Pub Date : 2024-07-25DOI: 10.1093/pnasnexus/pgae302
Dhruv Mittal, Sara M Constantino, Vítor V Vasconcelos
The world is grappling with emerging, urgent, large-scale problems such as climate change, pollution, biodiversity loss, and pandemics, which demand immediate and coordinated action. Social processes like conformity and social norms can either help maintain behaviors (e.g., cooperation in groups) or drive rapid societal change (e.g., rapid rooftop solar uptake), even without comprehensive policy measures. While the role of individual heterogeneity in such processes is well-studied, there is limited work on the expression of individuals' preferences and the role of anti-conformists—individuals who value acting differently from others—especially in dynamic environments. We introduce anti-conformists into a game-theoretical collective decision-making framework that includes a complex network of agents with heterogeneous preferences about two alternative options. We study how anti-conformists' presence changes the population's ability to express evolving personal preferences. We find that anti-conformists facilitate the expression of preferences, even when they diverge from prevailing norms, breaking the “spiral of silence” whereby individuals do not act on their preferences when they believe others disapprove. Centrally placed anti-conformists reduce by 5-fold the number of anti-conformists needed for a population to express its preferences. In dynamic environments where a previously unpopular choice becomes preferred, anti-conformists catalyze social tipping and reduce the ‘cultural lag,’ even beyond the role of committed minorities—that is, individuals with a commitment to a specific cause. This research highlights the role of dissenting voices in shaping collective behavior, including their potential to catalyze the adoption of new technologies as they become favorable and to enrich democracy by facilitating the expression of views.
{"title":"Anti-conformists catalyze societal transitions and facilitate the expression of evolving preferences","authors":"Dhruv Mittal, Sara M Constantino, Vítor V Vasconcelos","doi":"10.1093/pnasnexus/pgae302","DOIUrl":"https://doi.org/10.1093/pnasnexus/pgae302","url":null,"abstract":"The world is grappling with emerging, urgent, large-scale problems such as climate change, pollution, biodiversity loss, and pandemics, which demand immediate and coordinated action. Social processes like conformity and social norms can either help maintain behaviors (e.g., cooperation in groups) or drive rapid societal change (e.g., rapid rooftop solar uptake), even without comprehensive policy measures. While the role of individual heterogeneity in such processes is well-studied, there is limited work on the expression of individuals' preferences and the role of anti-conformists—individuals who value acting differently from others—especially in dynamic environments. We introduce anti-conformists into a game-theoretical collective decision-making framework that includes a complex network of agents with heterogeneous preferences about two alternative options. We study how anti-conformists' presence changes the population's ability to express evolving personal preferences. We find that anti-conformists facilitate the expression of preferences, even when they diverge from prevailing norms, breaking the “spiral of silence” whereby individuals do not act on their preferences when they believe others disapprove. Centrally placed anti-conformists reduce by 5-fold the number of anti-conformists needed for a population to express its preferences. In dynamic environments where a previously unpopular choice becomes preferred, anti-conformists catalyze social tipping and reduce the ‘cultural lag,’ even beyond the role of committed minorities—that is, individuals with a commitment to a specific cause. This research highlights the role of dissenting voices in shaping collective behavior, including their potential to catalyze the adoption of new technologies as they become favorable and to enrich democracy by facilitating the expression of views.","PeriodicalId":516525,"journal":{"name":"PNAS Nexus","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141785212","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-25DOI: 10.1093/pnasnexus/pgae300
Matteo Bottacchiari, Mirko Gallo, Marco Bussoletti, Carlo Massimo Casciola
Topological transitions of lipid membranes are ubiquitous in key biological processes for cell life, like neurotransmission, fertilization, morphogenesis, and viral infections. Despite this, they are not well understood due to their multiscale nature, which limits the use of molecular models and calls for a mesoscopic approach such as the celebrated Canham-Helfrich one. Unfortunately, such a model cannot handle topological transitions, hiding the crucial involved forces and the appearance of the experimentally observed hemifused intermediates. In this work, we describe the membrane as a diffuse interface preserving the Canham-Helfrich elasticity. We show that pivotal features of the hemifusion pathway are captured by this mesoscopic approach, e.g. a (meta)stable hemifusion state and the fusogenic behavior of negative monolayer spontaneous curvatures. The membrane lateral stress profile is calculated as a function of the elastic rigidities, yielding a coarse-grained version of molecular models findings. Insights into the fusogenic mechanism are reported and discussed.
