Pub Date : 2024-10-01Epub Date: 2024-10-02DOI: 10.1098/rsif.2024.0378
Yi Yang, Tian Yuan, Ferdinando Rodriguez Y Baena, Daniele Dini, Wenbo Zhan
Convection-enhanced delivery (CED) can effectively overcome the blood-brain barrier by infusing drugs directly into diseased sites in the brain using a catheter, but its clinical performance still needs to be improved. This is strongly related to the highly anisotropic characteristics of brain white matter, which results in difficulties in controlling drug transport and distribution in space. In this study, the potential to improve the delivery of six drugs by adjusting the placement of the infusion catheter is examined using a mathematical model and accurate numerical simulations that account simultaneously for the interstitial fluid (ISF) flow and drug transport processes in CED. The results demonstrate the ability of this direct infusion to enhance ISF flow and therefore facilitate drug transport. However, this enhancement is highly anisotropic, subject to the orientation of local axon bundles and is limited within a small region close to the infusion site. Drugs respond in different ways to infusion direction: the results of our simulations show that while some drugs are almost insensitive to infusion direction, this strongly affects other compounds in terms of isotropy of drug distribution from the catheter. These findings can serve as a reference for planning treatments using CED.
{"title":"Effect of infusion direction on convection-enhanced drug delivery to anisotropic tissue.","authors":"Yi Yang, Tian Yuan, Ferdinando Rodriguez Y Baena, Daniele Dini, Wenbo Zhan","doi":"10.1098/rsif.2024.0378","DOIUrl":"10.1098/rsif.2024.0378","url":null,"abstract":"<p><p>Convection-enhanced delivery (CED) can effectively overcome the blood-brain barrier by infusing drugs directly into diseased sites in the brain using a catheter, but its clinical performance still needs to be improved. This is strongly related to the highly anisotropic characteristics of brain white matter, which results in difficulties in controlling drug transport and distribution in space. In this study, the potential to improve the delivery of six drugs by adjusting the placement of the infusion catheter is examined using a mathematical model and accurate numerical simulations that account simultaneously for the interstitial fluid (ISF) flow and drug transport processes in CED. The results demonstrate the ability of this direct infusion to enhance ISF flow and therefore facilitate drug transport. However, this enhancement is highly anisotropic, subject to the orientation of local axon bundles and is limited within a small region close to the infusion site. Drugs respond in different ways to infusion direction: the results of our simulations show that while some drugs are almost insensitive to infusion direction, this strongly affects other compounds in terms of isotropy of drug distribution from the catheter. These findings can serve as a reference for planning treatments using CED.</p>","PeriodicalId":17488,"journal":{"name":"Journal of The Royal Society Interface","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11444765/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142365727","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-01Epub Date: 2024-10-02DOI: 10.1098/rsif.2024.0276
Muhammad Usama Ashraf, Daniel Nyqvist, Claudio Comoglio, Vladimir Nikora, Andrea Marion, Paolo Domenici, Costantino Manes
Fatigue curves quantify fish swimming performance, providing information about the time ([Formula: see text]) fish can swim against a steady flow velocity (Uf) before fatiguing. Such curves represent a key tool for many applications in ecological engineering, especially for fish pass design and management. Despite years of research, though, our current ability to model fatigue curves still lacks theoretical foundations and relies primarily on fitting empirical data, as obtained from time-consuming and costly experiments. In the present article, we address this shortcoming by proposing a theoretical analysis that builds upon concepts of fish hydrodynamics to derive scaling laws linking statistical properties of [Formula: see text] to velocities Uf, pertaining to the so-called burst range. Theoretical arguments, in the present study, suggest that the proposed scaling laws may hold true for all fish species and sizes. A new experimental database obtained from over 800 trials and five small-sized Cypriniformes support theoretical predictions satisfactorily and calls for further experiments on more fish species and sizes to confirm their general validity.
