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Error Thresholds in Presence of Epistatic Interactions 存在表观相互作用时的误差阈值
Pub Date : 2024-09-18 DOI: arxiv-2409.11944
David A. Herrera-Martí
Models for viral populations with high replication error rates (such as RNAviruses) rely on the quasi-species concept, in which mutational pressure beyondthe so-called ``Error Threshold" leads to a loss of essential geneticinformation and population collapse, an effect known as the ``ErrorCatastrophe". We explain how crossing this threshold, as a result of increasingmutation rates, can be understood as a second order phase transition, even inthe presence of lethal mutations. In particular, we show that, in fitnesslandscapes with a single peak, this collapse is equivalent to aferro-paramagnetic transition, where the back-mutation rate plays the role ofthe external magnetic field. We then generalise this framework to ruggedfitness landscapes, like the ones that arise from epistatic interactions, andprovide numerical evidence that there is a transition from a high averagefitness regime to a low average fitness one, similarly to single-peakedlandscapes. The onset of the transition is heralded by a sudden change in thesusceptibility to changes in the mutation rate. We use insight from ReplicaSymmetry Breaking mechanisms in spin glasses, in particular by considering thatthe fluctuations of the genotype similarity distribution are an orderparameter.
复制错误率较高的病毒种群(如 RNA 病毒)的模型依赖于准物种概念,其中突变压力超过所谓的 "错误阈值 "会导致基本遗传信息的丢失和种群崩溃,这种效应被称为 "错误灾难"。我们解释了如何将突变率增加导致的跨越这一阈值理解为二阶相变,即使存在致死突变也是如此。我们特别指出,在具有单一峰值的适配地貌中,这种坍塌等同于铁-顺磁转换,其中后向突变率扮演了外部磁场的角色。然后,我们将这一框架推广到崎岖的适配性景观,比如由表观相互作用产生的景观,并提供了数值证据,证明与单峰景观类似,存在着从高平均适配性机制向低平均适配性机制的过渡。突变率的突然变化预示着过渡的开始。我们利用了自旋玻璃中复制对称性破坏机制的启示,特别是考虑到基因型相似性分布的波动是一个阶参数。
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引用次数: 0
Choice of Reference Surfaces to assess Plant Health through leaf scale temperature monitoring 选择参考表面,通过叶片温度监测评估植物健康状况
Pub Date : 2024-09-17 DOI: arxiv-2409.10968
Rather Laasani Sanya Shabir, Shivani Chauhan, Navneet Kumar
We use infrared thermal imaging to remotely monitor the temperature of theleaves and plant which in turn is an indicative of their health and stress; inparticular water stress. A series of experiments were conducted using FlukeTiX580 thermal imager on tomato plants to correlate the leaf temperature todifferent stages such as healthy, dying/wilted, and completely dead/dry. Theleaf temperature was compared to a series of paper-based reference surfacetemperatures; these are of different colors and some are dry while some arewet. All the reference surfaces were insulated at the bottom ensuring the heatinteraction between their top surfaces and ambient only. The surfaces were keptsufficiently far from one another. The healthy leaf temperature was found to beclose to that of white dry and black wet reference surfaces whereas the wiltedand dying leaves temperature were observed to range between yellow and redsignifying that this temperature range can better predict the onset of waterstress in the leaves. The completely dead/dry leaves were observed to rangebetween green and blue dry surfaces, respectively. However, most of the deadleaf temperature data was found to be accumulated closer to the green surfacesignifying green dry surface can better indicate a dead leaf condition. Thedying leaves were observed to exhibit 8-10 degree centigrade highertemperatures as compared to the healthy leaves in similar ambient conditions.Temperature-based health assessment provides us with a timely intervention toprevent leaf death compared to the optical monitoring since IR images revealedelevated leaf temperature 2-3 days before the optical unhealthiness (appearanceof yellowness on the leaf) was noticed.