{"title":"The diffuse interface description of fluid lipid membranes captures key features of the hemifusion pathway and lateral stress profile","authors":"Matteo Bottacchiari, Mirko Gallo, Marco Bussoletti, Carlo Massimo Casciola","doi":"10.1093/pnasnexus/pgae300","DOIUrl":"https://doi.org/10.1093/pnasnexus/pgae300","url":null,"abstract":"Topological transitions of lipid membranes are ubiquitous in key biological processes for cell life, like neurotransmission, fertilization, morphogenesis, and viral infections. Despite this, they are not well understood due to their multiscale nature, which limits the use of molecular models and calls for a mesoscopic approach such as the celebrated Canham-Helfrich one. Unfortunately, such a model cannot handle topological transitions, hiding the crucial involved forces and the appearance of the experimentally observed hemifused intermediates. In this work, we describe the membrane as a diffuse interface preserving the Canham-Helfrich elasticity. We show that pivotal features of the hemifusion pathway are captured by this mesoscopic approach, e.g. a (meta)stable hemifusion state and the fusogenic behavior of negative monolayer spontaneous curvatures. The membrane lateral stress profile is calculated as a function of the elastic rigidities, yielding a coarse-grained version of molecular models findings. Insights into the fusogenic mechanism are reported and discussed.","PeriodicalId":516525,"journal":{"name":"PNAS Nexus","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141774958","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-25DOI: 10.1093/pnasnexus/pgae298
Andrew N Black, Andrew J Mularo, Jong Yoon Jeon, David Haukos, Kristin J Bondo, Kent A Fricke, Andy Gregory, Blake Grisham, Zachary E Lowe, J Andrew DeWoody
Population genomics can reveal cryptic biological diversity that may impact fitness while simultaneously serving to delineate relevant conservation units. Here, we leverage the power of whole genome resequencing for conservation by studying 433 individual Lesser Prairie-Chicken (Tympanuchus pallidicinctus; LEPC, a federally endangered species of conservation concern in the United States) and Greater Prairie-Chicken (T. cupido; GRPC, a legally huntable species throughout much of its range). The genomic diversity of two formally recognized Distinct Population Segments (DPSs) of LEPCs is similar but they are genetically distinct. Neither DPS is depleted of its genomic diversity, neither is especially inbred, and temporal diversity is relatively stable in both conservation units. Interspecific differentiation between the two species was only slightly higher than that observed between LEPC DPSs, due largely to bidirectional introgression. The high resolution provided by our dataset identified a genomic continuum between the two species such that individuals sampled from the hybrid zone were imperfectly assigned to their presumptive species when considering only their physical characteristics. The admixture between the two species is reflected in the spectrum of individual ancestry coefficients, which has legal implications for the “take” of individuals under the Endangered Species Act (ESA). Overall, our data highlight the recurring dissonance between static policies and dynamic species boundaries that are increasingly obvious in the population genomic era.
