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Luo Y, Patel DK, Li Z, Hu Y, Luo H, Yao L, Majidi C. Intrinsically Multistable Soft Actuator Driven by Mixed-Mode Snap-Through Instabilities. Adv Sci (Weinh) 2024; 11:e2307391. [PMID: 38447200 PMCID: PMC11095224 DOI: 10.1002/advs.202307391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Revised: 12/07/2023] [Indexed: 03/08/2024]
Abstract
Actuators utilizing snap-through instabilities are widely investigated for high-performance fast actuators and shape reconfigurable structures owing to their rapid response and limited reliance on continuous energy input. However, prevailing approaches typically involve a combination of multiple bistable actuator units and achieving multistability within a single actuator unit still remains an open challenge. Here, a soft actuator is presented that uses shape memory alloy (SMA) and mixed-mode elastic instabilities to achieve intrinsically multistable shape reconfiguration. The multistable actuator unit consists of six stable states, including two pure bending states and four bend-twist states. The actuator is composed of a pre-stretched elastic membrane placed between two elastomeric frames embedded with SMA coils. By controlling the sequence and duration of SMA activation, the actuator is capable of rapid transition between all six stable states within hundreds of milliseconds. Principles of energy minimization are used to identify actuation sequences for various types of stable state transitions. Bending and twisting angles corresponding to various prestretch ratios are recorded based on parameterizations of the actuator's geometry. To demonstrate its application in practical conditions, the multistable actuator is used to perform visual inspection in a confined space, light source tracking during photovoltaic energy harvesting, and agile crawling.
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Affiliation(s)
- Yichi Luo
- Department of Mechanical EngineeringCarnegie Mellon UniversityPittsburghPA15213USA
| | - Dinesh K. Patel
- Human‐Computer Interaction Institute, School of Computer ScienceCarnegie Mellon UniversityPittsburghPA15213USA
| | - Zefang Li
- Department of Mechanical EngineeringCarnegie Mellon UniversityPittsburghPA15213USA
| | - Yafeng Hu
- Department of Materials Science and EngineeringCarnegie Mellon UniversityPittsburghPA15213USA
| | - Hao Luo
- Department of Mechanical EngineeringCarnegie Mellon UniversityPittsburghPA15213USA
| | - Lining Yao
- Human‐Computer Interaction Institute, School of Computer ScienceCarnegie Mellon UniversityPittsburghPA15213USA
| | - Carmel Majidi
- Department of Mechanical EngineeringCarnegie Mellon UniversityPittsburghPA15213USA
- Department of Materials Science and EngineeringCarnegie Mellon UniversityPittsburghPA15213USA
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Liu J, Li C. Data-driven energy landscape reveals critical genes in cancer progression. NPJ Syst Biol Appl 2024; 10:27. [PMID: 38459043 PMCID: PMC10923824 DOI: 10.1038/s41540-024-00354-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Accepted: 02/26/2024] [Indexed: 03/10/2024] Open
Abstract
The evolution of cancer is a complex process characterized by stable states and transitions among them. Studying the dynamic evolution of cancer and revealing the mechanisms of cancer progression based on experimental data is an important topic. In this study, we aim to employ a data-driven energy landscape approach to analyze the dynamic evolution of cancer. We take Kidney renal clear cell carcinoma (KIRC) as an example. From the energy landscape, we introduce two quantitative indicators (transition probability and barrier height) to study critical shifts in KIRC cancer evolution, including cancer onset and progression, and identify critical genes involved in these transitions. Our results successfully identify crucial genes that either promote or inhibit these transition processes in KIRC. We also conduct a comprehensive biological function analysis on these genes, validating the accuracy and reliability of our predictions. This work has implications for discovering new biomarkers, drug targets, and cancer treatment strategies in KIRC.
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Affiliation(s)
- Juntan Liu
- Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai, 200433, China
- Shanghai Center for Mathematical Sciences, Fudan University, Shanghai, 200433, China
| | - Chunhe Li
- Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai, 200433, China.
- Shanghai Center for Mathematical Sciences, Fudan University, Shanghai, 200433, China.
- School of Mathematical Sciences and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, 200433, China.
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Khorasani N, Sadeghi M. A computational model of stem cells' internal mechanism to recapitulate spatial patterning and maintain the self-organized pattern in the homeostasis state. Sci Rep 2024; 14:1528. [PMID: 38233402 PMCID: PMC10794714 DOI: 10.1038/s41598-024-51386-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Accepted: 01/04/2024] [Indexed: 01/19/2024] Open
Abstract
The complex functioning of multi-cellular tissue development relies on proper cell production rates to replace dead or differentiated specialized cells. Stem cells are critical for tissue development and maintenance, as they produce specialized cells to meet the tissues' demands. In this study, we propose a computational model to investigate the stem cell's mechanism, which generates the appropriate proportion of specialized cells, and distributes them to their correct position to form and maintain the organized structure in the population through intercellular reactions. Our computational model focuses on early development, where the populations overall behavior is determined by stem cells and signaling molecules. The model does not include complicated factors such as movement of specialized cells or outside signaling sources. The results indicate that in our model, the stem cells can organize the population into a desired spatial pattern, which demonstrates their ability to self-organize as long as the corresponding leading signal is present. We also investigate the impact of stochasticity, which provides desired non-genetic diversity; however, it can also break the proper boundaries of the desired spatial pattern. We further examine the role of the death rate in maintaining the system's steady state. Overall, our study sheds light on the strategies employed by stem cells to organize specialized cells and maintain proper functionality. Our findings provide insight into the complex mechanisms involved in tissue development and maintenance, which could lead to new approaches in regenerative medicine and tissue engineering.
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Affiliation(s)
- Najme Khorasani
- School of Biological Sciences, Institute for Research in Fundamental Sciences (IPM), Tehran, Iran.
| | - Mehdi Sadeghi
- National Institute of Genetic Engineering and Biotechnology (NIGEB), Tehran, Iran
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Song P, Li X, Cui J, Chen K, Chu Y. Investigation on the Impact of Excitation Amplitude on AFM-TM Microcantilever Beam System's Dynamic Characteristics and Implementation of an Equivalent Circuit. Sensors (Basel) 2023; 24:107. [PMID: 38202969 PMCID: PMC10781406 DOI: 10.3390/s24010107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Revised: 12/18/2023] [Accepted: 12/23/2023] [Indexed: 01/12/2024]
Abstract
Alterations in the dynamical properties of an atomic force microscope microcantilever beam system in tapping mode can appreciably impact its measurement precision. Understanding the influence mechanism of dynamic parameter changes on the system's motion characteristics is vital to improve the accuracy of the atomic force microscope in tapping mode (AFM-TM). In this study, we categorize the mathematical model of the AFM-TM microcantilever beam system into systems 1 and 2 based on actual working conditions. Then, we analyze the alterations in the dynamic properties of both systems due to external excitation variations using bifurcation diagrams, phase trajectories, Lyapunov indices, and attraction domains. The numerical simulation results show that when the dimensionless external excitation g < 0.183, the motion state of system 2 is period 1. When g < 0.9, the motion state of system 1 is period 1 motion. Finally, we develop the equivalent circuit model of the AFM-TM microcantilever beam and perform related software simulations, along with practical circuit experiments. Our experimental results indicate that the constructed equivalent circuit can effectively analyze the dynamic characteristics of the AFM-TM microcantilever beam system in the presence of complex external environmental factors. It is observed that the practical circuit simulation attenuates high-frequency signals, resulting in a 31.4% reduction in excitation amplitude compared to numerical simulation results. This provides an essential theoretical foundation for selecting external excitation parameters for AFM-TM cantilever beams and offers a novel method for analyzing the dynamics of micro- and nanomechanical systems, as well as other nonlinear systems.
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Affiliation(s)
- Peijie Song
- School of Electrical Engineering. Lanzhou Jiaotong University, Lanzhou 730070, China;
- Gansu Institute of Metrology, Lanzhou 730050, China
| | - Xiaojuan Li
- Gansu Institute of Metrology, Lanzhou 730050, China
| | - Jianjun Cui
- Geometric Sciences Institute, National Institute of Metrology, Beijing 100013, China; (J.C.)
| | - Kai Chen
- Geometric Sciences Institute, National Institute of Metrology, Beijing 100013, China; (J.C.)
| | - Yandong Chu
- School of Electrical Engineering. Lanzhou Jiaotong University, Lanzhou 730070, China;
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Mironov IV, Khristichenko MY, Nechepurenko YM, Grebennikov DS, Bocharov GA. Bifurcation analysis of multistability and hysteresis in a model of HIV infection. Vavilovskii Zhurnal Genet Selektsii 2023; 27:755-767. [PMID: 38213700 PMCID: PMC10777289 DOI: 10.18699/vjgb-23-88] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Revised: 09/15/2023] [Accepted: 09/19/2023] [Indexed: 01/13/2024] Open
Abstract
The infectious disease caused by human immunodeficiency virus type 1 (HIV-1) remains a serious threat to hu- man health. The current approach to HIV-1 treatment is based on the use of highly active antiretroviral therapy, which has side effects and is costly. For clinical practice, it is highly important to create functional cures that can enhance immune control of viral growth and infection of target cells with a subsequent reduction in viral load and restoration of the immune status. HIV-1 control efforts with reliance on immunotherapy remain at a conceptual stage due to the complexity of a set of processes that regulate the dynamics of infection and immune response. For this reason, it is extremely important to use methods of mathematical modeling of HIV-1 infection dynamics for theoretical analysis of possibilities of reducing the viral load by affecting the immune system without the usage of antiviral therapy. The aim of our study is to examine the existence of bi-, multistability and hysteresis properties with a meaningful mathematical model of HIV-1 infection. The model describes the most important blocks of the processes of interaction between viruses and the human body, namely, the spread of infection in productively and latently infected cells, the appearance of viral mutants and the develop- ment of the T cell immune response. Furthermore, our analysis aims to study the possibilities of transferring the clinical pattern of the disease from a more severe state to a milder one. We analyze numerically the conditions for the existence of steady states of the mathematical model of HIV-1 infection for the numerical values of model parameters correspond- ing to phenotypically different variants of the infectious disease course. To this end, original computational methods of bifurcation analysis of mathematical models formulated with systems of ordinary differential equations and delay differ- ential equations are used. The macrophage activation rate constant is considered as a bifurcation parameter. The regions in the model parameter space, in particular, for the rate of activation of innate immune cells (macrophages), in which the properties of bi-, multistability and hysteresis are expressed, have been identified, and the features characterizing transi- tion kinetics between stable equilibrium states have been explored. Overall, the results of bifurcation analysis of the HIV-1 infection model form a theoretical basis for the development of combination immune-based therapeutic approaches to HIV-1 treatment. In particular, the results of the study of the HIV-1 infection model for parameter sets corresponding to different phenotypes of disease dynamics (typical, long-term non-progressing and rapidly progressing courses) indicate that an effective functional treatment (cure) of HIV-1-infected patients requires the development of a personalized ap- proach that takes into account both the properties of the HIV-1 quasispecies population and the patient's immune status.
