Autonomous Reaction Research Articles

Noise-induced oscillation and stochastic resonance in an autonomous chemical reaction system.

An autonomous three-variable chemical reaction model, which has been developed to describe kinetic oscillations in the NO+CO reaction, subjected to external parametric noise, is investigated. Noise-induced coherent oscillations (NICO's) in the absence of deterministic oscillations are observed near supercritical Hopf bifurcation points, and the NICO strength goes through a maximum with increments of noise intensity, characteristic of the occurrence of stochastic resonance. On the other hand, these phenomena do not appear if the limit cycle is created by a saddle-loop bifurcation.

Autonomous Navigation of Rovers for Planetary Exploration

For planetary surface exploration, micro-rovers are very attractive to provide mobility functions at small mass requirements. This paper summarises the requirements for a Mars-rover and outlines the control concepts for navigation. In this context autonomous reaction capabilities are necessary, in combination with remote control schemes, to deal with significant signal propagation delays. Specific navigation aspects addressed in this paper include path tracking, instrument fine positioning and hazard avoidance. Finally test facilities to validate these concepts in simulations on Earth are reviewn.

心拍変動と自律神経機能：その臨床と展望 心拍変動による動的自律神経反応の分析：呼吸および心周期信号のｃｏｍｐｌｅｘ ｄｅｍｏｄｕｌａｔｉｏｎ

心拍変動と自律神経機能：その臨床と展望 心拍変動による動的自律神経反応の分析：呼吸および心周期信号のｃｏｍｐｌｅｘ ｄｅｍｏｄｕｌａｔｉｏｎ

Autonomous objects: A natural model for complex applications

Object-oriented database systems are emerging as the “next generation” DBMSs for advanced applications, e.g., VLSI design, mechanical CAD/CAM, software engineering, etc. However, a close analysis indicates that the requirements imposed by these application domains cannot be met by an object-oriented model that relies purely onpassive objects. In this work we go beyond the conventionalsingle-thread-of-control paradigm of passive object models and propose a model ofactive objects which can autonomously initiate responses to environmental changes.Autonomous objects cooperate with each other by synchronous orasynchronous message passing—giving rise to themultiple-thread-of-control in such an environment. It is shown howevents—to which active objects react—can be incorporated into this model. We propose a nondeterministic computational model for the individual active objects that allows the autonomous reaction upon events. We show that this very sparse extension to an object-oriented model gives rise to several high-level features which can be controlled by events. The object-oriented paradigm allows one to isolate the rules according to which events are being raised. This leads to a potentially rather efficient execution model compared to existing relational concepts, which are typically globally-defined event trigger mechanisms.

Measurements and calculations of oscillations and phase relations in the driven gas-phase combustion of acetaldehyde

Oscillations in light emission and species concentrations, are measured as periodic perturbations are simultaneously applied to the input rates of acetaldehyde and oxygen in the gas-phase combustion of acetaldehyde in a continuous-flow stirred tank reactor for conditions where the autonomous reaction itself is oscillatory. The experimental results are compared with the predictions of a five-variable thermokinetic model. We measure periodic responses in the fundamental entrainment band (ratio of frequency of perturbation to frequency of response equal to unity) for four different values of phase shift between the acetaldehyde and oxygen perturbation wave forms as we vary the frequency and amplitude of the external periodic perturbations. Outside of the entrainment bands we find quasiperiodic response. We determine the phases of the light emission and six species concentrations, as measured with a mass spectrometer, with respect to the periodic perturbation, the variation of these phases across the fundamental entrainment band for different values of reactant phase shift and for different amplitudes of perturbation, and the effects of the phase shift between the two input perturbations on the light emission response of the system for different frequencies of perturbation. Both the experiments and calculations predict a widening of the entrainment band with an increase in perturbation amplitude, and the same variation in bandwidths for the four values of reactant phase shift studied. The experiments and calculations also predict the same general trends in light phase and species phases (difference between the light emission and species concentrations with respect to the perturbing wave form) as the band is traversed for different amplitudes of perturbation and for different values of reactant phase shift. Some discrepancies in the species phases exist; however, the similarities which exist between the experiments and the calculations provide further substantiation for the model. We find that changing the phase shift between reactant inflows from 0° to 360° produces a sharp change in light phase near 180°, in both the experiments and calculations. In general, we also find that the light emission remains entrained near the total flux minimum of the perturbing wave form, and we attribute this correlation to the net heat loss which arises from the reactant flux through the reactor.