{"title":"Discordance between taxonomy and population genomic data: An avian example relevant to the United States Endangered Species Act","authors":"Andrew N Black, Andrew J Mularo, Jong Yoon Jeon, David Haukos, Kristin J Bondo, Kent A Fricke, Andy Gregory, Blake Grisham, Zachary E Lowe, J Andrew DeWoody","doi":"10.1093/pnasnexus/pgae298","DOIUrl":"https://doi.org/10.1093/pnasnexus/pgae298","url":null,"abstract":"Population genomics can reveal cryptic biological diversity that may impact fitness while simultaneously serving to delineate relevant conservation units. Here, we leverage the power of whole genome resequencing for conservation by studying 433 individual Lesser Prairie-Chicken (Tympanuchus pallidicinctus; LEPC, a federally endangered species of conservation concern in the United States) and Greater Prairie-Chicken (T. cupido; GRPC, a legally huntable species throughout much of its range). The genomic diversity of two formally recognized Distinct Population Segments (DPSs) of LEPCs is similar but they are genetically distinct. Neither DPS is depleted of its genomic diversity, neither is especially inbred, and temporal diversity is relatively stable in both conservation units. Interspecific differentiation between the two species was only slightly higher than that observed between LEPC DPSs, due largely to bidirectional introgression. The high resolution provided by our dataset identified a genomic continuum between the two species such that individuals sampled from the hybrid zone were imperfectly assigned to their presumptive species when considering only their physical characteristics. The admixture between the two species is reflected in the spectrum of individual ancestry coefficients, which has legal implications for the “take” of individuals under the Endangered Species Act (ESA). Overall, our data highlight the recurring dissonance between static policies and dynamic species boundaries that are increasingly obvious in the population genomic era.","PeriodicalId":516525,"journal":{"name":"PNAS Nexus","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141785213","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-22DOI: 10.1093/pnasnexus/pgae285
Mayar Allam, Thomas Hu, Zhou Fang, Michelle Pi, Ankur Singh, Ahmet F Coskun
Secondary lymphoid organs (SLOs), including tonsils, lymph nodes, and Peyer’s Patches, exhibit complementary immune functions. However, little is known about the spatial organization of immune cells and extracellular matrix (ECM) in the SLOs. Traditional imaging is limited to a few markers, confining our understanding of the differences between the SLOs. Herein, Imaging mass cytometry (IMC) addressed this gap by simultaneously profiling 25-plex proteins in SLO tissues at subcellular resolution. The antibody panel targeted immune, stromal, chemokine, epigenetic, and functional markers. For robust cell identification, a computational workflow SpatialVizPheno was developed to spatially phenotype 999,970 cells using two approaches, including manual gating and semi-supervised gating, iterative clustering, and annotation. Lymph nodes exhibited the highest density of B cells while the intestinal tissues contained the highest proportion of regulatory and follicular helper T cells. SpatialVizPheno identified the most prevalent interaction between follicular dendritic cells and stromal cells, plasmablasts/plasma cells, and the stromal cells across the lymphoid tissues. Collagen-enriched regions were associated with the spatial orientation of B cell follicles in both tonsil and lymph node tissues, but not in intestinal lymphoid tissues. Such spatial differences of immunophenotypes and ECM in different SLO tissues can be used to quantify the relationship between cellular organization and ultimate immune responses.
继发性淋巴器官（SLO）包括扁桃体、淋巴结和佩耶氏斑块，具有互补的免疫功能。然而，人们对 SLO 中免疫细胞和细胞外基质（ECM）的空间组织知之甚少。传统的成像仅限于少数标记物，限制了我们对 SLO 之间差异的了解。在这里，成像质控细胞仪（IMC）通过以亚细胞分辨率同时分析 SLO 组织中的 25 种复合物蛋白质，弥补了这一不足。抗体组针对免疫、基质、趋化因子、表观遗传和功能标记物。为了进行可靠的细胞鉴定，我们开发了一种计算工作流程 SpatialVizPheno，使用两种方法对 999,970 个细胞进行空间表型，包括手动选取和半监督选取、迭代聚类和注释。淋巴结中 B 细胞的密度最高，而肠道组织中调节性和滤泡辅助性 T 细胞的比例最高。SpatialVizPheno 确定了淋巴组织中滤泡树突状细胞与基质细胞、浆细胞/浆细胞和基质细胞之间最普遍的相互作用。在扁桃体和淋巴结组织中，胶原富集区与 B 细胞滤泡的空间定向有关，但在肠道淋巴组织中则没有。不同 SLO 组织中免疫表型和 ECM 的这种空间差异可用于量化细胞组织与最终免疫反应之间的关系。
