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Adaptação transcultural e validação da Family Dynamics Measure II (FDM II) para familiares de mulheres portadoras de câncer de mama no Brasil; Cross-cultural adaptation and validation of the Family Dynamics Measure II (FDM II) for family members of women with breast cancer in Brazil

Imada, Teresa Cristina Martins Leite
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 29/07/2008 PT
Relevância na Pesquisa
36.15%
O câncer de mama é uma doença que mobiliza o sistema familiar da mulher que o apresenta, e a forma como os familiares ajustam-se à doença tem efeito sobre o processo de enfrentamento da mulher. Conhecer a dinâmica familiar e identificar aspectos da interação entre os membros da família que ficam comprometidos com o surgimento da doença e que prejudicam o ajustamento e a qualidade de vida das mulheres e seus familiares é uma das etapas iniciais para se desenvolver serviços adequados à população em foco. A utilização de instrumentos de avaliação do funcionamento familiar, adequadamente construídos e validados, é uma estratégia que tem se mostrado como de grande relevância. No Brasil, não foram encontrados instrumentos que atendessem a esse fim. Portanto, optou-se pela adaptação transcultural e validação de um instrumento norte-americano de avaliação familiar, o que consistiu no objetivo desse estudo. O instrumento escolhido foi a Family Dynamics Measure II (FDM II), uma escala composta por 66 itens construída por um grupo de enfermeiras com base na teoria do sistema familiar saudável de Barnhill. O processo de adaptação do instrumento envolveu a tradução, a retro-tradução, a verificação da equivalência da versão retro-traduzida pela autora principal da escala...

A seleção natural e a estrutura, dinâmica e diversificação de assembleias de espécies mutualistas; Natural selection and the structure, dynamics, and diversification of mutualistic assemblages

Raimundo, Rafael Luís Galdini
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 16/04/2015 PT
Relevância na Pesquisa
36.03%
A adaptação e a diversificação em sistemas multiespecíficos são crescentemente reconhecidas como processos relevantes para a compreensão da biodiversidade. Nosso objetivo foi investigar como a seleção natural relacionada a interações ecológicas influencia a estrutura, dinâmica e diversificação de assembleias mutualistas. Primeiro, modelamos como mutualismo e competição intraespecífica geram regimes seletivos antagônicos que definem padrões de diversificação. Nossos modelos preveem que em mutualismos de baixa intimidade, nos quais cada organismo têm muitos parceiros individuais, fenótipos extremos têm interações mutualísticas desajustadas em relação à complementaridade de traços, contrabalanceando efeitos diversificadores da competição intraespecífica e restringindo a especiação. Em sistemas de alta intimidade, nos quais mutualismos têm maior impacto adaptativo e cada organismo têm poucos parceiros, tal seleção estabilizadora imposta por mutualismos é reduzida, favorecendo a diversificação. Entretanto, mutualismos de baixa intimidade são mais ricos que mutualismos íntimos na natureza. Sob baixa intimidade de interações, adições de espécies não-aparentadas envolvidas em dinâmicas de convergência constituem explicação plausível para essa discrepância. Em sistemas de alta intimidade...

Chemotactic Response and Adaptation Dynamics in Escherichia coli

Clausznitzer, Diana; Oleksiuk, Olga; Løvdok, Linda; Sourjik, Victor; Endres, Robert G.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
36.13%
Adaptation of the chemotaxis sensory pathway of the bacterium Escherichia coli is integral for detecting chemicals over a wide range of background concentrations, ultimately allowing cells to swim towards sources of attractant and away from repellents. Its biochemical mechanism based on methylation and demethylation of chemoreceptors has long been known. Despite the importance of adaptation for cell memory and behavior, the dynamics of adaptation are difficult to reconcile with current models of precise adaptation. Here, we follow time courses of signaling in response to concentration step changes of attractant using in vivo fluorescence resonance energy transfer measurements. Specifically, we use a condensed representation of adaptation time courses for efficient evaluation of different adaptation models. To quantitatively explain the data, we finally develop a dynamic model for signaling and adaptation based on the attractant flow in the experiment, signaling by cooperative receptor complexes, and multiple layers of feedback regulation for adaptation. We experimentally confirm the predicted effects of changing the enzyme-expression level and bypassing the negative feedback for demethylation. Our data analysis suggests significant imprecision in adaptation for large additions. Furthermore...

