Determinação da acurácia do analisador hematológico Cobas b 121 para valores de hematócrito de cães, gatos e equinos em comparação ao padrão ouro laboratorial

O objetivo do presente estudo foi determinar a concordância entre os valores de volume globular (VG) obtidos através de microcentrifugação e os valores de hematócrito (Hct) obtidos pelo hemogasômetro Cobas b 121 em cães, gatos e cavalos. Amostras de sangue venoso ou arterial foram coletadas utilizando seringas pré-heparinizadas específicas para hemogasometria. Após a coleta, todas as amostras foram analisadas imediatamente e os valores foram determinados pelo método de microhematócrito e pelo hemogasômetro. O teste de Bland Altman foi utilizado para determinação do viés e limites de concordância. A correlação de Person foi determinada e o Teste t utilizado para comparar as médias de VG e Hct. Foram incluídos no estudo 45 cães, 45 gatos e 33 cavalos. As médias ± DP (mínimomáximo) dos valores de VG obtidos pelo microhematócrito e Hct determinados pelo analisador foram: cães, 34,9 ± 9,9 (9,0-55,0) % e 32,5 ± 8,8 (10,4-50,6) %; gatos, 29,0 ± 9,6 (11,0-51,0) % e 26,9 ± 9,3 (10,2-50,9) %; cavalos, 34,2 ± 6,5 (24,0-47,0) % e 34,1 ± 6,0 (22,5-46,1) %. Não houve diferença significativa entre os valores obtidos pelos dois métodos. Os valores de viés ± DP de cada espécie foram: cães, 2,4 ± 2,6%; gatos, 2,2 ± 2,3%; cavalos, 0,1 ± 2,4%. O viés encontrado foi positivo na maior parte das análises, indicando que o analisador subestimou o Hct. Houve correlação muito forte entre os valores mensurados pelos dois métodos. Os valores do coeficiente de correlação (r) foram: cães, 0,97; gatos, 0,98; cavalos 0,93 (P < 0,0001). Frente aos resultados, conclui-se que o analisador hematológico apresenta boa acurácia na determinação do Hct de cães, gatos e cavalos nas faixas de hematócrito incluídas nesse estudo.The aim of the present study was to determine the agreement between the packed cell volume (PCV) values obtained through microcentrifugation and the hematocrit (Hct) values obtained by the Cobas b 121 blood gas analyzer in dogs, cats and horses. Venous or arterial blood samples were collected using pre-heparinized syringes specific for blood gas analysis. After collection, samples were analyzed immediately and values were determined by the microhematocrit method and the blood gas analyzer. The Bland Altman method was used to determine the bias and limits of agreement. Person's correlation was determined and the t test was used to compare the means of VG and Hct. A total of 45 dogs, 45 cats and 33 horses were included in the study. The means ± SD (minimum-maximum) of VG values obtained by microhematocrit and Hct determined by the analyzer were: dogs, 34.9 ± 9.9 (9.0-55.0) % and 32.5 ± 8 .8 (10.4-50.6) %; cats, 29.0 ± 9.6 (11.0-51.0) % and 26.9 ± 9.3 (10.2-50.9) %; horses, 34.2 ± 6.5 (24.0-47.0) % and 34.1 ± 6.0 (22.5-46.1) %. There was no significant difference between the values obtained by the two methods. The bias ± SD values for each species were: dogs, 2.4 ± 2.6%; cats, 2.2 ± 2.3%; horses, 0.1 ± 2.4%. The bias was positive in most analyses, indicating that the Cobas analyzer underestimated Hct. There was a very strong correlation between Hct values measured by the two methods. Pearson’s correlation coefficients (r) were: dogs, 0.97; cats, 0.98; horses 0.93 (P < 0.0001). In view of the results, it is concluded that the Cobas b 121 blood gas analyzer demonstrates good accuracy in determining the Hct of dogs, cats and horses in the range of Hct values included in this study

Comparative measurements of carbon dioxide fluxes from two nearby towers in a central Amazonian rainforest: the Manaus LBA site