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Affiliation(s)
- I V Mironov
- Keldysh Institute of Applied Mathematics of the Russian Academy of Sciences, Moscow, Russia Sechenov First Moscow State Medical University of the Ministry of Health of the Russian Federation, Moscow, Russia
| | - M Yu Khristichenko
- Keldysh Institute of Applied Mathematics of the Russian Academy of Sciences, Moscow, Russia Marchuk Institute of Numerical Mathematics of the Russian Academy of Sciences, Moscow, Russia
| | - Yu M Nechepurenko
- Keldysh Institute of Applied Mathematics of the Russian Academy of Sciences, Moscow, Russia Marchuk Institute of Numerical Mathematics of the Russian Academy of Sciences, Moscow, Russia
| | - D S Grebennikov
- Sechenov First Moscow State Medical University of the Ministry of Health of the Russian Federation, Moscow, Russia Marchuk Institute of Numerical Mathematics of the Russian Academy of Sciences, Moscow, Russia
| | - G A Bocharov
- Sechenov First Moscow State Medical University of the Ministry of Health of the Russian Federation, Moscow, Russia Marchuk Institute of Numerical Mathematics of the Russian Academy of Sciences, Moscow, Russia
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Flores-Garza E, Hernández-Pando R, García-Zárate I, Aguirre P, Domínguez-Hüttinger E. Bifurcation analysis of a tuberculosis progression model for drug target identification. Sci Rep 2023; 13:17567. [PMID: 37845271 PMCID: PMC10579266 DOI: 10.1038/s41598-023-44569-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Accepted: 10/10/2023] [Indexed: 10/18/2023] Open
Abstract
Tuberculosis (TB) is a major cause of morbidity and mortality worldwide. The emergence and rapid spread of drug-resistant M. tuberculosis strains urge us to develop novel treatments. Experimental trials are constrained by laboratory capacity, insufficient funds, low number of laboratory animals and obsolete technology. Systems-level approaches to quantitatively study TB can overcome these limitations. Previously, we proposed a mathematical model describing the key regulatory mechanisms underlying the pathological progression of TB. Here, we systematically explore the effect of parameter variations on disease outcome. We find five bifurcation parameters that steer the clinical outcome of TB: number of bacteria phagocytosed per macrophage, macrophages death, macrophage killing by bacteria, macrophage recruitment, and phagocytosis of bacteria. The corresponding bifurcation diagrams show all-or-nothing dose-response curves with parameter regions mapping onto bacterial clearance, persistent infection, or history-dependent clearance or infection. Importantly, the pathogenic stage strongly affects the sensitivity of the host to these parameter variations. We identify parameter values corresponding to a latent-infection model of TB, where disease progression occurs significantly slower than in progressive TB. Two-dimensional bifurcation analyses uncovered synergistic parameter pairs that could act as efficient compound therapeutic approaches. Through bifurcation analysis, we reveal how modulation of specific regulatory mechanisms could steer the clinical outcome of TB.
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Affiliation(s)
- Eliezer Flores-Garza
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad Universitaria, 04510, Mexico, Mexico
| | - Rogelio Hernández-Pando
- Sección de Patología Experimental, Departamento de Patología, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Vasco de Quiroga 15, Belisario Domínguez Secc. 16, Tlalpan, 14080, Mexico City, Mexico
| | - Ibrahim García-Zárate
- Facultad de Ciencias, Universidad Nacional Autónoma de México, Ciudad Universitaria, Coyoacán, 04510, Mexico City, Mexico
| | - Pablo Aguirre
- Departamento de Matemática, Universidad Técnica Federico Santa María, Casilla 110-V, Valparaíso, Chile
| | - Elisa Domínguez-Hüttinger
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad Universitaria, 04510, Mexico, Mexico.
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Lin X, Pan F, Ma Y, Wei Y, Yang K, Wu Z, Guan J, Ding B, Liu B, Xiang J, Chen Y. Mechanical Fourier transform for programmable metamaterials. Proc Natl Acad Sci U S A 2023; 120:e2305380120. [PMID: 37669372 PMCID: PMC10500267 DOI: 10.1073/pnas.2305380120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Accepted: 08/02/2023] [Indexed: 09/07/2023] Open
Abstract
Proactively programming materials toward target nonlinear mechanical behaviors is crucial to realize customizable functions for advanced devices and systems, which arouses persistent explorations for rapid and efficient inverse design strategies. Herein, we propose a "mechanical Fourier transform" strategy to program mechanical behaviors of materials by mimicking the concept of Fourier transform. In this strategy, an arbitrary target force-displacement curve is decomposed into multiple cosine curves and a constant curve, each of which is realized by a rationally designed multistable module in an array-structured metamaterial. Various target curves with distinct shapes can be rapidly programmed and reprogrammed through only amplitude modulation on the modules. Two exemplary metamaterials are demonstrated to validate the strategy with a macroscale prototype based on magnet lattice and a microscale prototype based on an etched silicon wafer. This strategy applies to a variety of scales, constituents, and structures, and paves a way for the property programming of materials.
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Affiliation(s)
- Xin Lin
- Institute of Solid Mechanics, Beihang University, Beijing100191, China
| | - Fei Pan
- School of Aeronautic Science and Engineering, Beihang University, Beijing100191, China
| | - Yong Ma
- Institute of Solid Mechanics, Beihang University, Beijing100191, China
| | - Yuling Wei
- Institute of Solid Mechanics, Beihang University, Beijing100191, China
| | - Kang Yang
- School of Materials Science and Engineering, Beihang University, Beijing100191, China
- School of Materials Science and Engineering, Anhui University of Technology, Maanshan243002, China
| | - Zihong Wu
- School of Materials Science and Engineering, Beihang University, Beijing100191, China
| | - Juan Guan
- School of Materials Science and Engineering, Beihang University, Beijing100191, China
| | - Bin Ding
- Institute of Solid Mechanics, Beihang University, Beijing100191, China
| | - Bin Liu
- Department of Engineering Mechanics, Tsinghua University, Beijing100084, China
| | - Jinwu Xiang
- School of Aeronautic Science and Engineering, Beihang University, Beijing100191, China
| | - Yuli Chen
- Institute of Solid Mechanics, Beihang University, Beijing100191, China
- Tianmushan Laboratory, Xixi Octagon City, Yuhang District, Hangzhou310023, China
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Peretz O, Ben Abu E, Zigelman A, Givli S, Gat AD. Multistable Metafluid based Energy Harvesting and Storage. Adv Mater 2023; 35:e2301483. [PMID: 37269148 DOI: 10.1002/adma.202301483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 05/11/2023] [Indexed: 06/04/2023]
Abstract
The thermodynamic properties of fluids play a crucial role in many engineering applications, particularly in the context of energy. Fluids with multistable thermodynamic properties may offer new paths for harvesting and storing energy via transitions between equilibria states. Such artificial multistable fluids can be created using the approach employed in metamaterials, which controls macro-properties through micro-structure composition. In this work, the dynamics of such "metafluids" is examined for a configuration of calorically-perfect compressible gas contained within multistable elastic capsules flowing in a fluid-filled tube. The velocity-, pressure-, and temperature-fields of multistable compressible metafluids is studied by both analytically and experimentally, focusing on transitions between different equilibria. The dynamics of a single capsule is first examine, which may move or change equilibrium state, due to fluidic forces. The interaction and motion of multiple capsules within a fluid-filled tube is then studied. It shows that such a system can be used to harvest energy from external temperature variations in either time or space. Thus, fluidic multistability allows specific quanta of energy to be captured and stored indefinitely as well as transported as a fluid, via tubes, at standard atmospheric conditions without the need for thermal isolation.
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Affiliation(s)
- Ofek Peretz
- Faculty of Mechanical Engineering, Technion - Israel Institute of Technology, Haifa, 3200003, Israel
| | - Ezra Ben Abu
- Faculty of Mechanical Engineering, Technion - Israel Institute of Technology, Haifa, 3200003, Israel
| | - Anna Zigelman
- Faculty of Mechanical Engineering, Technion - Israel Institute of Technology, Haifa, 3200003, Israel
| | - Sefi Givli
- Faculty of Mechanical Engineering, Technion - Israel Institute of Technology, Haifa, 3200003, Israel
| | - Amir D Gat
- Faculty of Mechanical Engineering, Technion - Israel Institute of Technology, Haifa, 3200003, Israel
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Wu L, Pasini D. In Situ Activation of Snap-Through Instability in Multi-Response Metamaterials through Multistable Topological Transformation. Adv Mater 2023; 35:e2301109. [PMID: 37246407 DOI: 10.1002/adma.202301109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2023] [Revised: 04/17/2023] [Indexed: 05/30/2023]
Abstract
Snap-through instability has been widely leveraged in metamaterials to attain non-monotonic responses for a specific subset of applications where conventional monotonic materials fail to perform. In the remaining more plentiful set of ordinary applications, snap-through instability is harmful, and current snapping metamaterials become inadequate because their capacity to snap cannot be suppressed post-fabrication. Here, a class of topology-transformable metamaterials is introduced to enable in situ activation and deactivation of the snapping capacity, providing a remarkable level of versatility in switching between responses from monotonic to monostable and bistable snap-through. Theoretical analysis, numerical simulations, and experiments are combined to unveil the role played by contact in the topological transformation capable of increasing the geometry incompatibility and confinement stiffness of selected architectural members. The strategy here presented for post-fabrication reprogrammability of matter and on-the-fly response switching paves the way to multifunctionality for application in multiple sectors from mechanical logic gates, and adjustable energy dissipators, to in situ adaptable sport equipment.
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Affiliation(s)
- Lei Wu
- Department of Mechanical Engineering, McGill University, Montreal, Quebec H3A 0C3, Canada
| | - Damiano Pasini
- Department of Mechanical Engineering, McGill University, Montreal, Quebec H3A 0C3, Canada
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Sugawara SE. The multistability of predictive technology in nuclear disasters. Soc Stud Sci 2023; 53:495-521. [PMID: 37025046 DOI: 10.1177/03063127231161609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Postphenomenological studies have explored technological mediation between the human body and the world by analysing the bodily experience of the world. Applying this analytical perspective to predictive technology requires some expansions because humans cannot directly experience the future world. I conceptualize pre-spectival focus, which refers to how human attention is directed to the making-future-present process, and which features or aspects of its process are foregrounded or backgrounded. Through the concept of pre-spectival focus and actor-network theory (ANT), this article examines the case of System for the Prediction of Environmental Emergency Dose Information (SPEEDI), a Japanese technology used to simulate the atmospheric dispersion of radionuclides released from nuclear reactors. SPEEDI provides prediction maps representing radiological consequences and was expected to support evacuation decisions during nuclear emergencies. However, this was not the case with the Fukushima disaster, which led to a socio-technical controversy regarding SPEEDI's usage. Based on bibliographic surveys and several interviews, I encapsulate four multistable uses of SPEEDI: prediction as supporting advice, prediction as a tool for evacuation drills, prediction as self-protection, and prediction as a source of misunderstanding. Relevant actors perceive the predictions of a nuclear disaster in each stability depending on the diversity of their pre-spectival foci, which is also related to the forms of life nourished through their professional and daily lives. A distinct rivalry can be observed between the two actor-networks around nuclear emergency management in which SPEEDI is differently enrolled: the social control network and self-determination network. In the former, the residents are constituted as passive selves who obediently follow governmental instructions; in the latter, residents are included as autonomous subjects who can actively decide protective actions. Moreover, I discuss future postphenomenology-ANT studies on predictive technologies based on these analyses.
