Journal of Physics A: Mathematical and Theoretical
We consider a system of clusters of various sizes or masses, subject to aggregation and fragmenta... more We consider a system of clusters of various sizes or masses, subject to aggregation and fragmentation by collision with monomers or by self-disintegration. The aggregation rate for the cluster of size or mass k is given by a kernel proportional to k a , whereas the collision and disintegration kernels are given by λ k b and μ k a , respectively, with 0 ⩽ a , b ⩽ 1 and positive factors λ and µ. We study the emergence of oscillations in the phase diagram ( μ , λ ) for two models: ( a , b ) = ( 1 , 0 ) and ( 1 , 1 ) . It is shown that the monomer population satisfies a class of integral equations possessing oscillatory solutions in a finite domain in the plane ( μ , λ ) . We evaluate analytically this domain and give an estimate of the oscillation frequency. In particular, these oscillations are found to occur generally for small but nonzero values of the parameter µ, far smaller than λ.
Background: A number of cellular-and molecular-level studies of autophagy assessment have been ca... more Background: A number of cellular-and molecular-level studies of autophagy assessment have been carried out with the help of various biochemical and morphological indices. Still there exists ambiguity for the assessment of the autophagy status and of the causal relationship between autophagy and related cellular changes. To circumvent such difficulties, we probe new quantitative indices of autophagy which are important for defining autophagy activation and further assessing its roles associated with different physiopathological states. Methods: Our approach is based on the minimal autophagy model that allows us to understand underlying dynamics of autophagy from biological experiments. Specifically, based on the model, we reconstruct the experimental context-specific autophagy profiles from the target autophagy system, and two quantitative indices are defined from the model-driven profiles. The indices are then applied to the simulation-based analysis, for the specific and quantitative interpretation of the system. Results: Two quantitative indices measuring autophagy activities in the induction of sequestration fluxes and in the selective degradation are proposed, based on the model-driven autophagy profiles such as the time evolution of autophagy fluxes, levels of autophagosomes/autolysosomes, and corresponding cellular changes. Further, with the help of the indices, those biological experiments of the target autophagy system have been successfully analyzed, implying that the indices are useful not only for defining autophagy activation but also for assessing its role in a specific and quantitative manner. Conclusions: Such quantitative autophagy indices in conjunction with the computeraided analysis should provide new opportunities to characterize the causal relationship between autophagy activity and the corresponding cellular change, based on the system-level understanding of the autophagic process at good time resolution, complementing the current in vivo and in vitro assays.
Background: Neurons have specialized structures that facilitate information transfer using electr... more Background: Neurons have specialized structures that facilitate information transfer using electrical and chemical signals. Within the perspective of neural computation, the neuronal structure is an important prerequisite for the versatile computational capabilities of neurons resulting from the integration of diverse synaptic input patterns, complex interactions among the passive and active dendritic local currents, and the interplay between dendrite and soma to generate action potential output. For this, characterization of the relationship between the structure and neuronal spike dynamics could provide essential information about the cellular-level mechanism supporting neural computations. Results: This work describes simulations and an information-theoretic analysis to investigate how specific neuronal structure affects neural dynamics and information processing. Correlation analysis on the Allen Cell Types Database reveals biologically relevant structural features that determine neural dynamics-eight highly correlated structural features are selected as the primary set for characterizing neuronal structures. These features are used to characterize biophysically realistic multi-compartment mathematical models for primary neurons in the direct and indirect hippocampal pathways consisting of the pyramidal cells of Cornu Ammonis 1 (CA1) and CA3 and the granule cell in the dentate gyrus (DG). Simulations reveal that the dynamics of these neurons vary depending on their specialized structures and are highly sensitive to structural modifications. Information-theoretic analysis confirms that structural factors are critical for versatile neural information processing at a single-cell and a neural circuit level; not only basic AND/OR but also linearly non-separable XOR functions can be explained within the information-theoretic framework. Conclusions: Providing quantitative information on the relationship between the structure and the dynamics/information flow of neurons, this work would help us understand the design and coding principles of biological neurons and may be beneficial for designing biologically plausible neuron models for artificial intelligence (AI) systems.