{"title":"Decoding burst swimming performance: a scaling perspective on time-to-fatigue.","authors":"Muhammad Usama Ashraf, Daniel Nyqvist, Claudio Comoglio, Vladimir Nikora, Andrea Marion, Paolo Domenici, Costantino Manes","doi":"10.1098/rsif.2024.0276","DOIUrl":"10.1098/rsif.2024.0276","url":null,"abstract":"<p><p>Fatigue curves quantify fish swimming performance, providing information about the time ([Formula: see text]) fish can swim against a steady flow velocity (<i>U<sub>f</sub></i>) before fatiguing. Such curves represent a key tool for many applications in ecological engineering, especially for fish pass design and management. Despite years of research, though, our current ability to model fatigue curves still lacks theoretical foundations and relies primarily on fitting empirical data, as obtained from time-consuming and costly experiments. In the present article, we address this shortcoming by proposing a theoretical analysis that builds upon concepts of fish hydrodynamics to derive scaling laws linking statistical properties of [Formula: see text] to velocities <i>U<sub>f</sub></i>, pertaining to the so-called burst range. Theoretical arguments, in the present study, suggest that the proposed scaling laws may hold true for all fish species and sizes. A new experimental database obtained from over 800 trials and five small-sized Cypriniformes support theoretical predictions satisfactorily and calls for further experiments on more fish species and sizes to confirm their general validity.</p>","PeriodicalId":17488,"journal":{"name":"Journal of The Royal Society Interface","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11444792/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142365726","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-01Epub Date: 2024-10-02DOI: 10.1098/rsif.2024.0485
Maria L Hernandez-Miranda, Dichu Xu, Aya A Ben Issa, David A Johnston, Martin Browne, Richard B Cook, Bram G Sengers, Nicholas Evans
Extracellular matrix (ECM) stiffness is fundamental in cell division, movement and differentiation. The stiffness that cells sense is determined not only by the elastic modulus of the ECM material but also by ECM geometry and cell density. We hypothesized that these factors would influence cell traction-induced matrix deformations and cellular differentiation in bone marrow stromal cells (BMSCs). To achieve this, we cultivated BMSCs on polyacrylamide hydrogels that varied in elastic modulus and geometry and measured cell spreading, cell-imparted matrix deformations and differentiation. At low cell density BMSCs spread to a greater extent on stiff compared with soft hydrogels, or on thin compared with thick hydrogels. Cell-imparted matrix deformations were greater on soft compared with stiff hydrogels or thick compared with thin hydrogels. There were no significant differences in osteogenic differentiation relative to hydrogel elastic modulus and thickness. However, increased cell density and/or prolonged culture significantly reduced matrix deformations on soft hydrogels to levels similar to those on stiff substrates. This suggests that at high cell densities cell traction-induced matrix displacements are reduced by both neighbouring cells and the constraint imposed by an underlying stiff support. This may explain observations of the lack of difference in osteogenic differentiation as a function of stiffness.
{"title":"Geometric constraint of mechanosensing by modification of hydrogel thickness prevents stiffness-induced differentiation in bone marrow stromal cells.","authors":"Maria L Hernandez-Miranda, Dichu Xu, Aya A Ben Issa, David A Johnston, Martin Browne, Richard B Cook, Bram G Sengers, Nicholas Evans","doi":"10.1098/rsif.2024.0485","DOIUrl":"10.1098/rsif.2024.0485","url":null,"abstract":"<p><p>Extracellular matrix (ECM) stiffness is fundamental in cell division, movement and differentiation. The stiffness that cells sense is determined not only by the elastic modulus of the ECM material but also by ECM geometry and cell density. We hypothesized that these factors would influence cell traction-induced matrix deformations and cellular differentiation in bone marrow stromal cells (BMSCs). To achieve this, we cultivated BMSCs on polyacrylamide hydrogels that varied in elastic modulus and geometry and measured cell spreading, cell-imparted matrix deformations and differentiation. At low cell density BMSCs spread to a greater extent on stiff compared with soft hydrogels, or on thin compared with thick hydrogels. Cell-imparted matrix deformations were greater on soft compared with stiff hydrogels or thick compared with thin hydrogels. There were no significant differences in osteogenic differentiation relative to hydrogel elastic modulus and thickness. However, increased cell density and/or prolonged culture significantly reduced matrix deformations on soft hydrogels to levels similar to those on stiff substrates. This suggests that at high cell densities cell traction-induced matrix displacements are reduced by both neighbouring cells and the constraint imposed by an underlying stiff support. This may explain observations of the lack of difference in osteogenic differentiation as a function of stiffness.