Forests around Manaus have staged the oldest and the longest forest-atmosphere CO2 exchange studies made anywhere in the Amazon. Since July 1999 the exchange of CO2, water, and energy, as well as weather variables, have been measured almost continuously over two forests, 11 km apart, in the Cuieiras reserve near Manaus, Brazil. This paper presents the sites and climatology of the region based upon the new data sets. The landscape consists of plateaus dissected by often waterlogged valleys, and the two sites differ in terms of the relative areas of those two landscape components represented in the tower footprints. The radiation and wind climate was similar to both towers. Generally, both the long-wave and short-wave radiation input was less in the wet than in the dry season. The energy balance closure was imperfect (on average 80%) in both towers, with little variation in energy partitioning between the wet and dry seasons; likely a result of anomalously high rainfall in the 1999 dry season. Fluxes of CO2 also showed little seasonal variation except for a slightly shorter daytime uptake duration and somewhat lower respiratory fluxes in the dry season. The net effect is one of lower daily net ecosystem exchange (NEE) in the dry season. The tower, which has less waterlogged valley areas in its footprint, measured a higher overall CO2 uptake rate. We found that on first sight, NEE is underestimated during calm nights, as was observed in many other tower sites before. However, a closer inspection of the diurnal variation of CO2 storage fluxes and NEE suggests that at least part of the nighttime deficits is recovered from either lateral influx of CO2 from valleys or outgassing of soil storage. Therefore there is a high uncertainty in the magnitude of nocturnal NEE, and consequently preliminary estimates of annual carbon uptake reflecting this range from 1 to 8 T ha-1 y-1, with an even higher upper range for the less waterlogged area. The high uptake rates are clearly unsustainable and call for further investigations into the integral carbon balance of Amazon landscapes

Boletim agrometeorológico 1996.

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Uma comparação entre diferentes estimativas da condutância superficial numa floresta primária na amazônia central

Neste trabalho foi realizada a estimativa da condutância superficial para transferência de vapor d'agua, característica de uma floresta primária próxima a Manaus, à partir de dois diferentes métodos baseados em equações de regressão que procuram associar essa condutância a diferentes variáveis físicas. A equação proposta por Allen (1986) foi estabelecida através da correlação com a radiação líquida média diária, enquanto a estimativa proposta por Roberts et al. (1990) procurou correlacionar a condutância estomática com o déficit de umidade específica e a radiação solar, utilizando dados médios horários e, neste caso, estes valores foram reunidos para representar a média diária correspondente. Uma comparação entre os resultados estimados por tais métodos apresentou o primeiro (Allen) com estimativas sempre inferiores ao segundo (Roberts), da ordem de 30%(±8) na média. Os desvios de ambos também foram relativamente diferentes e, embora tivesse apresentado índices mais elevados de condutância, os desvios do método de Roberts foram de magnitude inferior aos do método de Allen c, portanto, seus valores mostraram-se mais estáveis. As diferenças menores foram observadas no período relativo à estação seca, principalmente nos meses de agosto, setembro e outubro, quando estiveram dentro do limite determinado pela soma dos desvios padrões de ambos.The estimate of the surface conductance for water vapor transfer typical of a primary forest has been carried out, near Manaus, using two different methods based on regression equations which try to associate this conductance to distinct physical variables. The equation proposed by Allen (1986) was established through the correlation with the daily mean net radiation. The estimate proposed by Roberts et al. (1990) tried to correlate the stomatal conductance to the specific humidity deficit and to the solar radiation, using hourly mean data, and in this instance these values have been used to calculate the corresponding daily mean. A comparison of the estimated results using these methods showed the first one (Allen) with estimates always lower than the second one (Roberts), of about 30%(±8) on the average. The deviations of both methods have also been relatively different, and although Roberts has shown higher conductance indices, the deviations were of lesser magnitude than those of Allen, being these values more stable. The lowest differences have been observed during the dry period, mainly in the months of August, September, and October, when they were within the limit determined by the sum of the standard deviations of both of them