The European Physical Journal E最新文献

{"title":"Modeling straight and circle swimmers: from single swimmer to collective motion","authors":"Francesco Michele Ventrella,&nbsp;Guido Boffetta,&nbsp;Massimo Cencini,&nbsp;Filippo De Lillo","doi":"10.1140/epje/s10189-024-00458-z","DOIUrl":"10.1140/epje/s10189-024-00458-z","url":null,"abstract":"<p>We propose a simple numerical model for the motion of microswimmers based on the immersed boundary method. The swimmer, either pusher or puller, is represented by a distribution of point forces corresponding to the body and the flagellum. We study in particular the minimal model consisting of only three beads (two for the body and one for the flagellum) connected by rigid, inextensible links. When the beads are collinear, standard straight swimming is realized and, in the absence of propulsion, we demonstrate that the model recovers Jeffery’s equation for a thin rod. Conversely, by imposing an angle between body and flagellum the swimmer moves on circular orbits. We discuss how two swimmers, in collinear or non-collinear geometry, scatter upon encounter. Finally, we explore the dynamics of a large number of swimmers reacting to one another only via hydrodynamic interactions, and exemplify their complex collective dynamics in both straight and circular swimmers.</p>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"47 11","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142646615","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multibody interactions between protein inclusions in the pointlike curvature model for tense and tensionless membranes","authors":"Jean-Baptiste Fournier","doi":"10.1140/epje/s10189-024-00456-1","DOIUrl":"10.1140/epje/s10189-024-00456-1","url":null,"abstract":"<p>The pointlike curvature constraint (PCC) model and the disk detachment angle (DDA) model for the deformation-mediated interaction of conical integral protein inclusions in biomembranes are compared in the small deformation regime. Given the radius of membrane proteins, which is comparable to the membrane thickness, it is not obvious which of the two models should be considered the most adequate. For two proteins in a tensionless membranes, the PCC and DDA models coincide at the leading-order <span>(sim r^{-4})</span> in their separation but differ at the next order. Yet, for distances larger than twice the proteins diameter, the difference is less than <span>(10%)</span>. Like the DDA model, the PCC model includes all multibody interactions in a non-approximate way. The asymptotic <span>(sim r^{-4})</span> many-body energy of triangular and square protein clusters is exactly the same in both models. Pentagonal clusters, however, behave differently; they have a vanishing energy in the PCC model, while they have a non-vanishing weaker <span>(sim r^{-6})</span> asymptotic power law in the DDA model. We quantify the importance of multibody interactions in small polygonal clusters of three, four and five inclusions with identical or opposite curvatures in tensionless or tense membranes. We find that the pairwise approximation is almost always very poor. At short separation, the three-body interaction is not sufficient to account for the full many-body interaction. This is confirmed by equilibrium Monte Carlo simulations of up to ten inclusions.</p>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"47 10","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142443254","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Research on sedimentation characteristics of squirmer in a power-law fluid","authors":"Amin Ullah,&nbsp;Jianzhong Lin,&nbsp;Yuxiang Yin","doi":"10.1140/epje/s10189-024-00457-0","DOIUrl":"10.1140/epje/s10189-024-00457-0","url":null,"abstract":"<div><p>Sedimentation characteristics of a squirmer in a power-law fluid within a vertical channel are studied numerically using the two-dimensional lattice Boltzmann method. The effects of swimming type (− 5 ≤ <i>β</i> ≤ 5), self-propelling strength (0.5 ≤ <i>α</i> ≤ 1.1), power-law indexes (0.5 ≤ <i>n</i> ≤ 1.5), and the density ratio of the squirmer to the fluid (<i>γ</i> = 1.01, 1.5 and 2.3) on the sedimentation of the squirmer are analyzed. Four settlement patterns are identified: steady falling in the center, downward along the wall, oscillating with large amplitude and oscillating around the centerline. The squirmer in the channel exhibits more fluctuations in shear-thinning (<i>n</i> &lt; 1) and Newtonian (<i>n</i> = 1) fluids compared to shear-thickening fluids (<i>n</i> &gt; 1). Additionally, a puller (<i>β</i> &gt; 0) settles faster than a pusher (<i>β</i> &lt; 0) in shear-thinning and Newtonian fluids. Puller generates flow towards their head and away from their tail, exhibiting small amplitude oscillations. Pushers exhibit higher amplitude oscillations throughout the channel, creating flow towards their tail and away from their head. At lower <i>γ</i>, the fluctuation of the squirmer is less pronounced compared to higher <i>γ</i>.</p><h3>Graphical abstract</h3><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"47 10","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142434831","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of repulsive interaction and initial velocity on collective motion process","authors":"I. Tarras,&nbsp;A. Eddakoun,&nbsp;A. Hader,&nbsp;S. Moushi,&nbsp;I. Bakassi,&nbsp;R. Et Touizi,&nbsp;I. Achik,&nbsp;M. Eddahby,&nbsp;A. El Bachiri,&nbsp;Y. Boughaleb","doi":"10.1140/epje/s10189-024-00455-2","DOIUrl":"10.1140/epje/s10189-024-00455-2","url":null,"abstract":"<div><p>Self-propelled collective motion is a highly complex phenomenon, necessitating advanced practical and theoretical tools for comprehension. The significance of studying collective motion becomes apparent in its diverse applications. For instance, addressing evacuation challenges in scenarios with multiple agents can be achieved