我们利用红外热成像技术远程监控叶片和植株的温度,这反过来又表明了它们的健康状况和压力,尤其是水分压力。我们使用 FlukeTiX580 热成像仪对番茄植株进行了一系列实验,将叶片温度与不同阶段(如健康、枯萎/萎蔫和完全枯死/干枯)相关联。叶片温度与一系列基于纸张的参考表面温度进行比较;这些参考表面颜色不同,有些是干的,有些是湿的。所有参考表面都在底部进行了隔热处理,以确保其上部表面只与周围环境发生热交互。这些表面之间保持足够的距离。研究发现,健康叶片的温度接近于白色干燥和黑色潮湿参照表面的温度,而枯萎和濒死叶片的温度则介于黄色和红色之间,这表明该温度范围能更好地预测叶片中水胁迫的发生。完全死亡/干燥的叶片温度分别介于绿色和蓝色干燥表面之间。不过,大部分枯叶温度数据都积聚在靠近绿色表面的地方,这表明绿色干燥表面能更好地指示枯叶状况。与光学监测相比,基于温度的健康评估为我们提供了及时的干预措施,以防止叶片死亡,因为红外图像显示叶片温度在发现光学不健康(叶片出现黄斑)前 2-3 天升高。
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引用次数: 0
Physical Insights into Electromagnetic Efficiency of Wireless Implantable Bioelectronics 无线植入式生物电子器件电磁效率的物理启示
Pub Date : 2024-09-16 DOI: arxiv-2409.10763
Mingxiang Gao, Denys Nikolayev, Zvonimir Sipus, Anja K. Skrivervik
Autonomous implantable bioelectronics rely on wireless connectivity,necessitating highly efficient electromagnetic (EM) radiation systems. However,limitations in power, safety, and data transmission currently impede theadvancement of innovative wireless medical devices, such as tetherless neuralinterfaces, electroceuticals, and surgical microrobots. To overcome thesechallenges and ensure sufficient link and power budgets for wirelessimplantable systems, this study explores the mechanisms behind EM radiation andlosses, offering strategies to enhance radiation efficiency in wirelessimplantable bioelectronics. Using analytical modeling, the EM waves emitted bythe implant are expanded as a series of spherical harmonics, enabling adetailed analysis of the radiation mechanisms. This framework is then extendedto approximate absorption losses caused by the lossy and dispersive propertiesof tissues through derived analytical expressions. The radiation efficiency andin-body path loss are quantified and compared in terms of three primary lossmechanisms. The impact of various parameters on the EM efficiency ofimplantable devices is analyzed and quantified, including operating frequency,implant size, body-air interface curvature, and implantation location.Additionally, a rapid estimation technique is introduced to determine theoptimal operating frequency for specific scenarios, along with a set of designprinciples aimed at improving radiation performance. The design strategiesderived in this work - validated through numerical and experimentaldemonstrations on realistic implants - reveal a potential improvement inimplant radiation efficiency or gain by a factor of five to ten, leading to acorresponding increase in overall link efficiency compared to conventionaldesigns.
