Project acronym COGTOM
Project Cognitive tomography of mental representations
Researcher (PI) Mate Miklos LENGYEL
Host Institution (HI) KOZEP-EUROPAI EGYETEM
Country Hungary
Call Details Consolidator Grant (CoG), SH4, ERC-2016-COG
Summary Internal models are fundamental to our understanding of how the mind constructs percepts, makes decisions, controls movements, and interacts with others. Yet, we lack principled quantitative methods to systematically estimate internal models from observable behaviour, and current approaches for discovering their mental representations remain heuristic and piecemeal. I propose to develop a set of novel 'doubly Bayesian' data analytical methods, using state-of-the-art Bayesian statistical and machine learning techniques to infer humans' internal models formalised as prior distributions in Bayesian models of cognition. This approach, cognitive tomography, takes a series of behavioural observations, each of which in itself may have very limited information content, and accumulates a detailed reconstruction of the internal model based on these observations. I also propose a set of stringent, quantifiable criteria which will be systematically applied at each step of the proposed work to rigorously assess the success of our approach. These methodological advances will allow us to track how the structured, task-general internal models that are so fundamental to humans' superior cognitive abilities, change over time as a result of decay, interference, and learning. We will apply cognitive tomography to a variety of experimental data sets, collected by our collaborators, in paradigms ranging from perceptual learning, through visual and motor structure learning, to social and concept learning. These analyses will allow us to conclusively and quantitatively test our central hypothesis that, rather than simply changing along a single 'memory strength' dimension, internal models typically change via complex and consistent patterns of transformations along multiple dimensions simultaneously. To facilitate the widespread use of our methods, we will release and support off-the-shelf usable implementations of our algorithms together with synthetic and real test data sets.
Summary
Internal models are fundamental to our understanding of how the mind constructs percepts, makes decisions, controls movements, and interacts with others. Yet, we lack principled quantitative methods to systematically estimate internal models from observable behaviour, and current approaches for discovering their mental representations remain heuristic and piecemeal. I propose to develop a set of novel 'doubly Bayesian' data analytical methods, using state-of-the-art Bayesian statistical and machine learning techniques to infer humans' internal models formalised as prior distributions in Bayesian models of cognition. This approach, cognitive tomography, takes a series of behavioural observations, each of which in itself may have very limited information content, and accumulates a detailed reconstruction of the internal model based on these observations. I also propose a set of stringent, quantifiable criteria which will be systematically applied at each step of the proposed work to rigorously assess the success of our approach. These methodological advances will allow us to track how the structured, task-general internal models that are so fundamental to humans' superior cognitive abilities, change over time as a result of decay, interference, and learning. We will apply cognitive tomography to a variety of experimental data sets, collected by our collaborators, in paradigms ranging from perceptual learning, through visual and motor structure learning, to social and concept learning. These analyses will allow us to conclusively and quantitatively test our central hypothesis that, rather than simply changing along a single 'memory strength' dimension, internal models typically change via complex and consistent patterns of transformations along multiple dimensions simultaneously. To facilitate the widespread use of our methods, we will release and support off-the-shelf usable implementations of our algorithms together with synthetic and real test data sets.
Max ERC Funding
1 179 462 €
Duration
Start date: 2017-05-01, End date: 2022-04-30
Project acronym DeCode
Project Dendrites and memory: role of dendritic spikes in information coding by hippocampal CA3 pyramidal neurons
Researcher (PI) Judit MAKARA
Host Institution (HI) KIRSERLETI ORVOSTUDOMANYI KUTATOINTEZET
Country Hungary
Call Details Consolidator Grant (CoG), LS5, ERC-2017-COG
Summary The hippocampus is essential for building episodic memories. Coding of locations, contexts or events in the hippocampus is based on the correlated activity of neuronal ensembles; however, the mechanisms promoting the recruitment of individual neurons into information-coding ensembles are poorly understood.
