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Dynamic systems theory

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https://www.readbyqxmd.com/read/28230845/dynamic-models-of-large-scale-brain-activity
#1
REVIEW
Michael Breakspear
Movement, cognition and perception arise from the collective activity of neurons within cortical circuits and across large-scale systems of the brain. While the causes of single neuron spikes have been understood for decades, the processes that support collective neural behavior in large-scale cortical systems are less clear and have been at times the subject of contention. Modeling large-scale brain activity with nonlinear dynamical systems theory allows the integration of experimental data from multiple modalities into a common framework that facilitates prediction, testing and possible refutation...
February 23, 2017: Nature Neuroscience
https://www.readbyqxmd.com/read/28230127/theory-of-chaotic-orbital-variations-confirmed-by-cretaceous-geological-evidence
#2
Chao Ma, Stephen R Meyers, Bradley B Sageman
Variations in the Earth's orbit and spin vector are a primary control on insolation and climate; their recognition in the geological record has revolutionized our understanding of palaeoclimate dynamics, and has catalysed improvements in the accuracy and precision of the geological timescale. Yet the secular evolution of the planetary orbits beyond 50 million years ago remains highly uncertain, and the chaotic dynamical nature of the Solar System predicted by theoretical models has yet to be rigorously confirmed by well constrained (radioisotopically calibrated and anchored) geological data...
February 22, 2017: Nature
https://www.readbyqxmd.com/read/28226470/behavioral-informatics-dynamical-models-for-measuring-and-assessing-behaviors-for-precision-interventions
#3
Misha Pavel, Holly Jimison, Bonnie Spring, Misha Pavel, Holly Jimison, Bonnie Spring, Bonnie Spring, Holly Jimison, Misha Pavel
Poor health-related behaviors represent a major challenge to healthcare due to their significant impact on chronic and acute diseases and their effect on the quality of life. Recent advances in technology have enabled an unprecedented opportunity to assess objectively, unobtrusively and continuously human behavior and have opened the possibility of optimizing individual-tailored, precision interventions within the framework of behavioral informatics. A key prerequisite for this optimization is the ability to assess and predict effects of interventions...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28226468/from-good-intentions-to-healthy-habits-towards-integrated-computational-models-of-goal-striving-and-habit-formation
#4
Peter Pirolli, Peter Pirolli, Peter Pirolli
Computational models were developed in the ACT-R neurocognitive architecture to address some aspects of the dynamics of behavior change. The simulations aim to address the day-to-day goal achievement data available from mobile health systems. The models refine current psychological theories of self-efficacy, intended effort, and habit formation, and provide an account for the mechanisms by which goal personalization, implementation intentions, and remindings work.
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28225613/dehydrogenation-free-energy-of-co-2-aq-from-density-functional-theory-based-molecular-dynamics
#5
Florian H Hodel, Sandra Luber
Electron and proton transfers are important steps occurring in nature and in artificial (catalytic) reaction mechanisms. The often employed approach of calculating the energy differences of those steps using methods involving geometry optimizations neglects the influence of dynamic effects such as solvent rearrangement. To further investigate this issue and inspired by recent research in water oxidation, we calculate in the present study the dehydrogenation free energy of aqueous Co(2+), which is the free energy change associated with the first step of the reaction mechanism of model Co(II)-based water oxidation catalysts...
February 22, 2017: Journal of Chemical Theory and Computation
https://www.readbyqxmd.com/read/28223518/integrated-view-of-internal-friction-in-unfolded-proteins-from-single-molecule-fret-contact-quenching-theory-and-simulations
#6
Andrea Soranno, Andrea Holla, Fabian Dingfelder, Daniel Nettels, Dmitrii E Makarov, Benjamin Schuler
Internal friction is an important contribution to protein dynamics at all stages along the folding reaction. Even in unfolded and intrinsically disordered proteins, internal friction has a large influence, as demonstrated with several experimental techniques and in simulations. However, these methods probe different facets of internal friction and have been applied to disparate molecular systems, raising questions regarding the compatibility of the results. To obtain an integrated view, we apply here the combination of two complementary experimental techniques, simulations, and theory to the same system: unfolded protein L...
February 21, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28222198/algorithmic-design-of-a-noise-resistant-and-efficient-closed-loop-deep-brain-stimulation-system-a-computational-approach
#7
Sofia D Karamintziou, Ana Luísa Custódio, Brigitte Piallat, Mircea Polosan, Stéphan Chabardès, Pantelis G Stathis, George A Tagaris, Damianos E Sakas, Georgia E Polychronaki, George L Tsirogiannis, Olivier David, Konstantina S Nikita
Advances in the field of closed-loop neuromodulation call for analysis and modeling approaches capable of confronting challenges related to the complex neuronal response to stimulation and the presence of strong internal and measurement noise in neural recordings. Here we elaborate on the algorithmic aspects of a noise-resistant closed-loop subthalamic nucleus deep brain stimulation system for advanced Parkinson's disease and treatment-refractory obsessive-compulsive disorder, ensuring remarkable performance in terms of both efficiency and selectivity of stimulation, as well as in terms of computational speed...
