O estudo teve o objetivo de testar a hipótese de que o efeito alcalinizante da solução de Ringer com lactato (SRL) pode ser maior nos animais portadores de acidose metabólica do que nos sadios, como consequência da necessidade de retorno ao equilíbrio. Seis ovelhas receberam a SRL em volume correspondente a 10% do peso corporal, administrada por infusão contínua intravenosa, durante quatro horas, em duas condições definidas: enquanto eram saudáveis e após a indução experimental de acidose láctica ruminal aguda (ALRA). Amostras de sangue venoso e de urina foram colhidas em quatro momentos: antes do início da infusão, na metade do volume infundido, ao término da infusão e duas horas após. Foram determinados valores de pH sanguíneo e urinário, de pCO2, HCO3 - e BE no sangue, de Na+, K+, Cl-, SID, AG, PPT, Atot e lactato L no plasma, e das excreções fracionadas urinárias de Na+, K+, Cl- e lactato L. A SRL provocou hemodiluição, mas não interferiu nos equilíbrios eletrolítico e acidobase das ovelhas sadias. Apesar de eficaz para reverter a desidratação, não foi capaz de corrigir a acidose metabólica presente após a indução da ALRA.

The aim of this study was to investigate if the alkalinizing effect of lactated Ringer's solution (LRS) is greater in animals with metabolic acidosis than in healthy ones, as a result of the need to restore acid-base balance. LRS was intravenously infused in a volume corresponding to 10% of body weight, continously during four hours, in two definite conditions in the same six ewes: when they were healthy and after experimentally induced acute rumen lactic acidosis (ARLA). Venous blood and urine samples were taken in four moments: before the beginning, in the middle, at the end of the infusion and two hours after. Blood and urine pH, blood pCO2, HCO3 - and BE, and plasma Na+, K+, Cl-, TP and L lactate were measured. Na+, K+, Cl- and L lactate fractional clearance and plasma SID, AG, and Atot were calculated. LRS caused hemodilution but didn't change electrolyte and acid-base balances in healthy ewes. When ewes were affected by ARLA, the infusion of this solution was effective for dehydration reversion but was unable to correct metabolic acidosis.

Luego de una breve revisión del reciente campo de la Sociofísica, se presenta un modelo tipo autómata celular de una influencia cultural externa o propaganda masiva actuando en un sistema social. El modelo está basado en la dinámica de diseminación cultural de Axelrod. Se encuentra que la propaganda induce una transición de fase en el sistema: si la intensidad de la propaganda aplicada es menor que un valor umbral, ésta logra imponer su estado en todo el sistema; es decir, el sistema adquiere un estado ordenado homogéneo e igual al estado cultural de la propaganda. Sin embargo, si la intensidad de la propaganda es mayor que el valor umbral, entonces el sistema alcanza un estado desordenado caracterizado por la presencia de muchos grupos culturales distintos. Estos estados se describen en el espacio de parámetros del sistema, dado por la intensidad de la propaganda y por el número de opciones culturales disponibles.

After a brief review of the recent field of Sociophysics, we present a cellular automata model of an external cultural influence or message, such as a controlled mass media, acting on a social system. The model is based on the rules of cultural dissemination proposed by Axelrod. It is found that the external message induces a phase transition in the system: if the intensity of the message is less than some threshold value, the message can impose its cultural state to the system, that is, the system reaches an ordered, homogeneous state equal to the cultural state of the message. However, if the intensity of the transmitted message is above the threshold value, the system reaches a disordered state characterized by the presence of many different cultural groups. These states are described in the space of parameters of the system, consisting of the intensity of the message or mass media influence and the number of available cultural options.

A system of electronic oscillators was designed to study experimentally the emergence of self-organization when the radiation acts as the mechanism of interacction between the oscilators. The experimental array consists of a set of pulsed LEDs (Light Emision Diodes) and photo-resistors. The distance between the oscillating elements can be varied in order to modify the degree of coupling among them. The system is not completely homogeneous due to existing differences among the different electronic components of each oscillator. The occurrence of out of phase synchronization and the formation of spatiotemporal patterns are observed in this system.

Se diseñó y construyó un sistema electrónico de osciladores luminosos para estudiar experimentalmente el surgimiento de auto-organización cuando la radiación actúa como mecanismo de acoplamiento entre los osciladores. El montaje experimental consiste en un conjunto de LEDs (diodos emisores de luz) pulsados y fotorresistencias. La distancia entre los elementos osciladores puede variarse para modificar el grado de acoplamiento entre ellos. El sistema es heterogéneo debido a las diferencias existentes entre los distintos componentes electrónicos de cada oscilador. Se observó la ocurrencia de fenómenos de sincronización y formación de patrones espacio-temporales en este sistema.