自主植入式生物电子学依赖于无线连接,因此需要高效的电磁辐射系统。然而,目前功率、安全性和数据传输方面的限制阻碍了创新型无线医疗设备的发展,如无系神经接口、电疗设备和外科微型机器人。为了克服这些挑战,确保无线植入系统有足够的链路和功率预算,本研究探讨了电磁辐射和损耗背后的机制,提出了提高无线植入生物电子学辐射效率的策略。通过分析建模,植入物发射的电磁波被扩展为一系列球面谐波,从而实现了对辐射机制的详细分析。然后,通过推导出的分析表达式,将这一框架扩展到由组织的损耗和色散特性引起的近似吸收损耗。根据三种主要损耗机制对辐射效率和体内路径损耗进行了量化和比较。分析并量化了各种参数对植入式设备电磁效率的影响,包括工作频率、植入物尺寸、体-气界面曲率和植入位置。此外,还介绍了一种快速估算技术,用于确定特定情况下的最佳工作频率,以及一套旨在改善辐射性能的设计原则。与传统设计相比,这项工作中得出的设计策略--通过在现实植入物上进行数值和实验演示验证--揭示了植入物辐射效率或增益提高五到十倍的潜力,从而相应地提高了整体链接效率。
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引用次数: 0
Pseudo-RNA with parallel aligned single-strands and periodic base sequence as a new universality class 具有平行排列单链和周期性碱基序列的伪 RNA 是一种新的普遍性类别
Pub Date : 2024-09-16 DOI: arxiv-2409.10158
R. Dengler
We investigate a field theory for RNA-like polymers with periodic basesequence GCGCG..., where only single-strands aligned in the same direction formdouble strands. The field theory is derived from a lattice model thatincorporates excluded volume effects, base sequence, and temperature dependentrenaturation/denaturation. The artificial directionality leads to a novel universality class, notrelated to conventional branched polymers and Lee-Yang field theory. Thisuniversality class is unstable against natural pairing, where oppositelyaligned single-strands form double strands. The denaturation/renaturationtransition is a continuous crossover between two $varphi_{n=0}^{4}$ criticalpoints and the critical point of the new universality class.
我们研究了具有周期性碱基序列 GCGCG... 的类 RNA 聚合物的场理论,在这种聚合物中,只有在同一方向排列的单链才能形成双链。该场理论源自一个晶格模型,该模型结合了排除体积效应、碱基序列和随温度变化的饱和/变性。人为的方向性导致了一种新的普遍性类别,与传统的支化聚合物和李-杨场理论无关。这种普遍性在自然配对时并不稳定,在自然配对时,对齐的单链会形成双链。变性/再变性转换是两个 $varphi_{n=0}^{4}$ 临界点与新普遍性类别临界点之间的连续交叉。
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引用次数: 0
Hydrodynamic hovering of swimming bacteria above surfaces 游泳细菌在水面上的水动力盘旋
Pub Date : 2024-09-16 DOI: arxiv-2409.10447
Pyae Hein Htet, Debasish Das, Eric Lauga
Flagellated bacteria are hydrodynamically attracted to rigid walls, yet pastwork shows a 'hovering' state where they swim stably at a finite height abovesurfaces. We use numerics and theory to reveal the physical origin of hovering.Simulations first show that hovering requires an elongated cell body andresults from a tilt away from the wall. Theoretical models then identify twoessential asymmetries: the response of width-asymmetric cells to active flowscreated by length-asymmetric cells. A minimal model reconciles near andfar-field hydrodynamics, capturing all key features of hovering.
鞭毛细菌在流体力学上会被刚性壁面吸引,但过去的研究显示它们有一种 "悬停 "状态,即在有限高度的壁面上稳定游动。我们利用数值和理论揭示了悬停的物理起源。模拟首先表明,悬停需要一个拉长的细胞体,并由远离墙壁的倾斜产生。然后,理论模型确定了两个重要的不对称现象:宽度不对称细胞对长度不对称细胞产生的活跃气流的响应。一个最小模型调和了近场和远场流体力学,捕捉到了悬停的所有关键特征。
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引用次数: 0
The structure of inter-reaction times in reaction-diffusion processes and consequences for counting statistics 反应扩散过程中反应间时间的结构及其对计数统计的影响
Pub Date : 2024-09-15 DOI: arxiv-2409.11433
Benjamin Garcia de Figueiredo, Justin M. Calabrese, William F. Fagan, Ricardo Martinez-Garcia
Many natural phenomena are quantified by counts of observable events, fromthe annihilation of quasiparticles in a lattice to predator-prey encounters ona landscape to spikes in a neural network. These events are triggered at randomintervals when an underlying dynamical system occupies a set of reactive statesin its phase space. We derive a general expression for the distribution oftimes between events in such counting processes assuming the underlyingtriggering dynamics is a stochastic process that converges to a stationarydistribution. Our results contribute to resolving a long-standing dichotomy inthe study of reaction-diffusion processes, showing the inter-reaction pointprocess interpolates between a reaction- and a diffusion-limited regime. At lowreaction rates, the inter-reaction process is Poisson with a rate depending onstationary properties of the event-triggering stochastic process. At highreaction rates, inter-reaction times are dominated by the hitting times to thereactive states. To further illustrate the power of this approach we apply ourframework to obtain the counting statistics of two counting processes appearingin several biophysical scenarios. First, we study the common situation ofestimating an animal's activity level by how often it crosses a detector,showing that the mean number of crossing events can decrease monotonically withthe hitting rate, a seemingly 'paradoxical' result that could possibly lead tomisinterpretation of experimental count data. Second, we derive the ensemblestatistics for the detection of many particles, recovering and generalizingknown results in the biophysics of chemosensation. Overall, we develop aunifying theoretical framework to quantify inter-event time distributions inreaction-diffusion systems that clarifies existing debates in the literatureand provide examples of application to real-world scenarios.