{"title":"Spatial immunophenotyping using multiplexed imaging of immune follicles in secondary lymphoid tissues","authors":"Mayar Allam, Thomas Hu, Zhou Fang, Michelle Pi, Ankur Singh, Ahmet F Coskun","doi":"10.1093/pnasnexus/pgae285","DOIUrl":"https://doi.org/10.1093/pnasnexus/pgae285","url":null,"abstract":"Secondary lymphoid organs (SLOs), including tonsils, lymph nodes, and Peyer’s Patches, exhibit complementary immune functions. However, little is known about the spatial organization of immune cells and extracellular matrix (ECM) in the SLOs. Traditional imaging is limited to a few markers, confining our understanding of the differences between the SLOs. Herein, Imaging mass cytometry (IMC) addressed this gap by simultaneously profiling 25-plex proteins in SLO tissues at subcellular resolution. The antibody panel targeted immune, stromal, chemokine, epigenetic, and functional markers. For robust cell identification, a computational workflow SpatialVizPheno was developed to spatially phenotype 999,970 cells using two approaches, including manual gating and semi-supervised gating, iterative clustering, and annotation. Lymph nodes exhibited the highest density of B cells while the intestinal tissues contained the highest proportion of regulatory and follicular helper T cells. SpatialVizPheno identified the most prevalent interaction between follicular dendritic cells and stromal cells, plasmablasts/plasma cells, and the stromal cells across the lymphoid tissues. Collagen-enriched regions were associated with the spatial orientation of B cell follicles in both tonsil and lymph node tissues, but not in intestinal lymphoid tissues. Such spatial differences of immunophenotypes and ECM in different SLO tissues can be used to quantify the relationship between cellular organization and ultimate immune responses.","PeriodicalId":516525,"journal":{"name":"PNAS Nexus","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141774959","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-19DOI: 10.1093/pnasnexus/pgae281
Yuan-Chi Chien, C Alexander Valencia, Han Yong Lee, Gyeong Mee Yoon, Dongwook Kim
Elucidating kinase-substrate relationships is pivotal for deciphering cellular signaling mechanisms, yet it remains challenging due to the complexity of kinase networks. Herein, we report the development of a versatile DNA-based kinase assay platform for high-throughput profiling of plant protein kinase activities and substrate preferences. Our approach employs DNA-linked peptide substrates, facilitating quantitative and specific kinase activity detection through next-generation DNA sequencing. Leveraging DNA barcodes as quantitative readouts, our approach establishes a high-throughput, sensitive, and specific platform for dissecting kinase-substrate networks in plants, representing a powerful tool for elucidating signaling mechanisms in plants.
阐明激酶与底物之间的关系对于破译细胞信号传导机制至关重要，但由于激酶网络的复杂性，这项工作仍具有挑战性。在此，我们报告了基于 DNA 的多功能激酶检测平台的开发情况，该平台可用于高通量植物蛋白激酶活性和底物偏好分析。我们的方法采用与 DNA 链接的多肽底物，通过下一代 DNA 测序促进定量和特异性激酶活性检测。利用 DNA 条形码作为定量读数，我们的方法建立了一个高通量、灵敏和特异的平台，用于剖析植物激酶-底物网络，是阐明植物信号转导机制的有力工具。
{"title":"DNA-Encoded probe-based assay for profiling plant kinase activities","authors":"Yuan-Chi Chien, C Alexander Valencia, Han Yong Lee, Gyeong Mee Yoon, Dongwook Kim","doi":"10.1093/pnasnexus/pgae281","DOIUrl":"https://doi.org/10.1093/pnasnexus/pgae281","url":null,"abstract":"Elucidating kinase-substrate relationships is pivotal for deciphering cellular signaling mechanisms, yet it remains challenging due to the complexity of kinase networks. Herein, we report the development of a versatile DNA-based kinase assay platform for high-throughput profiling of plant protein kinase activities and substrate preferences. Our approach employs DNA-linked peptide substrates, facilitating quantitative and specific kinase activity detection through next-generation DNA sequencing. Leveraging DNA barcodes as quantitative readouts, our approach establishes a high-throughput, sensitive, and specific platform for dissecting kinase-substrate networks in plants, representing a powerful tool for elucidating signaling mechanisms in plants.","PeriodicalId":516525,"journal":{"name":"PNAS Nexus","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141744985","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-16DOI: 10.1093/pnasnexus/pgae279
Skylar M L Bodt, Jinghua Ge, Wen Ma, David V Rasicci, Rohini Desetty, J Andrew McCammon, Christopher M Yengo
Inherited mutations in human beta-cardiac myosin (M2β) can lead to severe forms of heart failure. The E525K mutation in M2β is associated with dilated cardiomyopathy (DCM) and was found to stabilize the interacting heads motif (IHM) and autoinhibited super-relaxed (SRX) state in dimeric heavy meromyosin. However, in monomeric M2β subfragment 1 (S1) we found that E525K enhances (3-fold) the maximum steady-state actin-activated ATPase activity (kcat) and decreases (6-fold) the actin concentration at which ATPase is one-half maximal (KATPase). We also found a 3 to 4-fold increase in the actin-activated power stroke and phosphate release rate constants at 30 μM actin, which overall enhanced the duty ratio 3-fold. Loaded motility assays revealed that the enhanced intrinsic motor activity translates to increased ensemble force in M2β S1. Glutamate 525, located near the actin binding region in the so-called activation loop, is