ABSTRACT Previously we have developed a free boundary model for local thermal coagulation induced... more ABSTRACT Previously we have developed a free boundary model for local thermal coagulation induced by laser light absorption when the tissue region affected directly by laser light is sufficiently small and heat diffusion into the surrounding tissue governs the necrosis growth. In the present paper keeping in mind the obtained results we state the point of view on the necrosis formation under these conditions as the basis of an individual layer therapy mode exhibiting specific properties. In particular, roughly speaking, the size of the resulting necrosis domain is determined by the physical characteristics of the tissue and its response to local heating, and by the applicator form rather than the treatment duration and the irradiation power.
When heated the living tissue exhibits random nonuniformities in the temperature that are due to ... more When heated the living tissue exhibits random nonuniformities in the temperature that are due to the discreetness of vessel arrangement. Because of strong temperature dependence of the thermal coagulation rate these nonuniformities should substantially affect the necrosis growth induced by local heating. In the present work we study their effect on the form of a necrosis domain when its growth is limited by heat diffusion into the surrounding tissue. In particular, we analyze the mean amplitude and the correlation length of the interface perturbations depending on the main characteristics of the random temperature nonuniformities.
The present chapter is devoted to the experiential now as an individual fundamental entity of the... more The present chapter is devoted to the experiential now as an individual fundamental entity of the complex present that plays the pivot role in dynamics of the human temporality. In our theory, the implementation cost of action strategies is determined by effort. For this reason, we elucidate its essential properties and develop the multi-component theory of subjective effort. Turning to the laws of psychophysics, we develop the description of subjective effort in terms of one-dimensional clouds in the space of effort magnitudes experienced by the subject. Two components of subjective effort are singled out. One is the experienced effort of bodily executed actions. The other is the mental effort related to monitoring the results of bodily actions. The available psychological and physiological data that enable us to develop the original mathematical description of subjective effort are presented. In particular, the power-law of memory load, the regularities of speed-accuracy tradeoff are used to construct the mental effort of monitoring which admits the interpretation as quasi-entropy of subject’s actions. To fuse the two types of subjective effort, we propose a new concept of an endless cloud cycle dealing with effort-as-experienced and effort-as-evaluated. This concept enables us to employ the notion of time-to-fatigue in order to make the two types of subjective effort mutually commensurable. As a result, a nonlinear model for the effort fusion is elaborated, which may be treated as an analogy to free energy. The appendix presents the details of the mathematical constructions and experimental data on binary categorization that underlie the mathematical description of subjective effort including the experienced effort of bodily executed actions and the mental effort of monitoring the results of bodily actions.
This chapter finalizes the qualitative description of the complex present and two main issues are... more This chapter finalizes the qualitative description of the complex present and two main issues are the focus of attention. First, our approach to describing intentional, goal-oriented actions is elucidated. The proposed multi-component time formalism of human actions contains two constituent components: the human temporality with complex temporal structure and physical environment: physical objects affected by human actions and other physical objects able to influence the former objects.
A continuous time model for the multiagent system with reinforcement learning and time-scale-free... more A continuous time model for the multiagent system with reinforcement learning and time-scale-free memory effects is developed. The agents are assumed to act independently of one another and try to optimize the choice of possible actions via trial-and-error search. To gain information about the action value the agents accumulate in their memory the rewards obtained at each moment of taking a specific action. The contribution of the rewards in the past to the agent perception of action value at the current moment of time is described within an integral relation having a kernel of power form. Finally a fractional order differential equation governing the dynamics of the multiagent system at hand is obtained. The agents actually interact with one another in a implicit way via the dependence of the reward of a given agent on the choice of the other agents. The pairwise interaction model as adopted to describe this effect. By the way of example, a system of the rock-paper-scissors type is analyzed in detail, including the stability analysis and numerical simulation. The paper also focuses attention on the explanation of the observed periodic variations in the human choice and opinion using the notion of non-transitive interaction causing instability onset rather than the notion of non-transitive preference relation.
We analyze the necrosis growth due to thermal coagulation induced by laser light absorption and l... more We analyze the necrosis growth due to thermal coagulation induced by laser light absorption and limited by heat diffusion into the surrounding live tissue. The tissue is assumed to contain a certain tumor in the undamaged tissue whereof the blood perfusion rate does not change during the action. By contrast, the normal tissue responds strongly to increase in the tissue temperature and the blood perfusion rate can grow by tenfold. We study in detail the necrosis formation under conditions typical for a real course of thermal therapy treatment, the duration of the action is taken about 5 minutes when a necrosis domain of size about or above 1 cm is formed. In particular, if the tumor size is sufficiently large, it exceeds 1 cm, and the tissue response is not too delayed, the delay time does not exceed 1 min, then there are conditions under which the relative volume of the damaged normal tissue is small in comparison with the tumor volume after the tumor is coagulated totally.
We present preliminary experimental data that enable us to suggest that heat transfer in cellular... more We present preliminary experimental data that enable us to suggest that heat transfer in cellular tissue under local strong heating is a more complex phenomenon than a simple heat diffusion. Namely, we demonstrate that under local strong heating of a muscle tissue heat transfer in it exhibits substantial anisotropy unexplained in the context of the standard diffusion model. The observed temperature dynamics is also characterized by nonlinear behavior as well as by a certain repeat reversibility. The latter means that the time variations in the temperature of a cellular tissue undergoing repeated acts of heating go in the same way at least approximately. We explain the observed anomalous properties of heat transfer by suggesting the flow of the interstitial liquid to appear due to nonuniform heating which, in turn, affects the heat transfer. A possible mechanism responsible for this effect is discussed.