从晶格中准粒子的湮灭,到景观中捕食者与猎物的相遇,再到神经网络中的尖峰,许多自然现象都是通过对可观测事件的计数来量化的。当底层动力系统在其相空间中占据一组反应状态时,这些事件就会以随机间隔触发。我们推导出了此类计数过程中事件间隔时间分布的一般表达式,假设底层触发动力学是一个收敛于静态分布的随机过程。我们的结果有助于解决反应-扩散过程研究中长期存在的二分法问题,表明反应间点过程介于反应限制和扩散限制机制之间。在低反应速率下,反应间过程是泊松过程,其速率取决于事件触发随机过程的静态特性。在高反应速率下,反应间时间主要由到达反应状态的时间决定。为了进一步说明这种方法的威力,我们应用我们的框架来获取在多个生物物理场景中出现的两个计数过程的计数统计量。首先,我们研究了通过动物穿越探测器的频率来估计其活动水平的常见情况,结果表明穿越事件的平均次数会随着命中率的下降而单调减少,这一看似 "矛盾 "的结果可能会导致对实验计数数据的误解。其次,我们推导出了许多粒子检测的集合统计,恢复并推广了化学感受生物物理学中的已知结果。总之,我们建立了一个统一的理论框架来量化反应扩散系统中的事件间时间分布,澄清了现有文献中的争论,并提供了应用于现实世界场景的实例。
{"title":"The structure of inter-reaction times in reaction-diffusion processes and consequences for counting statistics","authors":"Benjamin Garcia de Figueiredo, Justin M. Calabrese, William F. Fagan, Ricardo Martinez-Garcia","doi":"arxiv-2409.11433","DOIUrl":"https://doi.org/arxiv-2409.11433","url":null,"abstract":"Many natural phenomena are quantified by counts of observable events, from\u0000the annihilation of quasiparticles in a lattice to predator-prey encounters on\u0000a landscape to spikes in a neural network. These events are triggered at random\u0000intervals when an underlying dynamical system occupies a set of reactive states\u0000in its phase space. We derive a general expression for the distribution of\u0000times between events in such counting processes assuming the underlying\u0000triggering dynamics is a stochastic process that converges to a stationary\u0000distribution. Our results contribute to resolving a long-standing dichotomy in\u0000the study of reaction-diffusion processes, showing the inter-reaction point\u0000process interpolates between a reaction- and a diffusion-limited regime. At low\u0000reaction rates, the inter-reaction process is Poisson with a rate depending on\u0000stationary properties of the event-triggering stochastic process. At high\u0000reaction rates, inter-reaction times are dominated by the hitting times to the\u0000reactive states. To further illustrate the power of this approach we apply our\u0000framework to obtain the counting statistics of two counting processes appearing\u0000in several biophysical scenarios. First, we study the common situation of\u0000estimating an animal's activity level by how often it crosses a detector,\u0000showing that the mean number of crossing events can decrease monotonically with\u0000the hitting rate, a seemingly 'paradoxical' result that could possibly lead to\u0000misinterpretation of experimental count data. Second, we derive the ensemble\u0000statistics for the detection of many particles, recovering and generalizing\u0000known results in the biophysics of chemosensation. Overall, we develop a\u0000unifying theoretical framework to quantify inter-event time distributions in\u0000reaction-diffusion systems that clarifies existing debates in the literature\u0000and provide examples of application to real-world scenarios.","PeriodicalId":501040,"journal":{"name":"arXiv - PHYS - Biological Physics","volume":"97 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142265670","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Light-induced cortical excitability reveals programmable shape dynamics in starfish oocytes 光诱导皮层兴奋性揭示了海星卵母细胞的可编程形状动力学