Journal of Physics A: Mathematical and Theoretical, 2021
The integrate-and-fire (IF) model is the most widely used simple spiking neuron model in neuromor... more The integrate-and-fire (IF) model is the most widely used simple spiking neuron model in neuromorphic computing as well as in artificial neural network algorithms. Here, we characterize the dynamics and information processing of IF models using computer simulations and information-theoretic approaches. Neural dynamics is analysed by means of the time evolution of axonal spikes and the phase-plane portrait, and the coding efficiency of a neuron is estimated by the ratio of mutual information of input and output spikes for the binary hidden neural state. The exponential IF model exhibits higher similarity to the biophysical model in both neural dynamics and coding, compared to other IF type models. Electronic circuit simulations based on the simulation programme with integrated circuit emphasis reveal the nonlinear current–voltage characteristics of the IF neuron models and criticalities in the neural networks. Relevant information-theoretic measures indicate that the computational capabilities of neuromorphic devices largely depend on the neuron models. Such an approach combined with the analysis of neural dynamics provides a useful tool to investigate underlying dynamics of mathematical neuron models; it is applicable to the design and evaluation of neuromorphic models.
This study examines the human behavioral dynamics of pedestrians crossing a street with vehicular... more This study examines the human behavioral dynamics of pedestrians crossing a street with vehicular traffic. To this end, an experiment was constructed in which human participants cross a road between two moving vehicles in a virtual reality setting. A mathematical model is developed in which the position is given by a simple function. The model is used to extract information on each crossing by performing root-mean-square deviation (RMSD) minimization of the function from the data. By isolating the parameter adjusted to gap features, we find that the subjects primarily changed the timing of the acceleration to adjust to changing gap conditions, rather than walking speed or duration of acceleration. Moreover, this parameter was also adjusted to the vehicle speed and vehicle type, even when the gap size and timing were not changed. The model is found to provide a description of gap affordance via a simple inequality of the fitting parameters. In addition, the model turns out to predict...
Entropy plays a key role in statistical physics of complex systems, which in general exhibit dive... more Entropy plays a key role in statistical physics of complex systems, which in general exhibit diverse aspects of emergence on different scales. However, it still remains not fully resolved how entropy varies with the coarse-graining level and the description scale. In this paper, we consider a Yule-type growth model, where each element is characterized by its size being either continuous or discrete. Entropy is then defined directly from the probability distribution of the states of all elements as well as from the size distribution of the system. Probing in detail their relations and time evolutions, we find that heterogeneity in addition to correlations between elements could induce loss of information during the coarse-graining procedure. It is also revealed that the expansion of the size space domain depends on the description level, leading to a difference between the continuous description and the discrete one.
Journal of Physics A: Mathematical and Theoretical, 2011
The master equation approach is proposed to describe the evolution of passengers in a subway syst... more The master equation approach is proposed to describe the evolution of passengers in a subway system. With the transition rate constructed from simple geographical consideration, the evolution equation for the distribution of subway passengers is found to bear skew distributions including log-normal, Weibull, and power-law distributions. This approach is then applied to the Metropolitan Seoul Subway system: Analysis of the trip data of all passengers in a day reveals that the data in most cases fit well to the log-normal distributions. Implications of the results are also discussed.
Dynamics of a coarse-grained model for the room-temperature ionic liquid, 1-ethyl-3methylimidazol... more Dynamics of a coarse-grained model for the room-temperature ionic liquid, 1-ethyl-3methylimidazolium hexafluorophosphate, couched in the united-atom site representation are studied via molecular dynamics simulations. The dynamically heterogeneous behavior of the model resembles that of fragile supercooled liquids. At or close to room temperature, the model ionic liquid exhibits slow dynamics, characterized by nonexponential structural relaxation and subdiffusive behavior. The structural relaxation time, closely related to the viscosity, shows a super-Arrhenius behavior. Local excitations, defined as displacement of an ion exceeding a threshold distance, are found to be mainly responsible for structural relaxation in the alternating structure of cations and anions. As the temperature is lowered, excitations become
The Metropolitan Seoul Subway system is examined through the use of the gravity model. Exponents ... more The Metropolitan Seoul Subway system is examined through the use of the gravity model. Exponents describing the power-law dependence on the time distance between stations are obtained, which reveals a universality for subway lines of the same topology. In the short (time) distance regime the number of passengers between stations does not grow with the decrease in the distance, thus deviating from the power-law behavior. It is found that such reduction in passengers is well described by the Hill function. Further, temporal fluctuations in the passenger flow data, fitted to the gravity model modified by the Hill function, are analyzed to reveal the Yule-type nature inherent in the structure of Seoul.
