Stability analysis

稳定性分析
  • 文章类型: Journal Article
    宫颈癌是最常见的癌症类型之一,它主要由高风险的人乳头瘤病毒(HPV)引起,并继续以惊人的速度传播。虽然HPV的影响之前已经调查过,目前只有少量的数学模型来说明HPV在宫颈癌中的动态作用.目标是开发一个宿主内密度依赖性确定性模型,用于基底细胞的动力学含义。病毒体,和结合免疫和功能反应的淋巴细胞。使用基本复制数等流行病学模型技术对模型进行分析,并使用MatlabODE求解器对模型进行仿真。在模型中考虑了六个区室;易感细胞(S),感染细胞(I),癌前细胞(P),癌细胞(C),病毒体(V),和淋巴细胞(L)。下一代矩阵(NGM),生存功能,和特征多项式方法用于确定表示为R0的基本再现数。R0是使用三种方法获得的,因为NGM有一些弱点,因此需要其他两种方法。这项研究的结果表明,当R0*<1时,无疾病平衡点是局部渐近稳定的,如果R0*≤1,则局部渐近稳定,如果R0*>1,则局部平衡是全局渐近稳定的。获得的结果表明,癌前细胞向癌细胞的进展速率(θ)对模型具有最直接的影响。当(θ)增加0.08时,该模型能够将患者的寿命估计为10天。这项研究的结果将有助于医疗保健提供者,公共卫生当局,和非政府健康团体制定有效的预防策略来减缓宫颈癌的发展。应该做更多的研究来确定可能导致宫颈癌患者死亡的癌细胞的确切数量,因为本文估计比例为75%。
    Cervical cancer is one of the most common types of cancer and it is caused mostly by high-risk Human Papillomavirus (HPV) and continues to spread at an alarming rate. While HPV impacts have been investigated before, there are currently only a scanty number of mathematical models that account for HPV\'s dynamic role in cervical cancer. The objectives were to develop an in-host density-dependent deterministic model for the dynamics implications of basal cells, virions, and lymphocytes incorporating immunity and functional responses. Analyze the model using techniques of epidemiological models such as basic reproduction number and simulate the model using Matlab ODE solver. Six compartments are considered in the model that is; Susceptible cells (S), Infected cells (I), Precancerous cells (P), Cancerous cells (C), Virions (V), and Lymphocytes (L). Next generation matrix (NGM), survival function, and characteristic polynomial method were used to determine the basic reproduction number denoted as R 0 . R 0 was obtained using three methods because NGM has some weaknesses hence the need for the other two methods. The findings from this research indicated that Disease-Free Equilibrium point is locally asymptotically stable whenever R 0 * < 1 and globally asymptotically stable if R 0 * ≤ 1 and the Endemic Equilibrium is globally asymptotically stable if R 0 * > 1 . The results obtained shows that the progression rate of precancerous cells to cancerous cells ( θ ) has the most direct impact on the model. The model was able to estimate the longevity of a patient as 10 days when ( θ ) increases by 0.08 . The findings of this research will help healthcare providers, public health authorities, and non-governmental health groups in creating effective prevention strategies to slow the development of cervical cancer. More research should be done to determine the exact number of cancerous cells that can lead to the death of a cervical cancer patient since this paper estimated a proportion of 75 % .
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  • 文章类型: Journal Article
    在目前的研究中,我们采用Atangana-Baleanu意义上的新型分形分数算子来研究相互作用浮游植物物种模型的动力学。最初,我们利用Picard-Lindelöf定理来验证模型解的唯一性和存在性。然后,我们探索浮游植物模型中的平衡点,并进行Hyers-Ulam稳定性分析。此外,我们提出了一个利用牛顿多项式的数值方案来验证我们的分析结果。数值模拟说明了模型在各种分形和分数参数值上的动力学行为,通过图形表示可视化。我们的模拟表明,平衡点的稳定性不受长期记忆效应的影响。其特征在于分形分数阶值。然而,分形分数参数的增加加速了解收敛到其预期平衡状态。
    In the current study, we employ the novel fractal-fractional operator in the Atangana-Baleanu sense to investigate the dynamics of an interacting phytoplankton species model. Initially, we utilize the Picard-Lindelöf theorem to validate the uniqueness and existence of solutions for the model. We then explore equilibrium points within the phytoplankton model and conduct Hyers-Ulam stability analysis. Additionally, we present a numerical scheme utilizing the Newton polynomial to validate our analytical findings. Numerical simulations illustrate the dynamical behavior of the model across various fractal and fractional parameter values, visualized through graphical representations. Our simulations reveal that the stability of equilibrium points is not significantly impacted with the long-term memory effect, which is characterized by fractal-fractional order values. However, an increase in fractal-fractional parameters accelerates the convergence of solutions to their intended equilibrium states.