</p>","PeriodicalId":17488,"journal":{"name":"Journal of The Royal Society Interface","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11444768/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142365728","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Gabora and Steel (Gabora L, Steel M. 2021 An evolutionary process without variation and selection. J. R. Soc. Interface 18, 20210334. [doi:10.1098/rsif.2021.0334]) claim that cumulative adaptive evolution is possible without natural selection, that is, without variation and competition. To support this claim, the authors modelled a theoretical process called self-other reorganization (SOR) that envisages a population of reflexively autocatalytic sets that can accumulate beneficial changes without any form of birth, death or selection, that is without population dynamics. The authors claim that despite being non-Darwinian, adaptive evolution happens in SOR, deeming it relevant to the origin of life and to cultural evolution. We analysed SOR and the claim that it implements evolution without variation and selection. We found that the authors, by design, ignore the growth and/or degradation of autocatalytic sets or their components, assuming all effects are beneficial and all entities in SOR are identical and immutable. We prove that due to these assumptions, SOR is a trivial model of horizontal percolation of beneficial effects over a static population. We implemented an extended model of SOR including more realistic assumptions to prove that accounting for any of the ignored processes inevitably leads to conventional Darwinian dynamics. Our analysis directly challenges the authors' claims, revealing evidence of an overly fragile foundation. While the best-case scenario the authors incorrectly generalize from may be mathematically valid, stripping away their unrealistic assumptions reveals that SOR does not represent real entities (e.g. protocells) but rather models the triviality that fast horizontal diffusion of effects can effectively equalize a population. Adaptation in SOR is solely because the authors only consider beneficial effects. The omission of death/growth dynamics and maladaptive effects renders SOR unrealistic and its relevance to evolution, cultural or biological, questionable.
加博拉和斯蒂尔(Gabora L, Steel M. 2021):没有变异和选择的进化过程。J. R. Soc. Interface 18, 20210334.[doi:10.1098/rsif.2021.0334])声称,没有自然选择,即没有变异和竞争,累积适应性进化是可能的。为了支持这一观点,作者模拟了一个名为 "自他重组"(SOR)的理论过程,该过程设想了一个由反射性自催化集合组成的种群,它可以在没有任何形式的出生、死亡或选择(即没有种群动态)的情况下积累有益的变化。作者声称,尽管 SOR 不是达尔文进化论,但适应性进化却发生在 SOR 中,并认为它与生命起源和文化进化有关。我们分析了 SOR 以及它在没有变异和选择的情况下实现进化的说法。我们发现,作者有意忽略了自催化集或其组成部分的增长和/或退化,假定所有影响都是有益的,而且 SOR 中的所有实体都是相同和不可改变的。我们证明,由于这些假设,SOR 是一个在静态种群中横向渗透有益效应的微不足道的模型。我们实施了一个扩展的 SOR 模型,其中包括更现实的假设,以证明考虑任何一个被忽略的过程都不可避免地会导致传统的达尔文动力学。我们的分析直接挑战了作者的说法,揭示了基础过于脆弱的证据。虽然作者错误地概括出的最佳情况可能在数学上是有效的,但撇开他们不切实际的假设,就会发现 SOR 并不代表真实的实体(如原细胞),而是模拟了快速水平扩散效应可以有效平衡种群的微不足道之处。SOR 中的适应性仅仅是因为作者只考虑了有益效应。由于忽略了死亡/增长动态和不适应效应,SOR 是不现实的,其与文化或生物进化的相关性也值得怀疑。
{"title":"Tautology explains evolution without variation and selection. A Comment on: 'An evolutionary process without variation and selection' (2021), by Gabora et al.","authors":"István Zachar,Jakab Máté,Szabolcs Számadó","doi":"10.1098/rsif.2023.0579","DOIUrl":"https://doi.org/10.1098/rsif.2023.0579","url":null,"abstract":"Gabora and Steel (Gabora L, Steel M. 2021 An evolutionary process without variation and selection. J. R. Soc. Interface 18, 20210334. [doi:10.1098/rsif.2021.0334]) claim that cumulative adaptive evolution is possible without natural selection, that is, without variation and competition. To support this claim, the authors modelled a theoretical process called self-other reorganization (SOR) that envisages a population of reflexively autocatalytic sets that can accumulate beneficial changes without any form of birth, death or selection, that is without population dynamics. The authors claim that despite being non-Darwinian, adaptive evolution happens in SOR, deeming it relevant to the origin of life and to cultural evolution. We analysed SOR and the claim that it implements evolution without variation and selection. We found that the authors, by design, ignore the growth and/or degradation of autocatalytic sets or their components, assuming all effects are beneficial and all entities in SOR are identical