Avaliação da carga parasitária de helmintos e protozoários em bezerros manejados em sistema orgânico

The objective of this study was to evaluate the influence of helminths eggs and protozoan oocysts elimination in calves' feces kept in organic system production. The study was conducted from January 2008 to December 2009. Coproparasitological examinations were carried biweekly of 18 calves in pastures rotating system on Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA) Agrobiology. The egg counting average data had been submitted to the Kruskal Willis test and the larvae counting percentile values to the qui-square test. The average counting of eggs per gram of faces (EGF) varied of 250 the 800, characterizing low and moderate infection. Animals with inferior age the six months had presented superior results of EGF (P <.05) to the ones of between six and twelve months age. The biggest degrees of infection had been observed in the late spring and summer. In the fecal examinations was identified the following helminths: Haemonchus (73%), Trichostrongylus (24%) and Oesophagostomum (3%). The practical handling adopted in organic system production had been capable to keep the animals in moderate levels of infection, being indicated that it had helmintoses control in rotating system of pastures.

Influência da pós-carga sobre a taxa de variação da tensão desenvolvida (dT/dt). Estudo em músculo cardíaco isolado.

PURPOSE: To evaluate the effects of afterload on peak rate of tension rise (dT/dt) in the isolated muscle. METHODS: Left ventricular papillary muscles from Wistar rats were studied in isometric and isotonic afterloaded contractions. Muscles were analised in Krebs-Henseleit solution with calcium concentration of 2.52mM at 28 degrees C. The resting muscle length (preload) was maintained constant. The peak isometric developed tension (DT) and dT/dt were measured during increases of afterload (25, 50, 75 and 100% from DT). RESULTS: A rise in afterload corresponding to 50, 75 and 100% of DT, did not cause an increase in dT/dt values (p > 0.05). The dT/dt value decreased (p < 0.05) when afterload was changed from 75% to 25% of DT. CONCLUSION: The data suggest that an increase in the afterload from 50% of the DT did not promote changes in the dT/dt.

Influencia da Carga no Comportamento quanto ao Desgaste de um Aco ABNT-1020 Bifasico Revenido a 450°C

The wear rate of the dual-phase steel ABNT-1020 tempered at 450°C sliding against cemented steel ABNT-1020 in function of load value is investigated in wide load range. The alteration in behavior of this function at intermediate load level, like in the case of low hardness steel sliding against high hardness steel, is observed. The analysis by scanning electronic microscope before and after this alteration showed a change of wear mechanism from plastic displacement to embrittlement.

Sazonalidade, tarifa mais conveniente e fator de carga em indústria de processamento de cana

This paper represents the results of the work carried out in order to study the condition of seasonal consumer, the load factor and the more convenient tariff for a sugar mill located in the Vale do Paranapanema, SP, Brazil. Therefore, data of consume and registered demand were collected during the quadriennium 1990 to 1994. The studies showed that the factory did not maintain the condition of seasonal consumer of electric energy during the analysed period. Low values of the load factor observed in the period showed a non rational use of electric energy supplied by the concessionary. The results showed that only in one situation (load retired in top equal to 90%) the most convenient tariff is the horo-sazonal azul. In the other situations the most convenient tariff is the conventional one.

Implicações da agregação espacial de parasitas para a dinâmica populacional na interação hospedeiro-parasita

Some aspects of the widely observed over-dispersed pattern of the distribution of parasites within the host population are examined. It has been established in the parasitological literature that most hosts usually harbour few parasites, while only few hosts harbour a large proportion of the parasite population. Factors that may influence the pattern of distribution of parasites, the relation between the level of parasite aggregation and the prevalence of infection, and changes in this level of aggregation as a function of host age are analysed. Factors which determine the diversity of species in parasite communities are presented, and aspects of exploitative and interference competition among parasites and their relations with biological control procedures are also considered. Attention is also focused on the regulatory and destabilizing processes influencing the dynamic behaviour of host-parasite population interactions.

Modelo para o estudo da dinâmica evolutiva dos aspectos fisiográficos dos pantanais

This paper studies the applicability of a model to the evolutive dynamics of Pantanal physiography. The Miranda-Aquidauana Pantanal has developed as a pre-existent fluvial plain in the beginning, from Paraguay river, whose ancient marks, recognized by weathering alteration volumes, show components that make possible its relative age determination and consequently permit the comprehension of the ancient and recent dynamic evolutions, that are responsible for the present physiographic form.

Control preventivo dinamico de sistemas de energia electrica usando redespacho de generacion y corte de carga

A model for preventive control in electrical systems is presented, taking into account the dynamic aspects of the network. Among these aspects, the effects provoked by perturbations which cause oscillations in synchronous machine angles (transient stability), such as electric equipment outages and short circuits, are presented. The energy function is used to measure the stability of the system using a procedure defined as the security margin. The control actions employed are load shedding and generation reallocation. An application of the methodology to a system located in southern Brazil, which is composed of 10 synchronous machines, 45 busses, and 72 transmission lines. The results confirm the theoretical studies.

Coeficientes de perda de carga em valvulas e acessorios no escoamento laminar de fluidos nao-Newtonianos

Friction loss coefficients for laminar flow of xantan gum solutions (concentrations in the range of 0.1-0.5% by weight) through valves and fittings were experimentally determined. The rheological behavior, studied by means of a concentric cylinder rheometer, was pseudoplastic, being well described by the Ostwald-De Waele model with non-linear correlation coefficients (r) between 0.998 and 0.999. In the pressure drop measurements the following fittings were employed: completely open and half way open ball valve, completely open and half way open angle valve, tee used like coupling, tee used like a 90° elbow, short radius 90° elbow and coupling. The results showed that the friction loss coefficients increased with decreasing generalized Reynolds number. The friction loss coefficients could be well adjusted by a potential model, suggested by Kittredge & Rowley (1957) for Newtonian fluids, K f = A(Re g) -B, with correlation coefficients between 0.837 and 0.999.