through an examination of collective motion. Research indicates that the transition of individuals (such as birds, fish, etc.) from a state of rest to equilibrium constitutes a phase transition. Our interest of the issue is to delve into the nature of this transitional phase and elucidate the parameters that shape it. Hence, the primary aim of this paper is to grasp the kinetic phase transition by examining how initial velocity and repulsive interactions impact the dynamics of the system. To gain insight into the complex behavior of multi-agent systems, we apply an extended version of the classical Vicsek model. This extension includes an additional interaction zone, the repulsive zone, where particles repel each other at close range to avoid collisions. Our study uses numerical simulations to explore the system's behavior under various conditions. The focus of this study is the impact of initial velocity on the collective movement of particles. The importance of this research lies in comprehending how velocity affects the overall movement. The conclusion we can draw from these results is that the initial velocity affects both the noise and the density. The novelty of the work is the transition phase, yet it lacks universal characteristics because the critical noise depends on the initial velocity system and the repulsion radius zone. Notably, the repulsion radius and particle density play pivotal roles in achieving a phase transition from one equilibrium state to another aligned equilibrium state.</p><h3>Graphical abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"47 10","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142434732","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A structural determinant of the behavior of water at hydration and nanoconfinement conditions","authors":"Nicolás A. Loubet,&nbsp;Alejandro R. Verde,&nbsp;Gustavo A. Appignanesi","doi":"10.1140/epje/s10189-024-00454-3","DOIUrl":"10.1140/epje/s10189-024-00454-3","url":null,"abstract":"<p>The molecular nature of the phases that conform the two-liquid scenario is elucidated in this work in the light of a molecular principle governing water structuring, which unveils the relevance of the contraction and reorientation of the second molecular shell to allow for the existence of coordination defects in water’s hydrogen bond network. In turn, such principle is shown to also determine the behavior of hydration and nanoconfined water while enabling to define conditions for wettability (quantifying hydrophobicity and predicting drying transitions), thus opening the possibility to unravel the active role of water in central fields of research.</p>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"47 9","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142338910","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Conduction in heterogeneous systems in the low-frequency regime: variational principles and boundary integral equations","authors":"Francisco J. Solis,&nbsp;Vikram Jadhao","doi":"10.1140/epje/s10189-024-00449-0","DOIUrl":"10.1140/epje/s10189-024-00449-0","url":null,"abstract":"<p>The response of a homogeneous material to the presence of an external low-frequency oscillating electric field can be described by means of an effective complex conductivity. Low frequencies are characterized by negligible magnetic and radiative effects. The properties of heterogeneous systems, composed of multiple homogeneous regions, can be determined from those of the individual components and their geometric arrangement. Examples of such heterogeneous systems include soft materials such as colloidal suspensions, electrolyte systems, and biological tissues. The difference in the intrinsic conductivities between the homogeneous regions leads to the creation of an oscillating charge density localized at the interfaces between these regions. We show how to express key properties of these systems using this dynamic charge as a fundamental variable. We derive a boundary integral equation for the charges and reconstruct potentials and fields from its solution. We present a variational principle that recovers the fundamental equations for the system in terms of the oscillating charge and show that, in some formulations, the associated functional can be interpreted in terms of the power dissipated in the system. The boundary integral equations are numerically solved using a finite element method for a few illustrative cases.</p><p>Net field and accumulated surface charge in a two-region system. The two regions have contrasting complex conductivities. The system is in the presence of an oscillatory, uniform electric field</p>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"47 9","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142338911","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reinforcement learning of biomimetic navigation: a model problem for sperm chemotaxis","authors":"Omar Mohamed,&nbsp;Alan C. H. Tsang","doi":"10.1140/epje/s10189-024-00451-6","DOIUrl":"10.1140/epje/s10189-024-00451-6","url":null,"abstract":"<p>Motile biological cells can respond to local environmental cues and exhibit various navigation strategies to search for specific targets. These navigation strategies usually involve tuning of key biophysical parameters of the cells, such that the cells can modulate their trajectories to move in response to the detected signals. Here we introduce a reinforcement learning approach to modulate key biophysical parameters and realize navigation strategies reminiscent to those developed by biological cells. We present this approach using sperm chemotaxis toward an egg as a paradigm. By modulating the trajectory curvature of a sperm cell model, the navigation strategies informed by reinforcement learning are capable to resemble sperm chemotaxis observed in experiments. This approach provides an alternative method to capture biologically relevant navigation strategies, which may inform the necessary parameter modulations required for obtaining specific navigation strategies and guide the design of biomimetic micro-robotics.