and immutable. We prove that due to these assumptions, SOR is a trivial model of horizontal percolation of beneficial effects over a static population. We implemented an extended model of SOR including more realistic assumptions to prove that accounting for any of the ignored processes inevitably leads to conventional Darwinian dynamics. Our analysis directly challenges the authors' claims, revealing evidence of an overly fragile foundation. While the best-case scenario the authors incorrectly generalize from may be mathematically valid, stripping away their unrealistic assumptions reveals that SOR does not represent real entities (e.g. protocells) but rather models the triviality that fast horizontal diffusion of effects can effectively equalize a population. Adaptation in SOR is solely because the authors only consider beneficial effects. The omission of death/growth dynamics and maladaptive effects renders SOR unrealistic and its relevance to evolution, cultural or biological, questionable.","PeriodicalId":17488,"journal":{"name":"Journal of The Royal Society Interface","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142262997","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Randall W Davis,Lorenzo Fiori,Bernd Würsig,Dara N Orbach
For 88 years, biologists and engineers have sought to understand the hydrodynamics enabling dolphins to swim at speeds seemingly beyond their energetic capabilities, a phenomenon known as Gray's paradox. Hydromechanical models calculating the drag of swimming dolphins estimated power requirements for sustained high-speed swimming, which were physiologically impossible. Using an uncrewed aerial vehicle, we calculated the total power of free-ranging dusky dolphins (Lagenorhynchus obscurus) at speeds from 0.9 to 6.9 m s-1, deriving drag coefficients (Cd) and drag. Our results showed that the Cd decreased exponentially with speed, reducing drag by up to 89% at speeds >2 m s-1, with an additional 17% reduction during porpoising (>4.0 m s-1). At 6.9 m s-1, drag was 32 N, with a power of 15.8 W kg-1, nearly identical to the mass-specific allometric prediction for the maximum aerobic capacity of other mammals and physiologically possible. The Cd at speeds >2.5 m s-1 indicated reduced turbulence in the boundary layer around the dolphin's body, thereby reducing drag. The ability of dusky dolphins to swim at sustained high speeds resulted from an exponential decrease in Cd, which was further reduced by porpoising, thereby explaining the low drag and locomotory power that resolved Gray's paradox.
88 年来,生物学家和工程师一直试图了解使海豚能够以看似超出其能量能力的速度游泳的流体力学,这种现象被称为格雷悖论。计算海豚游动阻力的水力学模型估计了持续高速游动所需的动力,而这在生理上是不可能的。我们利用无人驾驶飞行器,计算了自由活动的暗色海豚(Lagenorhynchus obscurus)在 0.9 至 6.9 米/秒速度下的总功率,得出了阻力系数(Cd)和阻力。我们的结果表明,Cd 随速度呈指数下降,速度大于 2 米/秒时,阻力最多可减少 89%,而在海豚游动时(大于 4.0 米/秒),阻力还可减少 17%。在 6.9 m s-1 时,阻力为 32 N,功率为 15.8 W kg-1,几乎与其他哺乳动物最大有氧能力的特定质量异速预测值相同,在生理学上是可能的。速度大于 2.5 米/秒时的 Cd 表明海豚身体周围边界层的湍流减少,从而降低了阻力。暗色海豚以持续高速游泳的能力来自于 Cd 的指数式下降,而这种下降又因海豚的游动而进一步减少,从而解释了低阻力和解决格雷悖论的运动能力。
{"title":"Drag reduction and locomotory power in dolphins: Gray's paradox revealed.","authors":"Randall W Davis,Lorenzo Fiori,Bernd Würsig,Dara N Orbach","doi":"10.1098/rsif.2024.0227","DOIUrl":"https://doi.org/10.1098/rsif.2024.0227","url":null,"abstract":"For 88 years, biologists and engineers have sought to understand the hydrodynamics enabling dolphins to swim at speeds seemingly beyond their energetic capabilities, a phenomenon known as Gray's paradox. Hydromechanical models calculating the drag of swimming dolphins estimated power requirements for sustained high-speed swimming, which were physiologically impossible. Using an uncrewed aerial vehicle, we calculated the total power of free-ranging dusky dolphins (Lagenorhynchus obscurus) at speeds from 0.9 to 6.9 m s-1, deriving drag coefficients (Cd) and drag. Our results showed that the Cd decreased exponentially with speed, reducing drag by up to 89% at speeds >2 m s-1, with an additional 17% reduction during porpoising (>4.0 m s-1). At 6.9 m s-1, drag was 32 N, with a power of 15.8 W kg-1, nearly identical to the mass-specific allometric prediction for the maximum aerobic capacity of other mammals and physiologically possible. The Cd at speeds >2.5 m s-1 indicated reduced turbulence in the boundary layer around the dolphin's body, thereby reducing drag. The ability of dusky dolphins to swim at sustained high speeds resulted from an exponential decrease in Cd, which was further reduced by porpoising, thereby explaining the low drag and locomotory power that resolved Gray's paradox.","PeriodicalId":17488,"journal":{"name":"Journal of The Royal Society Interface","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142175239","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Diogo G Pires,Nuno M Silva,Bárbara M de Sousa,João L Marques,António Ramos,Jorge A F Ferreira,Raul Morais,Sandra I Vieira,Marco P Soares Dos Santos