In particular, the recurrent synaptic network of pyramidal cells (PCs) in the hippocampal CA3 area, receiving external inputs from the entorhinal cortex and the dentate gyrus, is thought to be essential for associative memory. Current models of the associative functions of CA3 are mainly based on plasticity of these synaptic connections. Recent work by us and others however suggests that active, voltage-dependent properties of CA3PC dendrites may also promote ensemble functions. Dendritic voltage-dependent ion channels allow nonlinear amplification of spatiotemporally correlated synaptic inputs (such as those produced by ensemble activity) and can even generate local dendritic spikes, which may elicit specific action potential patterns and induce synaptic plasticity. Furthermore, dendritic processing may be modulated by activity-dependent regulation of dendritic ion channels. However, still little is known about the active properties of CA3PC dendrites and their functions during spatial coding or memory tasks.
The general aim of my research program is to understand the cellular mechanisms that underlie the formation of hippocampal memory-coding neuronal ensembles. Specifically, we will test the hypothesis that active input integration by dendrites of individual CA3PCs plays an important role in their recruitment into specific context-coding ensembles. By combining in vitro (patch-clamp electrophysiology and two-photon (2P) microscopy in slices) and in vivo (2P imaging and activity-dependent labelling in behaving rodents) approaches, we will provide an in-depth understanding of the dendritic components contributing to the generation of the CA3 ensemble code.
Summary
The hippocampus is essential for building episodic memories. Coding of locations, contexts or events in the hippocampus is based on the correlated activity of neuronal ensembles; however, the mechanisms promoting the recruitment of individual neurons into information-coding ensembles are poorly understood.
In particular, the recurrent synaptic network of pyramidal cells (PCs) in the hippocampal CA3 area, receiving external inputs from the entorhinal cortex and the dentate gyrus, is thought to be essential for associative memory. Current models of the associative functions of CA3 are mainly based on plasticity of these synaptic connections. Recent work by us and others however suggests that active, voltage-dependent properties of CA3PC dendrites may also promote ensemble functions. Dendritic voltage-dependent ion channels allow nonlinear amplification of spatiotemporally correlated synaptic inputs (such as those produced by ensemble activity) and can even generate local dendritic spikes, which may elicit specific action potential patterns and induce synaptic plasticity. Furthermore, dendritic processing may be modulated by activity-dependent regulation of dendritic ion channels. However, still little is known about the active properties of CA3PC dendrites and their functions during spatial coding or memory tasks.
The general aim of my research program is to understand the cellular mechanisms that underlie the formation of hippocampal memory-coding neuronal ensembles. Specifically, we will test the hypothesis that active input integration by dendrites of individual CA3PCs plays an important role in their recruitment into specific context-coding ensembles. By combining in vitro (patch-clamp electrophysiology and two-photon (2P) microscopy in slices) and in vivo (2P imaging and activity-dependent labelling in behaving rodents) approaches, we will provide an in-depth understanding of the dendritic components contributing to the generation of the CA3 ensemble code.
Max ERC Funding
1 990 314 €
Duration
Start date: 2018-06-01, End date: 2023-05-31
Project acronym InvGroGra
Project Asymptotic invariants of discrete groups, sparse graphs and locally symmetric spaces
Researcher (PI) Miklos Abert
Host Institution (HI) RENYI ALFRED MATEMATIKAI KUTATOINTEZET
Country Hungary
Call Details Consolidator Grant (CoG), PE1, ERC-2014-CoG
Summary The PI proposes to study the asymptotic behavior of various invariants of discrete groups and their actions, of sparse graphs and of locally symmetric spaces. The game is to connect the asymptotic behavior of an invariant on a sequence of finite models to an analytic invariant on a suitable limit object of the sequence and then use the connection to get new results in both the finite and infinite worlds. The recently emerging notion of invariant random subgroups, initiated by the PI, serves as a unifying language for convergence.
These invariants include the minimal number of generators, deficiency, Betti numbers over arbitrary fields, various spectral and representation theoretic invariants, graph polynomials and entropy. The limit objects arising are invariant processes on groups, profinite actions, graphings, invariant random subgroups and measured complexes. The analytic invariants include L2 Betti numbers, spectral and Plancherel measures, cost and its higher order versions, matching and chromatic measures and entropy per site.
Energy typically flows both ways between the finite and infinite world and also between the different invariants. We list five recent applications from the PI that emerged from such connections. 1) Any large volume locally symmetric semisimple space has large injectivity radius at most of its points; 2) The rank gradient of a chain equals the cost-1 of the profinite action of the chain; 3) Countable-to-one cellular automata over a sofic group preserve the Lebesque measure; 4) Ramanujan graphs have essentially large girth; 5) The matching measure is continuous for graph convergence, giving new estimates on monomer-dimer free energies.