2017: PloS One
https://www.readbyqxmd.com/read/28221835/social-information-on-fear-and-food-drives-animal-grouping-and-fitness
#8
Michael A Gil, Zachary Emberts, Harrison Jones, Colette M St Mary
Empirical studies in select systems suggest that social information-the incidental or deliberate information produced by animals and available to other animals-can fundamentally shape animal grouping behavior. However, to understand the role of social information in animal behavior and fitness, we must establish general theory that quantifies effects of social information across ecological contexts and generates expectations that can be applied across systems. Here we used dynamic state variable modeling to isolate effects of social information about food and predators on grouping behavior and fitness...
March 2017: American Naturalist
https://www.readbyqxmd.com/read/28221348/self-assembly-of-nanoparticles-into-biomimetic-capsid-like-nanoshells
#9
Ming Yang, Henry Chan, Gongpu Zhao, Joong Hwan Bahng, Peijun Zhang, Petr Král, Nicholas A Kotov
Nanoscale compartments are one of the foundational elements of living systems. Capsids, carboxysomes, exosomes, vacuoles and other nanoshells easily self-assemble from biomolecules such as lipids or proteins, but not from inorganic nanomaterials because of difficulties with the replication of spherical tiling. Here we show that stabilizer-free polydispersed inorganic nanoparticles (NPs) can spontaneously organize into porous nanoshells. The association of water-soluble CdS NPs into self-limited spherical capsules is the result of scale-modified electrostatic, dispersion and other colloidal forces...
March 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28218316/theoretical-study-of-hcn-water-interaction-five-dimensional-potential-energy-surfaces
#10
Ernesto Quintas Sánchez, Marie-Lise Dubernet
A new five-dimensional potential energy surface is calculated at the coupled-cluster CCSD(T) level of theory for the HCN-water system, treating both monomers as rigid rotors. The associated methodology, which combines extensive ab initio calculations of moderate accuracy (CCSD(T)/AVDZ) and a fitting procedure involving a much lower angular coverage with more accurate ab initio calculations (CCSD(T)/CBS), is described in detail. This methodology provides a time-saving approach to compute quantitatively accurate potential energy surfaces with reasonable computational effort...
February 20, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28218249/complexity-variability-assessment-of-nonlinear-time-varying-cardiovascular-control
#11
Gaetano Valenza, Luca Citi, Ronald G Garcia, Jessica Noggle Taylor, Nicola Toschi, Riccardo Barbieri
The application of complex systems theory to physiology and medicine has provided meaningful information about the nonlinear aspects underlying the dynamics of a wide range of biological processes and their disease-related aberrations. However, no studies have investigated whether meaningful information can be extracted by quantifying second-order moments of time-varying cardiovascular complexity. To this extent, we introduce a novel mathematical framework termed complexity variability, in which the variance of instantaneous Lyapunov spectra estimated over time serves as a reference quantifier...
February 20, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28217892/animal-pee-in-the-sea-consumer-mediated-nutrient-dynamics-in-the-world-s-changing-oceans
#12
REVIEW
Jacob E Allgeier, Deron E Burkepile, Craig A Layman
Humans have drastically altered the abundance of animals in marine ecosystems via exploitation. Reduced abundance can destabilize food webs, leading to cascading indirect effects that dramatically reorganize community structure and shift ecosystem function. However, the additional implications of these top-down changes for biogeochemical cycles via consumer-mediated nutrient dynamics (CND) are often overlooked in marine systems, particularly in coastal areas. Here, we review research that underscores the importance of this bottom-up control at local, regional, and global scales in coastal marine ecosystems, and the potential implications of anthropogenic change to fundamentally alter these processes...
February 20, 2017: Global Change Biology
https://www.readbyqxmd.com/read/28217739/grounded-and-embodied-mathematical-cognition-promoting-mathematical-insight-and-proof-using-action-and-language
#13
Mitchell J Nathan, Candace Walkington
We develop a theory of grounded and embodied mathematical cognition (GEMC) that draws on action-cognition transduction for advancing understanding of how the body can support mathematical reasoning. GEMC proposes that participants' actions serve as inputs capable of driving the cognition-action system toward associated cognitive states. This occurs through a process of transduction that promotes valuable mathematical insights by eliciting dynamic depictive gestures that enact spatio-temporal properties of mathematical entities...