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  • 文章类型: Journal Article
    猴痘的复苏导致相当大的医疗保健风险,需要有效的免疫计划。这项工作调查了英国的猴痘疾病动态,关注真实数据下疫苗接种的影响。关键问题是正确预测疾病的传播并评估免疫工作的成功。我们构建了猴痘感染的数学模型,并将其扩展到考虑Caputo导数的分数情况。分析确保了积极性,有界性,和非整数系统解的唯一性。我们在无病平衡(DFE)D0处进行了局部渐近稳定性分析(LAS),显示了R0<1的结果。此外,我们证明了多个特有均衡的存在,并为后向分叉提供了条件,以图形方式说明。使用来自英国的真实案例数据,用非线性最小二乘法估计模型参数。我们的研究结果表明,不接种疫苗,R2≈0.8,而接种疫苗将其降低至R2v=0.48。我们进行敏感性分析,以确定影响疾病消除的关键参数,通过图表呈现结果。要用数值求解分数模型,我们概述了一个数值方案,并在各种参数假设下提供了详细的结果。我们的研究结果表明,高疫苗效力,疫苗的低下降率,增加感染者的疫苗接种可以显着减少英国未来的猴痘病例。本研究为猴痘动力学提供了一个全面的框架,并为有效的疾病控制和预防提供了公共卫生策略。
    The resurgence of monkeypox causes considerable healthcare risks needing efficient immunization programs. This work investigates the monkeypox disease dynamics in the UK, focusing on the impact of vaccination under real data. The key difficulty is to correctly predict the spread of the disease and evaluate the success of immunization efforts. We construct a mathematical model for monkeypox infection and extend it to the fractional case considering the Caputo derivative. The analysis ensures the positivity, boundedness, and uniqueness of the solution for the non-integer system. We conduct a local asymptotical stability analysis (LAS) at the disease-free equilibrium (DFE) D0, showing the result for R0<1. Additionally, we demonstrate the existence of multiple endemic equilibria and provide conditions for backward bifurcation, which are illustrated graphically. Using real case data from the UK, we estimate model parameters via the nonlinear least square method. Our results show that, without vaccination, R2≈0.8, whereas vaccination reduces it to R2v=0.48. We perform sensitivity analysis to identify key parameters influencing disease elimination, presenting the outcomes through graphs. To solve numerically the fractional model, we outline a numerical scheme and provide detailed results under various parameter assumptions. Our findings suggest that high vaccine efficacy, a low waning rate of the vaccines, and increased vaccination of the infected people can significantly reduce the future cases of monkeypox in the UK. The present study offers a comprehensive framework for monkeypox dynamics and informs public health strategies for effective disease control and prevention.
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  • 文章类型: Journal Article
    目的:肿瘤微环境(TME)在肿瘤进展和治疗反应中起着至关重要的作用。Radiomics通过从医学图像中提取定量特征,提供了一种非侵入性的方法来研究TME。在这项研究中,我们提出了一种新的方法来评估前庭神经鞘瘤(VS)的TME中影像组学特征的稳定性和辨别能力。
    方法:分析242例VS患者的磁共振成像(MRI)数据,包括对比增强T1加权(ceT1)和高分辨率T2加权(hrT2)序列。从不同大小的同心肿瘤周围区域提取影像组学特征。利用组内相关系数(ICC)评估特征稳定性和判别能力,为ICCmin和ICCmax建立分位数阈值。
    结果:确定的ICCmin和ICCmax阈值分别为0.45和0.72。特征分为四类:稳定和判别(S-D),稳定和非判别(S-ND),不稳定和判别(US-D),以及不稳定和非判别性(US-ND)。在ceT1和hrT2序列中,不同的特征组表现出不同比例的S-D特征。使用Jaccard指数评估ceT1和hrT2序列之间的S-D特征的相似性,对于从0.68(强度特征)到1.00(相邻灰度色调差矩阵(NGTDM)特征)的所有特征组的值为0.78。
    结论:这项研究提供了一个框架,用于识别TME中稳定和有区别的放射组学特征,可以作为潜在的生物标志物或患者预后的预测因子,最终改善VS患者的管理。
    OBJECTIVE: The tumor microenvironment (TME) plays a crucial role in tumor progression and treatment response. Radiomics offers a non-invasive approach to studying the TME by extracting quantitative features from medical images. In this study, we present a novel approach to assess the stability and discriminative ability of radiomics features in the TME of vestibular schwannoma (VS).