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Mangal U, Noh K, Lee S, Cha JK, Song JS, Cha JY, Lee KJ, Kim KM, Kwon JS, Choi SH. Multistability and hysteresis in states of oral microbiota: Is it impacting the dental clinical cohort studies? J Periodontal Res 2023; 58:381-391. [PMID: 36641544 DOI: 10.1111/jre.13098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 12/06/2022] [Accepted: 01/03/2023] [Indexed: 01/16/2023]
Abstract
INTRODUCTION Microbiome from a "healthy cohort" is used as a reference for comparison to cases and intervention. However, the studies with cohort-based clinical research have not sufficiently accounted for the multistability in oral microbial community. The screening is limited to phenotypic features with marked variations in microbial genomic markers. Herein, we aimed to assess the stability of the oral microbiome across time from an intervention-free "healthy" cohort. METHODS We obtained 33 supragingival samples of 11 healthy participants from the biobank. For each participant, we processed one sample as baseline (T0) and two samples spaced at 1-month (T1) and 3-month (T2) intervals for 16S ribosomal RNA gene sequencing analysis. RESULTS We observed that taxonomic profiling had a similar pattern of dominant genera, namely, Rothia, Prevotella, and Hemophilus, at all time points. Shannon diversity revealed a significant increase from T0 (p < .05). Bray Curtis dissimilarity was significant (R = -.02, p < .01) within the cohort at each time point. Community stability had negative correlation to synchrony (r = -.739; p = .009) and variance (r = -.605; p = .048) of the species. Clustering revealed marked differences in the grouping patterns between the three time points. For all time points, the clusters presented a substantially dissimilar set of differentially abundant taxonomic and functional biomarkers. CONCLUSION Our observations indicate towards the presence of multistable states within the oral microbiome in an intervention-free healthy cohort. For a conclusive and meaningful long-term reference, dental clinical research should account for multistability in the personalized therapy approach to improve the identification and classification of reliable markers.
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Affiliation(s)
- Utkarsh Mangal
- Department of Orthodontics, Yonsei University College of Dentistry, Seoul, Korea.,Institute of Craniofacial Deformity, Yonsei University College of Dentistry, Seoul, Korea
| | - Kowoon Noh
- Institute of Craniofacial Deformity, Yonsei University College of Dentistry, Seoul, Korea.,Department and Research Institute of Dental Biomaterials and Bioengineering, Yonsei University College of Dentistry, Seoul, Korea.,BK21 FOUR Project, Yonsei University College of Dentistry, Seoul, Korea
| | - Seeyoon Lee
- Department of Orthodontics, Yonsei University College of Dentistry, Seoul, Korea
| | - Jae-Kook Cha
- Department of Periodontology, Research Institute of Periodontal Regeneration, Yonsei University College of Dentistry, Seoul, Korea
| | - Je Seon Song
- Department of Pediatric Dentistry, Yonsei University College of Dentistry, Seoul, Korea.,Oral Science Research Center, College of Dentistry, Yonsei University, Seoul, Korea
| | - Jung-Yul Cha
- Department of Orthodontics, Yonsei University College of Dentistry, Seoul, Korea.,Institute of Craniofacial Deformity, Yonsei University College of Dentistry, Seoul, Korea
| | - Kee-Joon Lee
- Department of Orthodontics, Yonsei University College of Dentistry, Seoul, Korea.,Institute of Craniofacial Deformity, Yonsei University College of Dentistry, Seoul, Korea
| | - Kwang-Mahn Kim
- Department and Research Institute of Dental Biomaterials and Bioengineering, Yonsei University College of Dentistry, Seoul, Korea
| | - Jae-Sung Kwon
- Department and Research Institute of Dental Biomaterials and Bioengineering, Yonsei University College of Dentistry, Seoul, Korea.,BK21 FOUR Project, Yonsei University College of Dentistry, Seoul, Korea
| | - Sung-Hwan Choi
- Department of Orthodontics, Yonsei University College of Dentistry, Seoul, Korea.,Institute of Craniofacial Deformity, Yonsei University College of Dentistry, Seoul, Korea
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Wang X, Qu H, Li X, Kuang Y, Wang H, Guo S. Multi-triangles cylindrical origami and inspired metamaterials with tunable stiffness and stretchable robotic arm. PNAS Nexus 2023; 2:pgad098. [PMID: 37065617 PMCID: PMC10096905 DOI: 10.1093/pnasnexus/pgad098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 02/14/2023] [Accepted: 03/13/2023] [Indexed: 04/18/2023]
Abstract
Kresling pattern origami-inspired structural design has been widely investigated using its bistable property and the single coupling degree of freedom (DOF). In order to obtain new properties or new origami-inspired structures, it needs to innovate the crease lines in the flat sheet of Kresling pattern origami. Here, we present a derivative of Kresling pattern origami-multi-triangles cylindrical origami (MTCO) with tristable property. The truss model is modified based on the switchable active crease lines during the folding motion of the MTCO. Using the energy landscape obtained from the modified truss model, the tristable property is validated and extended to Kresling pattern origami. Simultaneously, the high stiffness property of the third stable state and some special stable states are discussed. In addition, MTCO-inspired metamaterials with deployable property and tunable stiffness, and MTCO-inspired robotic arms with wide movement ranges and rich motion forms are created. These works promote research on Kresling pattern origami, and the design ideas of the metamaterials and robotic arms play a positive role in improving the stiffness of deployable structures and conceiving motion robots.
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Affiliation(s)
- Xiaolei Wang
- Robotics Research Center, School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044, PR China
- Research Center of Robotics Technology and Equipment, Tangshan Research Institute, Beijing Jiaotong University, Tangshan 063000, China
| | - Haibo Qu
- To whom correspondence should be addressed. or
| | - Xiao Li
- Robotics Research Center, School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044, PR China
- Research Center of Robotics Technology and Equipment, Tangshan Research Institute, Beijing Jiaotong University, Tangshan 063000, China
| | - Yili Kuang
- Robotics Research Center, School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044, PR China
- Research Center of Robotics Technology and Equipment, Tangshan Research Institute, Beijing Jiaotong University, Tangshan 063000, China
| | - Haoqian Wang
- Robotics Research Center, School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044, PR China
- Research Center of Robotics Technology and Equipment, Tangshan Research Institute, Beijing Jiaotong University, Tangshan 063000, China
| | - Sheng Guo
- To whom correspondence should be addressed. or
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13
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Marrone JI, Sepulchre JA, Ventura AC. A nested bistable module within a negative feedback loop ensures different types of oscillations in signaling systems. Sci Rep 2023; 13:529. [PMID: 36631477 DOI: 10.1038/s41598-022-27047-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Accepted: 12/23/2022] [Indexed: 01/12/2023] Open
Abstract
In this article, we consider a double phosphorylation cycle, a ubiquitous signaling component, having the ability to display bistability, a behavior strongly related to the existence of positive feedback loops. If this component is connected to other signaling elements, it very likely undergoes some sort of protein-protein interaction. In several cases, these interactions result in a non-explicit negative feedback effect, leading to interlinked positive and negative feedbacks. This combination was studied in the literature as a way to generate relaxation-type oscillations. Here, we show that the two feedbacks together ensure two types of oscillations, the relaxation-type ones and a smoother type of oscillations functioning in a very narrow range of frequencies, in such a way that outside that range, the amplitude of the oscillations is severely compromised. Even more, we show that the two feedbacks are essential for both oscillatory types to emerge, and it is their hierarchy what determines the type of oscillation at work. We used bifurcation analyses and amplitude vs. frequency curves to characterize and classify the oscillations. We also applied the same ideas to another simple model, with the goal of generalizing what we learned from signaling models. The results obtained display the wealth of oscillatory dynamics that exists in a system with a bistable module nested within a negative feedback loop, showing how to transition between different types of oscillations and other dynamical behaviors such as excitability. Our work provides a framework for the study of other oscillatory systems based on bistable modules, from simple two-component models to more complex examples like the MAPK cascade and experimental cases like cell cycle oscillators.
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14
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Lea-Carnall CA, Tanner LI, Montemurro MA. Noise-modulated multistable synapses in a Wilson-Cowan-based model of plasticity. Front Comput Neurosci 2023; 17:1017075. [PMID: 36817317 PMCID: PMC9931909 DOI: 10.3389/fncom.2023.1017075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Accepted: 01/10/2023] [Indexed: 02/05/2023] Open
Abstract
Frequency-dependent plasticity refers to changes in synaptic strength in response to different stimulation frequencies. Resonance is a factor known to be of importance in such frequency dependence, however, the role of neural noise in the process remains elusive. Considering the brain is an inherently noisy system, understanding its effects may prove beneficial in shaping therapeutic interventions based on non-invasive brain stimulation protocols. The Wilson-Cowan (WC) model is a well-established model to describe the average dynamics of neural populations and has been shown to exhibit bistability in the presence of noise. However, the important question of how the different stable regimes in the WC model can affect synaptic plasticity when cortical populations interact has not yet been addressed. Therefore, we investigated plasticity dynamics in a WC-based model of interacting neural populations coupled with activity-dependent synapses in which a periodic stimulation was applied in the presence of noise of controlled intensity. The results indicate that for a narrow range of the noise variance, synaptic strength can be optimized. In particular, there is a regime of noise intensity for which synaptic strength presents a triple-stable state. Regulating noise intensity affects the probability that the system chooses one of the stable states, thereby controlling plasticity. These results suggest that noise is a highly influential factor in determining the outcome of plasticity induced by stimulation.
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Affiliation(s)
- Caroline A Lea-Carnall
- School of Health Sciences, Manchester Academic Health Science Centre, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Lisabel I Tanner
- School of Health Sciences, Manchester Academic Health Science Centre, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Marcelo A Montemurro
- School of Mathematics and Statistics, Faculty of Science, Technology, Engineering and Mathematics, The Open University, Milton Keynes, United Kingdom
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15
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Huang L, Clauss B, Lu M. What Makes a Functional Gene Regulatory Network? A Circuit Motif Analysis. J Phys Chem B 2022; 126:10374-10383. [PMID: 36471236 PMCID: PMC9896654 DOI: 10.1021/acs.jpcb.2c05412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
One of the key questions in systems biology is to understand the roles of gene regulatory circuits in determining cellular states and their functions. In previous studies, some researchers have inferred large gene networks from genome wide genomics/transcriptomics data using the top-down approach, while others have modeled core gene circuits of small sizes using the bottom-up approach. Despite many existing systems biology studies, there is still no general rule on what sizes of gene networks and what types of circuit motifs a system would need to achieve robust biological functions. Here, we adopt a gene circuit motif analysis to discover four-node circuits responsible for multiplicity (rich in dynamical behavior), flexibility (versatile to alter gene expression), or both. We identify the most reoccurring two-node circuit motifs and the co-occurring motif pairs. Furthermore, we investigate the contributing factors of multiplicity and flexibility for large gene networks of different types and sizes. We find that gene networks of intermediate sizes tend to have combined high levels of multiplicity and flexibility. Our study will contribute to a better understanding of the dynamical mechanisms of gene regulatory circuits and provide insights into rational designs of robust gene circuits in synthetic and systems biology.
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Affiliation(s)
- Lijia Huang
- Center for Theoretical Biological Physics, Northeastern University, Boston, MA 02115, USA
- Department of Bioengineering, Northeastern University, Boston, MA 02115, USA
| | - Benjamin Clauss
- Center for Theoretical Biological Physics, Northeastern University, Boston, MA 02115, USA
- Genetics Program, Graduate School of Biomedical Sciences, Tufts University, Boston, MA 02111, USA
| | - Mingyang Lu
- Center for Theoretical Biological Physics, Northeastern University, Boston, MA 02115, USA
- Department of Bioengineering, Northeastern University, Boston, MA 02115, USA
- Genetics Program, Graduate School of Biomedical Sciences, Tufts University, Boston, MA 02111, USA
- The Jackson Laboratory, Bar Harbor, ME 04609, USA
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16
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Harlapur P, Duddu AS, Hari K, Kulkarni P, Jolly MK. Functional Resilience of Mutually Repressing Motifs Embedded in Larger Networks. Biomolecules 2022; 12. [PMID: 36551270 DOI: 10.3390/biom12121842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 12/03/2022] [Accepted: 12/06/2022] [Indexed: 12/14/2022] Open
Abstract
Elucidating the design principles of regulatory networks driving cellular decision-making has important implications for understanding cell differentiation and guiding the design of synthetic circuits. Mutually repressing feedback loops between 'master regulators' of cell fates can exhibit multistable dynamics enabling "single-positive" phenotypes: (high A, low B) and (low A, high B) for a toggle switch, and (high A, low B, low C), (low A, high B, low C) and (low A, low B, high C) for a toggle triad. However, the dynamics of these two motifs have been interrogated in isolation in silico, but in vitro and in vivo, they often operate while embedded in larger regulatory networks. Here, we embed these motifs in complex larger networks of varying sizes and connectivity to identify hallmarks under which these motifs maintain their canonical dynamical behavior. We show that an increased number of incoming edges onto a motif leads to a decay in their canonical stand-alone behaviors. We also show that this decay can be exacerbated by adding self-inhibition but not self-activation loops on the 'master regulators'. These observations offer insights into the design principles of biological networks containing these motifs and can help devise optimal strategies for the integration of these motifs into larger synthetic networks.