Pub Date : 2024-09-13 DOI: arxiv-2409.08651
Jinghui Liu, Tom Burkart, Alexander Ziepke, John Reinhard, Yu-Chen Chao, Tzer Han Tan, S. Zachary Swartz, Erwin Frey, Nikta Fakhri
Chemo-mechanical waves on active deformable surfaces are a key component formany vital cellular functions. In particular, these waves play a major role inforce generation and long-range signal transmission in cells that dynamicallychange shape, as encountered during cell division or morphogenesis.Reconstituting and controlling such chemically controlled cell deformations isa crucial but unsolved challenge for the development of synthetic cells. Here,we develop an optogenetic method to elucidate the mechanism responsible forcoordinating surface contraction waves that occur in oocytes of the starfishPatiria miniata during meiotic cell division. Using spatiotemporally-patternedlight stimuli as a control input, we create chemo-mechanical corticalexcitations that are decoupled from meiotic cues and drive diverse shapedeformations ranging from local pinching to surface contraction waves and celllysis. We develop a quantitative model that entails the hierarchy of chemicaland mechanical dynamics, which allows to relate the variety of mechanicalresponses to optogenetic stimuli. Our framework systematically predicts andexplains transitions of programmed shape dynamics. Finally, we qualitativelymap the observed shape dynamics to elucidate how the versatility ofintracellular protein dynamics can give rise to a broad range of mechanicalphenomenologies. More broadly, our results pave the way toward real-timecontrol over dynamical deformations in living organisms and can advance thedesign of synthetic cells and life-like cellular functions.
活性可变形表面上的化学机械波是许多重要细胞功能的关键组成部分。特别是在细胞分裂或形态发生过程中,这些波在动态改变形状的细胞中起着产生力和远距离信号传输的重要作用。重建和控制这种化学控制的细胞变形是开发合成细胞的一个关键但尚未解决的挑战。在这里,我们开发了一种光遗传学方法来阐明海星(Patiria miniata)卵母细胞在减数分裂过程中发生的表面收缩波的协调机制。利用时空图案光刺激作为控制输入,我们产生了与减数分裂线索脱钩的化学机械皮层兴奋,并驱动了从局部挤压到表面收缩波和细胞溶解等各种形状的变形。我们建立了一个包含化学和机械动力学层次的定量模型,可以将各种机械反应与光遗传刺激联系起来。我们的框架系统地预测并解释了程序化形状动力学的转变。最后,我们对观察到的形状动力学进行了定性描绘,以阐明细胞内蛋白质动力学的多功能性是如何产生各种机械现象的。更广泛地说,我们的研究成果为实时控制生物体内的动态变形铺平了道路,并能推动合成细胞和类生命细胞功能的设计。
{"title":"Light-induced cortical excitability reveals programmable shape dynamics in starfish oocytes","authors":"Jinghui Liu, Tom Burkart, Alexander Ziepke, John Reinhard, Yu-Chen Chao, Tzer Han Tan, S. Zachary Swartz, Erwin Frey, Nikta Fakhri","doi":"arxiv-2409.08651","DOIUrl":"https://doi.org/arxiv-2409.08651","url":null,"abstract":"Chemo-mechanical waves on active deformable surfaces are a key component for\u0000many vital cellular functions. In particular, these waves play a major role in\u0000force generation and long-range signal transmission in cells that dynamically\u0000change shape, as encountered during cell division or morphogenesis.