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In this longitudinal study, we aimed at determining whether children who efficiently use finger counting are more likely to develop internalized arithmetic strategies than children who are less efficient. More precisely, we analyzed the behavior of 24 kindergarteners aged between 5 and 6 years who used their fingers to solve addition problems, and we were interested in determining the evolution of their finger counting strategies towards mental strategies after 2 years (Grade 2). Our results show that kindergarteners who were the most proficient in calculating on fingers were the more likely to have abandoned this strategy in Grade 2. This shows that the use of efficient finger counting strategies early during development optimizes the shift to mental strategies later on during school years. Moreover, children who still use their fingers to solve additions in Grade 2 present lower working memory capacities than children who had already abandoned this strategy.

The paper examines the optimal two-part tariff problem in the residential electricity sector. It is shown that, even with distributional concerns, the optimal tariff for a public monopoly is not uniform across regions if marginal costs are differentiated. This sub-optimality result does extend to the case of a regulated private monopoly. It is also shown that the imposition of a uniform tariff constraint gives raise to a trade-off between equity and efficiency. Finally, a simple tariff reform is examined, proving able to provide (both for a public and a private monopoly) a strong Pareto improvement.

Fil: Poletti C., Oscar Héctor. Universidad Nacional del Nordeste. Facultad de Medicina; Argentina. Fil: Barrios, M. Lilian. Universidad Nacional del Nordeste. Facultad de Medicina; Argentina. Objetivo: Ponderar prevalencia de sobrepeso y obesidad en escolares de Corrientes. Material y Método: Estudio transversal observacional. Entre marzo de 2000 y septiembre de 2002, se determinó peso y talla en escolares de 6 a 11 años de edad de la ciudad de Corrientes. Los indicadores antropométricos utilizados fueron peso/edad; talla/edad y peso/talla, que se convirtieron a puntos Z de desvío estándar y luego comparados con estándares NCHS. Resultados: Estudiamos 3 931 escolares con edad promedio de 8,2 años. El 8,3% de los niños presentó obesidad y el 14,1% sobrepeso. La mediana para puntaje Z de talla/edad fue de -041 (IC 95% -0,45 a -0,38), para peso/edad: -0,15 (-0,17 a -0,08) y peso/talla: 0,24 (0,02 a 0,26). Conclusiones: En los escolares de Corrientes existe una alta prevalencia de obesidad y sobrepeso, coexistiendo con talla baja, problemas pendientes a resolver. Se hace perentorio implementar programas preventivos y de educación nutricional aplicados a las escuelas primarias. Objective: To measure the prevalence of overweight and obesity ¡n schoolchildren from Corrientes. Methods and Materials: Between March 2000 and September 2002, a cross sectional study was performed in shoolchildren of both sexes, aged 6-11 years in the population of Corrientes. The valúes for helght/age, weight/age and weight/height were converted ¡nto z scores, and compared with NCHS reference valúes. Results: 3.931 children were studied, 14,1% were overwelght and 8,3% obese. Average z scores for height/age were -0.45 (95% Cl -0.45 to -0.38), weight/age -0.15 (range -0.17 to -0.08) and weight/height 0.24 (range 0.20 to 0.26). Conclusions: Our results show that obesity and overweight children coexlst with those who are underweight. There is a preemptory need of health education and prevention in schools.

Objetivo:Ponderar prevalencia de sobrepeso y obesidad en escolares de Corrientes. Material y Método: Estudio transversal observacional. Entre marzo de 2000 y septiembre de 2002, se determinó peso y talla en escolares de 6 a 11 años de edad de la ciudad de Corrientes. Los indicadores antropométricos utilizados fueron peso/edad; talla/edad y peso/talla, que se convirtieron a puntos Z de desvío estándar y luego comparados con estándares NCHS. Resultados: Estudiamos 3 931 escolares con edad promedio de 8,2 años. El 8,3% de los niños presentó obesidad y el 14,1% sobrepeso. La mediana para puntaje Z de talla/edad fue de -041(IC 95% -0,45 a -0,38), para peso/edad: -0,15 (-0,17 a -0,08) y peso/talla: 0,24 (0,02 a 0,26). Conclusiones: En los escolares de Corrientes existe una alta prevalencia de obesidad y sobrepeso, coexistiendo con talla baja, problemas pendientes a resolver. Se hace perentorio implementar programas preventivos y de educación nutricional aplicados a las escuelas primarias Objective: To measure the prevalence of overweight and obesity in schoolchildren from Corrientes. Methods and Materials: Between March 2000 and September 2002, a cross sectional study was performed in shoolchildren of both sexes, aged 6-11 years in the population of Corrientes. The values for height/age, weight/age and weight/height were converted into z scores, and compared with NCHS reference values. Results: 3.931 children were studied, 14,1% were overweight and 8,3% obese. Average z scores for height/age were -0.45 (95% CI -0.45 to -0.38), weight/age -0.15 (range -0.17 to -0.08) and weight/height 0.24 (range 0.20 to 0.26). Conclusions: Our results show that obesity and overweight children coexist with those who are underweight. There is a preemptory need of health education and prevention

The purpose of the study was to assay monoamines in cerebrospinal fluid (CSF) obtained from the trigeminal cistern of 64 patients with intractable facial pain. The CSF was analyzed for homovanillic acid (HVA), 5-hydroxyindoleacetic acid (5-HIAA), and 3-methoxy-4-hydroxyphenylglycol (MHPG), end-product markers of activity for the dopamine, serotonin, and norepinephrine systems, respectively. HVA averaged 121 ng/mL in these facial pain patients, compared to 150 to 550 ng/mL in 10 studies of ventricular brain CSF in assorted psychiatric and pain patients. 5-HIAA averaged 29 to ng/mL in our facial pain patients compared to 60 to 120 ng/mL in nine studies of ventricular brain CSF in assorted psychiatric and neurological patients. Trigeminal cistern CSF MHPG averaged 9 ng/mL, similar to the range of 13 studies of lumbar CSF of assorted psychiatric and pain diagnoses. These results indicate that (1) the electrochemical detection method provides a unique way of accurately measuring nanogram concentrations of multiple monoamines in a little as 0.25 mL of CSF; (2) trigeminal cistern and posterior fossa brain CSF monoamine metabolites reflect a different profile of dopaminergic and serotonergic functioning in these facial pain patients from that previously reported with lumbar CSF measurements of other patients; and (3) trigeminal sensory ganglion or brain dopamine and serotonin systems may be concomitantly dysfunctional in intractable facial pain.