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17
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Liu K, Pratapa PP, Misseroni D, Tachi T, Paulino GH. Triclinic Metamaterials by Tristable Origami with Reprogrammable Frustration. Adv Mater 2022; 34:e2107998. [PMID: 35790039 DOI: 10.1002/adma.202107998] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 06/22/2022] [Indexed: 06/15/2023]
Abstract
Geometrical-frustration-induced anisotropy and inhomogeneity are explored to achieve unique properties of metamaterials that set them apart from conventional materials. According to Neumann's principle, to achieve anisotropic responses, the material unit cell should possess less symmetry. Based on such guidelines, a triclinic metamaterial system of minimal symmetry is presented, which originates from a Trimorph origami pattern with a simple and insightful geometry: a basic unit cell with four tilted panels and four corresponding creases. The intrinsic geometry of the Trimorph origami, with its changing tilting angles, dictates a folding motion that varies the primitive vectors of the unit cell, couples the shear and normal strains of its extrinsic bulk, and leads to an unusual Poisson effect. Such an effect, associated with reversible auxeticity in the changing triclinic frame, is observed experimentally, and predicted theoretically by elegant mathematical formulae. The nonlinearities of the folding motions allow the unit cell to display three robust stable states, connected through snapping instabilities. When the tristable unit cells are tessellated, phenomena that resemble linear and point defects emerge as a result of geometric frustration. The frustration is reprogrammable into distinct stable and inhomogeneous states by arbitrarily selecting the location of a single or multiple point defects. The Trimorph origami demonstrates the possibility of creating origami metamaterials with symmetries that are hitherto nonexistent, leading to triclinic metamaterials with tunable anisotropy for potential applications such as wave propagation control and compliant microrobots.
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Affiliation(s)
- Ke Liu
- Department of Advanced Manufacturing and Robotics, Peking University, Beijing, 100871, China
| | - Phanisri P Pratapa
- Department of Civil Engineering, Indian Institute of Technology Madras, Chennai, TN, 600036, India
| | - Diego Misseroni
- Department of Civil, Environmental and Mechanical Engineering, University of Trento, Trento, 38123, Italy
| | - Tomohiro Tachi
- Graduate School of Arts and Sciences, University of Tokyo, Tokyo, 153-8902, Japan
| | - Glaucio H Paulino
- Department of Civil and Environmental Engineering, Princeton University, Princeton, NJ, 08544, USA
- Princeton Institute for the Science and Technology of Materials (PRISM), Princeton University, Princeton, NJ, 08544, USA
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18
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Abstract
Origami has emerged as a design paradigm to realize morphing structures with rich kinematic and mechanical properties. Biological examples augment the potential design space by suggesting intriguing routes for achieving self-folding from architected materials. We introduce a class of multistable self-folding origami adaptable after fabrication inspired by the earwig wing. This is achieved by designing bilayer creases that display anisotropic shrinkage in response to external stimulation, enabling a mechanism for prestrain adaptation. We establish a bilayer model for stretchable straight and trapezoidal (β) creases to generate bistable origami structures. We adapt the topology of the structure’s energy landscapes by tuning the fold prestrain level as a function of the stimulation time. The proposed method and model allows for converting flat sheets with arranged facets and prestrained mountain-valley creases into self-folding multistable structures. Introducing multistability from self-folding avoids ambiguous folding branches present in the rich configuration space at the flat state. The obtained crease prestrain programming is leveraged to manufacture a biomimetic earwig wing featuring the complex crease pattern, structural stability and rapid closure of the biological counterpart. The presented method provides a route for encoding prestrain in self-folding origami, the multistability of which is adaptable after fabrication.
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Affiliation(s)
- Salvador Rojas
- School of Mechanical Engineering, Purdue University, West Lafayette, IN 47907, USA
| | - Katherine S. Riley
- School of Mechanical Engineering, Purdue University, West Lafayette, IN 47907, USA
| | - Andres F. Arrieta
- School of Mechanical Engineering, Purdue University, West Lafayette, IN 47907, USA
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19
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Franović I, Eydam S, Yanchuk S, Berner R. Collective Activity Bursting in a Population of Excitable Units Adaptively Coupled to a Pool of Resources. Front Netw Physiol 2022; 2:841829. [PMID: 36926089 PMCID: PMC10013072 DOI: 10.3389/fnetp.2022.841829] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 02/16/2022] [Indexed: 06/18/2023]
Abstract
We study the collective dynamics in a population of excitable units (neurons) adaptively interacting with a pool of resources. The resource pool is influenced by the average activity of the population, whereas the feedback from the resources to the population is comprised of components acting homogeneously or inhomogeneously on individual units of the population. Moreover, the resource pool dynamics is assumed to be slow and has an oscillatory degree of freedom. We show that the feedback loop between the population and the resources can give rise to collective activity bursting in the population. To explain the mechanisms behind this emergent phenomenon, we combine the Ott-Antonsen reduction for the collective dynamics of the population and singular perturbation theory to obtain a reduced system describing the interaction between the population mean field and the resources.
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Affiliation(s)
- Igor Franović
- Scientific Computing Laboratory, Center for the Study of Complex Systems, Institute of Physics Belgrade, University of Belgrade, Belgrade, Serbia
| | - Sebastian Eydam
- Neural Circuits and Computations Unit, RIKEN Center for Brain Science, Wako, Japan
| | - Serhiy Yanchuk
- Institut für Mathematik, Technische Universität Berlin, Berlin, Germany
- Potsdam Institute for Climate Impact Research, Potsdam, Germany
- Institut für Mathematik, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Rico Berner
- Institut für Physik, Humboldt-Universität zu Berlin, Berlin, Germany
- Institut für Theoretische Physik, Technische Universität Berlin, Berlin, Germany
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20
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Abstract
Ambiguous figures (aka bistable, multistable, or reversible images) have fascinated scientists as well as laypersons for centuries. It may be surprising indeed how one and the same physical depiction can be experienced in perceptual awareness in cardinally different ways. In the most well-known examples of such illusions of multistability, the phenomenal change relates just to visual organization. Much less common are perceptions of alternating emotional content in the ambiguous visual image. Here, I introduce one such example.
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Affiliation(s)
- Talis Bachmann
- Institute of Psychology and School of Law (Tallinn branch), Tallinn, Estonia
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21
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Hayes C, Feliu E, Soyer OS. Multisite Enzymes as a Mechanism for Bistability in Reaction Networks. ACS Synth Biol 2022; 11:596-607. [PMID: 35073044 DOI: 10.1021/acssynbio.1c00272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Here, we focus on a common class of enzymes that have multiple substrate binding sites (multisite enzymes) and analyze their capacity to generate bistable dynamics in the reaction networks that they are embedded in. These networks include both substrate-product-substrate cycles and substrate-to-product conversion with subsequent product consumption. Using mathematical techniques, we show that the inherent binding and catalysis reactions arising from multiple substrate-enzyme complexes create a potential for bistable dynamics in such reaction networks. We construct a generic model of an enzyme with n-substrate binding sites and derive an analytical solution for the steady-state concentration of all enzyme-substrate complexes. By studying these expressions, we obtain a mechanistic understanding of bistability, derive parameter combinations that guarantee bistability, and show how changing specific enzyme kinetic parameters and enzyme levels can lead to bistability in reaction networks involving multisite enzymes. Thus, the presented findings provide a biochemical and mathematical basis for predicting and engineering bistability in multisite enzymes.
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Affiliation(s)
| | - Elisenda Feliu
- Department of Mathematics, University of Copenhagen, DK-2100 Copenhagen, Denmark
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22
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Campbell O, Vanderwal T, Weber AM. Fractal-Based Analysis of fMRI BOLD Signal During Naturalistic Viewing Conditions. Front Physiol 2022; 12:809943. [PMID: 35087421 PMCID: PMC8787275 DOI: 10.3389/fphys.2021.809943] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Accepted: 12/14/2021] [Indexed: 01/04/2023] Open
Abstract
Background: Temporal fractals are characterized by prominent scale-invariance and self-similarity across time scales. Monofractal analysis quantifies this scaling behavior in a single parameter, the Hurst exponent (H). Higher H reflects greater correlation in the signal structure, which is taken as being more fractal. Previous fMRI studies have observed lower H during conventional tasks relative to resting state conditions, and shown that H is negatively correlated with task difficulty and novelty. To date, no study has investigated the fractal dynamics of BOLD signal during naturalistic conditions. Methods: We performed fractal analysis on Human Connectome Project 7T fMRI data (n = 72, 41 females, mean age 29.46 ± 3.76 years) to compare H across movie-watching and rest. Results: In contrast to previous work using conventional tasks, we found higher H values for movie relative to rest (mean difference = 0.014; p = 5.279 × 10-7; 95% CI [0.009, 0.019]). H was significantly higher in movie than rest in the visual, somatomotor and dorsal attention networks, but was significantly lower during movie in the frontoparietal and default networks. We found no cross-condition differences in test-retest reliability of H. Finally, we found that H of movie-derived stimulus properties (e.g., luminance changes) were fractal whereas H of head motion estimates were non-fractal. Conclusions: Overall, our findings suggest that movie-watching induces fractal signal dynamics. In line with recent work characterizing connectivity-based brain state dynamics during movie-watching, we speculate that these fractal dynamics reflect the configuring and reconfiguring of brain states that occurs during naturalistic processing, and are markedly different than dynamics observed during conventional tasks.
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Affiliation(s)
- Olivia Campbell
- School of Biomedical Engineering, University of British Columbia, Vancouver, BC, Canada
| | - Tamara Vanderwal
- British Columbia (BC) Children's Hospital Research Institute, UBC, Vancouver, BC, Canada.,Department of Psychiatry, University of British Columbia, Vancouver, BC, Canada
| | - Alexander Mark Weber
- School of Biomedical Engineering, University of British Columbia, Vancouver, BC, Canada.,British Columbia (BC) Children's Hospital Research Institute, UBC, Vancouver, BC, Canada.,Division of Neurology, Department of Pediatrics, University of British Columbia, Vancouver, BC, Canada.,Department of Neuroscience, University of British Columbia, Vancouver, BC, Canada
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23
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Geiß C, Salas E, Guevara-Coto J, Régnier-Vigouroux A, Mora-Rodríguez RA. Multistability in Macrophage Activation Pathways and Metabolic Implications. Cells 2022; 11:cells11030404. [PMID: 35159214 PMCID: PMC8834178 DOI: 10.3390/cells11030404] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 01/18/2022] [Accepted: 01/22/2022] [Indexed: 12/22/2022] Open
Abstract
Macrophages are innate immune cells with a dynamic range of reversible activation states including the classical pro-inflammatory (M1) and alternative anti-inflammatory (M2) states. Deciphering how macrophages regulate their transition from one state to the other is key for a deeper understanding of inflammatory diseases and relevant therapies. Common regulatory motifs reported for macrophage transitions, such as positive or double-negative feedback loops, exhibit a switchlike behavior, suggesting the bistability of the system. In this review, we explore the evidence for multistability (including bistability) in macrophage activation pathways at four molecular levels. First, a decision-making module in signal transduction includes mutual inhibitory interactions between M1 (STAT1, NF-KB/p50-p65) and M2 (STAT3, NF-KB/p50-p50) signaling pathways. Second, a switchlike behavior at the gene expression level includes complex network motifs of transcription factors and miRNAs. Third, these changes impact metabolic gene expression, leading to switches in energy production, NADPH and ROS production, TCA cycle functionality, biosynthesis, and nitrogen metabolism. Fourth, metabolic changes are monitored by metabolic sensors coupled to AMPK and mTOR activity to provide stability by maintaining signals promoting M1 or M2 activation. In conclusion, we identify bistability hubs as promising therapeutic targets for reverting or blocking macrophage transitions through modulation of the metabolic environment.