\u0000Reconstituting and controlling such chemically controlled cell deformations is\u0000a crucial but unsolved challenge for the development of synthetic cells. Here,\u0000we develop an optogenetic method to elucidate the mechanism responsible for\u0000coordinating surface contraction waves that occur in oocytes of the starfish\u0000Patiria miniata during meiotic cell division. Using spatiotemporally-patterned\u0000light stimuli as a control input, we create chemo-mechanical cortical\u0000excitations that are decoupled from meiotic cues and drive diverse shape\u0000deformations ranging from local pinching to surface contraction waves and cell\u0000lysis. We develop a quantitative model that entails the hierarchy of chemical\u0000and mechanical dynamics, which allows to relate the variety of mechanical\u0000responses to optogenetic stimuli. Our framework systematically predicts and\u0000explains transitions of programmed shape dynamics. Finally, we qualitatively\u0000map the observed shape dynamics to elucidate how the versatility of\u0000intracellular protein dynamics can give rise to a broad range of mechanical\u0000phenomenologies. More broadly, our results pave the way toward real-time\u0000control over dynamical deformations in living organisms and can advance the\u0000design of synthetic cells and life-like cellular functions.","PeriodicalId":501040,"journal":{"name":"arXiv - PHYS - Biological Physics","volume":"22 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142269512","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Influence of cell density and in-vivo aging on erythrocyte aggregability: Dissociation dynamics in extensional flow 细胞密度和体内老化对红细胞聚集性的影响延伸流中的解离动力学
Pub Date : 2024-09-13 DOI: arxiv-2409.08877
Midhun Puthumana Melepattu, Guillaume Maîtrejean, Christian Wagner, Thomas Podgorski
Blood rheology and microcirculation are strongly influenced by red blood cell(RBC) aggregation. The aggregability of RBCs can vary significantly due tofactors such as their mechanical and membrane surface properties, which areaffected by cell aging in vivo. In this study, we investigate RBC aggregabilityas a function of their density, a marker of cell age and mechanical properties,by separating RBCs from healthy donors into different density fractions usingPercoll density gradient centrifugation. We examine the dissociation rates ofaggregates in a controlled medium supplemented with Dextran, employing anextensional flow technique based on hyperbolic microfluidic constrictions andimage analysis, assisted by a convolutional neural network (CNN). In contrastto other techniques, our microfluidic experimental approach highlights thebehavior of RBC aggregates in dynamic flow conditions relevant tomicrocirculation. Our results demonstrate that aggregate dissociation isstrongly correlated with cell density and that aggregates formed from thedenser fractions of RBCs are significantly more robust than those from theaverage cell population. This study provides insight into the effect of RBCaging in vivo on their mechanical properties and aggregability, underscoringthe importance of further exploration of RBC aggregation in the context ofcellular senescence and its potential implications for hemodynamics.Additionally, it suggests that this technique can complement existing methodsfor improved evaluation of RBC aggregability in health and disease.