</p>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"47 9","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11436411/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142338912","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Comprehensive study on the different types of soil desiccation cracks and their implications for soil identification using deep learning techniques","authors":"Emanual Daimari,&nbsp;Sai Ratna,&nbsp;P. V. S. S. R. Chandra Mouli,&nbsp;V. Madhurima","doi":"10.1140/epje/s10189-024-00453-4","DOIUrl":"10.1140/epje/s10189-024-00453-4","url":null,"abstract":"<div><p>Rapid drying of soil leads to its fracture. The cracks left behind by these fractures are best seen in soils such as clays that are fine in the texture and shrink on drying, but this can be seen in other soils too. Hence, different soils from the same region show different characteristic desiccation cracks and can thus be used to identify the soil type. In this paper, three types soils namely clay, silt, and sandy-clay-loam from the Brahmaputra river basin in India are studied for their crack patterns using both conventional studies of hierarchical crack patterns using Euler numbers and fractal dimensions, as well as by applying deep-learning techniques to the images. Fractal dimension analysis is found to be an useful pre-processing tool for deep learning image analysis. Feed forward neural networks with and without data augmentation and with the use of filters and noise suggest that data augmentation increases the robustness and improves the accuracy of the model. Even on the introduction of noise, to mimic a real-life situation, 92.09% accuracy in identification of soil was achieved, proving the combination of conventional studies of desiccation crack images with deep learning algorithms to be an effective tool for identification of real soil types.</p><h3>Graphical abstract</h3><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"47 9","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142338897","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rotational dynamics of a disk in a thin film of weakly nematic fluid subject to linear friction","authors":"Abdallah Daddi-Moussa-Ider,&nbsp;Elsen Tjhung,&nbsp;Marc Pradas,&nbsp;Thomas Richter,&nbsp;Andreas M. Menzel","doi":"10.1140/epje/s10189-024-00452-5","DOIUrl":"10.1140/epje/s10189-024-00452-5","url":null,"abstract":"<div><p>Dynamics at low Reynolds numbers experiences recent revival in the fields of biophysics and active matter. While in bulk isotropic fluids it is exhaustively studied, this is less so in anisotropic fluids and in confined situations. Here, we combine the latter two by studying the rotation of a disk-like inclusion in a uniaxially anisotropic, globally oriented, incompressible two-dimensional fluid film. In terms of a perturbative expansion in parameters that quantify anisotropies in viscosity and in additional linear friction with a supporting substrate or other type of confinement, we derive analytical expressions for the resulting hydrodynamic flow and pressure fields as well as for the resistance and mobility coefficients of the rotating disk. It turns out that, in contrast to translational motion, the solutions remain well-behaved also in the absence of the additional linear friction. Comparison with results from finite-element simulations shows very good agreement with those from our analytical calculations. Besides applications to describe technological systems, for instance, in the area of microfluidics and thin cells of aligned nematic liquid crystals, our solutions are important for quantitative theoretical approaches to fluid membranes and thin films in general featuring a preferred direction.</p></div>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"47 9","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11424714/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142338913","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Surface conversion of the dynamics of bacteria escaping chemorepellents","authors":"Asma Braham,&nbsp;Laurence Lemelle,&nbsp;Romain Ducasse,&nbsp;Houyem Toukabri,&nbsp;Eleonore Mottin,&nbsp;Benoit Fabrèges,&nbsp;Vincent Calvez,&nbsp;Christophe Place","doi":"10.1140/epje/s10189-024-00450-7","DOIUrl":"10.1140/epje/s10189-024-00450-7","url":null,"abstract":"<p>Flagellar swimming hydrodynamics confers a recognized advantage for attachment on solid surfaces. Whether this motility further enables the following environmental cues was experimentally explored. Motile <i>E. coli</i> (OD ~ 0.1) in a 100 µm-thick channel were exposed to off-equilibrium gradients set by a chemorepellent Ni(NO₃)₂-source (250 mM). Single bacterial dynamics at the solid surface was analyzed by dark-field videomicroscopy at a fixed position. The number of bacteria indicated their congregation into a wave escaping from the repellent source. Besides the high velocity drift in the propagation direction within the wave, an unexpectedly high perpendicular component drift was also observed. Swimming hydrodynamics CW-bends the bacteria trajectories during their <i>primo</i> approach to the surface (&lt; 2 µm), and a high enough tumbling frequency likely preserves a notable lateral drift. This comprehension substantiates a survival strategy tailored to toxic environments, which involves drifting along surfaces, promoting the inception of colonization at the most advantageous sites.</p>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"47 9","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epje/s10189-024-00450-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142247386","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}