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Affiliation(s)
- Carsten Geiß
- Institute for Developmental Biology and Neurobiology (IDN), Johannes Gutenberg University, 55128 Mainz, Germany;
- Correspondence: (C.G.); (R.A.M.-R.)
| | - Elvira Salas
- Department of Biochemistry, Faculty of Medicine, Campus Rodrigo Facio, University of Costa Rica, San José 11501-2060, Costa Rica;
| | - Jose Guevara-Coto
- Department of Computer Sciences and Informatics (ECCI), Faculty of Engineering, Campus Rodrigo Facio, University of Costa Rica, San José 11501-2060, Costa Rica;
- Research Center for Information and Communication Technologies (CITIC), Campus Rodrigo Facio, University of Costa Rica, San José 11501-2060, Costa Rica
| | - Anne Régnier-Vigouroux
- Institute for Developmental Biology and Neurobiology (IDN), Johannes Gutenberg University, 55128 Mainz, Germany;
| | - Rodrigo A. Mora-Rodríguez
- Institute for Developmental Biology and Neurobiology (IDN), Johannes Gutenberg University, 55128 Mainz, Germany;
- Research Center on Surgery and Cancer (CICICA), Campus Rodrigo Facio, University of Costa Rica, San José 11501-2060, Costa Rica
- Research Center for Tropical Diseases (CIET), Lab of Tumor Chemosensitivity (LQT), Faculty of Microbiology, Campus Rodrigo Facio, University of Costa Rica, San José 11501-2060, Costa Rica
- Correspondence: (C.G.); (R.A.M.-R.)
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24
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Spiechowicz J, Hänggi P, Łuczka J. Velocity Multistability vs. Ergodicity Breaking in a Biased Periodic Potential. Entropy (Basel) 2022; 24:98. [PMID: 35052124 DOI: 10.3390/e24010098] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 01/04/2022] [Accepted: 01/05/2022] [Indexed: 11/17/2022]
Abstract
Multistability, i.e., the coexistence of several attractors for a given set of system parameters, is one of the most important phenomena occurring in dynamical systems. We consider it in the velocity dynamics of a Brownian particle, driven by thermal fluctuations and moving in a biased periodic potential. In doing so, we focus on the impact of ergodicity-A concept which lies at the core of statistical mechanics. The latter implies that a single trajectory of the system is representative for the whole ensemble and, as a consequence, the initial conditions of the dynamics are fully forgotten. The ergodicity of the deterministic counterpart is strongly broken, and we discuss how the velocity multistability depends on the starting position and velocity of the particle. While for non-zero temperatures the ergodicity is, in principle, restored, in the low temperature regime the velocity dynamics is still affected by initial conditions due to weak ergodicity breaking. For moderate and high temperatures, the multistability is robust with respect to the choice of the starting position and velocity of the particle.
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25
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Sahoo S, Nayak SP, Hari K, Purkait P, Mandal S, Kishore A, Levine H, Jolly MK. Immunosuppressive Traits of the Hybrid Epithelial/Mesenchymal Phenotype. Front Immunol 2022; 12:797261. [PMID: 34975907 PMCID: PMC8714906 DOI: 10.3389/fimmu.2021.797261] [Citation(s) in RCA: 41] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 11/24/2021] [Indexed: 12/13/2022] Open
Abstract
Recent preclinical and clinical data suggests enhanced metastatic fitness of hybrid epithelial/mesenchymal (E/M) phenotypes, but mechanistic details regarding their survival strategies during metastasis remain unclear. Here, we investigate immune-evasive strategies of hybrid E/M states. We construct and simulate the dynamics of a minimalistic regulatory network encompassing the known associations among regulators of EMT (epithelial-mesenchymal transition) and PD-L1, an established immune-suppressor. Our simulations for the network consisting of SLUG, ZEB1, miR-200, CDH1 and PD-L1, integrated with single-cell and bulk RNA-seq data analysis, elucidate that hybrid E/M cells can have high levels of PD-L1, similar to those seen in cells with a full EMT phenotype, thus obviating the need for cancer cells to undergo a full EMT to be immune-evasive. Specifically, in breast cancer, we show the co-existence of hybrid E/M phenotypes, enhanced resistance to anti-estrogen therapy and increased PD-L1 levels. Our results underscore how the emergent dynamics of interconnected regulatory networks can coordinate different axes of cellular fitness during metastasis.
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Affiliation(s)
- Sarthak Sahoo
- Undergraduate Program, Indian Institute of Science, Bangalore, India.,Centre for BioSystems Science and Engineering, Indian Institute of Science, Bangalore, India
| | | | - Kishore Hari
- Centre for BioSystems Science and Engineering, Indian Institute of Science, Bangalore, India
| | - Prithu Purkait
- Undergraduate Program, Indian Institute of Science, Bangalore, India
| | - Susmita Mandal
- Centre for BioSystems Science and Engineering, Indian Institute of Science, Bangalore, India
| | - Akash Kishore
- Department of Computer Science & Engineering, Sri Sivasubramaniya Nadar (SSN) College of Engineering, Chennai, India
| | - Herbert Levine
- Center for Theoretical Biological Physics, Northeastern University, Boston, MA, United States.,Departments of Physics and Bioengineering, Northeastern University, Boston, MA, United States
| | - Mohit Kumar Jolly
- Centre for BioSystems Science and Engineering, Indian Institute of Science, Bangalore, India
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26
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McKinley J, Zhang M, Wead A, Williams C, Tognoli E, Beetle C. Third party stabilization of unstable coordination in systems of coupled oscillators. J Phys Conf Ser 2021; 2090:012167. [PMID: 37333713 PMCID: PMC10275349 DOI: 10.1088/1742-6596/2090/1/012167] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
The Haken-Kelso-Bunz (HKB) system of equations is a well-developed model for dyadic rhythmic coordination in biological systems. It captures ubiquitous empirical observations of bistability - the coexistence of in-phase and antiphase motion - in neural, behavioral, and social coordination. Recent work by Zhang and colleagues has generalized HKB to many oscillators to account for new empirical phenomena observed in multiagent interaction. Utilising this generalization, the present work examines how the coordination dynamics of a pair of oscillators can be augmented by virtue of their coupling to a third oscillator. We show that stable antiphase coordination emerges in pairs of oscillators even when their coupling parameters would have prohibited such coordination in their dyadic relation. We envision two lines of application for this theoretical work. In the social sciences, our model points toward the development of intervention strategies to support coordination behavior in heterogeneous groups (for instance in gerontology, when younger and older individuals interact). In neuroscience, our model will advance our understanding of how the direct functional connection of mesoscale or microscale neural ensembles might be switched by their changing coupling to other neural ensembles. Our findings illuminate a crucial property of complex systems: how the whole is different than the system's parts.
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Affiliation(s)
- Joseph McKinley
- Department of Physics, Florida Atlantic University, 777 Glades Road, Boca Raton, FL 33431 USA
| | - Mengsen Zhang
- Department of Psychiatry, University of North Carolina at Chapel Hill, 116 Manning Drive, Chapel Hill, NC 27514 USA
| | - Alice Wead
- College of Nursing, Florida Atlantic University, 777 Glades Road, Boca Raton, FL 33431 USA
| | - Christine Williams
- College of Nursing, Florida Atlantic University, 777 Glades Road, Boca Raton, FL 33431 USA
| | - Emmanuelle Tognoli
- Center for Complex Systems and Brain Sciences, Florida Atlantic University, 777 Glades Road, Boca Raton, FL 33431 USA
| | - Christopher Beetle
- Department of Physics, Florida Atlantic University, 777 Glades Road, Boca Raton, FL 33431 USA
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27
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Gyorgy A. Context-Dependent Stability and Robustness of Genetic Toggle Switches with Leaky Promoters. Life (Basel) 2021; 11:life11111150. [PMID: 34833026 PMCID: PMC8624834 DOI: 10.3390/life11111150] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 10/21/2021] [Accepted: 10/26/2021] [Indexed: 01/22/2023] Open
Abstract
Multistable switches are ubiquitous building blocks in both systems and synthetic biology. Given their central role, it is thus imperative to understand how their fundamental properties depend not only on the tunable biophysical properties of the switches themselves, but also on their genetic context. To this end, we reveal in this article how these factors shape the essential characteristics of toggle switches implemented using leaky promoters such as their stability and robustness to noise, both at single-cell and population levels. In particular, our results expose the roles that competition for scarce transcriptional and translational resources, promoter leakiness, and cell-to-cell heterogeneity collectively play. For instance, the interplay between protein expression from leaky promoters and the associated cost of relying on shared cellular resources can give rise to tristable dynamics even in the absence of positive feedback. Similarly, we demonstrate that while promoter leakiness always acts against multistability, resource competition can be leveraged to counteract this undesirable phenomenon. Underpinned by a mechanistic model, our results thus enable the context-aware rational design of multistable genetic switches that are directly translatable to experimental considerations, and can be further leveraged during the synthesis of large-scale genetic systems using computer-aided biodesign automation platforms.
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Affiliation(s)
- Andras Gyorgy
- Division of Engineering, New York University Abu Dhabi, Abu Dhabi P.O. Box 129188, United Arab Emirates
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28
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Abstract
Intelligence of physical agents, such as human-made (e.g., robots, autonomous cars) and biological (e.g., animals, plants) ones, is not only enabled by their computational intelligence (CI) in their brain, but also by their physical intelligence (PI) encoded in their body. Therefore, it is essential to advance the PI of human-made agents as much as possible, in addition to their CI, to operate them in unstructured and complex real-world environments like the biological agents. This article gives a perspective on what PI paradigm is, when PI can be more significant and dominant in physical and biological agents at different length scales and how bioinspired and abstract PI methods can be created in agent bodies. PI paradigm aims to synergize and merge many research fields, such as mechanics, materials science, robotics, mechanical design, fluidics, active matter, biology, self-assembly and collective systems, to enable advanced PI capabilities in human-made agent bodies, comparable to the ones observed in biological organisms. Such capabilities would progress the future robots and other machines beyond what can be realized using the current frameworks.