Besides asymptotic group theory and graph theory, the tools of the proposed research come from probability theory, ergodic theory and statistical mechanics. The proposed research will lead to further applications in 3-manifold theory, geometry and ergodic theory.
Summary
The PI proposes to study the asymptotic behavior of various invariants of discrete groups and their actions, of sparse graphs and of locally symmetric spaces. The game is to connect the asymptotic behavior of an invariant on a sequence of finite models to an analytic invariant on a suitable limit object of the sequence and then use the connection to get new results in both the finite and infinite worlds. The recently emerging notion of invariant random subgroups, initiated by the PI, serves as a unifying language for convergence.
These invariants include the minimal number of generators, deficiency, Betti numbers over arbitrary fields, various spectral and representation theoretic invariants, graph polynomials and entropy. The limit objects arising are invariant processes on groups, profinite actions, graphings, invariant random subgroups and measured complexes. The analytic invariants include L2 Betti numbers, spectral and Plancherel measures, cost and its higher order versions, matching and chromatic measures and entropy per site.
Energy typically flows both ways between the finite and infinite world and also between the different invariants. We list five recent applications from the PI that emerged from such connections. 1) Any large volume locally symmetric semisimple space has large injectivity radius at most of its points; 2) The rank gradient of a chain equals the cost-1 of the profinite action of the chain; 3) Countable-to-one cellular automata over a sofic group preserve the Lebesque measure; 4) Ramanujan graphs have essentially large girth; 5) The matching measure is continuous for graph convergence, giving new estimates on monomer-dimer free energies.
Besides asymptotic group theory and graph theory, the tools of the proposed research come from probability theory, ergodic theory and statistical mechanics. The proposed research will lead to further applications in 3-manifold theory, geometry and ergodic theory.
Max ERC Funding
1 386 250 €
Duration
Start date: 2015-07-01, End date: 2021-06-30
Project acronym JAXPERTISE
Project Joint action expertise: Behavioral, cognitive, and neural mechanisms for joint action learning
Researcher (PI) Natalie Sebanz
Host Institution (HI) KOZEP-EUROPAI EGYETEM
Country Hungary
Call Details Consolidator Grant (CoG), SH4, ERC-2013-CoG
Summary Human life is full of joint action and our achievements are, to a large extent, joint achievements that require the coordination of two or more individuals. Piano duets and tangos, but also complex technical and medical operations rely on and exist because of coordinated actions. In recent years, research has begun to identify the basic mechanisms of joint action. This work focused on simple tasks that can be performed together without practice. However, a striking aspect of human joint action is the expertise interaction partners acquire together. How people acquire joint expertise is still poorly understood. JAXPERTISE will break new ground by identifying the behavioural, cognitive, and neural mechanisms underlying the learning of joint action. Participating in joint activities is also a motor for individual development. Although this has long been recognized, the mechanisms underlying individual learning through engagement in joint activities remain to be spelled out from a cognitive science perspective. JAXPERTISE will make this crucial step by investigating how joint action affects source memory, semantic memory, and individual skill learning. Carefully designed experiments will optimize the balance between capturing relevant interpersonal phenomena and maximizing experimental control. The proposed studies employ behavioural measures, electroencephalography, and physiological measures. Studies tracing learning processes in novices will be complemented by studies analyzing expert performance in music and dance. New approaches, such as training participants to regulate each other’s brain activity, will lead to methodological breakthroughs. JAXPERTISE will generate basic scientific knowledge that will be relevant to a large number of different disciplines in the social sciences, cognitive sciences, and humanities. The insights gained in this project will have impact on the design of robot helpers and the development of social training interventions.