highly conserved and predicted to form a salt-bridge with another conserved residue (lysine 484) in the relay helix. Enhanced sampling molecular dynamics simulations predict that the charge reversal mutation disrupts the E525-K484 salt-bridge, inducing conformations with a more flexible relay helix and a wide phosphate release tunnel. Our results highlight a highly conserved allosteric pathway associated with actin activation of the power stroke and phosphate release and suggest an important feature of the autoinhibited IHM is to prevent this region of myosin from interacting with actin. The ability of the E525K mutation to stabilize the IHM likely overrides the enhanced intrinsic motor properties, which may be key to triggering DCM pathogenesis.
{"title":"Dilated cardiomyopathy mutation in beta-cardiac myosin enhances actin activation of the power stroke and phosphate release","authors":"Skylar M L Bodt, Jinghua Ge, Wen Ma, David V Rasicci, Rohini Desetty, J Andrew McCammon, Christopher M Yengo","doi":"10.1093/pnasnexus/pgae279","DOIUrl":"https://doi.org/10.1093/pnasnexus/pgae279","url":null,"abstract":"Inherited mutations in human beta-cardiac myosin (M2β) can lead to severe forms of heart failure. The E525K mutation in M2β is associated with dilated cardiomyopathy (DCM) and was found to stabilize the interacting heads motif (IHM) and autoinhibited super-relaxed (SRX) state in dimeric heavy meromyosin. However, in monomeric M2β subfragment 1 (S1) we found that E525K enhances (3-fold) the maximum steady-state actin-activated ATPase activity (kcat) and decreases (6-fold) the actin concentration at which ATPase is one-half maximal (KATPase). We also found a 3 to 4-fold increase in the actin-activated power stroke and phosphate release rate constants at 30 μM actin, which overall enhanced the duty ratio 3-fold. Loaded motility assays revealed that the enhanced intrinsic motor activity translates to increased ensemble force in M2β S1. Glutamate 525, located near the actin binding region in the so-called activation loop, is highly conserved and predicted to form a salt-bridge with another conserved residue (lysine 484) in the relay helix. Enhanced sampling molecular dynamics simulations predict that the charge reversal mutation disrupts the E525-K484 salt-bridge, inducing conformations with a more flexible relay helix and a wide phosphate release tunnel. Our results highlight a highly conserved allosteric pathway associated with actin activation of the power stroke and phosphate release and suggest an important feature of the autoinhibited IHM is to prevent this region of myosin from interacting with actin. The ability of the E525K mutation to stabilize the IHM likely overrides the enhanced intrinsic motor properties, which may be key to triggering DCM pathogenesis.","PeriodicalId":516525,"journal":{"name":"PNAS Nexus","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141718107","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-13DOI: 10.1093/pnasnexus/pgae276
Emma Fraxanet, Max Pellert, Simon Schweighofer, Vicenç Gómez, David Garcia
Political conflict is an essential element of democratic systems, but can also threaten their existence if it becomes too intense. This happens particularly when most political issues become aligned along the same major fault line, splitting society into two antagonistic camps. In the 20th century, major fault lines were formed by structural conflicts, like owners vs workers, center vs periphery, etc. But these classical cleavages have since lost their explanatory power. Instead of theorizing new cleavages, we present the FAULTANA (FAULT-line Alignment Network Analysis) pipeline, a computational method to uncover major fault lines in data of signed online interactions. Our method makes it possible to quantify the degree of antagonism prevalent in different online debates, as well as how aligned each debate is to the major fault line. This makes it possible to identify the wedge issues driving polarization, characterized by both intense antagonism and alignment. We apply our approach to large-scale data sets of Birdwatch, a US-based Twitter factchecking community and the discussion forums of DerStandard, an Austrian online newspaper. We find that both online communities are divided into two large groups and that their separation follows political identities and topics. In addition, for DerStandard, we pinpoint issues that reinforce societal fault lines and thus drive polarization. We also identify issues that trigger online conflict without strictly aligning with those dividing lines (e.g. COVID-19). Our methods allow us to construct a time-resolved picture of affective polarization that shows the separate contributions of cohesiveness and divisiveness to the dynamics of alignment during contentious elections and events.