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Affiliation(s)
- Metin Sitti
- Physical Intelligence Department, Max Planck Institute for Intelligent Systems, 70569 Stuttgart, Germany
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29
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Bhatt V, Yadav S, Jha PK, Bhattacherjee AB. Polariton multistability in a nonlinear optomechanical cavity. J Phys Condens Matter 2021; 33:365302. [PMID: 34171855 DOI: 10.1088/1361-648x/ac0ea9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Accepted: 06/25/2021] [Indexed: 06/13/2023]
Abstract
We theoretically study the polariton multistability in a solid state based optomechanical resonator embedded with a quantum well and aχ(2)second order nonlinear medium. The excitonic transition inside the quantum well is strongly coupled to the optical cavity mode. The polariton formed due to the mixing of cavity photons and exciton states are coupled to the mechanical mode which gives rise to the bistable behavior. A transition from bistability to tristability occurs in the presence of a strongχ(2)nonlinearity. Switching between bistability and tristability can also be controlled using exciton-cavity and optomechanical coupling making the system highly tunable. Tristability appears at low input power making it a suitable candidate for polaritonic devices which requires low input power.
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Affiliation(s)
- Vijay Bhatt
- Department of Physics, DDU College, University of Delhi, New Delhi 110078, India
| | - Surabhi Yadav
- Department of Physics, Birla Institute of Technology and Science, Pilani, Hyderabad Campus, Hyderabad-500078, India
| | - Pradip K Jha
- Department of Physics, DDU College, University of Delhi, New Delhi 110078, India
| | - Aranya B Bhattacherjee
- Department of Physics, Birla Institute of Technology and Science, Pilani, Hyderabad Campus, Hyderabad-500078, India
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30
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Abstract
Bacteria can be harnessed to synthesise high-value chemicals. A promising strategy for increasing productivity uses inducible control systems to switch metabolism from growth to chemical synthesis once a large population of cell factories are generated. However, use of expensive chemical inducers limits scalability of this approach for biotechnological applications. Switching using cheap nutrients is an appealing alternative, but their tightly regulated uptake and consumption again limits scalability. Here, using mathematical models of fatty acid uptake in E. coli as an exemplary case study, we unravel how the cell's native regulation and program of induction can be engineered to minimise inducer usage. We show that integrating positive feedback loops into the circuitry creates an irreversible metabolic switch, which, requiring only temporary induction, drastically reduces inducer usage. Our proposed switch should be widely applicable, irrespective of the product of interest, and brings closer the realization of scalable and sustainable microbial chemical production.
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Affiliation(s)
- Ahmad A Mannan
- Warwick Integrative Synthetic Biology Centre, School of Engineering, University of Warwick, Coventry, CV4 7AL, United Kingdom
| | - Declan G Bates
- Warwick Integrative Synthetic Biology Centre, School of Engineering, University of Warwick, Coventry, CV4 7AL, United Kingdom.
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31
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Margazoglou G, Grafke T, Laio A, Lucarini V. Dynamical landscape and multistability of a climate model. Proc Math Phys Eng Sci 2021; 477:20210019. [PMID: 35153562 PMCID: PMC8299554 DOI: 10.1098/rspa.2021.0019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 05/04/2021] [Indexed: 12/15/2022] Open
Abstract
We apply two independent data analysis methodologies to locate stable climate states in an intermediate complexity climate model and analyse their interplay. First, drawing from the theory of quasi-potentials, and viewing the state space as an energy landscape with valleys and mountain ridges, we infer the relative likelihood of the identified multistable climate states and investigate the most likely transition trajectories as well as the expected transition times between them. Second, harnessing techniques from data science, and specifically manifold learning, we characterize the data landscape of the simulation output to find climate states and basin boundaries within a fully agnostic and unsupervised framework. Both approaches show remarkable agreement, and reveal, apart from the well known warm and snowball earth states, a third intermediate stable state in one of the two versions of PLASIM, the climate model used in this study. The combination of our approaches allows to identify how the negative feedback of ocean heat transport and entropy production via the hydrological cycle drastically change the topography of the dynamical landscape of Earth’s climate.
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Affiliation(s)
- Georgios Margazoglou
- Department of Mathematics and Statistics, University of Reading, Reading, UK.,Centre for the Mathematics of Planet Earth, University of Reading, Reading, UK
| | - Tobias Grafke
- Mathematics Institute, University of Warwick, Coventry, UK
| | - Alessandro Laio
- International School for Advanced Studies (SISSA), Trieste, Italy
| | - Valerio Lucarini
- Department of Mathematics and Statistics, University of Reading, Reading, UK.,Centre for the Mathematics of Planet Earth, University of Reading, Reading, UK
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32
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Abstract
Decoding the dynamics of cellular decision-making and cell differentiation is a central question in cell and developmental biology. A common network motif involved in many cell-fate decisions is a mutually inhibitory feedback loop between two self-activating 'master regulators' A and B, also called as toggle switch. Typically, it can allow for three stable states-(high A, low B), (low A, high B) and (medium A, medium B). A toggle triad-three mutually repressing regulators A, B and C, i.e. three toggle switches arranged circularly (between A and B, between B and C, and between A and C)-can allow for six stable states: three 'single positive' and three 'double positive' ones. However, the operating principles of larger toggle polygons, i.e. toggle switches arranged circularly to form a polygon, remain unclear. Here, we simulate using both discrete and continuous methods the dynamics of different sized toggle polygons. We observed a pattern in their steady state frequency depending on whether the polygon was an even or odd numbered one. The even-numbered toggle polygons result in two dominant states with consecutive components of the network expressing alternating high and low levels. The odd-numbered toggle polygons, on the other hand, enable more number of states, usually twice the number of components with the states that follow 'circular permutation' patterns in their composition. Incorporating self-activations preserved these trends while increasing the frequency of multistability in the corresponding network. Our results offer insights into design principles of circular arrangement of regulatory units involved in cell-fate decision making, and can offer design strategies for synthesizing genetic circuits.
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Affiliation(s)
- Souvadra Hati
- Centre for BioSystems Science and Engineering, Indian Institute of Science, Bangalore, India.,Undergraduate Programme, Indian Institute of Science, Bangalore, India
| | - Atchuta Srinivas Duddu
- Centre for BioSystems Science and Engineering, Indian Institute of Science, Bangalore, India
| | - Mohit Kumar Jolly
- Centre for BioSystems Science and Engineering, Indian Institute of Science, Bangalore, India
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33
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Abstract
Soft materials are inherently flexible and make suitable candidates for soft robots intended for specific tasks that would otherwise not be achievable (e.g., smart grips capable of picking up objects without prior knowledge of their stiffness). Moreover, soft robots exploit the mechanics of their fundamental building blocks and aim to provide targeted functionality without the use of electronics or wiring. Despite recent progress, locomotion in soft robotics applications has remained a relatively young field with open challenges yet to overcome. Justly, harnessing structural instabilities and utilizing bistable actuators have gained importance as a solution. This report focuses on substrate-free reconfigurable structures composed of multistable unit cells with a nonconvex strain energy potential, which can exhibit structural transitions and produce strongly nonlinear transition waves. The energy released during the transition, if sufficient, balances the dissipation and kinetic energy of the system and forms a wave front that travels through the structure to effect its permanent or reversible reconfiguration. We exploit a triangular unit cell’s design space and provide general guidelines for unit cell selection. Using a continuum description, we predict and map the resulting structure’s behavior for various geometric and material properties. The structural motion created by these strongly nonlinear metamaterials has potential applications in propulsion in soft robotics, morphing surfaces, reconfigurable devices, mechanical logic, and controlled energy absorption.
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Affiliation(s)
- Romik Khajehtourian
- Mechanics and Materials Lab, Department of Mechanical and Process Engineering, ETH Zürich, Zürich, Switzerland
| | - Dennis M Kochmann
- Mechanics and Materials Lab, Department of Mechanical and Process Engineering, ETH Zürich, Zürich, Switzerland
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34
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Yong C, Gyorgy A. Stability and Robustness of Unbalanced Genetic Toggle Switches in the Presence of Scarce Resources. Life (Basel) 2021; 11:271. [PMID: 33805212 PMCID: PMC8064337 DOI: 10.3390/life11040271] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Revised: 03/17/2021] [Accepted: 03/19/2021] [Indexed: 12/24/2022] Open
Abstract
While the vision of synthetic biology is to create complex genetic systems in a rational fashion, system-level behaviors are often perplexing due to the context-dependent dynamics of modules. One major source of context-dependence emerges due to the limited availability of shared resources, coupling the behavior of disconnected components. Motivated by the ubiquitous role of toggle switches in genetic circuits ranging from controlling cell fate differentiation to optimizing cellular performance, here we reveal how their fundamental dynamic properties are affected by competition for scarce resources. Combining a mechanistic model with nullcline-based stability analysis and potential landscape-based robustness analysis, we uncover not only the detrimental impacts of resource competition, but also how the unbalancedness of the switch further exacerbates them. While in general both of these factors undermine the performance of the switch (by pushing the dynamics toward monostability and increased sensitivity to noise), we also demonstrate that some of the unwanted effects can be alleviated by strategically optimized resource competition. Our results provide explicit guidelines for the context-aware rational design of toggle switches to mitigate our reliance on lengthy and expensive trial-and-error processes, and can be seamlessly integrated into the computer-aided synthesis of complex genetic systems.
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Affiliation(s)
- Chentao Yong
- Department of Chemical and Biological Engineering, New York University, New York, NY 10003, USA;
| | - Andras Gyorgy
- Department of Electrical and Computer Engineering, New York University Abu Dhabi, Abu Dhabi 129188, United Arab Emirates
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35
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Chauhan L, Ram U, Hari K, Jolly MK. Topological signatures in regulatory network enable phenotypic heterogeneity in small cell lung cancer. eLife 2021; 10:e64522. [PMID: 33729159 PMCID: PMC8012062 DOI: 10.7554/elife.64522] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Accepted: 03/16/2021] [Indexed: 02/07/2023] Open
Abstract
Phenotypic (non-genetic) heterogeneity has significant implications for the development and evolution of organs, organisms, and populations. Recent observations in multiple cancers have unraveled the role of phenotypic heterogeneity in driving metastasis and therapy recalcitrance. However, the origins of such phenotypic heterogeneity are poorly understood in most cancers. Here, we investigate a regulatory network underlying phenotypic heterogeneity in small cell lung cancer, a devastating disease with no molecular targeted therapy. Discrete and continuous dynamical simulations of this network reveal its multistable behavior that can explain co-existence of four experimentally observed phenotypes. Analysis of the network topology uncovers that multistability emerges from two teams of players that mutually inhibit each other, but members of a team activate one another, forming a 'toggle switch' between the two teams. Deciphering these topological signatures in cancer-related regulatory networks can unravel their 'latent' design principles and offer a rational approach to characterize phenotypic heterogeneity in a tumor.
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Affiliation(s)
- Lakshya Chauhan
- Centre for BioSystems Science and Engineering, Indian Institute of ScienceBangaloreIndia
- Undergraduate Programme, Indian Institute of ScienceBangaloreIndia
| | - Uday Ram
- Centre for BioSystems Science and Engineering, Indian Institute of ScienceBangaloreIndia
- Undergraduate Programme, Indian Institute of ScienceBangaloreIndia
| | - Kishore Hari
- Centre for BioSystems Science and Engineering, Indian Institute of ScienceBangaloreIndia
| | - Mohit Kumar Jolly
- Centre for BioSystems Science and Engineering, Indian Institute of ScienceBangaloreIndia
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36
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Singh D, Bocci F, Kulkarni P, Jolly MK. Coupled Feedback Loops Involving PAGE4, EMT and Notch Signaling Can Give Rise to Non-genetic Heterogeneity in Prostate Cancer Cells. Entropy (Basel) 2021; 23:288. [PMID: 33652914 PMCID: PMC7996788 DOI: 10.3390/e23030288] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 02/18/2021] [Accepted: 02/23/2021] [Indexed: 12/12/2022]
Abstract
Non-genetic heterogeneity is emerging as a crucial factor underlying therapy resistance in multiple cancers. However, the design principles of regulatory networks underlying non-genetic heterogeneity in cancer remain poorly understood. Here, we investigate the coupled dynamics of feedback loops involving (a) oscillations in androgen receptor (AR) signaling mediated through an intrinsically disordered protein PAGE4, (b) multistability in epithelial-mesenchymal transition (EMT), and c) Notch-Delta-Jagged signaling mediated cell-cell communication, each of which can generate non-genetic heterogeneity through multistability and/or oscillations. Our results show how different coupling strengths between AR and EMT signaling can lead to monostability, bistability, or oscillations in the levels of AR, as well as propagation of oscillations to EMT dynamics. These results reveal the emergent dynamics of coupled oscillatory and multi-stable systems and unravel mechanisms by which non-genetic heterogeneity in AR levels can be generated, which can act as a barrier to most existing therapies for prostate cancer patients.