One of Aesop's (La Fontain's) famous fables 'The Ant and the Grasshopper' is widely known to give... more One of Aesop's (La Fontain's) famous fables 'The Ant and the Grasshopper' is widely known to give a moral lesson through comparison between the hard working ant and the party-loving grasshopper. Here we show a slightly different version of this fable, namely, "The Ant and the Metrohopper," which describes human mobility patterns in modern urban life. Numerous real transportation networks and the trajectory data have been studied in order to understand mobility patterns. We study trajectories of commuters on the public transportation of Metropolitan Seoul, Korea. Smart cards (Integrated Circuit Cards; ICCs) are used in the public transportation system, which allow collection of transit transaction data, including departure and arrival stations and time. This empirical analysis provides human mobility patterns, which impact traffic forecasting and transportation optimization, as well as urban planning.
The principle of least effort has been widely used to explain phenomena related to human behavior... more The principle of least effort has been widely used to explain phenomena related to human behavior ranging from topics in language to those in social systems. It has precedence in the principle of least action from the Lagrangian formulation of classical mechanics. In this study, we present a model for interceptive human walking based on the least action principle. Taking inspiration from Lagrangian mechanics, a Lagrangian is defined as effort minus security, with two different specific mathematical forms. The resulting Euler–Lagrange equations are then solved to obtain the equations of motion. The model is validated using experimental data from a virtual reality crossing simulation with human participants. We thus conclude that the least action principle provides a useful tool in the study of interceptive walking.
During our previous research, we isolated lactobacilli strains: E5-1, M1-3 and ZPZ, that have ant... more During our previous research, we isolated lactobacilli strains: E5-1, M1-3 and ZPZ, that have antagonistic activities against A. baumannii, S. aureus, K. pneumoniae and Enterobacter gergoviae that are prevalent in Yerevan hospitals. The aim of the current investigation was to evaluate radioprotective activities of these strains. 90 healthy adult Wistar rats in the weight range 150-200g were randomly placed into the following nine groups: control, control-placebo, irradiated, three control-lactobacilli and three irradiatedlactobacilli. The three irradiated-lactobacilli groups received an appropriate feeding cannula for seven days prior to receiving a 4.5 Gy irradiation. A significant decrease in the blood leukocyte count (WBC) was described after the seventh day of rats' irradiation ((0.8050.07)x10 9 /L vs. (7.1250.39) x10 9 /L and (6.8450.77)x10 9 /L; P<0.05). We did not find any significant changes in the rats' blood glucose levels (BGL) adopted placebo ((5.7950.37) mMol/L vs. (6.4250.33) mMol/L; P>0.05), but an insignificant increase within the normal range was observed for the irradiated-E5-1 rats ((5.7950.37) mMol/L and ((6.4350.33) mMol/L vs. (8.1250.2) mMol/L; P < 0.05)). Parallel to this, we described a statistically confirmed decrease of WBC after the trial by the LactobacillusM1-3 ((5.2150.12)x10 9 /L vs. (7.1250.39)x10 9 /L and (6.8450.77)x10 9 /L; P<0.05). Also, the irradiated-E5-1 rats kept their initial BGL after the irradiation: (7.7050.16) vs. 6.74; P<0.05 (in comparison with irradiated rats) and (7.750.16) vs. (8.1250.2); P>0.05 (in comparison with control-E5-1 rats). This group of rats were also characterized by the statistically confirmed increase of WBC in comparison with its irradiated controls ((0.8050.07)x10 9 /L vs. 1.58x10 9 /L; P<0.05), and decrease of WBC in comparison with its controls ((6.750.38)x10 9 /L vs. 1.58x10 9 /L; P<0.05). These findings are of significance for the LactobacillusE5-1 application as a starter for the production of functional food with radioprotective activities.
Background Autophagy is an evolutionarily conserved intracellular process that is used for delive... more Background Autophagy is an evolutionarily conserved intracellular process that is used for delivering proteins and organelles to the lysosome for degradation. For decades, autophagy has been speculated to regulate amyloid-β peptide (Aβ) accumulation, which is involved in Alzheimer’s disease (AD); however, specific autophagic effects on the Aβ kinetics only have begun to be explored. Results We develop a mathematical model for autophagy with respect to Aβ kinetics and perform simulations to understand the quantitative relationship between Aβ levels and autophagy activity. In the case of an abnormal increase in the Aβ generation, the degradation, secretion, and clearance rates of Aβ are significantly changed, leading to increased levels of Aβ. When the autophagic Aβ degradation is defective in addition to the increased Aβ generation, the Aβ-regulation failure is accompanied by elevated concentrations of autophagosome and autolysosome, which may further clog neurons. Conclusions The mo...
