Characterizing Individual Communication Patterns (2009)
Malmgren, R. Dean, Hofman, Jake M., Amaral, Luis A. N., Watts, Duncan J.
The increasing availability of electronic communication data, such as that arising from e-mail exchange, presents social and information scientists with new possibilities for characterizing...
A Poissonian explanation for heavy-tails in e-mail communication (2009)
Malmgren, R. Dean, Stouffer, Daniel B., Motter, Adilson E., Amaral, Luis A. N.
Patterns of deliberate human activity and behavior are of utmost importance in areas as diverse as disease spread, resource allocation, and emergency response. Because of its widespread availability...
Log-normal statistics in e-mail communication patterns (2006)
Stouffer, Daniel B., Malmgren, R. Dean, Amaral, Luis A. N.
Following up on Barabasi's recent letter to Nature [435, 207--211 (2005)], we systematically investigate the time series of e-mail usage for 3,188 users at a university. We focus on two quantities...
Comment on Barabasi, Nature 435, 207 (2005) (2005)
Stouffer, Daniel B., Malmgren, R. Dean, Amaral, Luis A. N.
In a recent letter, Barabasi claims that the dynamics of a number of human activities are scale-free [1]. He specifically reports that the probability distribution of time intervals tau between...
Canalizing Kauffman networks: non-ergodicity and its effect on their critical behavior (2005)
Moreira, Andre A., Amaral, Luis A. N.
Boolean Networks have been used to study numerous phenomena, including gene regulation, neural networks, social interactions, and biological evolution. Here, we propose a general method for...
Emergence of Complex Dynamics in a Simple Model of Signaling Networks (2004)
Amaral, Luis A. N., Diaz-Guilera, Albert, Moreira, Andre A., Goldberger, Ary L., Lipsitz, Lewis A.
A variety of physical, social and biological systems generate complex fluctuations with correlations across multiple time scales. In physiologic systems, these long-range correlations are altered...
Modularity from Fluctuations in Random Graphs and Complex Networks (2004)
Guimera, Roger, Sales-Pardo, Marta, Amaral, Luis A. N.
The mechanisms by which modularity emerges in complex networks are not well understood but recent reports have suggested that modularity may arise from evolutionary selection. We show that finding...
Keitt, Timothy H., Amaral, Luis A. N., Buldyrev, Sergey V., Stanley, H. E.
We consider statistical patterns of variation in growth rates for over 400 species of breeding birds across North America surveyed from 1966 to 1998. We report two results. First, the standard...
Analytical solution of a model for complex food webs (2001)
Camacho, Juan, Guimera, Roger, Amaral, Luis A. N.
We investigate numerically and analytically a recently proposed model for food webs [Nature {\bf 404}, 180 (2000)] in the limit of large web sizes and sparse interaction matrices. We obtain...
Erratum: Small-world networks: Evidence for a crossover picture (1999)
Barthelemy, Marc, Amaral, Luis A. N.
We correct the value of the exponent \tau.
Small-world networks: Evidence for a crossover picture (1999)
Barthelemy, Marc, Amaral, Luis A. N.
Watts and Strogatz [Nature 393, 440 (1998)] have recently introduced a model for disordered networks and reported that, even for very small values of the disorder $p$ in the links, the network...
Universal features in the growth dynamics of complex organizations (1998)
Lee, Youngki, Amaral, Luis A. N., Canning, David, Meyer, Martin, Stanley, H. Eugene
We analyze the fluctuations in the gross domestic product (GDP) of 152 countries for the period 1950--1992. We find that (i) the distribution of annual growth rates for countries of a given GDP...
Environmental changes, co-extinction, and patterns in the fossil record (1998)
Amaral, Luis A. N., Meyer, Martin
We introduce a new model for large scale evolution and extinction in which species are organized into food chains. The system evolves by two processes: origination/speciation and extinction. In the...
Stochastic Feedback and the Regulation of Biological Rhythms (1997)
Ivanov, Plamen Ch., Amaral, Luis A. N., Goldberger, Ary, Stanley, H. Eugene
We propose a general approach to the question of how biological rhythms spontaneously self-regulate, based on the concept of ``stochastic feedback''. We illustrate this approach by considering the...
Fractal dynamics in physiology: Alterations with disease and aging
Goldberger, Ary L., Amaral, Luis A. N., Hausdorff, Jeffrey M., Ivanov, Plamen Ch., Stanley, H. Eugene
According to classical concepts of physiologic control, healthy systems are self-regulated to reduce variability and maintain physiologic constancy. Contrary to the predictions of homeostasis,...
Fractal dynamics in physiology: Alterations with disease and aging
Goldberger, Ary L., Amaral, Luis A. N., Hausdorff, Jeffrey M., Ivanov, Plamen Ch., Stanley, H. Eugene
According to classical concepts of physiologic control, healthy systems are self-regulated to reduce variability and maintain physiologic constancy. Contrary to the predictions of homeostasis,...
Keitt, Timothy H, Amaral, Luis A N, Buldyrev, Sergey V, Stanley, H Eugene
We consider statistical patterns of variation in growth rates for over 400 species of breeding birds across North America surveyed from 1966 to 1998. We report two results. First, the standard...
Cascading failure and robustness in metabolic networks
Smart, Ashley G., Amaral, Luis A. N., Ottino, Julio M.
We investigate the relationship between structure and robustness in the metabolic networks of Escherichia coli, Methanosarcina barkeri, Staphylococcus aureus, and Saccharomyces cerevisiae, using a...