Summary
Human life is full of joint action and our achievements are, to a large extent, joint achievements that require the coordination of two or more individuals. Piano duets and tangos, but also complex technical and medical operations rely on and exist because of coordinated actions. In recent years, research has begun to identify the basic mechanisms of joint action. This work focused on simple tasks that can be performed together without practice. However, a striking aspect of human joint action is the expertise interaction partners acquire together. How people acquire joint expertise is still poorly understood. JAXPERTISE will break new ground by identifying the behavioural, cognitive, and neural mechanisms underlying the learning of joint action. Participating in joint activities is also a motor for individual development. Although this has long been recognized, the mechanisms underlying individual learning through engagement in joint activities remain to be spelled out from a cognitive science perspective. JAXPERTISE will make this crucial step by investigating how joint action affects source memory, semantic memory, and individual skill learning. Carefully designed experiments will optimize the balance between capturing relevant interpersonal phenomena and maximizing experimental control. The proposed studies employ behavioural measures, electroencephalography, and physiological measures. Studies tracing learning processes in novices will be complemented by studies analyzing expert performance in music and dance. New approaches, such as training participants to regulate each other’s brain activity, will lead to methodological breakthroughs. JAXPERTISE will generate basic scientific knowledge that will be relevant to a large number of different disciplines in the social sciences, cognitive sciences, and humanities. The insights gained in this project will have impact on the design of robot helpers and the development of social training interventions.
Max ERC Funding
1 992 331 €
Duration
Start date: 2014-08-01, End date: 2019-07-31
Project acronym MicroCONtACT
Project Microglial control of neuronal activity in the healthy and the injured brain
Researcher (PI) Adam DENES
Host Institution (HI) KIRSERLETI ORVOSTUDOMANYI KUTATOINTEZET
Country Hungary
Call Details Consolidator Grant (CoG), LS5, ERC-2016-COG
Summary Microglia are the main immune cells of the brain, but their role in brain injury is highly controversial due to the difficulties in selectively manipulating and imaging microglial actions in real time. Specifically, it is unclear whether microglia control neuronal survival after injury via shaping the activity of complex neuronal networks in vivo. To this end, we have combined fast in vivo two-photon imaging of neuronal calcium responses with selective microglial manipulation for the first time. Our data suggest that microglia constantly monitor and control neuronal network activity and these actions are essential to limit excitotoxicity and neuronal death after acute brain injury. We also identify microglia as key regulators of spreading depolarization in vivo. However, the underlying mechanisms remained unexplored. Here, I propose that microglia control neuronal excitability and based on preliminary data I set out to investigate how this occurs. We will combine selective, CSF1R-mediated microglia depletion with advanced neurophysiological methods such as in vivo calcium imaging and intracranial EEG for the first time, to reveal how microglia shape activity of complex neuronal networks in the healthy and the injured brain. Then, we will study microglia-neuron interactions from the network level to nanoscale level using in vivo two-photon imaging and super-resolution microscopy. We will apply novel chemogenic and optogenetic approaches to manipulate microglia in real time, assess their role in neuronal activity changes and investigate the molecular mechanisms in vitro and in vivo. Our unpublished data also suggest that inflammation – a key contributor to brain diseases – could disrupt microglia-neuron signaling and we set out to investigate the underlying mechanisms. By using state-of the-art research tools that had not been applied previously in this context, our studies are likely to reveal novel pathophysiological mechanisms relevant for common brain diseases.
Summary
Microglia are the main immune cells of the brain, but their role in brain injury is highly controversial due to the difficulties in selectively manipulating and imaging microglial actions in real time. Specifically, it is unclear whether microglia control neuronal survival after injury via shaping the activity of complex neuronal networks in vivo. To this end, we have combined fast in vivo two-photon imaging of neuronal calcium responses with selective microglial manipulation for the first time. Our data suggest that microglia constantly monitor and control neuronal network activity and these actions are essential to limit excitotoxicity and neuronal death after acute brain injury. We also identify microglia as key regulators of spreading depolarization in vivo. However, the underlying mechanisms remained unexplored. Here, I propose that microglia control neuronal excitability and based on preliminary data I set out to investigate how this occurs. We will combine selective, CSF1R-mediated microglia depletion with advanced neurophysiological methods such as in vivo calcium imaging and intracranial EEG for the first time, to reveal how microglia shape activity of complex neuronal networks in the healthy and the injured brain. Then, we will study microglia-neuron interactions from the network level to nanoscale level using in vivo two-photon imaging and super-resolution microscopy. We will apply novel chemogenic and optogenetic approaches to manipulate microglia in real time, assess their role in neuronal activity changes and investigate the molecular mechanisms in vitro and in vivo. Our unpublished data also suggest that inflammation – a key contributor to brain diseases – could disrupt microglia-neuron signaling and we set out to investigate the underlying mechanisms. By using state-of the-art research tools that had not been applied previously in this context, our studies are likely to reveal novel pathophysiological mechanisms relevant for common brain diseases.