Journal of Physics A: Mathematical and Theoretical
We consider a system of clusters of various sizes or masses, subject to aggregation and fragmenta... more We consider a system of clusters of various sizes or masses, subject to aggregation and fragmentation by collision with monomers or by self-disintegration. The aggregation rate for the cluster of size or mass k is given by a kernel proportional to k a , whereas the collision and disintegration kernels are given by λ k b and μ k a , respectively, with 0 ⩽ a , b ⩽ 1 and positive factors λ and µ. We study the emergence of oscillations in the phase diagram ( μ , λ ) for two models: ( a , b ) = ( 1 , 0 ) and ( 1 , 1 ) . It is shown that the monomer population satisfies a class of integral equations possessing oscillatory solutions in a finite domain in the plane ( μ , λ ) . We evaluate analytically this domain and give an estimate of the oscillation frequency. In particular, these oscillations are found to occur generally for small but nonzero values of the parameter µ, far smaller than λ.
Background: A number of cellular-and molecular-level studies of autophagy assessment have been ca... more Background: A number of cellular-and molecular-level studies of autophagy assessment have been carried out with the help of various biochemical and morphological indices. Still there exists ambiguity for the assessment of the autophagy status and of the causal relationship between autophagy and related cellular changes. To circumvent such difficulties, we probe new quantitative indices of autophagy which are important for defining autophagy activation and further assessing its roles associated with different physiopathological states. Methods: Our approach is based on the minimal autophagy model that allows us to understand underlying dynamics of autophagy from biological experiments. Specifically, based on the model, we reconstruct the experimental context-specific autophagy profiles from the target autophagy system, and two quantitative indices are defined from the model-driven profiles. The indices are then applied to the simulation-based analysis, for the specific and quantitative interpretation of the system. Results: Two quantitative indices measuring autophagy activities in the induction of sequestration fluxes and in the selective degradation are proposed, based on the model-driven autophagy profiles such as the time evolution of autophagy fluxes, levels of autophagosomes/autolysosomes, and corresponding cellular changes. Further, with the help of the indices, those biological experiments of the target autophagy system have been successfully analyzed, implying that the indices are useful not only for defining autophagy activation but also for assessing its role in a specific and quantitative manner. Conclusions: Such quantitative autophagy indices in conjunction with the computeraided analysis should provide new opportunities to characterize the causal relationship between autophagy activity and the corresponding cellular change, based on the system-level understanding of the autophagic process at good time resolution, complementing the current in vivo and in vitro assays.
Background: Neurons have specialized structures that facilitate information transfer using electr... more Background: Neurons have specialized structures that facilitate information transfer using electrical and chemical signals. Within the perspective of neural computation, the neuronal structure is an important prerequisite for the versatile computational capabilities of neurons resulting from the integration of diverse synaptic input patterns, complex interactions among the passive and active dendritic local currents, and the interplay between dendrite and soma to generate action potential output. For this, characterization of the relationship between the structure and neuronal spike dynamics could provide essential information about the cellular-level mechanism supporting neural computations. Results: This work describes simulations and an information-theoretic analysis to investigate how specific neuronal structure affects neural dynamics and information processing. Correlation analysis on the Allen Cell Types Database reveals biologically relevant structural features that determine neural dynamics-eight highly correlated structural features are selected as the primary set for characterizing neuronal structures. These features are used to characterize biophysically realistic multi-compartment mathematical models for primary neurons in the direct and indirect hippocampal pathways consisting of the pyramidal cells of Cornu Ammonis 1 (CA1) and CA3 and the granule cell in the dentate gyrus (DG). Simulations reveal that the dynamics of these neurons vary depending on their specialized structures and are highly sensitive to structural modifications. Information-theoretic analysis confirms that structural factors are critical for versatile neural information processing at a single-cell and a neural circuit level; not only basic AND/OR but also linearly non-separable XOR functions can be explained within the information-theoretic framework. Conclusions: Providing quantitative information on the relationship between the structure and the dynamics/information flow of neurons, this work would help us understand the design and coding principles of biological neurons and may be beneficial for designing biologically plausible neuron models for artificial intelligence (AI) systems.