Cellular Plasticity Enables Adaptation to Unforeseen Cell-Cycle Rewiring Challenges

Katzir, Yair; Stolovicki, Elad; Stern, Shay; Braun, Erez
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 18/09/2012 EN
Relevância na Pesquisa
36.04%
The fundamental dynamics of the cell cycle, underlying cell growth and reproduction, were previously found to be robust under a wide range of environmental and internal perturbations. This property was commonly attributed to its network structure, which enables the coordinated interactions among hundreds of proteins. Despite significant advances in deciphering the components and autonomous interactions of this network, understanding the interfaces of the cell cycle with other major cellular processes is still lacking. To gain insight into these interfaces, we used the process of genome-rewiring in yeast by placing an essential metabolic gene HIS3 from the histidine biosynthesis pathway, under the exclusive regulation of different cell-cycle promoters. In a medium lacking histidine and under partial inhibition of the HIS3p, the rewired cells encountered an unforeseen multitasking challenge; the cell-cycle regulatory genes were required to regulate the essential histidine-pathway gene in concert with the other metabolic demands, while simultaneously driving the cell cycle through its proper temporal phases. We show here that chemostat cell populations with rewired cell-cycle promoters adapted within a short time to accommodate the inhibition of HIS3p and stabilized a new phenotypic state. Furthermore...

How adaptation shapes spike rate oscillations in recurrent neuronal networks

Augustin, Moritz; Ladenbauer, Josef; Obermayer, Klaus
Fonte: Frontiers Media S.A. Publicador: Frontiers Media S.A.
Tipo: Artigo de Revista Científica
Publicado em 27/02/2013 EN
Relevância na Pesquisa
36.11%
Neural mass signals from in-vivo recordings often show oscillations with frequencies ranging from <1 to 100 Hz. Fast rhythmic activity in the beta and gamma range can be generated by network-based mechanisms such as recurrent synaptic excitation-inhibition loops. Slower oscillations might instead depend on neuronal adaptation currents whose timescales range from tens of milliseconds to seconds. Here we investigate how the dynamics of such adaptation currents contribute to spike rate oscillations and resonance properties in recurrent networks of excitatory and inhibitory neurons. Based on a network of sparsely coupled spiking model neurons with two types of adaptation current and conductance-based synapses with heterogeneous strengths and delays we use a mean-field approach to analyze oscillatory network activity. For constant external input, we find that spike-triggered adaptation currents provide a mechanism to generate slow oscillations over a wide range of adaptation timescales as long as recurrent synaptic excitation is sufficiently strong. Faster rhythms occur when recurrent inhibition is slower than excitation and oscillation frequency increases with the strength of inhibition. Adaptation facilitates such network-based oscillations for fast synaptic inhibition and leads to decreased frequencies. For oscillatory external input...

Adaptation Dynamics in Densely Clustered Chemoreceptors

Pontius, William; Sneddon, Michael W.; Emonet, Thierry
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
36.01%
In many sensory systems, transmembrane receptors are spatially organized in large clusters. Such arrangement may facilitate signal amplification and the integration of multiple stimuli. However, this organization likely also affects the kinetics of signaling since the cytoplasmic enzymes that modulate the activity of the receptors must localize to the cluster prior to receptor modification. Here we examine how these spatial considerations shape signaling dynamics at rest and in response to stimuli. As a model system, we use the chemotaxis pathway of Escherichia coli, a canonical system for the study of how organisms sense, respond, and adapt to environmental stimuli. In bacterial chemotaxis, adaptation is mediated by two enzymes that localize to the clustered receptors and modulate their activity through methylation-demethylation. Using a novel stochastic simulation, we show that distributive receptor methylation is necessary for successful adaptation to stimulus and also leads to large fluctuations in receptor activity in the steady state. These fluctuations arise from noise in the number of localized enzymes combined with saturated modification kinetics between the localized enzymes and the receptor substrate. An analytical model explains how saturated enzyme kinetics and large fluctuations can coexist with an adapted state robust to variation in the expression levels of the pathway constituents...