Bioelectronic bone implants are being widely recognized as a promising technology for highly personalized bone/implant interface sensing and biophysical therapeutic stimulation. Such bioelectronic devices are based on an innovative concept with the ability to be applied to a wide range of implants, including in fixation and prosthetic systems. Recently, biointerface sensing using capacitive patterns was proposed to overcome the limitations of standard imaging technologies and other non-imaging technologies; moreover, electric stimulation using capacitive patterns was proposed to overcome the limitations of non-instrumented implants. We here provide an innovative low-power miniaturized electronic system with ability to provide both therapeutic stimulation and bone/implant interface monitoring using network-architectured capacitive interdigitated patterns. It comprises five modules: sensing, electric stimulation, processing, communication and power management. This technology was validated using in vitro tests: concerning the sensing system, its ability to detect biointerface changes ranging from tiny to severe bone-implant interface changes in target regions was validated; concerning the stimulation system, its ability to significantly enhance bone cells' full differentiation, including matrix maturation and mineralization, was also confirmed. This work provides an impactful contribution and paves the way for the development of the new generation of orthopaedic biodevices.
{"title":"A millimetre-scale capacitive biosensing and biophysical stimulation system for emerging bioelectronic bone implants.","authors":"Diogo G Pires,Nuno M Silva,Bárbara M de Sousa,João L Marques,António Ramos,Jorge A F Ferreira,Raul Morais,Sandra I Vieira,Marco P Soares Dos Santos","doi":"10.1098/rsif.2024.0279","DOIUrl":"https://doi.org/10.1098/rsif.2024.0279","url":null,"abstract":"Bioelectronic bone implants are being widely recognized as a promising technology for highly personalized bone/implant interface sensing and biophysical therapeutic stimulation. Such bioelectronic devices are based on an innovative concept with the ability to be applied to a wide range of implants, including in fixation and prosthetic systems. Recently, biointerface sensing using capacitive patterns was proposed to overcome the limitations of standard imaging technologies and other non-imaging technologies; moreover, electric stimulation using capacitive patterns was proposed to overcome the limitations of non-instrumented implants. We here provide an innovative low-power miniaturized electronic system with ability to provide both therapeutic stimulation and bone/implant interface monitoring using network-architectured capacitive interdigitated patterns. It comprises five modules: sensing, electric stimulation, processing, communication and power management. This technology was validated using in vitro tests: concerning the sensing system, its ability to detect biointerface changes ranging from tiny to severe bone-implant interface changes in target regions was validated; concerning the stimulation system, its ability to significantly enhance bone cells' full differentiation, including matrix maturation and mineralization, was also confirmed. This work provides an impactful contribution and paves the way for the development of the new generation of orthopaedic biodevices.","PeriodicalId":17488,"journal":{"name":"Journal of The Royal Society Interface","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142175240","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-01Epub Date: 2024-09-04DOI: 10.1098/rsif.2024.0191
Michelle J Harter, Mark S Redfern, Patrick J Sparto, Harmut Geyer
Walking is unstable and requires active control. Foot placement is the primary strategy to maintain frontal-plane balance with contributions from lateral ankle torques, ankle push-off and trunk postural adjustments. Because these strategies interact, their individual contributions are difficult to study. Here, we used computational modelling to understand these individual contributions to frontal-plane walking balance control. A three-dimensional bipedal model was developed based on linear inverted pendulum dynamics. The model included controllers that implement the stabilization strategies seen in human walking. The control parameters were optimized to mimic human gait biomechanics for typical spatio-temporal parameters during steady-state walking and when perturbed by mediolateral ground shifts. Using the optimized model as a starting point, the contributions of each stabilization strategy were explored by progressively removing strategies. The lateral ankle and trunk strategies were more important than ankle push-off, with their removal causing up to 20% worse balance recovery compared with the full model, while removing ankle push-off led to minimal changes. Our results imply a potential benefit of preferentially training these strategies in populations with poor balance. Moreover, the proposed model could be used in future work to investigate how walking stability may be preserved in conditions reflective of injury or disease.