血液流变性和微循环受红细胞聚集的影响很大。红细胞的聚集性会受其机械和膜表面特性等因素的影响而发生显著变化,而这些因素又会受到体内细胞老化的影响。在本研究中,我们使用珀尔密度梯度离心法将健康供体的 RBC 分离成不同密度的部分,从而研究了 RBC 的聚集性与其密度的函数关系,密度是细胞年龄和机械特性的标志。在卷积神经网络(CNN)的辅助下,我们采用基于双曲微流体收缩和图像分析的外延流动技术,在添加右旋糖酐的可控培养基中检测了聚集体的解离率。与其他技术相比,我们的微流控实验方法突出了微循环相关动态流动条件下 RBC 聚集体的行为。我们的研究结果表明,聚集体的解离与细胞密度密切相关,RBC 的高密度部分形成的聚集体明显比平均细胞群形成的聚集体更稳健。这项研究深入揭示了体内 RBC 老化对其机械特性和聚集性的影响,强调了在细胞衰老背景下进一步探索 RBC 聚集及其对血液动力学潜在影响的重要性。
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引用次数: 0
Hybrid roles of adaptation and optimization in formation of vascular network 适应和优化在血管网络形成中的混合作用
Pub Date : 2024-09-12 DOI: arxiv-2409.07824
Yawei Wang, Zilu Qin, Yubo Fan
It was hypothesized that the structures of biological transport networks arethe result of either energy consumption or adaptation dynamics. Althoughapproaches based on these hypotheses can produce optimal network and form loopstructures, we found that neither possesses complete ability to generatecomplex networks that resemble vascular network in living organisms, whichmotivated us to propose a hybrid approach. This approach can replicate the pathdependency phenomenon of main branches and produce an optimal network thatresembles the real vascular network. We further show that there is a cleartransition in the structural pattern of the vascular network, shifting from`chive-like' to dendritic configuration after a period of sequenced adaptationand optimization.
根据假设,生物运输网络的结构是能量消耗或适应动态的结果。虽然基于这些假设的方法可以生成最优网络并形成环路结构,但我们发现这两种方法都不具备生成类似于生物体内血管网络的复杂网络的完整能力,这促使我们提出了一种混合方法。这种方法可以复制主枝的路径依赖现象,生成类似真实血管网络的最优网络。我们进一步证明,血管网络的结构模式有一个明显的转变,经过一段时间的有序适应和优化后,从 "树枝状 "结构转变为 "蜂巢状 "结构。
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引用次数: 0
Settling aerodynamics is a driver of symmetry in deciduous tree leaves 沉降空气动力学是落叶树叶片对称性的驱动因素
Pub Date : 2024-09-09 DOI: arxiv-2409.05514
Matthew D. Biviano, Kaare H. Jensen
Leaves shed by deciduous trees contain 40% of the annually sequesteredcarbon, and include nutrients vital to the expansion and health of forestecosystems. To achieve this, leaves must fall quickly to land near the parenttree -- otherwise, they are lost to the wind, like pollen or gliding seeds.However, the link between leaf shape and sedimentation speed remains unclear.To gauge the relative performance of extant leaves, we developed an automatedsedimentation apparatus (ASAP) capable of performing $sim100$ free fallexperiments per day on biomimetic paper leaves. The majority of 25representative leaves settle at rates similar to our control (a circular disc).Strikingly, the Arabidopsid mutant asymmetric leaves1 (as1) fell 15% slowerthan the wild type. Applying the as1-digital mutation to deciduous tree leavesrevealed a similar speed reduction. Data correlating shape and settling acrossa broad range of natural, mutated, and artificial leaves supportthefast-leaf-hypothesis: Deciduous leaves are symmetric and relatively unlobedin part because this maximizes their settling speed and concomitant nutrientretention.
落叶树落下的树叶含有每年固碳量的 40%,并含有对森林生态系统的扩展和健康至关重要的营养物质。为了实现这一目标,树叶必须快速落下,落到母树附近--否则,它们就会像花粉或滑翔种子一样随风而逝。然而,树叶形状与沉降速度之间的联系仍不清楚。为了衡量现存树叶的相对性能,我们开发了一种自动沉降装置(ASAP),每天能够在仿生纸树叶上进行100美元的自由落叶实验。25片具有代表性的叶片中,大多数叶片的沉降速度与我们的对照组(一个圆形圆盘)相似。将as1-数字突变应用于落叶乔木叶片,也发现了类似的速度降低。在广泛的天然叶片、变异叶片和人工叶片中,形状与沉降相关的数据支持了快叶假说:落叶之所以对称且相对无叶片,部分原因是这样可以最大限度地提高沉降速度,同时保留养分。
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引用次数: 0
期刊
arXiv - PHYS - Biological Physics
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