ABSTRACT Previously we have developed a free boundary model for local thermal coagulation induced... more ABSTRACT Previously we have developed a free boundary model for local thermal coagulation induced by laser light absorption when the tissue region affected directly by laser light is sufficiently small and heat diffusion into the surrounding tissue governs the necrosis growth. In the present paper keeping in mind the obtained results we state the point of view on the necrosis formation under these conditions as the basis of an individual layer therapy mode exhibiting specific properties. In particular, roughly speaking, the size of the resulting necrosis domain is determined by the physical characteristics of the tissue and its response to local heating, and by the applicator form rather than the treatment duration and the irradiation power.
When heated the living tissue exhibits random nonuniformities in the temperature that are due to ... more When heated the living tissue exhibits random nonuniformities in the temperature that are due to the discreetness of vessel arrangement. Because of strong temperature dependence of the thermal coagulation rate these nonuniformities should substantially affect the necrosis growth induced by local heating. In the present work we study their effect on the form of a necrosis domain when its growth is limited by heat diffusion into the surrounding tissue. In particular, we analyze the mean amplitude and the correlation length of the interface perturbations depending on the main characteristics of the random temperature nonuniformities.
The present chapter is devoted to the experiential now as an individual fundamental entity of the... more The present chapter is devoted to the experiential now as an individual fundamental entity of the complex present that plays the pivot role in dynamics of the human temporality. In our theory, the implementation cost of action strategies is determined by effort. For this reason, we elucidate its essential properties and develop the multi-component theory of subjective effort. Turning to the laws of psychophysics, we develop the description of subjective effort in terms of one-dimensional clouds in the space of effort magnitudes experienced by the subject. Two components of subjective effort are singled out. One is the experienced effort of bodily executed actions. The other is the mental effort related to monitoring the results of bodily actions. The available psychological and physiological data that enable us to develop the original mathematical description of subjective effort are presented. In particular, the power-law of memory load, the regularities of speed-accuracy tradeoff are used to construct the mental effort of monitoring which admits the interpretation as quasi-entropy of subject’s actions. To fuse the two types of subjective effort, we propose a new concept of an endless cloud cycle dealing with effort-as-experienced and effort-as-evaluated. This concept enables us to employ the notion of time-to-fatigue in order to make the two types of subjective effort mutually commensurable. As a result, a nonlinear model for the effort fusion is elaborated, which may be treated as an analogy to free energy. The appendix presents the details of the mathematical constructions and experimental data on binary categorization that underlie the mathematical description of subjective effort including the experienced effort of bodily executed actions and the mental effort of monitoring the results of bodily actions.
This chapter finalizes the qualitative description of the complex present and two main issues are... more This chapter finalizes the qualitative description of the complex present and two main issues are the focus of attention. First, our approach to describing intentional, goal-oriented actions is elucidated. The proposed multi-component time formalism of human actions contains two constituent components: the human temporality with complex temporal structure and physical environment: physical objects affected by human actions and other physical objects able to influence the former objects.
A continuous time model for the multiagent system with reinforcement learning and time-scale-free... more A continuous time model for the multiagent system with reinforcement learning and time-scale-free memory effects is developed. The agents are assumed to act independently of one another and try to optimize the choice of possible actions via trial-and-error search. To gain information about the action value the agents accumulate in their memory the rewards obtained at each moment of taking a specific action. The contribution of the rewards in the past to the agent perception of action value at the current moment of time is described within an integral relation having a kernel of power form. Finally a fractional order differential equation governing the dynamics of the multiagent system at hand is obtained. The agents actually interact with one another in a implicit way via the dependence of the reward of a given agent on the choice of the other agents. The pairwise interaction model as adopted to describe this effect. By the way of example, a system of the rock-paper-scissors type is analyzed in detail, including the stability analysis and numerical simulation. The paper also focuses attention on the explanation of the observed periodic variations in the human choice and opinion using the notion of non-transitive interaction causing instability onset rather than the notion of non-transitive preference relation.
We analyze the necrosis growth due to thermal coagulation induced by laser light absorption and l... more We analyze the necrosis growth due to thermal coagulation induced by laser light absorption and limited by heat diffusion into the surrounding live tissue. The tissue is assumed to contain a certain tumor in the undamaged tissue whereof the blood perfusion rate does not change during the action. By contrast, the normal tissue responds strongly to increase in the tissue temperature and the blood perfusion rate can grow by tenfold. We study in detail the necrosis formation under conditions typical for a real course of thermal therapy treatment, the duration of the action is taken about 5 minutes when a necrosis domain of size about or above 1 cm is formed. In particular, if the tumor size is sufficiently large, it exceeds 1 cm, and the tissue response is not too delayed, the delay time does not exceed 1 min, then there are conditions under which the relative volume of the damaged normal tissue is small in comparison with the tumor volume after the tumor is coagulated totally.
We present preliminary experimental data that enable us to suggest that heat transfer in cellular... more We present preliminary experimental data that enable us to suggest that heat transfer in cellular tissue under local strong heating is a more complex phenomenon than a simple heat diffusion. Namely, we demonstrate that under local strong heating of a muscle tissue heat transfer in it exhibits substantial anisotropy unexplained in the context of the standard diffusion model. The observed temperature dynamics is also characterized by nonlinear behavior as well as by a certain repeat reversibility. The latter means that the time variations in the temperature of a cellular tissue undergoing repeated acts of heating go in the same way at least approximately. We explain the observed anomalous properties of heat transfer by suggesting the flow of the interstitial liquid to appear due to nonuniform heating which, in turn, affects the heat transfer. A possible mechanism responsible for this effect is discussed.
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Papers by Ihor Lubashevsky