Journal of Physics A: Mathematical and Theoretical, 2021
The integrate-and-fire (IF) model is the most widely used simple spiking neuron model in neuromor... more The integrate-and-fire (IF) model is the most widely used simple spiking neuron model in neuromorphic computing as well as in artificial neural network algorithms. Here, we characterize the dynamics and information processing of IF models using computer simulations and information-theoretic approaches. Neural dynamics is analysed by means of the time evolution of axonal spikes and the phase-plane portrait, and the coding efficiency of a neuron is estimated by the ratio of mutual information of input and output spikes for the binary hidden neural state. The exponential IF model exhibits higher similarity to the biophysical model in both neural dynamics and coding, compared to other IF type models. Electronic circuit simulations based on the simulation programme with integrated circuit emphasis reveal the nonlinear current–voltage characteristics of the IF neuron models and criticalities in the neural networks. Relevant information-theoretic measures indicate that the computational capabilities of neuromorphic devices largely depend on the neuron models. Such an approach combined with the analysis of neural dynamics provides a useful tool to investigate underlying dynamics of mathematical neuron models; it is applicable to the design and evaluation of neuromorphic models.
This study examines the human behavioral dynamics of pedestrians crossing a street with vehicular... more This study examines the human behavioral dynamics of pedestrians crossing a street with vehicular traffic. To this end, an experiment was constructed in which human participants cross a road between two moving vehicles in a virtual reality setting. A mathematical model is developed in which the position is given by a simple function. The model is used to extract information on each crossing by performing root-mean-square deviation (RMSD) minimization of the function from the data. By isolating the parameter adjusted to gap features, we find that the subjects primarily changed the timing of the acceleration to adjust to changing gap conditions, rather than walking speed or duration of acceleration. Moreover, this parameter was also adjusted to the vehicle speed and vehicle type, even when the gap size and timing were not changed. The model is found to provide a description of gap affordance via a simple inequality of the fitting parameters. In addition, the model turns out to predict...
Entropy plays a key role in statistical physics of complex systems, which in general exhibit dive... more Entropy plays a key role in statistical physics of complex systems, which in general exhibit diverse aspects of emergence on different scales. However, it still remains not fully resolved how entropy varies with the coarse-graining level and the description scale. In this paper, we consider a Yule-type growth model, where each element is characterized by its size being either continuous or discrete. Entropy is then defined directly from the probability distribution of the states of all elements as well as from the size distribution of the system. Probing in detail their relations and time evolutions, we find that heterogeneity in addition to correlations between elements could induce loss of information during the coarse-graining procedure. It is also revealed that the expansion of the size space domain depends on the description level, leading to a difference between the continuous description and the discrete one.
Journal of Physics A: Mathematical and Theoretical, 2011
The master equation approach is proposed to describe the evolution of passengers in a subway syst... more The master equation approach is proposed to describe the evolution of passengers in a subway system. With the transition rate constructed from simple geographical consideration, the evolution equation for the distribution of subway passengers is found to bear skew distributions including log-normal, Weibull, and power-law distributions. This approach is then applied to the Metropolitan Seoul Subway system: Analysis of the trip data of all passengers in a day reveals that the data in most cases fit well to the log-normal distributions. Implications of the results are also discussed.
Dynamics of a coarse-grained model for the room-temperature ionic liquid, 1-ethyl-3methylimidazol... more Dynamics of a coarse-grained model for the room-temperature ionic liquid, 1-ethyl-3methylimidazolium hexafluorophosphate, couched in the united-atom site representation are studied via molecular dynamics simulations. The dynamically heterogeneous behavior of the model resembles that of fragile supercooled liquids. At or close to room temperature, the model ionic liquid exhibits slow dynamics, characterized by nonexponential structural relaxation and subdiffusive behavior. The structural relaxation time, closely related to the viscosity, shows a super-Arrhenius behavior. Local excitations, defined as displacement of an ion exceeding a threshold distance, are found to be mainly responsible for structural relaxation in the alternating structure of cations and anions. As the temperature is lowered, excitations become
The Metropolitan Seoul Subway system is examined through the use of the gravity model. Exponents ... more The Metropolitan Seoul Subway system is examined through the use of the gravity model. Exponents describing the power-law dependence on the time distance between stations are obtained, which reveals a universality for subway lines of the same topology. In the short (time) distance regime the number of passengers between stations does not grow with the decrease in the distance, thus deviating from the power-law behavior. It is found that such reduction in passengers is well described by the Hill function. Further, temporal fluctuations in the passenger flow data, fitted to the gravity model modified by the Hill function, are analyzed to reveal the Yule-type nature inherent in the structure of Seoul.