{"title":"Modelling strategies supplemental to foot placement for frontal-plane stability in walking.","authors":"Michelle J Harter, Mark S Redfern, Patrick J Sparto, Harmut Geyer","doi":"10.1098/rsif.2024.0191","DOIUrl":"10.1098/rsif.2024.0191","url":null,"abstract":"<p><p>Walking is unstable and requires active control. Foot placement is the primary strategy to maintain frontal-plane balance with contributions from lateral ankle torques, ankle push-off and trunk postural adjustments. Because these strategies interact, their individual contributions are difficult to study. Here, we used computational modelling to understand these individual contributions to frontal-plane walking balance control. A three-dimensional bipedal model was developed based on linear inverted pendulum dynamics. The model included controllers that implement the stabilization strategies seen in human walking. The control parameters were optimized to mimic human gait biomechanics for typical spatio-temporal parameters during steady-state walking and when perturbed by mediolateral ground shifts. Using the optimized model as a starting point, the contributions of each stabilization strategy were explored by progressively removing strategies. The lateral ankle and trunk strategies were more important than ankle push-off, with their removal causing up to 20% worse balance recovery compared with the full model, while removing ankle push-off led to minimal changes. Our results imply a potential benefit of preferentially training these strategies in populations with poor balance. Moreover, the proposed model could be used in future work to investigate how walking stability may be preserved in conditions reflective of injury or disease.</p>","PeriodicalId":17488,"journal":{"name":"Journal of The Royal Society Interface","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11371431/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142126013","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-01Epub Date: 2024-09-04DOI: 10.1098/rsif.2024.0148
Jiajia Shen, Martin Garrad, Qicheng Zhang, Vico Chun Hei Wong, Alberto Pirrera, Rainer M J Groh
Biology is a wellspring of inspiration in engineering design. This paper delves into the application of elastic instabilities-commonly used in biological systems to facilitate swift movement-as a power-amplification mechanism for soft robots. Specifically, inspired by the nonlinear mechanics of the hummingbird beak-and shedding further light on it-we design, build and test a novel, rapid-response, soft end effector. The hummingbird beak embodies the capacity for swift movement, achieving closure in less than [Formula: see text]. Previous work demonstrated that rapid movement is achieved through snap-through deformations, induced by muscular actuation of the beak's root. Using nonlinear finite element simulations coupled with continuation algorithms, we unveil a representative portion of the equilibrium manifold of the beak-inspired structure. The exploration involves the application of a sequence of rotations as exerted by the hummingbird muscles. Specific emphasis is placed on pinpointing and tailoring the position along the manifold of the saddle-node bifurcation at which the onset of elastic instability triggers dynamic snap-through. We show the critical importance of the intermediate rotation input in the sequence, as it results in the accumulation of elastic energy that is then explosively released as kinetic energy upon snap-through. Informed by our numerical studies, we conduct experimental testing on a prototype end effector fabricated using a compliant material (thermoplastic polyurethane). The experimental results support the trends observed in the numerical simulations and demonstrate the effectiveness of the bio-inspired design. Specifically, we measure the energy transferred by the soft end effector to a pendulum, varying the input levels in the sequence of prescribed rotations. Additionally, we demonstrate a potential robotic application in scenarios demanding explosive action. From a mechanics perspective, our work sheds light on how pre-stress fields can enable swift movement in soft robotic systems with the potential to facilitate high input-to-output energy efficiency.