{"title":"Unpacking polarization: Antagonism and alignment in signed networks of online interaction","authors":"Emma Fraxanet, Max Pellert, Simon Schweighofer, Vicenç Gómez, David Garcia","doi":"10.1093/pnasnexus/pgae276","DOIUrl":"https://doi.org/10.1093/pnasnexus/pgae276","url":null,"abstract":"Political conflict is an essential element of democratic systems, but can also threaten their existence if it becomes too intense. This happens particularly when most political issues become aligned along the same major fault line, splitting society into two antagonistic camps. In the 20th century, major fault lines were formed by structural conflicts, like owners vs workers, center vs periphery, etc. But these classical cleavages have since lost their explanatory power. Instead of theorizing new cleavages, we present the FAULTANA (FAULT-line Alignment Network Analysis) pipeline, a computational method to uncover major fault lines in data of signed online interactions. Our method makes it possible to quantify the degree of antagonism prevalent in different online debates, as well as how aligned each debate is to the major fault line. This makes it possible to identify the wedge issues driving polarization, characterized by both intense antagonism and alignment. We apply our approach to large-scale data sets of Birdwatch, a US-based Twitter factchecking community and the discussion forums of DerStandard, an Austrian online newspaper. We find that both online communities are divided into two large groups and that their separation follows political identities and topics. In addition, for DerStandard, we pinpoint issues that reinforce societal fault lines and thus drive polarization. We also identify issues that trigger online conflict without strictly aligning with those dividing lines (e.g. COVID-19). Our methods allow us to construct a time-resolved picture of affective polarization that shows the separate contributions of cohesiveness and divisiveness to the dynamics of alignment during contentious elections and events.","PeriodicalId":516525,"journal":{"name":"PNAS Nexus","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141612471","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-12DOI: 10.1093/pnasnexus/pgae256
Valeria Hernández-Hernández, Olivier C Marchand, Annamaria Kiss, Arezki Boudaoud
Plant cell growth depends on turgor pressure, the cell hydrodynamic pressure, which drives expansion of the extracellular matrix (the cell wall). Turgor pressure regulation depends on several physical, chemical and biological factors, including: vacuolar invertases, which modulate osmotic pressure of the cell, aquaporins, which determine the permeability of the plasma membrane to water, cell wall remodeling factors, which determine cell wall extensibility (inverse of effective viscosity), and plasmodesmata, which are membrane-lined channels that allow free movement of water and solutes between cytoplasms of neighbouring cells, like gap junctions in animals. Plasmodesmata permeability varies during plant development and experimental studies have correlated changes in the permeability of plasmodesmal channels to turgor pressure variations. Here we study the role of plasmodesmal permeability in cotton fiber growth, a type of cell that increases in length by at least 3 orders of magnitude in a few weeks. We incorporated plasmodesma-dependent movement of water and solutes into a classical model of plant cell expansion. We performed a sensitivity analysis to changes in values of model parameters and found that plasmodesmal permeability is among the most important factors for building up turgor pressure and expanding cotton fibers. Moreover, we found that non-monotonic behaviors of turgor pressure that have been reported previously in cotton fibers cannot be recovered without accounting for dynamic changes of the parameters used in the model. Altogether, our results suggest an important role for plasmodesmal permeability in the regulation of turgor pressure.