Catalysis of Protein Folding by Chaperones Accelerates Evolutionary Dynamics in Adapting Cell Populations

Çetinbaş, Murat; Shakhnovich, Eugene I.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
36%
Although molecular chaperones are essential components of protein homeostatic machinery, their mechanism of action and impact on adaptation and evolutionary dynamics remain controversial. Here we developed a physics-based ab initio multi-scale model of a living cell for population dynamics simulations to elucidate the effect of chaperones on adaptive evolution. The 6-loci genomes of model cells encode model proteins, whose folding and interactions in cellular milieu can be evaluated exactly from their genome sequences. A genotype-phenotype relationship that is based on a simple yet non-trivially postulated protein-protein interaction (PPI) network determines the cell division rate. Model proteins can exist in native and molten globule states and participate in functional and all possible promiscuous non-functional PPIs. We find that an active chaperone mechanism, whereby chaperones directly catalyze protein folding, has a significant impact on the cellular fitness and the rate of evolutionary dynamics, while passive chaperones, which just maintain misfolded proteins in soluble complexes have a negligible effect on the fitness. We find that by partially releasing the constraint on protein stability, active chaperones promote a deeper exploration of sequence space to strengthen functional PPIs...

Multi-level stakeholder influence mapping: visualizing power relations across actor levels in Nepal’s agricultural climate change adaptation regime

Sova, C.A.; Helfgott, A.; S. Chaudhury, A.; Matthews, D.; F. Thornton, T.; J. Vermeulen, S.
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
Publicado em //2015 EN
Relevância na Pesquisa
36.19%
Where power lies and how it is conceived in studies of governance and institutions is often not discussed. This is due to the ubiquitous nature of the topic. Power is shaped by a variety of institutional factors, including the architecture of governing structures, questions of scale and level, and access to key resources including knowledge and capital, among other factors. To date, there are relatively few tools available that allow policy makers, researchers, and development practitioners to render these power dynamics explicit and thus take steps to mitigate the potentially deleterious effects of power orientations. This paper proposes a methodology, multi-level stakeholder influence mapping (MSIM), for elucidating power dynamics between actors in complex system regimes. MSIM departs from existing power mapping techniques in that it relies on individual interviews conducted across multiple actor levels and utilizes a participatory mapping process for shared system boundary critique. MSIM was piloted in Nepal’s agricultural climate change adaptation regime with actors from the central, regional, and local operational levels. The results suggest that without proper consideration of the role of power in agricultural adaptation regimes...

Dynamics of Coupled Adaptive Elements : Bursting and Intermittent Oscillations Generated by Frustration in Networks

Inoue, Masayo; Kaneko, Kunihiko
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 14/07/2009
Relevância na Pesquisa
46.21%
Adaptation to environmental change is a common property of biological systems. Cells initially respond to external changes in the environment, but after some time, they regain their original state. By considering an element consisting of two variables that show such adaptation dynamics, we studied a coupled dynamical system containing such elements to examine the diverse dynamics in the system and classified the behaviors on the basis of the network structure that determined the interaction among elements. For a system with two elements, two types of behaviors, perfect adaptation and simple oscillation, were observed. For a system with three elements, in addition to these two types, novel types of dynamics, namely, rapid burst-type oscillation and a slow cycle, were discovered; depending on the initial conditions, these novel types of dynamics coexisted. These behaviors are a result of the characteristic dynamics of each element, i.e., fast response and slow adaptation processes. The behaviors depend on the network structure (in specific, a combination of positive or negative feedback among elements). Cooperativity among elements due to a positive feedback loop leads to simple oscillation, whereas frustration involving alternating positive and negative interactions among elements leads to the coexistence of rapid bursting oscillation and a slow cycle. These behaviors are classified on the basis of the frustration indices defined by the network structure. The period of the slow cycle is much longer than the original adaptation time scale...