    METHODS: Magnetic Resonance Imaging (MRI) data from 242 VS patients were analyzed, including contrast-enhanced T1-weighted (ceT1) and high-resolution T2-weighted (hrT2) sequences. Radiomics features were extracted from concentric peri-tumoral regions of varying sizes. The intraclass correlation coefficient (ICC) was used to assess feature stability and discriminative ability, establishing quantile thresholds for ICCmin and ICCmax.
    RESULTS: The identified thresholds for ICCmin and ICCmax were 0.45 and 0.72, respectively. Features were classified into four categories: stable and discriminative (S-D), stable and non-discriminative (S-ND), unstable and discriminative (US-D), and unstable and non-discriminative (US-ND). Different feature groups exhibited varying proportions of S-D features across ceT1 and hrT2 sequences. The similarity of S-D features between ceT1 and hrT2 sequences was evaluated using Jaccard\'s index, with a value of 0.78 for all feature groups which is ranging from 0.68 (intensity features) to 1.00 (Neighbouring Gray Tone Difference Matrix (NGTDM) features).
    CONCLUSIONS: This study provides a framework for identifying stable and discriminative radiomics features in the TME, which could serve as potential biomarkers or predictors of patient outcomes, ultimately improving the management of VS patients.
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  • 文章类型: Journal Article
    背景:PfK13蛋白突变与恶性疟原虫青蒿素抗性的出现有关。PfK13蛋白对于介导泛素化和控制PI3K/AKT途径至关重要。突变体PfK13变异会干扰底物结合,尤其是PfPI3K,这提高了PfPI3K水平。
    方法:DUET,DynaMut2,mCSM,iStable2.0,I-Mutant2.0和MuPro用于研究蛋白质稳定性,并使用HADDOCK2.4对接算法研究了野生型和突变型PfK13与PfPI3K的螺旋和催化结构域之间的蛋白质-底物结合。
    结果:i-Stable服务器分析预测,在与青蒿素抗性相关的9个突变中(F446I,Y493H,R539T,I543T,P553L,R561H,C580Y)降低了蛋白质的稳定性。催化结构域的HADDOCK评分强调了所报道的突变对PfK13蛋白的结合亲和力的显著影响。通过MM_GBSA技术进一步验证,野生型和突变型PfK13蛋白之间的结合自由能(ddG)分析揭示了由PfK13突变引起的相互作用的丧失。
    结论:研究发现表明,PfK13中的突变导致蛋白质结构不稳定,并影响PfPI3K的结合。尽管调查结果仍是初步的,需要进一步验证,考虑到PfK13和PfPI3K相互作用对克服青蒿素耐药性影响的重要性,为进一步研究提供了基础。
    BACKGROUND: PfK13 protein mutations are associated with the emergence of artemisinin resistance in Plasmodium falciparum. PfK13 protein is essential for mediating ubiquitination and controlling the PI3K/AKT pathway. Mutant PfK13 variations can interfere with substrate binding, especially with PfPI3K, which raises PfPI3K levels.
    METHODS: DUET, DynaMut2, mCSM, iStable 2.0, I-Mutant 2.0, and MuPro were utilized to study the protein stability and protein-substrate binding was studied using HADDOCK 2.4 docking algorithm between Wild-type and mutant PfK13 with the helical and catalytic domain of PfPI3K.
    RESULTS: i-Stable server analysis predicted that seven, out of the nine mutations associated with artemisinin resistance (F446I, Y493H, R539T, I543T, P553L, R561H, C580Y) reduced the protein stability. HADDOCK scores of the catalytic domain underscores the significant impact of the reported mutations on the binding affinity of the PfK13 protein. Further validation through the MM_GBSA technique, the binding free energy (DDG) between the wild-type and the mutant PfK13 protein analysis revealed a loss of interactions resulting from mutations in PfK13.
    CONCLUSIONS: The study finding suggest that mutations in the PfK13 cause destabilization in the protein structure and affects the binding of PfPI3K. Although the findings remain preliminary and require further validation, it provides the basis for further research considering the importance of the interaction of PfK13 and PfPI3K to overcome the impact of artemisinin resistance.
