Os dois métodos e o núcleo duro da teoria econômica

While methodological sciences have no object and are supposed to adopt a hypothetical-deductive method, substantive sciences including economics should use an empirical or historical-deductive method. The great classical economists and Keynes did that and were able to develop open models explaining how equally open economic systems work. Thus, the hard core of relevant economics is formed by the classical microeconomics and the classical theory of capitalist economic growth, and by Keynesian macroeconomics. In contrast, neoclassical economist aiming to build a mathematical science wrongly adopted the hypothetical-deductive method, and came to macroeconomic and growth models that do not have practical use in policymaking. The exception is Marshall's microeconomics that does not provide a model of real economic systems, but is useful to the analysis of markets.

Dois métodos ou duas antropologias?

This is a commentary to a well-known paper of Bresser-Pereira: The two methods and the hard core of economics. Therefore, it target a very suggestive article that seeks to examine the conceptions of man of classical political economy and Keynesian economics in contrast to the reductive conception of man found in positive economic theory, especially in neoclassical theory. It shows that both conceptions at large think with abstracts economic men. However, the first one reasons with individuals who are determined by the historical and social structures of the capitalistic economic system. The second one seeks to present them in a formal way, as if they were mere pieces of a large automaton, i.e., the mercantile system as a large and standardized mechanism. In the end, Marx is distinguished because he does not reflect based on a static anthropological foundation. For him, men are subjects that become because they can realize themselves only in the course of history.

On the economic analysis of response to preventive measures

There are many circumstances in which the effectiveness of preventive measures depends to a large extent on the compliance of the patient in changing his or her behavior or lifestyle. It is shown how economic techniques can be used (i) to describe the rationale of individuals and predict their behavior (Section 2); and (ii) to assess preventive measures that, by requiring a change of conduct, imply "costs" to the individual due to a decline in the quality of life (Appendix). Cigarette smoking and coronary heart disease are used as an illustration. While the analysis of Section 2 uses graphical techniques, a simple textbook-type of lifetime utility model with a mathematical emphasis is used in the Appendix. It is also shown that techniques often used to assess health care programs such as the QALYs (Quality-Adjusted Life Years) are inappropriate to the evaluation of preventive programs aiming at behavioral changes. Finally, topics that call for further research are indicated.

A mathematical model for malaria transmission relating global warming and local socioeconomic conditions

OBJECTIVE: Sensitivity analysis was applied to a mathematical model describing malaria transmission relating global warming and local socioeconomic conditions. METHODS: A previous compartment model was proposed to describe the overall transmission of malaria. This model was built up on several parameters and the prevalence of malaria in a community was characterized by the values assigned to them. To assess the control efforts, the model parameters can vary on broad intervals. RESULTS: By performing the sensitivity analysis on equilibrium points, which represent the level of malaria infection in a community, the different possible scenarios are obtained when the parameters are changed. CONCLUSIONS: Depending on malaria risk, the efforts to control its transmission can be guided by a subset of parameters used in the mathematical model.

Dynamics of experimental populations of native and introduced blowflies (Diptera: Calliphoridae): mathematical modelling and the transition from asymptotic equilibrium to bounded oscillations

The equilibrium dynamics of native and introduced blowflies is modelled using a density-dependent model of population growth that takes into account important features of the life-history in these flies. A theoretical analysis indicates that the product of maximum fecundity and survival is the primary determinant of the dynamics. Cochliomyia macellaria, a blowfly native to the Americas and the introduced Chrysomya megacephala and Chrysomya putoria, differ in their dynamics in that the first species shows a damping oscillatory behavior leading to a one-point equilibrium, whereas in the last two species population numbers show a two-point limit cycle. Simulations showed that variation in fecundity has a marked effect on the dynamics and indicates the possibility of transitions from one-point equilibrium to bounded oscillations and aperiodic behavior. Variation in survival has much less influence on the dynamics.

Mathematical equation correction to spectral and transport interferences in high-resolution continuum source flame atomic absorption spectrometry: determination of lead in phosphoric acid

In this work, a new mathematical equation correction approach for overcoming spectral and transport interferences was proposed. The proposal was applied to eliminate spectral interference caused by PO molecules at the 217.0005 nm Pb line, and the transport interference caused by variations in phosphoric acid concentrations. Correction may be necessary at 217.0005 nm to account for the contribution of PO, since Atotal217.0005 nm = A Pb217.0005 nm + A PO217.0005 nm. This may be easily done by measuring other PO wavelengths (e.g. 217.0458 nm) and calculating the relative contribution of PO absorbance (A PO) to the total absorbance (Atotal) at 217.0005 nm: A Pb217.0005 nm = Atotal217.0005 nm - A PO217.0005 nm = Atotal217.0005 nm - k (A PO217.0458 nm). The correction factor k is calculated from slopes of calibration curves built up for phosphorous (P) standard solutions measured at 217.0005 and 217.0458 nm, i.e. k = (slope217.0005 nm/slope217.0458 nm). For wavelength integrated absorbance of 3 pixels, sample aspiration rate of 5.0 ml min-1, analytical curves in the 0.1 - 1.0 mg L-1 Pb range with linearity better than 0.9990 were consistently obtained. Calibration curves for P at 217.0005 and 217.0458 nm with linearity better than 0.998 were obtained. Relative standard deviations (RSD) of measurements (n = 12) in the range of 1.4 - 4.3% and 2.0 - 6.0% without and with mathematical equation correction approach were obtained respectively. The limit of detection calculated to analytical line at 217.0005 nm was 10 µg L-1 Pb. Recoveries for Pb spikes were in the 97.5 - 100% and 105 - 230% intervals with and without mathematical equation correction approach, respectively.

Mathematical models to describe the volumetric shrinkage rate of red beans during drying

The present study aimed to determine the volumetric shrinkage rate of bean (Phaseolus vulgaris L.) seeds during air-drying under different conditions of air, temperature and relative humidity, and to adjust several mathematical models to the empiric values observed, and select the one that best represents the phenomenon. Six mathematical models were adjusted to the experimental values to represent the phenomenon. It was determined the degree of adjustment of each model from the value of the coefficient of determination, the behavior of the distribution of the residuals, and the magnitude of the average relative and estimated errors. The rate of volumetric shrinkage that occurred in bean seeds during drying is between 25 and 37%. It basically depends on the final moisture content, regardless of the air conditions during drying. The Modified Bala & Woods' model best represented the process.

Mathematical model to estimate of the deterioration of wooden poles in contact with soil used in rural areas

In São Paulo State, mainly in rural areas, the utilization of wooden poles is observed for different purposes. In this context, wood in contact with the ground presents faster deterioration, which is generally associated to environmental factors and, especially to the presence of fungi and insects. With the use of mathematical models, the useful life of wooden structures can be predicted by obtaining "climatic indexes" to indicate, comparatively among the areas studied, which have more or less tendency to fungi and insects attacks. In this work, by using climatological data of several cities at São Paulo State, a simplified mathematical model was obtained to measure the aggressiveness of the wood in contact with the soil.