Pathobiology of pulmonary fibrosis

Pulmonary fibrosis is characterized by an increase in lung matrix and alterations in the numbers and spatial relationships of lung parenchymal cells. The increase in matrix results from a proliferation and “activation” of fibroblasts (FB) with increased production and deposition of matrix macromolecules at sites of lung injury. Connective tissue cell activation is associated with increased gene expression of collagens, fibronectin, proteoglycans and other matrix components; cytoskeletal alterations; and probably also with changes in the expression of matrix receptors and matrix-degrading enzymes and inhibitors. The fibroproliferative reaction involves the participation of a variety of cytokines and inflammatory mediators by resident and inflammatory cells at sites of lung injury. Thickening of the alveolar wall can result secondary to matrix deposition within the interstitium and as a result of “mural incorporation” of organized airspace exudate. However, marked structural remodeling of the gas-exchange tissues, with the development of honeycomb lung, involves airspace fibrosis and alveolar collapse. The latter processes lead to areas of airspace obliteration secondary to airspace filling, and to fibrous adhesion of collapsed septa. The extent of airspace obliteration is determined largely by the severity or extent of epithelial injury. Although lung fibrosis is usually irreversible, the activated state is reversible after clearance of exudate and reepithelialization. A continuing and seemingly autonomous fibroproliferative reaction can result in the face of ongoing injury and delayed repair.

Autonomous splicing and complementation of in vivo-assembled spliceosomes.

We have used an in vivo system generating assayable amounts of a specific pre-mRNA to study the relationship between splicing and an operationally defined nuclear matrix preparation (NM). When NM is prepared by extraction of DNase I-treated nuclei with an approximately physiological concentration of KCl (0.1 M), a portion of NM-associated precursor can be spliced in vitro in the presence of ATP and Mg2+ and in the absence of splicing extract ("autonomous splicing"). We propose that the autonomous reaction, which does not exhibit a temporal lag and is half-complete in 5 min, occurs in fully assembled, matrix-bound ribonucleoprotein complexes (in vivo spliceosomes). Extraction of the NM with concentrations of KCl greater than 0.4 M eliminates autonomous splicing but leaves behind preassembled complexes that can be complemented for splicing with HeLa cell nuclear extract. The splicing complementing factor, representing one or more activities present in the nuclear extract and also in the cytoplasmic S100 fraction, is relatively heat resistant, devoid of an RNA component, and does not bind to DEAE-Sepharose in 0.1 M KCl. It exists in the nucleus in two forms; bound to autonomous spliceosomes and free in the nucleoplasm. Biochemical features of the complementation reaction, and conditions for reversible uncoupling of the two splicing steps are described and discussed.

A model of reaction for planning in dynamic environments

One shortcoming with most AI planning systems has been an inability to deal with execution-time discrepancies between actual and expected situations. Often, these exception situations jeopardize the immediate integrity and safety of the planning agent or its surroundings, with the only recourse being more time-consuming plan generation. In order to avoid such situations, potential exceptions must be predicted during plan execution. Since many application domains (particularly for autonomous systems) are inherently dynamic — in the sense that information is at best incomplete, perhaps erroneous, and changes over time independent of a planning agent's actions — managing action in the world becomes a difficult problem. Action and events in dynamic worlds must be monitored in order to coordinate an agent's actions with its surroundings. This allows the agent to predict and plan for potential future exception situations while acting in the present. This paper introduces an approach to autonomous reaction in dynamic environments. We have avoided the traditional distinction between generating and then executing plans through the use of a dynamic reaction system, which handles potential exception situations gracefully as it carries out assigned tasks. The reaction system manages constraints imposed by ongoing activity in the world, as well as those derived from long-term planning, to control observable behaviour. This approach provides the necessary stimulus/response behaviour required in dynamic situations, while using goal-directed constraints as heuristics for improved reactions. We present an overview of the salient features of dynamic worlds and their impact on traditional planning, introduce our model of dynamic reactivity, describe an implementation of the model and its performance in a dynamic simulation environment, and present an architecture incorporating long-term planning with short-term reactance suitable for autonomous systems applications.

兒童に於ける知的動作の實驗的研究

This experiment is a study of the relation between the intellectual congnition or the logical intelligence and the intellectual activity or the practical intelligence of the child.The subjects we used were ten superior children (C. A. 11; 9-12; 6, I. Q. 119-136) and ten inferior ones (C. A. 11; 7-12; 5, I. Q. 72-98) in the 6th grade of the primary school, and ten feeble-minded children (Debility and Inbecility C. A. 10; 2-14; 3, I. Q. 41-66) for the supplementary experiment.These children were told to lead a ball out of a detour-box by the tools.The principal results were as follows:1. Apprehension of the visual structure of a detour-situation was easy for the superior and inferior children but was considerable difficult for the feeble-minded. The process of thinking there observed from the autonomous habitual reaction to the discovery of a detour-course is regarded as a “dynamic change of figure-groud relief” in the thinking.2. In the detour-handling of rolling, scooping up, giving jumping motion to the ball there could be found no difference in the results of the three groups. This fact suggests that the intellectual congnition and the intellectual activity have no relation to each other insuch a problem.However, in a situation in which a preliminary cognition before handling determines the success or failure of the act, such as the one in which one fails to pass the ball over a place unless one has stopped a hole with some tool brforehand, the superior children showed a more excellent adaptation than the other groups. In such a case, therefore, we observe that the intellectual cognition positively and functionally affects the intellectual acitivity.3, “The solution by direct insight” of the total situation was very rare even with the superior children; but they showed a remarkably better results in the “solution by insight after errors”than the other two group. We wish to explain these facts as one of the concrete processes of the “recoganization of the total structure”.