Max ERC Funding
2 000 000 €
Duration
Start date: 2017-04-01, End date: 2022-03-31
Project acronym nanoAXON
Project Nano-physiology of small glutamatergic axon terminals
Researcher (PI) Janos SZABADICS
Host Institution (HI) KIRSERLETI ORVOSTUDOMANYI KUTATOINTEZET
Country Hungary
Call Details Consolidator Grant (CoG), LS5, ERC-2017-COG
Summary We will reveal the neuronal mechanisms of fundamental hippocampal and axonal functions using direct patch clamp recordings from the small axon terminals of the major glutamatergic afferent and efferent pathways of the dentate gyrus region. Specifically, we will investigate the intrinsic axonal properties and unitary synaptic functions of the axons in the dentate gyrus that originate from the entorhinal cortex, the hilar mossy cells and the hypothalamic supramammillary nucleus. The fully controlled access to the activity of individual neuronal projections allows us to address the crucial questions how upstream regions of the dentate gyrus convey physiologically relevant spike activities and how these activities are translated to unitary synaptic responses in individual dentate gyrus neurons. The successful information transfers by these mechanisms ultimately generate specific dentate gyrus cell activity that contributes to hippocampal memory functions. Comprehensive mechanistic insights are essential to understand the impacts of the activity patterns associated with fundamental physiological functions and attainable with the necessary details only with direct recordings from individual axons. For example, these knowledge are necessary to understand how single cell activities in the entorhinal cortex (carrying primary spatial information) contribute to spatial representation in the dentate (i.e. place fields). Furthermore, because the size of these recorded axon terminals matches that of the majority of cortical synapses, our discoveries will demonstrate basic biophysical and neuronal principles of axonal signaling that are relevant for universal neuronal functions throughout the CNS. Thus, an exceptional repertoire of methods, including recording from anatomically identified individual small axon terminals, voltage- and calcium imaging and computational simulations, places us in an advantaged position for revealing unprecedented information about neuronal circuits.
Summary
We will reveal the neuronal mechanisms of fundamental hippocampal and axonal functions using direct patch clamp recordings from the small axon terminals of the major glutamatergic afferent and efferent pathways of the dentate gyrus region. Specifically, we will investigate the intrinsic axonal properties and unitary synaptic functions of the axons in the dentate gyrus that originate from the entorhinal cortex, the hilar mossy cells and the hypothalamic supramammillary nucleus. The fully controlled access to the activity of individual neuronal projections allows us to address the crucial questions how upstream regions of the dentate gyrus convey physiologically relevant spike activities and how these activities are translated to unitary synaptic responses in individual dentate gyrus neurons. The successful information transfers by these mechanisms ultimately generate specific dentate gyrus cell activity that contributes to hippocampal memory functions. Comprehensive mechanistic insights are essential to understand the impacts of the activity patterns associated with fundamental physiological functions and attainable with the necessary details only with direct recordings from individual axons. For example, these knowledge are necessary to understand how single cell activities in the entorhinal cortex (carrying primary spatial information) contribute to spatial representation in the dentate (i.e. place fields). Furthermore, because the size of these recorded axon terminals matches that of the majority of cortical synapses, our discoveries will demonstrate basic biophysical and neuronal principles of axonal signaling that are relevant for universal neuronal functions throughout the CNS. Thus, an exceptional repertoire of methods, including recording from anatomically identified individual small axon terminals, voltage- and calcium imaging and computational simulations, places us in an advantaged position for revealing unprecedented information about neuronal circuits.
Max ERC Funding
1 994 025 €
Duration
Start date: 2018-04-01, End date: 2023-09-30
Project acronym NEPOSTRANS
Project Negotiating post-imperial transitions: from remobilization to nation-state consolidation. A comparative study of local and regional transitions in post-Habsburg East and Central Europe
Researcher (PI) Gabor EGRY
Host Institution (HI) POLITIKATORTENETI INTEZET KOZHASZNU NONPROFIT KFT
Country Hungary
Call Details Consolidator Grant (CoG), SH6, ERC-2017-COG
Summary The project’s goal is to provide a new, overall narrative of how the Habsburg Empire was replaced by nation states at the end of WWI and reconsider in the light of its results categories and concepts like state and statehood, local, regional and national, transition and transformation. A novel combination of historical comparison and histoire croisée enables the in-depth analyses of a set of local transitions in diverse regions (agrarian, industrial, commercial, urban, rural, multi-and mono-ethnic, borderland and mainland, litoral) and the combination of these results with the existing literature on other localities.
