

Ionic conduction in space charge regions

During the quadrennial term 1979–1982, major advances have been made in our knowledge of the rheology of the oceanic lithosphere by the skillful combination of experimental and theoretical rock mechanics, seismology and marine geophysics in increasingly sophisticated models for the flexure of the oceanic lithosphere at seamounts and island chains, along transform faults, and at subduction zones. The relative simplicity of plate bending geometry, thermal history, and mineralogical and chemical compositions of the oceanic plates in these settings make the geophysical observations very powerful constraints on the in situ rheology of the oceanic lithosphere. In the first part of this paper, I review the laboratory work on materials appropriate to the oceanic lithosphere with emphasis on contributions during the quadrennial period and the need for future work. The important results of flexure models incorporating realistic material properties are then summarized.

Rheology of the lithosphere

This chapter deals essentially with the reaction between two solids A and B to form one or more product phases (A m B n ). During the course of this heterogeneous solid-solid reaction A m B n separates the reactants spatially. Therefore the progress of the reaction has to be attributed to a transport of the reactants across phase boundaries and through the reaction product.

Solid state reactions

Preface Symbols and Definitions Introduction Thermodynamics of Point Defects One- and Two-dimensional Defects in Crystals Basic Kinetic Concepts and Situations Kinetics and Dynamics. Local Equilibrium Heterogeneous Solid State Reactions Oxidation of Metals Solids in Thermodynamic Potential Gradients Internal Reactions Reactions At and Across Interfaces Morphology Phase Transformations Reactions in Solids Under Irradiation Influence of Mechanical Stress Transport and Reactions In Special Systems Appendix: Experimental methods for in-situ investigations.

Hermann Schmalzried

Papers

Solid state reactions

Chemical kinetics of solids

Ionen- und Elektronenleitung in binären Oxiden und ihre Untersuchung mittels EMK-Messungen

Solid State Reactions

Internal solid state reactions