Cancer, a disease intimately linked to cellular mutations, is commonly believed to exhibit a positive association with the cell count and lifespan of a species. Despite this assumption, the observed uniformity in canc...
详细信息
Cancer, a disease intimately linked to cellular mutations, is commonly believed to exhibit a positive association with the cell count and lifespan of a species. Despite this assumption, the observed uniformity in cancer rates across species, referred to as the Peto's paradox, presents a conundrum. Recognizing that tumour progression is not solely dependent on cancer cells but involves intricate interactions among various cell types, this study employed a Lotka-Volterra (LV) ordinary differential equation model to analyze the evolution of cancerous cells and the cancer incidence in an immune environment. As a result, this study uncovered the sufficient conditions underlying the absence of correlation in Peto's paradox and provide insights into the reasons for the equitable distribution of cancer incidence across diverse species by applying nondimensionalization and drawing an analogy between the characteristic time interval for the variation of cell populations in the ODE model and that of cell cycles of a species.
College network education as the main development direction of modern education, although both for professional teachers and students provides a new platform, and provides sufficient conditions for the people to conti...
详细信息
College network education as the main development direction of modern education, although both for professional teachers and students provides a new platform, and provides sufficient conditions for the people to continue learning, but also show more quality problem, so the system understanding of college network education present situation, according to the practice of science of education evaluation system to judge the quality of education, To continuously improve the comprehensive management efficiency of network education in colleges and universities is the focus of attention of college education administrators at present. This paper studies the theoretical definition of ordinary differential equation model as the core, builds a quality evaluation system based on the innovation model of network education in colleges and universities, investigates and analyzes the implementation of network education in a university, and finally puts forward effective prospect prediction and improvement measures combined with the research results.
Resisting apoptosis is a hallmark of cancer. For this reason, it may be possible to force cancer cells to die by targeting components along the apoptotic signaling pathway. However, apoptosis signaling is challenging ...
详细信息
Resisting apoptosis is a hallmark of cancer. For this reason, it may be possible to force cancer cells to die by targeting components along the apoptotic signaling pathway. However, apoptosis signaling is challenging to understand due to dynamic and complex behaviors of ligands, receptors, and intracellular signaling components in response to cancer therapy. In this work, we forecast the apoptotic response based on the combined impact of these features. We expanded a previously established mathematical model of caspase-mediated apoptosis to include extracellular activation and receptor dynamics. In addition, three potential threshold values of caspase-3 necessary for the activation of apoptosis were selected to forecast which cells become apoptotic over time. We first vary ligand and receptor levels with the number of intracellular signaling proteins remaining consistent. Then, we vary the intracellular protein molecules in each simulated tumor cell to forecast the response of a heterogeneous population. By leveraging the benefits of computational modeling, we investigate the combined effect of several factors on the onset of apoptosis. This work provides quantitative insights for how the apoptotic signaling response can be forecasted, and precisely triggered, amongst heterogeneous cells via extracellular activation.
Assessing the transmission potential of emerging infectious diseases, such as COVID-19, is crucial for implementing prompt and effective intervention policies. The basic reproduc-tion number is widely used to measure ...
详细信息
Assessing the transmission potential of emerging infectious diseases, such as COVID-19, is crucial for implementing prompt and effective intervention policies. The basic reproduc-tion number is widely used to measure the severity of the early stages of disease out -breaks. The basic reproduction number of standard ordinary differential equation models is computed for homogeneous contact patterns;however, realistic contact patterns are far from homogeneous, specifically during the early stages of disease transmission. Hetero-geneity of contact patterns can lead to superspreading events that show a significantly high level of heterogeneity in generating secondary infections. This is primarily due to the large variance in the contact patterns of complex human behaviours. Hence, in this work, we investigate the impacts of heterogeneity in contact patterns on the basic reproduction number by developing two distinct model frameworks: 1) an SEIR-Erlang ordinary differ-ential equationmodel and 2) an SEIR stochastic agent-based model. Furthermore, we es-timated the transmission probability of both models in the context of COVID-19 in South Korea. Our results highlighted the importance of heterogeneity in contact patterns and in-dicated that there should be more information than one quantity (the basic reproduction number as the mean quantity), such as a degree-specific basic reproduction number in the distributional sense when the contact pattern is highly heterogeneous.(c) 2023 The Author(s). Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license ( http://***/licenses/by-nc-nd/4.0/ )
Totally asymmetric simple exclusion process (TASEP) modelling was shown to offer a parsimonious explanation for the experimentally confirmed ability of a single upstream open reading frames (uORFs) to upregulate downs...
详细信息
Totally asymmetric simple exclusion process (TASEP) modelling was shown to offer a parsimonious explanation for the experimentally confirmed ability of a single upstream open reading frames (uORFs) to upregulate downstream translation during the integrated stress response. As revealed by numerical simulations, the model predicts that reducing the density of scanning ribosomes upstream of certain uORFs increases the flow of ribosomes downstream. To gain a better insight into the mechanism which ensures the non-monotone relation between the upstream and downstream flows, in this work, we propose a phenomenological deterministic model approximating the TASEP model of the translation process. We establish the existence of a stationary solution featuring the decreasing density along the uORF for the deterministic model. Further, we find an explicit non-monotone relation between the upstream ribosome density and the downstream flow for the stationary solution in the limit of increasing uORF length and increasingly leaky initiation. The stationary distribution of the TASEP model, the stationary solution of the deterministic model and the explicit limit are compared numerically.
The TASEP modeling was shown to offer a parsimonious explanation for the experimentally confirmed ability of a single upstream Open Reading Frames (uORFs) to upregulate a downstream translation during the integrated s...