The team addresses four main themes: state, elites, identities and discourses. The focus is always local, the question is how these societies faced the momentous changes and found their place within empire and nation-state(s). It will look at interactions, cultures and especially rupture and continuity of people, norms, practices, institutional cultures in order to discover patterns of transitions and the social factors influencing them. Besides a typology of transitions, it also aims at gaining a new perspective on empire and nation state from this crucial moment of collapse and state-building.
The project is informed by New Imperial history, the idea of phantom boundaries, everyday ethnicity, integrated urban history. At the methodological level it builds on a symmetrical comparison of the selected cases and on an asymmetrical one with the existing literature, while the object of comparison is the transition that we conceptualize as an “intercrossing”. Through analysing this ‘transformation from below’ and connecting for the first time what has remained scattered both in historiography and in the social representations, the project aims to write a new history of modern Eastern Europe as a common legacy for an integrated European history.
Summary
The project’s goal is to provide a new, overall narrative of how the Habsburg Empire was replaced by nation states at the end of WWI and reconsider in the light of its results categories and concepts like state and statehood, local, regional and national, transition and transformation. A novel combination of historical comparison and histoire croisée enables the in-depth analyses of a set of local transitions in diverse regions (agrarian, industrial, commercial, urban, rural, multi-and mono-ethnic, borderland and mainland, litoral) and the combination of these results with the existing literature on other localities.
The team addresses four main themes: state, elites, identities and discourses. The focus is always local, the question is how these societies faced the momentous changes and found their place within empire and nation-state(s). It will look at interactions, cultures and especially rupture and continuity of people, norms, practices, institutional cultures in order to discover patterns of transitions and the social factors influencing them. Besides a typology of transitions, it also aims at gaining a new perspective on empire and nation state from this crucial moment of collapse and state-building.
The project is informed by New Imperial history, the idea of phantom boundaries, everyday ethnicity, integrated urban history. At the methodological level it builds on a symmetrical comparison of the selected cases and on an asymmetrical one with the existing literature, while the object of comparison is the transition that we conceptualize as an “intercrossing”. Through analysing this ‘transformation from below’ and connecting for the first time what has remained scattered both in historiography and in the social representations, the project aims to write a new history of modern Eastern Europe as a common legacy for an integrated European history.
Max ERC Funding
1 963 075 €
Duration
Start date: 2018-03-01, End date: 2023-02-28
Project acronym NOISE
Project Noise-Sensitivity Everywhere
Researcher (PI) Gabor Zoltan PETE
Host Institution (HI) RENYI ALFRED MATEMATIKAI KUTATOINTEZET
Country Hungary
Call Details Consolidator Grant (CoG), PE1, ERC-2017-COG
Summary "Noise-sensitivity of a Boolean function with iid random input bits means that resampling a tiny proportion of the input makes the output unpredictable. This notion arises naturally in computer science, but perhaps the most striking example comes from statistical physics, in large part due to the PI: the macroscopic geometry of planar percolation is very sensitive to noise. This can be recast in terms of Fourier analysis on the hypercube: a function is noise sensitive iff most of its Fourier weight is on ""high energy"" eigenfunctions of the random walk operator.
We propose to use noise sensitivity ideas in three main directions:
(A) Address some outstanding questions in the classical case of iid inputs: universality in critical planar percolation; the Friedgut-Kalai conjecture on Fourier Entropy vs Influence; noise in First Passage Percolation.
(B) In statistical physics, a key example is the critical planar FK-Ising model, with noise being Glauber dynamics. One task is to prove noise sensitivity of the macroscopic structure. A key obstacle is that hypercontractivity of the critical dynamics is not known.