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Affiliation(s)
- Divyoj Singh
- Centre for BioSystems Science and Engineering, Indian Institute of Science, Bangalore 560012, India;
- Undergraduate Programme, Indian Institute of Science, Bangalore 560012, India
| | - Federico Bocci
- Center for Theoretical Biological Physics, Rice University, Houston, TX 77005, USA;
- NSF-Simons Center for Multiscale Cell Fate Research, University of California, Irvine, CA 92697, USA
| | - Prakash Kulkarni
- Department of Medical Oncology and Experimental Therapeutics, City of Hope National Medical Center, Duarte, CA 91010, USA;
| | - Mohit Kumar Jolly
- Centre for BioSystems Science and Engineering, Indian Institute of Science, Bangalore 560012, India;
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37
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Abstract
This study examines a biology-inspired approach of using reconfigurable articulation to reduce the control requirement for soft robotic arms. We construct a robotic arm by assembling Kresling origami modules that exhibit predictable bistability. By switching between their two stable states, these origami modules can behave either like a flexible joint with low bending stiffness or like a stiff link with high stiffness, without requiring any continuous power supply. In this way, the robotic arm can exhibit pseudo-linkage kinematics with lower control requirements and improved motion accuracy. A unique advantage of using origami as the robotic arm skeleton is that its bending stiffness ratio between stable states is directly related to the underlying Kresling design. Therefore, we conduct extensive parametric analyses and experimental validations to identify the optimized Kresling pattern for articulation. The results indicate that a higher angle ratio, a smaller resting length at contracted stable state, and a large number of polygon sides can offer more significant and robust bending stiffness tuning. Based on this insight, we construct a proof-of-concept, tendon-driven robotic arm consisting of three modules and show that it can exhibit the desired reconfigurable articulation behavior. Moreover, the deformations of this manipulator are consistent with kinematic model predictions, which validate the possibility of using simple controllers for such compliant robotic systems.
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Affiliation(s)
- Joshua Kaufmann
- Department of Mechanical Engineering, Clemson University, Clemson, South Carolina, USA
| | - Priyanka Bhovad
- Department of Mechanical Engineering, Clemson University, Clemson, South Carolina, USA
| | - Suyi Li
- Department of Mechanical Engineering, Clemson University, Clemson, South Carolina, USA
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38
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Natiq H, Kamel Ariffin MR, Asbullah MA, Mahad Z, Najah M. Enhancing Chaos Complexity of a Plasma Model through Power Input with Desirable Random Features. Entropy (Basel) 2020; 23:e23010048. [PMID: 33396897 PMCID: PMC7823621 DOI: 10.3390/e23010048] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 12/21/2020] [Accepted: 12/23/2020] [Indexed: 11/18/2022]
Abstract
The present work introduces an analysis framework to comprehend the dynamics of a 3D plasma model, which has been proposed to describe the pellet injection in tokamaks. The analysis of the system reveals the existence of a complex transition from transient chaos to steady periodic behavior. Additionally, without adding any kind of forcing term or controllers, we demonstrate that the system can be changed to become a multi-stable model by injecting more power input. In this regard, we observe that increasing the power input can fluctuate the numerical solution of the system from coexisting symmetric chaotic attractors to the coexistence of infinitely many quasi-periodic attractors. Besides that, complexity analyses based on Sample entropy are conducted, and they show that boosting power input spreads the trajectory to occupy a larger range in the phase space, thus enhancing the time series to be more complex and random. Therefore, our analysis could be important to further understand the dynamics of such models, and it can demonstrate the possibility of applying this system for generating pseudorandom sequences.
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Affiliation(s)
- Hayder Natiq
- Information Technology Collage, Imam Ja’afar Al-Sadiq University, Baghdad 10001, Iraq;
- Institute for Mathematical Research, Universiti Putra Malaysia, UPM, Serdang 43400, Malaysia; (M.A.A.); (Z.M.)
| | - Muhammad Rezal Kamel Ariffin
- Institute for Mathematical Research, Universiti Putra Malaysia, UPM, Serdang 43400, Malaysia; (M.A.A.); (Z.M.)
- Department of Mathematics, Faculty of Science, Universiti Putra Malaysia, UPM, Serdang 43400, Malaysia
- Correspondence:
| | - Muhammad Asyraf Asbullah
- Institute for Mathematical Research, Universiti Putra Malaysia, UPM, Serdang 43400, Malaysia; (M.A.A.); (Z.M.)
- Centre of Foundation Studies for Agriculture Science, Universiti Putra Malaysia, UPM, Serdang 43400, Malaysia
| | - Zahari Mahad
- Institute for Mathematical Research, Universiti Putra Malaysia, UPM, Serdang 43400, Malaysia; (M.A.A.); (Z.M.)
| | - Mohammed Najah
- Institute of Informatics and Computing in Energy, Universiti Tenaga Nasional, Kajang 43000, Malaysia;
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39
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Adler A, Holliger C. Multistability and Reversibility of Aerobic Granular Sludge Microbial Communities Upon Changes From Simple to Complex Synthetic Wastewater and Back. Front Microbiol 2020; 11:574361. [PMID: 33324361 PMCID: PMC7726351 DOI: 10.3389/fmicb.2020.574361] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 10/12/2020] [Indexed: 01/31/2023] Open
Abstract
Aerobic granular sludge (AGS) is a promising alternative wastewater treatment to the conventional activated sludge system allowing space and energy saving. Basic understanding of AGS has mainly been obtained using simple wastewater containing acetate and propionate as carbon source. Yet, the aspect and performances of AGS grown in such model systems are different from those obtained in reactor treating real wastewater. The impact of fermentable and hydrolyzable compounds on already formed AGS was assessed separately by changing the composition of the influent from simple wastewater containing volatile fatty acids to complex monomeric wastewater containing amino acids and glucose, and then to complex polymeric wastewater containing also starch and peptone. The reversibility of the observed changes was assessed by changing the composition of the wastewater from complex monomeric back to simple. The introduction of fermentable compounds in the influent left the settling properties and nutrient removal performance unchanged, but had a significant impact on the bacterial community. The proportion of Gammaproteobacteria diminished to the benefit of Actinobacteria and the Saccharibateria phylum. On the other hand, the introduction of polymeric compounds altered the settling properties and denitrification efficiency, but induced smaller changes in the bacterial community. The changes induced by the wastewater transition were only partly reversed. Seven distinct stables states of the bacterial community were detected during the 921 days of experiment, four of them observed with the complex monomeric wastewater. The transitions between these states were not only caused by wastewater changes but also by operation failures and other incidences. However, the nutrient removal performance and settling properties of the AGS were globally maintained due to the functional redundancy of its bacterial community.
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Affiliation(s)
- Aline Adler
- Laboratory for Environmental Biotechnology, School for Architecture, Civil and Environmental Engineering, Environmental Engineering Institute, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
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40
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Brunetti M, Favata A, Vidoli S. Enhanced models for the nonlinear bending of planar rods: localization phenomena and multistability. Proc Math Phys Eng Sci 2020; 476:20200455. [PMID: 33223944 DOI: 10.1098/rspa.2020.0455] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 09/24/2020] [Indexed: 11/12/2022] Open
Abstract
We deduce a one-dimensional model of elastic planar rods starting from the Föppl-von Kármán model of thin shells. Such model is enhanced by additional kinematical descriptors that keep explicit track of the compatibility condition requested in the two-dimensional parent continuum, that in the standard rods models are identically satisfied after the dimensional reduction. An inextensible model is also proposed, starting from the nonlinear Koiter model of inextensible shells. These enhanced models describe the nonlinear planar bending of rods and allow to account for some phenomena of preeminent importance even in one-dimensional bodies, such as formation of singularities and localization (d-cones), otherwise inaccessible by the classical one-dimensional models. Moreover, the effects of the compatibility translate into the possibility to obtain multiple stable equilibrium configurations.
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Affiliation(s)
- Matteo Brunetti
- Department of Civil and Industrial Engineering, University of Pisa, Pisa, Italy
| | - Antonino Favata
- Department of Structural and Geotechnical Engineering, Sapienza University of Rome, Rome, Italy
| | - Stefano Vidoli
- Department of Structural and Geotechnical Engineering, Sapienza University of Rome, Rome, Italy
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41
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Vangelatos Z, Micheletti A, Grigoropoulos CP, Fraternali F. Design and Testing of Bistable Lattices with Tensegrity Architecture and Nanoscale Features Fabricated by Multiphoton Lithography. Nanomaterials (Basel) 2020; 10:nano10040652. [PMID: 32244533 PMCID: PMC7221601 DOI: 10.3390/nano10040652] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/16/2020] [Revised: 03/29/2020] [Accepted: 03/30/2020] [Indexed: 01/01/2023]
Abstract
A bistable response is an innate feature of tensegrity metamaterials, which is a conundrum to attain in other metamaterials, since it ushers unconventional static and dynamical mechanical behaviors. This paper investigates the design, modeling, fabrication and testing of bistable lattices with tensegrity architecture and nanoscale features. First, a method to design bistable lattices tessellating tensegrity units is formulated. The additive manufacturing of these structures is performed through multiphoton lithography, which enables the fabrication of microscale structures with nanoscale features and extremely high resolution. Different modular lattices, comprised of struts with 250 nm minimum radius, are tested under loading-unloading uniaxial compression nanoindentation tests. The compression tests confirmed the activation of the designed bistable twisting mechanism in the examined lattices, combined with a moderate viscoelastic response. The force-displacement plots of the 3D assemblies of bistable tensegrity prisms reveal a softening behavior during the loading from the primary stable configuration and a subsequent snapping event that drives the structure into a secondary stable configuration. The twisting mechanism that characterizes such a transition is preserved after unloading and during repeated loading-unloading cycles. The results of the present study elucidate that fabrication of multistable tensegrity lattices is highly feasible via multiphoton lithography and promulgates the fabrication of multi-cell tensegrity metamaterials with unprecedented static and dynamic responses.
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Affiliation(s)
- Zacharias Vangelatos
- Department of Mechanical Engineering, University of California, Berkeley, CA 94709, USA;
| | - Andrea Micheletti
- Department of Civil and Computer Science Engineering, University of Rome Tor Vergata, 00133 Rome RM, Italy;
| | - Costas P. Grigoropoulos
- Department of Mechanical Engineering, University of California, Berkeley, CA 94709, USA;
- Correspondence: ; Tel.: +1-510-642-2525
| | - Fernando Fraternali
- Department of Civil Engineering, University of Salerno, 84084 Fisciano SA, Italy;
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42
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Slesarenko V. Planar Mechanical Metamaterials with Embedded Permanent Magnets. Materials (Basel) 2020; 13:E1313. [PMID: 32183196 DOI: 10.3390/ma13061313] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 03/05/2020] [Accepted: 03/11/2020] [Indexed: 11/22/2022]
Abstract
The design space of mechanical metamaterials can be drastically enriched by the employment of non-mechanical interactions between unit cells. Here, the mechanical behavior of planar metamaterials consisting of rotating squares is controlled through the periodic embedment of modified elementary cells with attractive and repulsive configurations of the magnets. The proposed design of mechanical metamaterials produced by three-dimensional printing enables the efficient and quick reprogramming of their mechanical properties through the insertion of the magnets into various locations within the metamaterial. Experimental and numerical studies reveal that under equibiaxial compression various mechanical characteristics, such as buckling strain and post-buckling stiffness, can be finely tuned through the rational placement of the magnets. Moreover, this strategy is shown to be efficient in introducing bistability into the metamaterial with an initially single equilibrium state.