{"title":"A rapid-response soft end effector inspired by the hummingbird beak.","authors":"Jiajia Shen, Martin Garrad, Qicheng Zhang, Vico Chun Hei Wong, Alberto Pirrera, Rainer M J Groh","doi":"10.1098/rsif.2024.0148","DOIUrl":"https://doi.org/10.1098/rsif.2024.0148","url":null,"abstract":"<p><p>Biology is a wellspring of inspiration in engineering design. This paper delves into the application of elastic instabilities-commonly used in biological systems to facilitate swift movement-as a power-amplification mechanism for soft robots. Specifically, inspired by the nonlinear mechanics of the hummingbird beak-and shedding further light on it-we design, build and test a novel, rapid-response, soft end effector. The hummingbird beak embodies the capacity for swift movement, achieving closure in less than [Formula: see text]. Previous work demonstrated that rapid movement is achieved through snap-through deformations, induced by muscular actuation of the beak's root. Using nonlinear finite element simulations coupled with continuation algorithms, we unveil a representative portion of the equilibrium manifold of the beak-inspired structure. The exploration involves the application of a sequence of rotations as exerted by the hummingbird muscles. Specific emphasis is placed on pinpointing and tailoring the position along the manifold of the saddle-node bifurcation at which the onset of elastic instability triggers dynamic snap-through. We show the critical importance of the intermediate rotation input in the sequence, as it results in the accumulation of elastic energy that is then explosively released as kinetic energy upon snap-through. Informed by our numerical studies, we conduct experimental testing on a prototype end effector fabricated using a compliant material (thermoplastic polyurethane). The experimental results support the trends observed in the numerical simulations and demonstrate the effectiveness of the bio-inspired design. Specifically, we measure the energy transferred by the soft end effector to a pendulum, varying the input levels in the sequence of prescribed rotations. Additionally, we demonstrate a potential robotic application in scenarios demanding explosive action. From a mechanics perspective, our work sheds light on how pre-stress fields can enable swift movement in soft robotic systems with the potential to facilitate high input-to-output energy efficiency.</p>","PeriodicalId":17488,"journal":{"name":"Journal of The Royal Society Interface","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142125998","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-01Epub Date: 2024-09-25DOI: 10.1098/rsif.2024.0257
J Pablo Narvaez, Stephen P Yanoviak, Phillip M Bitzer, Jeffrey C Burchfield, Evan M Gora
Urbanization tends to increase local lightning frequency (i.e. the 'lightning enhancement' effect). Despite many urban areas showing lightning enhancement, the prevalence of these effects is unknown and the drivers underlying these patterns are poorly quantified. We conducted a global assessment of cloud-to-ground lightning flashes (lightning strikes) across 349 cities to evaluate how the likelihood and magnitude of lightning enhancement vary with geography, climate, air pollution, topography and urban development. The likelihood of exhibiting lightning enhancement increased with higher temperature and precipitation in urban areas relative to their natural surroundings (i.e. urban heat islands and elevated urban precipitation), higher regional lightning strike frequency, greater distance to water bodies and lower elevations. Lightning enhancement was stronger in cities with conspicuous heat islands and elevated urban precipitation effects, higher lightning strike frequency, larger urban areas and lower latitudes. The particularly strong effects of elevated urban temperature and precipitation indicate that these are dominant mechanisms by which cities cause local lightning enhancement.