Chemotactic response and adaptation dynamics in Escherichia coli

Clausznitzer, Diana; Oleksiuk, Olga; Lovdok, Linda; Sourjik, Victor; Endres, Robert G.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
36.13%
Adaptation of the chemotaxis sensory pathway of the bacterium Escherichia coli is integral for detecting chemicals over a wide range of background concentrations, ultimately allowing cells to swim towards sources of attractant and away from repellents. Its biochemical mechanism based on methylation and demethylation of chemoreceptors has long been known. Despite the importance of adaptation for cell memory and behavior, the dynamics of adaptation are difficult to reconcile with current models of precise adaptation. Here, we follow time courses of signaling in response to concentration step changes of attractant using in vivo fluorescence resonance energy transfer measurements. Specifically, we use a condensed representation of adaptation time courses for efficient evaluation of different adaptation models. To quantitatively explain the data, we finally develop a dynamic model for signaling and adaptation based on the attractant flow in the experiment, signaling by cooperative receptor complexes, and multiple layers of feedback regulation for adaptation. We experimentally confirm the predicted effects of changing the enzyme-expression level and bypassing the negative feedback for demethylation. Our data analysis suggests significant imprecision in adaptation for large additions. Furthermore...

Adaptation dynamics in densely clustered chemoreceptors

Pontius, William; Sneddon, Michael W.; Emonet, Thierry
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 19/09/2013
Relevância na Pesquisa
46.1%
In many sensory systems, transmembrane receptors are spatially organized in large clusters. Such arrangement may facilitate signal amplification and the integration of multiple stimuli. However, this organization likely also affects the kinetics of signaling since the cytoplasmic enzymes that modulate the activity of the receptors must localize to the cluster prior to receptor modification. Here we examine how these spatial considerations shape signaling dynamics at rest and in response to stimuli. As a model, we use the chemotaxis pathway of Escherichia coli, a canonical system for the study of how organisms sense, respond, and adapt to environmental stimuli. In bacterial chemotaxis, adaptation is mediated by two enzymes that localize to the clustered receptors and modulate their activity through methylation-demethylation. Using a novel stochastic simulation, we show that distributive receptor methylation is necessary for successful adaptation to stimulus and also leads to large fluctuations in receptor activity in the steady state. These fluctuations arise from noise in the number of localized enzymes combined with saturated modification kinetics between localized enzymes and receptor substrate. An analytical model explains how saturated enzyme kinetics and large fluctuations can coexist with an adapted state robust to variation in the expression level of the pathway constituents...

Stability and Diversity in Collective Adaptation

Sato, Yuzuru; Akiyama, Eizo; Crutchfield, James P.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
46.18%
We derive a class of macroscopic differential equations that describe collective adaptation, starting from a discrete-time stochastic microscopic model. The behavior of each agent is a dynamic balance between adaptation that locally achieves the best action and memory loss that leads to randomized behavior. We show that, although individual agents interact with their environment and other agents in a purely self-interested way, macroscopic behavior can be interpreted as game dynamics. Application to several familiar, explicit game interactions shows that the adaptation dynamics exhibits a diversity of collective behaviors. The simplicity of the assumptions underlying the macroscopic equations suggests that these behaviors should be expected broadly in collective adaptation. We also analyze the adaptation dynamics from an information-theoretic viewpoint and discuss self-organization induced by information flux between agents, giving a novel view of collective adaptation.; Comment: 22 pages, 23 figures; updated references, corrected typos, changed content

Who Replaces Whom? Local versus Non-local Replacement in Social and Evolutionary Dynamics

Banisch, Sven; Araújo, Tanya
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 10/07/2012
Relevância na Pesquisa
36.02%
In this paper, we inspect well-known population genetics and social dynamics models. In these models, interacting individuals, while participating in a self-organizing process, give rise to the emergence of complex behaviors and patterns. While one main focus in population genetics is on the adaptive behavior of a population, social dynamics is more often concerned with the splitting of a connected array of individuals into a state of global polarization, that is, the emergence of speciation. Applying computational and mathematical tools we show that the way the mechanisms of selection, interaction and replacement are constrained and combined in the modeling have an important bearing on both adaptation and the emergence of speciation. Differently (un)constraining the mechanism of individual replacement provides the conditions required for either speciation or adaptation, since these features appear as two opposing phenomena, not achieved by one and the same model. Even though natural selection, operating as an external, environmental mechanism, is neither necessary nor sufficient for the creation of speciation, our modeling exercises highlight the important role played by natural selection in the interplay of the evolutionary and the self-organization modeling methodologies.; Comment: 14 pages...