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43
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Abstract
This work addresses the challenge of underactuated pattern generation in continuous multistable structures. The examined configuration is a slender membrane which can concurrently sustain two different equilibria states, separated by transition regions, and is actuated by a viscous fluid. We first demonstrate the formation and motion of a single transition region and then sequencing of several such moving transition regions to achieve arbitrary patterns by controlling the inlet pressure of the actuating fluid. Finally, we show that nonuniform membrane properties, along with transient dynamics of the fluid, can be leveraged to directly snap through any segment of the membrane.
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44
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Flouriot G, Jehanno C, Le Page Y, Le Goff P, Boutin B, Michel D. The Basal Level of Gene Expression Associated with Chromatin Loosening Shapes Waddington Landscapes and Controls Cell Differentiation. J Mol Biol 2020; 432:2253-70. [PMID: 32105732 DOI: 10.1016/j.jmb.2020.02.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Revised: 02/13/2020] [Accepted: 02/13/2020] [Indexed: 01/01/2023]
Abstract
The baseline level of transcription, which is variable and difficult to quantify, seriously complicates the normalization of comparative transcriptomic data, but its biological importance remains unappreciated. We show that this currently neglected ingredient is essential for controlling gene network multistability and therefore cellular differentiation. Basal expression is correlated to the degree of chromatin loosening measured by DNA accessibility and systematically leads to cellular dedifferentiation as assessed by transcriptomic signatures, irrespective of the molecular and cellular tools used. Modeling gene network motifs formally involved in developmental bifurcations reveals that the epigenetic landscapes of Waddington are restructured by the level of nonspecific expression, such that the attractors of progenitor and differentiated cells can be mutually exclusive. This mechanism is universal and holds beyond the particular nature of the genes involved, provided the multistable circuits are correctly described with autonomous basal expression. These results explain the relationships long established between gene expression noise, chromatin decondensation and cellular dedifferentiation, and highlight how heterochromatin maintenance is essential for preventing pathological cellular reprogramming, age-related diseases, and cancer.
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Abstract
Transition waves that sequentially switch bistable elements from one stable configuration to another have received significant interest in recent years not only because of their rich physics but also, for their potential applications, including unidirectional propagation, energy harvesting, and mechanical computation. Here, we exploit the propagation of transition waves in a bistable one-dimensional (1D) linkage as a robust mechanism to realize structures that can be quickly deployed. We first use a combination of experiments and analyses to show that, if the bistable joints are properly designed, transition waves can propagate throughout the entire structure and transform the initial straight configuration into a curved one. We then demonstrate that such bistable linkages can be used as building blocks to realize deployable three-dimensional (3D) structures of arbitrary shape.
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46
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Jin L, Khajehtourian R, Mueller J, Rafsanjani A, Tournat V, Bertoldi K, Kochmann DM. Guided transition waves in multistable mechanical metamaterials. Proc Natl Acad Sci U S A 2020; 117:2319-2325. [PMID: 31969454 PMCID: PMC7007517 DOI: 10.1073/pnas.1913228117] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Transition fronts, moving through solids and fluids in the form of propagating domain or phase boundaries, have recently been mimicked at the structural level in bistable architectures. What has been limited to simple one-dimensional (1D) examples is here cast into a blueprint for higher dimensions, demonstrated through 2D experiments and described by a continuum mechanical model that draws inspiration from phase transition theory in crystalline solids. Unlike materials, the presented structural analogs admit precise control of the transition wave's direction, shape, and velocity through spatially tailoring the underlying periodic network architecture (locally varying the shape or stiffness of the fundamental building blocks, and exploiting interactions of transition fronts with lattice defects such as point defects and free surfaces). The outcome is a predictable and programmable strongly nonlinear metamaterial motion with potential for, for example, propulsion in soft robotics, morphing surfaces, reconfigurable devices, mechanical logic, and controlled energy absorption.
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Affiliation(s)
- Lishuai Jin
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138
- Department of Mechanics, Tianjin University, Tianjin 300072, China
| | - Romik Khajehtourian
- Department of Mechanical and Process Engineering, ETH Zürich, 8092 Zürich, Switzerland
| | - Jochen Mueller
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138
- Wyss Institute for Biologically Inspired Engineering, Cambridge, MA 02138
| | - Ahmad Rafsanjani
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138
- Department of Materials, ETH Zürich, 8093 Zürich, Switzerland
| | - Vincent Tournat
- Laboratoire d'Acoustique de l'Université du Mans, CNRS UMR 6613, Le Mans Université, 72085 Le Mans, France
| | - Katia Bertoldi
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138;
- Wyss Institute for Biologically Inspired Engineering, Cambridge, MA 02138
- Kavli Institute, Harvard University, Cambridge, MA 02138
| | - Dennis M Kochmann
- Department of Mechanical and Process Engineering, ETH Zürich, 8092 Zürich, Switzerland;
- Graduate Aerospace Laboratories, California Institute of Technology, Pasadena, CA 91125
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47
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Abstract
We compared perceptual multistability across modalities, using a visual plaid pattern (composed of two transparently overlaid drifting gratings) and auditory streaming (elicited by a repeating “ABA_” tone sequence). Both stimuli can be perceived as integrated (one plaid pattern, one stream comprising “A” and “B” tones) or segregated (two individual gratings, two tone streams). In the segregated case, either stream or grating can be perceived in the foreground. We queried auditory and visual perception with these three response options. We found that perceptual dominance of the integrated states was correlated across modalities: Participants who were more likely to perceive the plaid were also more likely to perceive the integrated auditory stream. When presenting both stimuli simultaneously and querying the auditory percept, eye-movement data showed that perceiving auditory and visual integration is related on a moment-by-moment basis. This suggests that in part common mechanisms underlie multistability in visual and auditory perception.
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Affiliation(s)
- Wolfgang Einhäuser
- Physics of Cognition Group, Institute of Physics, Chemnitz University of Technology, Germany
| | - Lucas F O da Silva
- Physics of Cognition Group, Institute of Physics, Chemnitz University of Technology, Germany; Cognitive Systems Lab, Institute of Physics, Chemnitz University of Technology, Germany
| | - Alexandra Bendixen
- Cognitive Systems Lab, Institute of Physics, Chemnitz University of Technology, Germany
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Abstract
Behaviors are realized through concerted activity in neural circuits. This activity results from a combination of neural connectivity and the properties of the involved neurons. By studying the activity of neurons in the human subthalamic nucleus during surgery for Parkinson’s disease, we report that these neurons have multiple stable states, and that brief electrical stimuli can lead to transitions between states. We thus suggest that these neurons function as finite state machines. The different states could influence the function of key motor circuits of the basal ganglia, and thus knowledge of these states in disease or in response to treatment could help to define new treatment strategies for people with movement disorders. To understand the function and dysfunction of neural circuits, it is necessary to understand the properties of the neurons participating in the behavior, the connectivity between these neurons, and the neuromodulatory status of the circuits at the time they are producing the behavior. Such knowledge of human neural circuits is difficult, at best, to obtain. Here, we study firing properties of human subthalamic neurons, using microelectrode recordings and microstimulation during awake surgery for Parkinson’s disease. We demonstrate that low-amplitude, brief trains of microstimulation can lead to persistent changes in neuronal firing behavior including switching between firing rates, entering silent periods, or firing several bursts then entering a silent period. We suggest that these multistable states reflect properties of finite state machines and could have implications for the function of circuits involving the subthalamic nucleus. Furthermore, understanding these states could lead to therapeutic strategies aimed at regulating the transitions between states.
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49
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Suwanmajo T, Krishnan J. Exploring the intrinsic behaviour of multisite phosphorylation systems as part of signalling pathways. J R Soc Interface 2019; 15:rsif.2018.0109. [PMID: 29950514 DOI: 10.1098/rsif.2018.0109] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 05/31/2018] [Indexed: 01/13/2023] Open
Abstract
Multisite phosphorylation is a basic way of chemically encoding substrate function and a recurring feature of cell signalling pathways. A number of studies have explored information processing characteristics of multisite phosphorylation, through studies of the intrinsic kinetics. Many of these studies focus on the module in isolation. In this paper, we build a bridge to connect the behaviour of multisite modification in isolation to that as part of pathways. We study the effect of activation of the enzymes (which are basic ways in which the module may be regulated), as well the effects of the modified substrates being involved in further modifications or exiting reaction compartments. We find that these effects can induce multiple kinds of transitions, including to behaviour not seen intrinsically in the multisite modification module. We then build on these insights to investigate how these multisite modification systems can be tuned by enzyme activation to realize a range of information processing outcomes for the design of synthetic phosphorylation circuits. Connecting the complexity of multisite modification kinetics, with the pathways in which they are embedded, serves as a basis for teasing out many aspects of their interaction, providing insights of relevance in systems biology, synthetic biology/chemistry and chemical information processing.
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Affiliation(s)
- Thapanar Suwanmajo
- Department of Chemical Engineering, Centre for Process Systems Engineering, Imperial College London, London SW7 2AZ, UK.,Centre of Excellence in Materials Science and Technology, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand.,Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand
| | - J Krishnan
- Department of Chemical Engineering, Centre for Process Systems Engineering, Imperial College London, London SW7 2AZ, UK .,Institute for Systems and Synthetic Biology, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
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50
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Fasoli D, Panzeri S. Stationary-State Statistics of a Binary Neural Network Model with Quenched Disorder. Entropy (Basel) 2019; 21:e21070630. [PMID: 33267344 PMCID: PMC7515124 DOI: 10.3390/e21070630] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 06/17/2019] [Accepted: 06/23/2019] [Indexed: 06/12/2023]
Abstract
In this paper, we study the statistical properties of the stationary firing-rate states of a neural network model with quenched disorder. The model has arbitrary size, discrete-time evolution equations and binary firing rates, while the topology and the strength of the synaptic connections are randomly generated from known, generally arbitrary, probability distributions. We derived semi-analytical expressions of the occurrence probability of the stationary states and the mean multistability diagram of the model, in terms of the distribution of the synaptic connections and of the external stimuli to the network. Our calculations rely on the probability distribution of the bifurcation points of the stationary states with respect to the external stimuli, calculated in terms of the permanent of special matrices using extreme value theory. While our semi-analytical expressions are exact for any size of the network and for any distribution of the synaptic connections, we focus our study on networks made of several populations, that we term "statistically homogeneous" to indicate that the probability distribution of their connections depends only on the pre- and post-synaptic population indexes, and not on the individual synaptic pair indexes. In this specific case, we calculated analytically the permanent, obtaining a compact formula that outperforms of several orders of magnitude the Balasubramanian-Bax-Franklin-Glynn algorithm. To conclude, by applying the Fisher-Tippett-Gnedenko theorem, we derived asymptotic expressions of the stationary-state statistics of multi-population networks in the large-network-size limit, in terms of the Gumbel (double exponential) distribution. We also provide a Python implementation of our formulas and some examples of the results generated by the code.
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