(C) Babai’s conjecture says that random walk on any finite simple group, with any generating set, mixes in time poly-logarithmic in the volume. Two key open cases are the alternating groups and the linear groups SL(n,F2). We will approach these questions by first proving fast mixing for certain macroscopic structures. For permutation groups, this is the cycle structure, and it is related to a conjecture of Tóth on the interchange process, motivated by a phase transition question in quantum mechanics.
We will apply ideas of statistical physics to group theory in other novel ways: using near-critical FK-percolation models to prove a conjecture of Gaboriau connecting the first ell2-Betti number of a group to its cost, and using random walk in random environment to prove the amenability of the interval exchange transformation group, refuting a conjecture of Katok."
Summary
"Noise-sensitivity of a Boolean function with iid random input bits means that resampling a tiny proportion of the input makes the output unpredictable. This notion arises naturally in computer science, but perhaps the most striking example comes from statistical physics, in large part due to the PI: the macroscopic geometry of planar percolation is very sensitive to noise. This can be recast in terms of Fourier analysis on the hypercube: a function is noise sensitive iff most of its Fourier weight is on ""high energy"" eigenfunctions of the random walk operator.
We propose to use noise sensitivity ideas in three main directions:
(A) Address some outstanding questions in the classical case of iid inputs: universality in critical planar percolation; the Friedgut-Kalai conjecture on Fourier Entropy vs Influence; noise in First Passage Percolation.
(B) In statistical physics, a key example is the critical planar FK-Ising model, with noise being Glauber dynamics. One task is to prove noise sensitivity of the macroscopic structure. A key obstacle is that hypercontractivity of the critical dynamics is not known.
(C) Babai’s conjecture says that random walk on any finite simple group, with any generating set, mixes in time poly-logarithmic in the volume. Two key open cases are the alternating groups and the linear groups SL(n,F2). We will approach these questions by first proving fast mixing for certain macroscopic structures. For permutation groups, this is the cycle structure, and it is related to a conjecture of Tóth on the interchange process, motivated by a phase transition question in quantum mechanics.
We will apply ideas of statistical physics to group theory in other novel ways: using near-critical FK-percolation models to prove a conjecture of Gaboriau connecting the first ell2-Betti number of a group to its cost, and using random walk in random environment to prove the amenability of the interval exchange transformation group, refuting a conjecture of Katok."
Max ERC Funding
1 386 364 €
Duration
Start date: 2018-02-01, End date: 2023-01-31
Project acronym POLBUSNETWORKS
Project Political and Business Networks
Researcher (PI) Adam Gyorgy SZEIDL
Host Institution (HI) KOZEP-EUROPAI EGYETEM
Country Hungary
Call Details Consolidator Grant (CoG), SH1, ERC-2016-COG
Summary I explore the role of networks involving firms---networks between firms and politicians, and networks between firms and firms--for economic outcomes. I focus on two broad questions. (1) What are the determinants and implications of political favor networks? Although political favoritism affects allocations in many countries, its mechanisms are not well understood. I develop a new model based on the idea of trust embedded in favor networks, and test in Hungarian data the model's implications about how political centralization shapes favoritism. I also quantify the welfare cost of misallocation created by favoritism. My results help understand how political institutions shape economic outcomes. (2) What is the impact of supply chain networks on firm performance? Inputs from suppliers account for the majority of firm sales, yet we know little about the contribution of suppliers to firm performance. I use a field experiment in China to measure the causal effect of suppliers and the underlying mechanisms. I then use observational data from Hungary to quantify the contribution of differences in suppliers to differences in firm performance. The results help understand how supply chains and their misallocation shape firm and aggregate productivity. My approach to both of these questions emphasizes the role of trust embedded in firm networks and how these trust-based networks create misallocation of resources. A key component of this research is the development of original datasets. Beyond documenting and explaining facts, I also hope to obtain policy implications on reducing favoritism and improving firm performance in developing countries.