Prediction and Adaptation in an Evolving Chaotic Environment

Hübler, Alfred; Pines, David
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 28/06/1993
Relevância na Pesquisa
36.12%
We describe the results of analytic calculations and computer simulations of adaptive predictors (predictive agents) responding to an evolving chaotic environment and to one another. Our simulations are designed to quantify adaptation and to explore co-adaptation for a simple calculable model of a complex adaptive system. We first consider the ability of a single agent, exposed to a chaotic environment, to model, control, and predict the future states of that environment. We then introduce a second agent which, in attempting to model and control both the chaotic environment and the first agent, modifies the extent to which that agent can identify patterns and exercise control. We find that (i) optimal adaptive predictors have an optimal memory and an optimal complexity, which are small for a rapidly changing map dynamics and (ii) that the predictive power can be increased by imposing chaos or random noise onto the map dynamics. The competition between the two predictive agents can lead either to chaos, or to metastable emergent behavior, best described as a leader-follower relationship. Our results suggest a correlation between optimal adaptation, optimal complexity, and emergent behavior, and provide preliminary support for the concept of optimal co-adaptation near the edge of chaos.; Comment: LaTeX file with 1Mb uuencoded...

Intrinsic adaptation in autonomous recurrent neural networks

Markovic, Dimitrije; Gros, Claudius
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 14/10/2011
Relevância na Pesquisa
36.02%
A massively recurrent neural network responds on one side to input stimuli and is autonomously active, on the other side, in the absence of sensory inputs. Stimuli and information processing depends crucially on the qualia of the autonomous-state dynamics of the ongoing neural activity. This default neural activity may be dynamically structured in time and space, showing regular, synchronized, bursting or chaotic activity patterns. We study the influence of non-synaptic plasticity on the default dynamical state of recurrent neural networks. The non-synaptic adaption considered acts on intrinsic neural parameters, such as the threshold and the gain, and is driven by the optimization of the information entropy. We observe, in the presence of the intrinsic adaptation processes, three distinct and globally attracting dynamical regimes, a regular synchronized, an overall chaotic and an intermittent bursting regime. The intermittent bursting regime is characterized by intervals of regular flows, which are quite insensitive to external stimuli, interseeded by chaotic bursts which respond sensitively to input signals. We discuss these finding in the context of self-organized information processing and critical brain dynamics.; Comment: 24 pages...

Shifting gears: Thermodynamics of genetic information storage suggest stress-dependence of mutation rate, which can accelerate adaptation

Hilbert, Lennart
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 11/04/2011
Relevância na Pesquisa
45.94%
Background: Acceleration of adaptation dynamics by stress-induced hypermutation has been found experimentally. Evolved evolvability is a prominent explanation. We investigate a more generally applicable explanation by a physical constraint. Methods and Results: A generic thermodynamical analysis of genetic information storage obviates physical constraints on the integrity of genetic information. The capability to employ metabolic resources is found as a major determinant of mutation probability in stored genetic information. Incorporation into a non-recombinant, asexual adaptation toy model predicts cases of markedly accelerated adaptation, driven by a transient increase of mutation rate. No change in the mutation rate as a genetic trait is required. The mutation rate of one and the same genotype varies dependent on stress level. Implications: Stress-dependent mutation rates are physically necessary and challenge a condition-independent genotype to mutation rate mapping. This holds implications for evolutionary theory and pathogen and cancer evolution.; Comment: 15 pages, 4 figures