One of Aesop's (La Fontain's) famous fables 'The Ant and the Grasshopper' is widely known to give... more One of Aesop's (La Fontain's) famous fables 'The Ant and the Grasshopper' is widely known to give a moral lesson through comparison between the hard working ant and the party-loving grasshopper. Here we show a slightly different version of this fable, namely, "The Ant and the Metrohopper," which describes human mobility patterns in modern urban life. Numerous real transportation networks and the trajectory data have been studied in order to understand mobility patterns. We study trajectories of commuters on the public transportation of Metropolitan Seoul, Korea. Smart cards (Integrated Circuit Cards; ICCs) are used in the public transportation system, which allow collection of transit transaction data, including departure and arrival stations and time. This empirical analysis provides human mobility patterns, which impact traffic forecasting and transportation optimization, as well as urban planning.
The principle of least effort has been widely used to explain phenomena related to human behavior... more The principle of least effort has been widely used to explain phenomena related to human behavior ranging from topics in language to those in social systems. It has precedence in the principle of least action from the Lagrangian formulation of classical mechanics. In this study, we present a model for interceptive human walking based on the least action principle. Taking inspiration from Lagrangian mechanics, a Lagrangian is defined as effort minus security, with two different specific mathematical forms. The resulting Euler–Lagrange equations are then solved to obtain the equations of motion. The model is validated using experimental data from a virtual reality crossing simulation with human participants. We thus conclude that the least action principle provides a useful tool in the study of interceptive walking.
During our previous research, we isolated lactobacilli strains: E5-1, M1-3 and ZPZ, that have ant... more During our previous research, we isolated lactobacilli strains: E5-1, M1-3 and ZPZ, that have antagonistic activities against A. baumannii, S. aureus, K. pneumoniae and Enterobacter gergoviae that are prevalent in Yerevan hospitals. The aim of the current investigation was to evaluate radioprotective activities of these strains. 90 healthy adult Wistar rats in the weight range 150-200g were randomly placed into the following nine groups: control, control-placebo, irradiated, three control-lactobacilli and three irradiatedlactobacilli. The three irradiated-lactobacilli groups received an appropriate feeding cannula for seven days prior to receiving a 4.5 Gy irradiation. A significant decrease in the blood leukocyte count (WBC) was described after the seventh day of rats' irradiation ((0.8050.07)x10 9 /L vs. (7.1250.39) x10 9 /L and (6.8450.77)x10 9 /L; P<0.05). We did not find any significant changes in the rats' blood glucose levels (BGL) adopted placebo ((5.7950.37) mMol/L vs. (6.4250.33) mMol/L; P>0.05), but an insignificant increase within the normal range was observed for the irradiated-E5-1 rats ((5.7950.37) mMol/L and ((6.4350.33) mMol/L vs. (8.1250.2) mMol/L; P < 0.05)). Parallel to this, we described a statistically confirmed decrease of WBC after the trial by the LactobacillusM1-3 ((5.2150.12)x10 9 /L vs. (7.1250.39)x10 9 /L and (6.8450.77)x10 9 /L; P<0.05). Also, the irradiated-E5-1 rats kept their initial BGL after the irradiation: (7.7050.16) vs. 6.74; P<0.05 (in comparison with irradiated rats) and (7.750.16) vs. (8.1250.2); P>0.05 (in comparison with control-E5-1 rats). This group of rats were also characterized by the statistically confirmed increase of WBC in comparison with its irradiated controls ((0.8050.07)x10 9 /L vs. 1.58x10 9 /L; P<0.05), and decrease of WBC in comparison with its controls ((6.750.38)x10 9 /L vs. 1.58x10 9 /L; P<0.05). These findings are of significance for the LactobacillusE5-1 application as a starter for the production of functional food with radioprotective activities.
Background Autophagy is an evolutionarily conserved intracellular process that is used for delive... more Background Autophagy is an evolutionarily conserved intracellular process that is used for delivering proteins and organelles to the lysosome for degradation. For decades, autophagy has been speculated to regulate amyloid-β peptide (Aβ) accumulation, which is involved in Alzheimer’s disease (AD); however, specific autophagic effects on the Aβ kinetics only have begun to be explored. Results We develop a mathematical model for autophagy with respect to Aβ kinetics and perform simulations to understand the quantitative relationship between Aβ levels and autophagy activity. In the case of an abnormal increase in the Aβ generation, the degradation, secretion, and clearance rates of Aβ are significantly changed, leading to increased levels of Aβ. When the autophagic Aβ degradation is defective in addition to the increased Aβ generation, the Aβ-regulation failure is accompanied by elevated concentrations of autophagosome and autolysosome, which may further clog neurons. Conclusions The mo...
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Papers by MooYoung Choi