详细信息
The TASEP modeling was shown to offer a parsimonious explanation for the experimentally confirmed ability of a single upstream Open Reading Frames (uORFs) to upregulate a downstream translation during the integrated stress response. As revealed by the numerical simulations, the model predicts that reducing the density of scanning ribosomes upstream of certain uORFs increases the flow of ribosomes downstream. To gain a better insight into the mechanism which ensures the counter intuitive non-monotone relation between the upstream and the downstream flows we propose a phenomenological deterministic model to approximate the modified TASEP model of the translation process. We establish the existence of a stationary solution featuring the decreasing density along the uORF for the deterministic model. Further, we find an explicit non-monotone relation between the upstream ribosome density and the downstream flow for the stationary solution in the limit of increasing uORF length and increasingly leaky initiation. The stationary distribution of the modified TASEP model, the stationary solution of the deterministic model and the explicit limit are compared numerically.
The processes underpinning solid tumour growth involve the interactions between various healthy and tumour tissue components and the vasculature, and can be affected in different ways by cancer treatment. In particula...
详细信息
The processes underpinning solid tumour growth involve the interactions between various healthy and tumour tissue components and the vasculature, and can be affected in different ways by cancer treatment. In particular, the growth-limiting mechanisms at play may influence tumour responses to treatment. In this paper, we propose a simple ordinary differential equation model of solid tumour growth to investigate how tumour-specific mechanisms of growth arrest may affect tumour response to different combination cancer therapies. We consider the interactions of tumour cells with the physical space in which they proliferate and a nutrient supplied by the tumour vasculature, with the aim of representing two distinct growth arrest mechanisms. More specifically, we wish to consider growth arrest due to (1) nutrient deficiency, which corresponds to balancing cell proliferation and death rates, and (2) competition for space, which corresponds to cessation of proliferation without cell death. We perform numerical simulations of the model and a steady-state analysis to determine the possible tumour growth scenarios described by the model. We find that there are three distinct growth regimes: the nutrient- and spatially limited regimes and a bi-stable regime, in which both growth arrest mechanisms are simultaneously active. Thus, the proposed model has the features required to investigate and distinguish tumour responses to different cancer treatments.
Purpose Critical torque (CT) is an important fatigue threshold in exercise physiology and can be used to analyze, predict, or optimize performance. The objective of this work is to reduce the experimental effort when ...
详细信息
Purpose Critical torque (CT) is an important fatigue threshold in exercise physiology and can be used to analyze, predict, or optimize performance. The objective of this work is to reduce the experimental effort when estimating CTs for sustained and intermittent isometric contractions using a model-based approach. Materials and methods We employ a phenomenological model of the time course of maximum voluntary isometric contraction (MVIC) torque and compute the highest sustainable torque output by solving an optimization problem. We then show that our results are consistent with the steady states obtained when simulating periodic maximum loading schemes. These simulations correspond to all-out tests, which are used to estimate CTs in practice. Based on these observations, the estimation of CTs can be formulated mathematically as a parameter estimation problem. To minimize the statistical uncertainty of the parameter estimates and consequently of the estimated CTs, we compute optimized testing sessions. This reduces the experimental effort even further. Results We estimate CTs of the elbow flexors for sustained isometric contractions to be 28% of baseline MVIC torque and for intermittent isometric contractions consisting of a 3 s contraction followed by 2 s rest to be 41% of baseline MVIC torque. We show that a single optimized testing session is sufficient when using our approach. Conclusions Our approach reduces the experimental effort considerably when estimating CTs for sustained and intermittent isometric contractions.
Oncolytic viral therapy is an increasingly promising cancer treatment using a virus to infect and kill cancer cells, but not normal cells. Initially it was thought that doses with more virus would lead to more cancer ...
详细信息
Oncolytic viral therapy is an increasingly promising cancer treatment using a virus to infect and kill cancer cells, but not normal cells. Initially it was thought that doses with more virus would lead to more cancer cell death, and that injecting the virus more frequently would help to maximize the infection. However, it has been shown that injecting the host with more virus can lead to the infection and hence death of CD4+ and CD8+ T cells, a detrimental effect. A mathematical model of this phenomena is developed and fit to experimental data. Using this model, we show that the time needed between doses to ensure that the T cells are not at a greater risk of infection is longer than what is used in most dosing protocols. We also show that more than 60% of CD4+ or 80% of CD8+ T cells may become infected via an oncolytic virus.
We present a new model of microbial population growth that focuses on the acquisition of metabolic energy through chemosynthesis and how this depends on the concentration of resources and byproducts. Due to entropy ef...
详细信息
We present a new model of microbial population growth that focuses on the acquisition of metabolic energy through chemosynthesis and how this depends on the concentration of resources and byproducts. Due to entropy effects, organisms extract the greater energy (i.e., they produce the greater amount of adenosine triphosphate) when they use resources that are abundant and generates byproducts that are rare. This effect, which we call the "abundant resource premium," has been neglected in traditional models of microbial growth because the total metabolic energy acquisition is generally far greater than this premium. This term, however, cannot be neglected for many microbes, such as sulfate reducers, iron oxidizers, and methanogens, which live under conditions of low-energy availability. Our model showed qualitatively different behaviors from those observed in traditional microbial population growth models, such as the Monod model. For example, the steady-state population density was maximum at an intermediate resource-utilizing ability, suggesting that high substrate acquisition is not always advantageous for a microbial population when the availability of metabolic energy is low. We discuss possible implications for evolutionary and ecosystem sciences. (C) 2019 Elsevier Ltd. All rights reserved.
暂无评论