{"title":"Effects of urbanization on cloud-to-ground lightning strike frequency: a global perspective.","authors":"J Pablo Narvaez, Stephen P Yanoviak, Phillip M Bitzer, Jeffrey C Burchfield, Evan M Gora","doi":"10.1098/rsif.2024.0257","DOIUrl":"https://doi.org/10.1098/rsif.2024.0257","url":null,"abstract":"<p><p>Urbanization tends to increase local lightning frequency (i.e. the 'lightning enhancement' effect). Despite many urban areas showing lightning enhancement, the prevalence of these effects is unknown and the drivers underlying these patterns are poorly quantified. We conducted a global assessment of cloud-to-ground lightning flashes (lightning strikes) across 349 cities to evaluate how the likelihood and magnitude of lightning enhancement vary with geography, climate, air pollution, topography and urban development. The likelihood of exhibiting lightning enhancement increased with higher temperature and precipitation in urban areas relative to their natural surroundings (i.e. urban heat islands and elevated urban precipitation), higher regional lightning strike frequency, greater distance to water bodies and lower elevations. Lightning enhancement was stronger in cities with conspicuous heat islands and elevated urban precipitation effects, higher lightning strike frequency, larger urban areas and lower latitudes. The particularly strong effects of elevated urban temperature and precipitation indicate that these are dominant mechanisms by which cities cause local lightning enhancement.</p>","PeriodicalId":17488,"journal":{"name":"Journal of The Royal Society Interface","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142349241","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-01Epub Date: 2024-09-06DOI: 10.1098/rsif.2024.0129
Brett Klaassen van Oorschot, Kelsy A Bryson, Olivia Danner, Joel F Eklof, Alessandra Lopez, Joshua Wah-Blumberg, Rachel E Pepper
Splash-cup plants disperse propagules via raindrops striking cup-shaped fruiting bodies. The seeds are ejected at velocities up to five times the impact speed of the raindrop and are dispersed up to 1 m from the parent plant. Here, we examine the effects of cup angles and the presence of seed mimics to understand the dynamics of this unique method of dispersal. Our findings demonstrate that: (i) cup angles that launched seeds the furthest ranged from approximately 30° to 50°, matching the range of angles seen in splash-cup plants. (ii) Seeds travel shorter distances than water droplets alone, and this distance depends on the number of seeds in the cup. (iii) Not all seeds are ejected from initially dry cups, leaving cups with some seeds and some water. (iv) Nearly all seeds are ejected from cups that contain both water and seeds, and those that are ejected travel significantly further than those from dry cups. These results confirm the possibility that the conical shape of splash cup plants may be adapted to maximize dispersal distance and benefit from multiple splash events. Our results also illustrate that future work on these plants should include seeds rather than water droplets alone.
{"title":"Dispersal distances from splash-cup plants depend on the cup's angle and contents.","authors":"Brett Klaassen van Oorschot, Kelsy A Bryson, Olivia Danner, Joel F Eklof, Alessandra Lopez, Joshua Wah-Blumberg, Rachel E Pepper","doi":"10.1098/rsif.2024.0129","DOIUrl":"https://doi.org/10.1098/rsif.2024.0129","url":null,"abstract":"<p><p>Splash-cup plants disperse propagules via raindrops striking cup-shaped fruiting bodies. The seeds are ejected at velocities up to five times the impact speed of the raindrop and are dispersed up to 1 m from the parent plant. Here, we examine the effects of cup angles and the presence of seed mimics to understand the dynamics of this unique method of dispersal. Our findings demonstrate that: (i) cup angles that launched seeds the furthest ranged from approximately 30° to 50°, matching the range of angles seen in splash-cup plants. (ii) Seeds travel shorter distances than water droplets alone, and this distance depends on the number of seeds in the cup. (iii) Not all seeds are ejected from initially dry cups, leaving cups with some seeds and some water. (iv) Nearly all seeds are ejected from cups that contain both water and seeds, and those that are ejected travel significantly further than those from dry cups. These results confirm the possibility that the conical shape of splash cup plants may be adapted to maximize dispersal distance and benefit from multiple splash events. Our results also illustrate that future work on these plants should include seeds rather than water droplets alone.</p>","PeriodicalId":17488,"journal":{"name":"Journal of The Royal Society Interface","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142140454","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}