2017: Cogn Res Princ Implic
https://www.readbyqxmd.com/read/28215288/applications-of-dynamic-systems-theory-to-cognition-and-development-new-frontiers
#14
S Perone, V R Simmering
A central goal in developmental science is to explain the emergence of new behavioral forms. Researchers consider potential sources of behavioral change depending partly on their theoretical perspective. This chapter reviews one perspective, dynamic systems theory, which emphasizes the interactions among multiple components to drive behavior and developmental change. To illustrate the central concepts of dynamic systems theory, we describe empirical and computational studies from a range of domains, including motor development, the Piagetian A-not-B task, infant visual recognition, visual working memory capacity, and language learning...
2017: Advances in Child Development and Behavior
https://www.readbyqxmd.com/read/28214530/automaton-model-of-protein-dynamics-of-conformational-and-functional-states
#15
REVIEW
Andrei Khrennikov, Ekaterina Yurova
In this conceptual paper we propose to explore the analogy between ontic/epistemic description of quantum phenomena and interrelation between dynamics of conformational and functional states of proteins. Another new idea is to apply theory of automata to model the latter dynamics. In our model protein's behavior is modeled with the aid of two dynamical systems, ontic and epistemic, which describe evolution of conformational and functional states of proteins, respectively. The epistemic automaton is constructed from the ontic automaton on the basis of functional (observational) equivalence relation on the space of ontic states...
February 15, 2017: Progress in Biophysics and Molecular Biology
https://www.readbyqxmd.com/read/28213928/problem-solving-phase-transitions-during-team-collaboration
#16
Travis J Wiltshire, Jonathan E Butner, Stephen M Fiore
Multiple theories of problem-solving hypothesize that there are distinct qualitative phases exhibited during effective problem-solving. However, limited research has attempted to identify when transitions between phases occur. We integrate theory on collaborative problem-solving (CPS) with dynamical systems theory suggesting that when a system is undergoing a phase transition it should exhibit a peak in entropy and that entropy levels should also relate to team performance. Communications from 40 teams that collaborated on a complex problem were coded for occurrence of problem-solving processes...
February 18, 2017: Cognitive Science
https://www.readbyqxmd.com/read/28212112/cancer-as-robust-intrinsic-state-shaped-by-evolution-a-key-issues-review
#17
Ruoshi Yuan, Xiaomei Zhu, Gaowei Wang, Site Li, Ping Ao
Cancer is a complex disease: its pathology cannot be properly understood in terms of independent players-genes, proteins, molecular pathways, or their simple combinations. This is similar to many-body physics of a condensed phase that many important properties are not determined by a single atom or molecule. The rapidly accumulating large 'omics' data also require a new mechanistic and global underpinning to organize for rationalizing cancer complexity. A unifying and quantitative theory was proposed by some of the present authors that cancer is a robust state formed by the endogenous molecular-cellular network, which is evolutionarily built for the developmental processes and physiological functions...
February 17, 2017: Reports on Progress in Physics
https://www.readbyqxmd.com/read/28211914/eco-evolutionary-feedbacks-can-rescue-cooperation-in-microbial-populations
#18
Clara Moreno-Fenoll, Matteo Cavaliere, Esteban Martínez-García, Juan F Poyatos
Bacterial populations whose growth depends on the cooperative production of public goods are usually threatened by the rise of cheaters that do not contribute but just consume the common resource. Minimizing cheater invasions appears then as a necessary mechanism to maintain these populations. However, that invasions result instead in the persistence of cooperation is a prospect that has yet remained largely unexplored. Here, we show that the demographic collapse induced by cheaters in the population can actually contribute to the rescue of cooperation, in a clear illustration of how ecology and evolution can influence each other...
February 13, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28211741/enhanced-crystal-growth-in-binary-lennard-jones-mixtures
#19
M Radu, K Kremer
We study the crystal growth in binary Lennard-Jones mixtures by molecular dynamics simulations. Growth dynamics, the structure of the liquid-solid interfaces as well as droplet incorporation into the crystal vary with solution properties. For demixed systems we observe a strongly enhanced crystal growth at the cost of enclosed impurities. Furthermore, we find different interface morphologies depending on solubility. We relate our observations to growth mechanisms based on the Gibbs-Thomson effect as well as to predictions of the Kardar-Parisi-Zhang theory in 2+1 dimensions...
February 3, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28211720/dynamical-response-near-quantum-critical-points
#20
Andrew Lucas, Snir Gazit, Daniel Podolsky, William Witczak-Krempa
We study high-frequency response functions, notably the optical conductivity, in the vicinity of quantum critical points (QCPs) by allowing for both detuning from the critical coupling and finite temperature. We consider general dimensions and dynamical exponents. This leads to a unified understanding of sum rules. In systems with emergent Lorentz invariance, powerful methods from quantum field theory allow us to fix the high-frequency response in terms of universal coefficients. We test our predictions analytically in the large-N O(N) model and using the gauge-gravity duality and numerically via quantum Monte Carlo simulations on a lattice model hosting the interacting superfluid-insulator QCP...
February 3, 2017: Physical Review Letters
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