Cortical free association dynamics: distinct phases of a latching network

Russo, Eleonora; Treves, Alessandro
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 05/03/2012
Relevância na Pesquisa
36.08%
A Potts associative memory network has been proposed as a simplified model of macroscopic cortical dynamics, in which each Potts unit stands for a patch of cortex, which can be activated in one of S local attractor states. The internal neuronal dynamics of the patch is not described by the model, rather it is subsumed into an effective description in terms of graded Potts units, with adaptation effects both specific to each attractor state and generic to the patch. If each unit, or patch, receives effective (tensor) connections from C other units, the network has been shown to be able to store a large number p of global patterns, or network attractors, each with a fraction a of the units active, where the critical load p_c scales roughly like p_c ~ (C S^2)/(a ln(1/a)) (if the patterns are randomly correlated). Interestingly, after retrieving an externally cued attractor, the network can continue jumping, or latching, from attractor to attractor, driven by adaptation effects. The occurrence and duration of latching dynamics is found through simulations to depend critically on the strength of local attractor states, expressed in the Potts model by a parameter w. Here we describe with simulations and then analytically the boundaries between distinct phases of no latching...

Adaptation dynamics of the quasispecies model

Jain, Kavita
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 26/02/2008
Relevância na Pesquisa
45.98%
We study the adaptation dynamics of an initially maladapted population evolving via the elementary processes of mutation and selection. The evolution occurs on rugged fitness landscapes which are defined on the multi-dimensional genotypic space and have many local peaks separated by low fitness valleys. We mainly focus on the Eigen's model that describes the deterministic dynamics of an infinite number of self-replicating molecules. In the stationary state, for small mutation rates such a population forms a {\it quasispecies} which consists of the fittest genotype and its closely related mutants. The quasispecies dynamics on rugged fitness landscape follow a punctuated (or step-like) pattern in which a population jumps from a low fitness peak to a higher one, stays there for a considerable time before shifting the peak again and eventually reaches the global maximum of the fitness landscape. We calculate exactly several properties of this dynamical process within a simplified version of the quasispecies model.; Comment: Proceedings of Statphys conference at IIT Guwahati, to be published in Pramana

Unstable Dynamics of Adaptation in Unknown Environment due to Novelty Seeking

Zgonnikov, Arkady; Lubashevsky, Ihor
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
36.1%
Learning and adaptation play great role in emergent socio-economic phenomena. Complex dynamics has been previously found in the systems of multiple learning agents interacting via a simple game. Meanwhile, the single agent adaptation is considered trivially stable. We advocate the idea that adopting a more complex model of the individual behavior may result in a more diverse spectrum of macro-level behaviors. We develop an adaptation model based on the reinforcement learning framework extended by an additional processing channel. We scrutiny the dynamics of the single agent adapting to the unknown environment; the agent is biased by novelty seeking, the intrinsic inclination for exploration. We demonstrate that the behavior of the novelty-seeking agent may be inherently unstable. One of the surprising results is that under certain conditions the increase of the novelty-seeking level may cause the agent to switch from the non-rational to the strictly rational behavior. Our results give evidence to the hypothesis that the intrinsic motives of agents should be paid no less attention than the extrinsic ones in the models of complex socio-economic systems.; Comment: 18 pages, 6 figures

Exploiting the adaptation dynamics to predict the distribution of beneficial fitness effects

John, Sona; Seetharaman, Sarada
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 26/02/2015
Relevância na Pesquisa
46.1%
Adaptation of asexual populations is driven by beneficial mutations and therefore, its dynamics depend on the distribution of beneficial fitness effects. This distribution, when the fitnesses are uncorrelated, can only be of three types.We numercially study the adaptation dynamics when the fitness of the beneficial mutations belongs to one of the three distributions to identify the quantities that show qualitatively different trends in each. We find that the fitness difference between successive mutations that spread in the population and the adaptation rate reached after a few generations display different patterns in the three domains of distribution of beneficial fitnesses. The former quantity decreases or is a constant or increases depending on whether the fitness distribution of beneficial fitnesses is truncated or decays as an exponential or decays as a power law, respectively. We also find that the rate of adaptation shows a strong dependence on the number of mutants produced when the fitness distribution decays as a power law, but is affected weakly otherwise. We discuss how these qualitatively different trends can be exploited to determine the distribution of beneficial fitness effects in experiments.; Comment: This article appeared as a version 3 of 1308.0962 is an error occurred while trying a new submission