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  • 文章类型: Journal Article
    COVID-19大流行带来了许多挫折,无论是对一个国家的经济还是像世界卫生组织这样的组织的全球使命,儿童基金会或GTFCC。挫折之一是由于缺乏霍乱疫苗接种,发展中国家霍乱病例增加。该模型通过引入另一种公共干预提出了解决方案,例如在水体中添加氯和接种疫苗。提出了一种新的分数阶时滞微分模型,有两种不同的延迟,一个代表疾病的潜伏期,另一个代表向水生环境添加消毒剂的延迟。该模型还考虑了将接受疫苗接种的人群。本研究利用繁殖数量的敏感性分析来分析证明控制措施在预防疾病传播方面的有效性。该分析为在水体中添加消毒剂和接种易感个体提供了数学证据。已经讨论了平衡点的稳定性。确定了稳定性切换曲线的存在性。数值模拟显示了延迟的影响,导致一些隔间的波动。它还描述了导数阶数对振荡的影响。
    The COVID-19 pandemic came with many setbacks, be it to a country\'s economy or the global missions of organizations like WHO, UNICEF or GTFCC. One of the setbacks is the rise in cholera cases in developing countries due to the lack of cholera vaccination. This model suggested a solution by introducing another public intervention, such as adding Chlorine to water bodies and vaccination. A novel delay differential model of fractional order was recommended, with two different delays, one representing the latent period of the disease and the other being the delay in adding a disinfectant to the aquatic environment. This model also takes into account the population that will receive a vaccination. This study utilized sensitivity analysis of reproduction number to analytically prove the effectiveness of control measures in preventing the spread of the disease. This analysis provided the mathematical evidence for adding disinfectants in water bodies and inoculating susceptible individuals. The stability of the equilibrium points has been discussed. The existence of stability switching curves is determined. Numerical simulation showed the effect of delay, resulting in fluctuations in some compartments. It also depicted the impact of the order of derivative on the oscillations.
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  • 文章类型: Journal Article
    近年来,已经进行了许多尝试来开发用于从发酵液或复杂混合物中选择性地回收工业上重要的产物的低成本吸附剂。当前的研究是一种新颖的尝试,使用廉价的吸附剂如膨润土(BT)从哈茨木霉中选择性吸附酯酶,活性炭(AC),二氧化硅(SiO2),和二氧化钛(TiO2)。由于其594.45m3/g的较大表面积,AC具有最高的酯酶吸附率,为97.58%。发现SiO2比酯酶具有最高的选择性,估计纯化倍数为7.2。有趣的是,在BT提取的发酵液中发现5.5的纯化倍数。采用功能化(FT-IR)和形态分析(SEM-EDX)对酯酶的吸附进行表征。酯酶在AC上的吸附,SiO2和TiO2很好地拟合了Freundlich等温线,证明了酯酶的多层吸附。建立了各种吸附剂中酯酶吸附的伪二级动力学模型。热力学分析表明,吸附是一个吸热过程。AC具有最低的吉布斯自由能-10.96kJ/mol,这支持酯酶和蛋白质的自发最大吸附。在解吸研究中,使用氯化钠从TiO2中提取酯酶的最大回收率为41.34%。不像其他吸附剂,AC吸附酯酶保持了其催化活性和稳定性,暗示它可以用作商业应用的固定系统。根据动力学分析,反应的总速率由反应动力学而不是外部传质阻力控制,如Damkohler数字所示。
    In recent years, numerous attempts have been made to develop a low-cost adsorbent for selectively recovering industrially important products from fermentation broth or complex mixtures. The current study is a novel attempt to selectively adsorb esterase from Trichoderma harzianum using cheap adsorbents like bentonite (BT), activated charcoal (AC), silicon dioxide (SiO2), and titanium dioxide (TiO2). AC had the highest esterase adsorption of 97.58% due to its larger surface area of 594.45 m3/g. SiO2 was found to have the highest selectivity over esterase, with an estimated purification fold of 7.2. Interestingly, the purification fold of 5.5 was found in the BT-extracted fermentation broth. The functional (FT-IR) and morphological analysis (SEM-EDX) were used to characterize the adsorption of esterase. Esterase adsorption on AC, SiO2, and TiO2 was well fitted by Freundlich isotherm, demonstrating multilayer adsorption of esterase. A pseudo-second-order kinetic model was developed for esterase adsorption in various adsorbents. Thermodynamic analysis revealed that adsorption is an endothermic process. AC has the lowest Gibbs free energy of -10.96 kJ/mol, which supports the spontaneous maximum adsorption of both esterase and protein. In the desorption study, the maximum recovery of esterase from TiO2 using sodium chloride was 41.34 %. Unlike other adsorbents, the AC-adsorbed esterase maintained its catalytic activity and stability, implying that it could be used as an immobilization system for commercial applications. According to the kinetic analysis, the overall rate of the reaction was controlled by reaction kinetics rather than external mass transfer resistance, as indicated by the Damkohler number.
