ABSTRACT High acidity and low soil P availability in the soils from the Pampa natural grasslands generally limit the forage growth and economic return. Thus, to increase the economic return and avoid environmental degradation and biodiversity loss due to replacement by intensive cropping systems, it is essential to improve the soil P availability. This study aimed to diagnose the nutritional status of the pluri-specific natural grasslands amended with different history of P sources. Additionally, we also try to indicate the most appropriate range of soil P availability for maximizing forage growth. The experiment started in 1997 in an area of Pampa natural grasslands in the state of Rio Grande do Sul, Brazil. The treatments evaluated the application of Gafsa hyperphosphate (HP) and triple superphosphate (SP) for four years (1997, 1998, 2002, and 2010). Soil and aboveground biomass sampling were performed five times from October 2010 to March 2011 to access aboveground biomass production, botanical composition, soil available P, and N and P nutrition index. Greater P availability in the soil amended with SP produced more forage and resulted in a higher P accumulation than in the soil amended with HP. The ideal range of soil P availability in the soils of natural grasslands ranged from 14 to 20 mg kg˗1, varying for different plant species. The species Paspalum plicatulum and Aristida laevis produce less aboveground biomass and accumulate less P in their tissue than Dichantelium sabulorum and Eustachys uliginosa, and P. notatum. Therefore, areas of natural grasslands dominated by D. sabulorum, E. uliginosa and P. notatum demand higher soil P availability to maintain high forage production. Soil P fertilization of pluri-specific natural grasslands in the Brazilian Pampa biome must consider the dominant forage species in the area and the soil P availability.

Este trabalho apresenta um modelo de despacho hidrotérmico à usinas individualizadas, utilizando métodos de otimização baseados em programação não linear. Para tanto, considera-se funções de custo futuro geradas por um modelo de decisão estratégica baseado em programação dinâmica e sistemas equivalentes de energia. O modelo proposto considera diversos cenários históricos de afluências hidrológicas às usinas hidrelétricas, os quais são simulados para um horizonte de planejamento da operação de médio/longo prazo. Os resultados obtidos através do modelo proposto, denominado Modelo Individualizado de Usinas Hidráulicas (MIUH), são comparados com os resultados obtidos a partir da utilização do modelo SUISHI-O adotado pelo Operador Nacional do Sistema Elétrico Brasileiro (ONS).

This paper presents a method to the hydrothermal dispatch using optimization techniques based on non linear programming techniques. To do so, the expected cost-to-go functions from a long term operation plannning strategic decision model are used. This decision model is based on stochastic dual dynamic programming and energy equivalent reservoirs. The proposed method considers a set of historical water inflow scenarios to the hydroelectric reservoirs. Those scenarios are used to simulate the long term operation planning to a given horizon. The results obtained from this disaggregation model (MIUH) are compared with those from the model officially adopted in the Brazilian power system, SUISHI-O. The latter is based on operation heuristics aiming at operating the reservoir maintaining the water storag e in similar levels, that is, trying to operate them in parallel.

INTRODUCCIÓN: la hipertrofia ventricular izquierda, asociada a peor pronóstico cardiovascular, aumenta el riesgo de morbilidad y mortalidad cuando la misma se relaciona con paroxismos de fibrilación auricular; esta arritmia puede predecirse con la medición electrocardiográfica de la onda P al calcular la duración máxima y mínima, y su dispersión. OBJETIVO: determinar las variaciones electrocardiográficas en la duración de la onda P según modificaciones de la presión arterial y de mediciones ecocardiográficas, en niños entre 8 a 11 años. MÉTODOS: se estudiaron 90 niños a quienes se les realizó electrocardiograma de superficie de doce derivaciones, ecocardiograma y toma de presión arterial. Se midieron los valores de P máxima, P mínima y las 12 derivaciones del electrocardiograma, y se calculó la dispersión de la onda P como la diferencia entre su duración máxima y mínima. RESULTADOS: no se encontraron diferencias significativas según género para los resultados de medias de dispersión de la onda P. El coeficiente de correlación (r) para la tensión arterial sistólica fue r=0,159 con una significación de p=0,03. Un análisis multivariado mostró una correlación significativa entre la dispersión de la onda P y la velocidad de la onda A del flujo de entrada mitral (r=0,227 y p=0,01). CONCLUSIONES: existe una dependencia de la dispersión de la onda P del electrocardiograma de variables tales como presión arterial sistólica y velocidad de la onda A del flujo sanguíneo de entrada mitral, hecho que ha sido relacionado con riesgo de fibrilación auricular en el adulto.

INTRODUCTION: left ventricular hypertrophy associated with worse cardiovascular prognosis increases the risk of morbidity and mortality when associated with paroxysms of atrial fibrillation. This arrhythmia can be predicted by measuring the maximum and minimum P wave duration in the electrocardiogram, and by calculating its dispersion. OBJECTIVE: to determine the electrocardiographic changes in P wave duration according to modifications in blood pressure and echocardiographic measurements in children between 8-11 years old. METHODS: we studied 90 children who underwent 12- lead surface electrocardiogram, echocardiogram and blood pressure measurements. We measured the values of maximum P, minimum P and 12-lead electrocardiogram, and calculated the P wave dispersion as the difference between its maximum and minimum duration. RESULTS: there were no significant differences by sex for the results of average P-wave dispersion The correlation coefficient (r) for systolic blood pressure was r = 0.159 with a significance of p = 0.03. A multivariate analysis showed a significant correlation between P wave dispersion and the velocity of the mitral inflow A wave(r = 0.227 and p = 0.01). CONCLUSIONS: there is a dependency between the dispersion of the P wave in the electrocardiogram and variables such as systolic blood pressure and A wave velocity of mitral inflow, fact that has been linked to risk of atrial fibrillation in adults.

Objective: To show the clinical management of rhabdomyolysis secondary to laparoscopic surgery and how clinical treatment may be enough for adequate resolution. Methods: Laparoscopic nephrectomy is a routine technique, which may have associated morbidity. We present one case of rhabdomyolysis which presented as gluteal pain and functional impotency, together with skin lesions, acute renal failure and elevated muscle enzymes. Results: In our case, the patient had a satisfactory outcome with medical treatment. We perform a bibliographic review in which we identify multiple risk factors, such as body mass index, surgical time, position during operation with lateral decubitus and 40-60° flexion. Prevention is the most important factor to avoid acute renal failure secondary to myoglobin. Conclusions: Prevention, early detection, and immediate start of therapeutic measures are essential for the good resolution of rhabdomyolysis after surgery.

Objetivos: Nos planteamos en este caso clínico mostrar el manejo de la rabdomiolisis secundaria a la cirugía laparoscópica y como el tratamiento médico puede ser suficiente para una correcta resolución del mismo. Métodos: La nefrectomía laparoscópica es una técnica de rutina, no exenta de morbilidad asociada. Presentamos un caso de rabdomiolisis que debutó como dolor glúteo e impotencia funcional, junto con alteraciones cutáneas, insuficiencia renal aguda y enzimas musculares elevadas. Resultados: En nuestro caso el paciente evolucionó satisfactoriamente con tratamiento médico. Hacemos una revisión de la literatura publicada, donde se identifican múltiples factores de riesgo, tales como el IMC (índice de masa corporal), tiempo quirúrgico, la posición durante el acto quirúrgico en decúbito lateral con flexión 40-60°. La prevención es el factor más importante para evitar la insuficiencia renal aguda por mioglobina. Conclusiones: La prevención, la detección precoz y la instauración inmediata de medidas terapeúticas son fundamentales para la buena resolución del cuadro de rabdomiolisis tras cirugía.