{"title":"A mechanohydraulic model supports a role for plasmodesmata in cotton fiber elongation","authors":"Valeria Hernández-Hernández, Olivier C Marchand, Annamaria Kiss, Arezki Boudaoud","doi":"10.1093/pnasnexus/pgae256","DOIUrl":"https://doi.org/10.1093/pnasnexus/pgae256","url":null,"abstract":"Plant cell growth depends on turgor pressure, the cell hydrodynamic pressure, which drives expansion of the extracellular matrix (the cell wall). Turgor pressure regulation depends on several physical, chemical and biological factors, including: vacuolar invertases, which modulate osmotic pressure of the cell, aquaporins, which determine the permeability of the plasma membrane to water, cell wall remodeling factors, which determine cell wall extensibility (inverse of effective viscosity), and plasmodesmata, which are membrane-lined channels that allow free movement of water and solutes between cytoplasms of neighbouring cells, like gap junctions in animals. Plasmodesmata permeability varies during plant development and experimental studies have correlated changes in the permeability of plasmodesmal channels to turgor pressure variations. Here we study the role of plasmodesmal permeability in cotton fiber growth, a type of cell that increases in length by at least 3 orders of magnitude in a few weeks. We incorporated plasmodesma-dependent movement of water and solutes into a classical model of plant cell expansion. We performed a sensitivity analysis to changes in values of model parameters and found that plasmodesmal permeability is among the most important factors for building up turgor pressure and expanding cotton fibers. Moreover, we found that non-monotonic behaviors of turgor pressure that have been reported previously in cotton fibers cannot be recovered without accounting for dynamic changes of the parameters used in the model. Altogether, our results suggest an important role for plasmodesmal permeability in the regulation of turgor pressure.","PeriodicalId":516525,"journal":{"name":"PNAS Nexus","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141612473","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-12DOI: 10.1093/pnasnexus/pgae280
Kazuhiro Horii, Bakushi Ogawa, Noriko Nagase, Iori Morimoto, Chikara Abe, Takenori Ogawa, Samuel Choi, Fumiaki Nin
Ultrasound, or sound at frequencies exceeding the conventional range of human hearing, is not only audible to mice, microbats, and dolphins, but also creates an auditory sensation when delivered through bone conduction in humans. Although ultrasound is utilized for brain activation and in hearing aids, the physiological mechanism of ultrasonic hearing remains unknown. In guinea pigs, we found that ultrasound above the hearing range delivered through ossicles of the middle ear evokes an auditory brainstem response and a mechano-electrical transduction current through hair cells, as shown by the local field potential called the cochlear microphonic potential (CM). The CM synchronizes with ultrasound, and like the response to audible sounds is actively and nonlinearly amplified. In vivo optical nano-vibration analysis revealed that the sensory epithelium in the hook region, the basal extreme of the cochlear turns, resonates in response both to ultrasound within the hearing range and to harmonics beyond the hearing range. The results indicate that hair cells can respond to stimulation at the optimal frequency and its harmonics, and the hook region detects ultrasound stimuli with frequencies more than two octaves higher than the upper limit of the ordinary hearing range.