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  • 文章类型: Journal Article
    从(21)维旋转黑洞构造薄壳虫洞的动机源于研究该特定时空中非最小耦合标量场的影响的愿望。通过研究这种场在存在旋转的情况下的行为,我们可以深入了解低维系统中重力场和标量场之间的相互作用。此外,这种构造使我们能够探索黑洞物理学与可穿越虫洞等奇异现象之间的潜在联系。考虑围绕平衡喉部半径的径向扰动,以探索物理参数特定值的稳定配置。然后,状态方程,特别是用于外来物质的类幻影和广义Chaplygin气体模型,用于对反向旋转的薄壳虫孔的稳定性进行广泛研究。我们的结果表明,标量场的存在增强了反向旋转的薄壳虫洞的稳定性。
    The motivation for constructing a thin-shell wormhole from a (2+1)-dimensional rotating black hole arises from the desire to study the effects of a nonminimally coupled scalar field in this particular spacetime. By investigating the behavior of such a field in the presence of rotation, we can gain insights into the interplay between gravity and scalar fields in lower-dimensional systems. Additionally, this construction allows us to explore potential connections between black hole physics and exotic phenomena like traversable wormholes. The radial perturbation around the equilibrium throat radius is considered to explore the stable configuration for specific values of physical parameters. Then, the equations of state, specifically the phantom-like and generalized Chaplygin gas model for exotic matter is used to conduct an extensive investigation into the stability of the counter-rotating thin-shell wormholes. Our results show that the presence of a scalar field enhances the stability of the counter-rotating thin-shell wormholes.
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  • 文章类型: Journal Article
    这项研究引入了分数阶模型来研究脊髓灰质炎疾病传播的动态,专注于它的意义,独特的结果,和结论。我们强调了解脊髓灰质炎传播动力学的重要性,并提出了一种使用具有指数衰减核的分数阶模型的新颖方法。经过严格的分析,包括应用CaputoFabrizio分数阶算子的存在性和稳定性评估,我们得出了疾病动态的关键见解。我们的发现揭示了不同的无病平衡点(DFE)和地方性平衡点(EE),揭示疾病的稳定性。此外,图形表示和数值模拟证明了疾病在各种参数值下的行为,加强我们对脊髓灰质炎传播动态的理解。总之,这项研究为脊髓灰质炎的传播提供了有价值的见解,并有助于更广泛地了解传染病的动态。
    This study introduces a fractional order model to investigate the dynamics of polio disease spread, focusing on its significance, unique results, and conclusions. We emphasize the importance of understanding polio transmission dynamics and propose a novel approach using a fractional order model with an exponential decay kernel. Through rigorous analysis, including existence and stability assessment applying the Caputo Fabrizio fractional operator, we derive key insights into the disease dynamics. Our findings reveal distinct disease-free equilibrium (DFE) and endemic equilibrium (EE) points, shedding light on the disease\'s stability. Furthermore, graphical representations and numerical simulations demonstrate the behavior of the disease under various parameter values, enhancing our understanding of polio transmission dynamics. In conclusion, this study offers valuable insights into the spread of polio and contributes to the broader understanding of infectious disease dynamics.
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  • 文章类型: Journal Article
    本文论证了,一种数值方法,用于求解涉及具有非奇异核的时间分数Atangana-BaleanuCaputo(ABC)导数的一维和二维Burgers方程。数值策略由时间分数(ABC)导数的正交规则以及一维和二维问题的Haar小波(HW)近似组成。该方案的关键特征是通过搭配过程将分数问题简化为线性方程组。求解该系统给出了给定问题的近似解。为了验证所开发方法的有效性,考虑了五个数值示例。除此之外,将获得的模拟与一些已发表的工作进行比较,并确定提出的技术更好。此外,在计算上给出了时空方向的收敛速度,显示了二阶收敛。还通过Lax-Richtmyer准则描述了所提出方案的稳定性。从仿真中可以明显看出,该方案对于时间分数问题非常有用。
    This paper demonstrates, a numerical method to solve the one and two dimensional Burgers\' equation involving time fractional Atangana-Baleanu Caputo ( ABC ) derivative with a non-singular kernel. The numerical stratagem consists of a quadrature rule for time fractional ( ABC ) derivative along with Haar wavelet (HW) approximations of one and two dimensional problems. The key feature of the scheme is to reduce fractional problems to the set of linear equations via collocation procedure. Solving the system gives the approximate solution of the given problem. To verify the effectiveness of the developed method five numerical examples are considered. Besides this, the obtained simulations are compared with some published work and identified that proposed technique is better. Moreover, computationally the convergence rate in spatiotemporal directions is presented which shows order two convergence. The stability of the proposed scheme is also described via Lax-Richtmyer criterion. From simulations it is obvious that the scheme is quite useful for the time fractional problems.
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