Summary
I explore the role of networks involving firms---networks between firms and politicians, and networks between firms and firms--for economic outcomes. I focus on two broad questions. (1) What are the determinants and implications of political favor networks? Although political favoritism affects allocations in many countries, its mechanisms are not well understood. I develop a new model based on the idea of trust embedded in favor networks, and test in Hungarian data the model's implications about how political centralization shapes favoritism. I also quantify the welfare cost of misallocation created by favoritism. My results help understand how political institutions shape economic outcomes. (2) What is the impact of supply chain networks on firm performance? Inputs from suppliers account for the majority of firm sales, yet we know little about the contribution of suppliers to firm performance. I use a field experiment in China to measure the causal effect of suppliers and the underlying mechanisms. I then use observational data from Hungary to quantify the contribution of differences in suppliers to differences in firm performance. The results help understand how supply chains and their misallocation shape firm and aggregate productivity. My approach to both of these questions emphasizes the role of trust embedded in firm networks and how these trust-based networks create misallocation of resources. A key component of this research is the development of original datasets. Beyond documenting and explaining facts, I also hope to obtain policy implications on reducing favoritism and improving firm performance in developing countries.
Max ERC Funding
1 833 214 €
Duration
Start date: 2017-05-01, End date: 2022-04-30
Project acronym RADIOSTAR
Project Radioactivities from Stars to Solar Systems
Researcher (PI) Maria Anna LUGARO
Host Institution (HI) CSILLAGASZATI ES FOLDTUDOMANYI KUTATOKOZPONT
Country Hungary
Call Details Consolidator Grant (CoG), PE9, ERC-2016-COG
Summary RADIOSTAR will exploit radioactive nuclei produced by nuclear reactions inside stars and ejected by stellar winds and supernova explosions to fill the missing pieces of the puzzle of the origin of our Solar System: What were the circumstances of the birth of our Sun? Were they similar to those of the majority of other stars in our Galaxy, or were they special? Radioactive nuclei are the key to answer these questions because meteoritic analysis has proven that many of them were present at the time of the birth of the Sun. Their origin, however, has been so far elusive. RADIOSTAR steps beyond the state-of-the-art to answer these open questions by (i) combining the evolution of radioactive nuclei in the Galaxy and within molecular clouds and (ii) considering all the seventeen radionuclides of interest and all their stellar sources and analysing the effects of uncertainties in their stellar production. This will allow us to:
- Use the decay of radioactive nuclei produced by the chemical evolution of the Galaxy as a clock to measure the lifetime of the Sun’s parent molecular cloud prior to the Sun’s birth;
- Calculate the self-pollution of this molecular cloud from the ejecta of stars with lives shorter than such lifetime;
- Discover if such self-pollution can fully explain the abundances of radioactive nuclei present at the time of the birth of the Sun, or whether special conditions are required.
RADIOSTAR will also have a far-reaching impact on our understanding of exoplanetary systems because the heat produced by radioactivity affects the evolution of planetesimals, with implications for the amount of water on terrestrial planets in the habitable zone. RADIOSTAR will open a new window into research on the effect of radioactivity on the evolution of planetesimals outside our Solar System.
Summary
RADIOSTAR will exploit radioactive nuclei produced by nuclear reactions inside stars and ejected by stellar winds and supernova explosions to fill the missing pieces of the puzzle of the origin of our Solar System: What were the circumstances of the birth of our Sun? Were they similar to those of the majority of other stars in our Galaxy, or were they special? Radioactive nuclei are the key to answer these questions because meteoritic analysis has proven that many of them were present at the time of the birth of the Sun. Their origin, however, has been so far elusive. RADIOSTAR steps beyond the state-of-the-art to answer these open questions by (i) combining the evolution of radioactive nuclei in the Galaxy and within molecular clouds and (ii) considering all the seventeen radionuclides of interest and all their stellar sources and analysing the effects of uncertainties in their stellar production. This will allow us to:
- Use the decay of radioactive nuclei produced by the chemical evolution of the Galaxy as a clock to measure the lifetime of the Sun’s parent molecular cloud prior to the Sun’s birth;
- Calculate the self-pollution of this molecular cloud from the ejecta of stars with lives shorter than such lifetime;
- Discover if such self-pollution can fully explain the abundances of radioactive nuclei present at the time of the birth of the Sun, or whether special conditions are required.
RADIOSTAR will also have a far-reaching impact on our understanding of exoplanetary systems because the heat produced by radioactivity affects the evolution of planetesimals, with implications for the amount of water on terrestrial planets in the habitable zone. RADIOSTAR will open a new window into research on the effect of radioactivity on the evolution of planetesimals outside our Solar System.
Max ERC Funding
1 726 300 €
Duration
Start date: 2017-09-01, End date: 2022-08-31