{"title":"The cochlear hook region detects harmonics beyond the canonical hearing range","authors":"Kazuhiro Horii, Bakushi Ogawa, Noriko Nagase, Iori Morimoto, Chikara Abe, Takenori Ogawa, Samuel Choi, Fumiaki Nin","doi":"10.1093/pnasnexus/pgae280","DOIUrl":"https://doi.org/10.1093/pnasnexus/pgae280","url":null,"abstract":"Ultrasound, or sound at frequencies exceeding the conventional range of human hearing, is not only audible to mice, microbats, and dolphins, but also creates an auditory sensation when delivered through bone conduction in humans. Although ultrasound is utilized for brain activation and in hearing aids, the physiological mechanism of ultrasonic hearing remains unknown. In guinea pigs, we found that ultrasound above the hearing range delivered through ossicles of the middle ear evokes an auditory brainstem response and a mechano-electrical transduction current through hair cells, as shown by the local field potential called the cochlear microphonic potential (CM). The CM synchronizes with ultrasound, and like the response to audible sounds is actively and nonlinearly amplified. In vivo optical nano-vibration analysis revealed that the sensory epithelium in the hook region, the basal extreme of the cochlear turns, resonates in response both to ultrasound within the hearing range and to harmonics beyond the hearing range. The results indicate that hair cells can respond to stimulation at the optimal frequency and its harmonics, and the hook region detects ultrasound stimuli with frequencies more than two octaves higher than the upper limit of the ordinary hearing range.","PeriodicalId":516525,"journal":{"name":"PNAS Nexus","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141612474","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-10DOI: 10.1093/pnasnexus/pgae274
Mark Z Jacobson, Daniel J Sambor, Yuanbei F Fan, Andreas Mühlbauer
Refractory bricks are bricks that can withstand high temperatures without damage to their structures. They have been used to insulate kilns, furnaces, and other hot enclosures for thousands of years. Firebricks are refractory bricks that can, with one composition, store heat, and with another, insulate the firebricks that store the heat. Because firebricks are made from common materials, the cost per kilowatt-hour-thermal of a firebrick storage system is less than one-tenth the cost per kilowatt-hour-electricity of a battery system. It has thus been hypothesized that using excess renewable electricity to produce and store industrial process heat in firebricks can provide a low-cost source of continuous heat for industry. Here it is hypothesized further that, upon a transition to 100% clean, renewable energy worldwide, using firebricks to store industrial process heat can reduce electricity-generator, electricity storage, and low-temperature heat storage needs, thereby reducing overall energy cost. Both hypotheses are tested across 149 countries combined into 29 world regions. Results suggest, relative to a base case with no firebricks, using firebricks may reduce, among all 149 countries, 2050 battery capacity by ∼14.5%, annual hydrogen production for grid electricity by ∼31%, underground low-temperature heat storage capacity by ∼27.3%; onshore wind nameplate capacity by ∼1.2%, land needs by ∼0.4%, and overall annual energy cost by ∼1.8%. In sum, the use of firebricks for storing industrial process heat appears to be a remarkable tool in reducing the cost of transitioning to clean, renewable energy across all energy sectors.
{"title":"Effects of firebricks for industrial process heat on the cost of matching all-sector energy demand with 100% wind-water-solar supply in 149 countries","authors":"Mark Z Jacobson, Daniel J Sambor, Yuanbei F Fan, Andreas Mühlbauer","doi":"10.1093/pnasnexus/pgae274","DOIUrl":"https://doi.org/10.1093/pnasnexus/pgae274","url":null,"abstract":"Refractory bricks are bricks that can withstand high temperatures without damage to their structures. They have been used to insulate kilns, furnaces, and other hot enclosures for thousands of years. Firebricks are refractory bricks that can, with one composition, store heat, and with another, insulate the firebricks that store the heat. Because firebricks are made from common materials, the cost per kilowatt-hour-thermal of a firebrick storage system is less than one-tenth the cost per kilowatt-hour-electricity of a battery system. It has thus been hypothesized that using excess renewable electricity to produce and store industrial process heat in firebricks can provide a low-cost source of continuous heat for industry. Here it is hypothesized further that, upon a transition to 100% clean, renewable energy worldwide, using firebricks to store industrial process heat can reduce electricity-generator, electricity storage, and low-temperature heat storage needs, thereby reducing overall energy cost. Both hypotheses are tested across 149 countries combined into 29 world regions. Results suggest, relative to a base case with no firebricks, using firebricks may reduce, among all 149 countries, 2050 battery capacity by ∼14.5%, annual hydrogen production for grid electricity by ∼31%, underground low-temperature heat storage capacity by ∼27.3%; onshore wind nameplate capacity by ∼1.2%, land needs by ∼0.4%, and overall annual energy cost by ∼1.8%. In sum, the use of firebricks for storing industrial process heat appears to be a remarkable tool in reducing the cost of transitioning to clean, renewable energy across all energy sectors.","PeriodicalId":516525,"journal":{"name":"PNAS Nexus","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141587574","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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