Américo Tristão Bernardes

Cross-over, thresholds, and interactions between science and technology: lessons for less-developed countries

Abstract Presently, science is an important precondition for the economic development of less-developed countries. This paper discusses the specific roles that science has at initial stages of development, pointing to its contributions for the countries’ absorptive capability. Furthermore, this paper specifies the role of science for initiating a positive interaction with technological development, since initial stages of development and during catching up processes. For less-developed countries, neither the linear model of technology nor an “inverted linear model” would take place: a more interactive approach is necessary for development. Using statistics of patents (USPTO) and scientific papers (ISI) for 120 countries (1974, 1982, 1990, and 1998), this paper analyses some evidences on thresholds levels of scientific production to originate an interactive relationship between science and technology. These data also document that the value of this threshold seems to double from one period to another. Although this paper presents tentative results, some policy implications are discussed: scientific institutional building must be seen as a component of modern industrial policies.

Monte Carlo simulation of a lattice model for micelle formation

We have investigated the aggregation into micelles of nonionic amphiphiles in water through Monte Carlo simulations of a very simple model system. Amphiphiles and water are modeled, respectively, as three‐site and one‐site molecules on a square lattice. The model presents characteristic properties of experimental micellization, namely, monomer vs amphiphile concentration with a plateau above a ‘‘critical’’ concentration (cmc) and a distribution of micelle sizes (polydispersity). Results of the numerical experiment were compared with predictions from statistical thermodynamic theory. Sample size and relaxation properties of the simulation have also been analyzed.

MONTE CARLO SIMULATION OF VOLATILITY CLUSTERING IN MARKET MODEL WITH HERDING

Through slow changes in the position of the traders, we introduce correlations between the volatility (root mean square change) of the prices at different times. We find this volatility correlation to decay slowly with time, as also observed in reality, and quite independent of the dimensionality of the lattice. We also make the trading activity of a cluster of traders proportional to the cluster size.

Matrices of science and technology interactions and patterns of structured growth: implications for development

Scientific and other non-patent references (NPRs) in patents are important tools to analyze interactions between science and technology. This paper organizes a database with 514,894 USPTO patents granted globally in 1974, 1982, 1990, 1998 and 2006. There are 165,762 patents with at least one reference to science and engineering (S&E) literature, from a total of 1,375,503 references. Through a lexical analysis, 71.1% of this S&E literature is classified by S&E fields. These data serve as the basis for the elaboration of global and national 3-dimensional matrices (technological domains, S&E fields and number of references). Three indicators are proposed to analyze these matrices, allowing us to identify patterns of structured growth that differentiate developed and non-developed countries. This differentiation informs suggestions for public policies for development, emphasizing the need for an articulation between the industrial and technological dimension and scientific side. The intertwinement of these two dimensions is a key component of developmental policies for the twenty-first century.

Science in the developing world: running twice as fast?

Physicists are increasingly interested in studying the behavior of financial markets; likewise, researchers have applied statistical physics tools to study economic development in - and interactions among - various countries. We recently introduced a model that creates an artificial world economy of countries, each of which has a population with scientific and technological capabilities. The models main goal is to probe the underlying mechanisms responsible for the interactions among science, technology, and development. So far, it has shown a strong correlation between economic development and scientific and technological production.

Immunization and Aging: a Learning Process in the Immune Network

The immune system can be thought as a complex network of different interacting elements. A cellular automaton, defined in shape-space, was recently shown to exhibit self-regulation and complex behavior and is, therefore, a good candidate to model the immune system. Using this model to simulate a real immune system we find good agreement with recent experiments on mice. The model exhibits the experimentally observed refractory behavior of the immune system under multiple antigen presentations as well as loss of its plasticity caused by aging.

Can males contribute to the genetic improvement of a species

In the time evolution of finite populations, the accumulation of harmful mutations in further generations might have lead to a temporal decay in the mean fitness of the whole population. This, in turn, would reduce the population size and so lead to its extinction. The production of genetically diverse offspring, through recombination, is a powerful mechanism in order to avoid this catastrophic route. From a selfish point of view, meiotic parthenogenesis can ensure the maintenance of better genomes, while sexual reproduction presents the risk of genome dilution. In this paper, by using Monte Carlo simulations of age-structured populations, through the Penna model, I compare the evolution of populations with different repoductive regimes. It is shown that sexual reproduction with male competition can produce better results than meiotic parthenogenesis. This contradicts results recently published, but agrees with the strong evidence that nature chose sexual reproduction instead of partenogenesis for most of the higher species.

Mutation load and the extinction of large populations

In the time evolution of finite populations, the accumulation of harmful mutations in further generations might lead to a temporal decay in the mean fitness of the whole population that, after sufficient time, would reduce population size and so lead to extinction. This joint action of mutation load and population reduction is called Mutational Meltdown and is usually considered only to occur in small asexual or very small sexual populations. However, the problem of extinction cannot be discussed in a proper way if one previously assumes the existence of an equilibrium state, as initially discussed in this paper. By performing simulations in a genetically inspired model for time-changing populations, we show that mutational meltdown also occurs in large asexual populations and that the mean time to extinction is a nonmonotonic function of the selection coefficient. The stochasticity of the extinction process is also discussed. The extinction of small sexual N ∼ 700 populations is shown and our results confirm the assumption that the existence of recombination might be a powerful mechanism to avoid extinction.

A methodology for unveiling global innovation networks: patent citations as clues to cross border knowledge flows

This paper presents a new methodology to describe global innovations networks. Using 167,315 USPTO patents granted in 2009 and the papers they cited, this methodology shows “scientific footprints of technology” that cross national boundaries, and how multinational enterprises interact globally with universities and other firms. The data and the map of these flows provide insights to support a tentative taxonomy of global innovation networks.

Analysis of chaotic behaviour in the population dynamics

Recently, we have shown that the Penna bitstring model for population senescence can be used to model cyclic or chaotic behaviours in population dynamics. In this paper, we analyse the attractor of the dynamics, through the calculation of the Lyapunov exponents. We obtained that the dynamics is characterized by the existence of some small exponents, which we relate to the existence of homeochaos, needed for the generation of stability and diversity in living systems.