ABSTRACT
The influence of temperature on the development and embryonation of Ascaris suum eggs was studied using coarse sand medium in an environmental chamber with 50% humidity. The time required for development and embryonation of eggs was examined under 3 different temperature conditions, 5degrees C, 25degrees C, and 35degrees C. A. suum eggs did not develop over 1 month at the temperature of 5degrees C. However, other temperature conditions, 25degrees C and 35degrees C, induced egg development to the 8-cell-stage at days 5-6 after incubation. All eggs examined developed to the 8-cell stage at day 6 after incubation in the sand medium at 25degrees C. The higher temperature, 35degrees C, slightly accelerated the A. suum egg development compared to 25degrees C, and the development to the 8-cell stage occurred within day 5 after incubation. The formation of larvae in A. suum eggs at temperatures of 35degrees C and 25degrees C appeared at days 17 and 19 after incubation, respectively. These findings show that 35degrees C condition shortens the time for the development of A. suum eggs to the 8-cell-stage in comparison to 25degrees C, and suggest the possibility of accelerated transmission of this parasite, resulting from global warming and ecosystem changes.
Subject(s)
Animals , Ascaris suum/embryology , Culture Media , Eggs/radiation effects , Humidity , Larva/growth & development , Silicon Dioxide , TemperatureABSTRACT
A umidade de equilíbrio deve ser determinada para o local onde a madeira será empregada. Isto pode ser feito através da determinação da umidade das amostras de madeira expostas às condições ambientais de temperatura e umidade relativa em ensaios de campo, de laboratório equipado com câmara de climatização ou estimativas por meio de modelos matemáticos. Neste trabalho foi determinada a umidade de equilíbrio da madeira - UEM do angelim vermelho (Dinizia excelsa Ducke), guariúba (Clarisia racemosa Ruiz & Pav.) e tauarí vermelho (Cariniana micrantha Ducke ), em duas condições de temperatura e três de umidade relativa em câmara de climatização. Encontrou-se diferenças entre a umidade de equilíbrio estimada pela equação de Simpson (1971) e o valor real determinado em câmara climática. Na simulação de ensaio a 25º C de temperatura e umidade relativa de 40% a UEM ficou em média 26,6% superior ao valor estimado pela equação de Simpson (1971), constituindo-se na maior variação. A menor variação foi de 2,1% registrada na espécie angelim vermelho na condição de 35º C e 80% de umidade relativa. A equação de Simpson, no geral, tendeu a superestimar os valores de UEM nas três espécies.
The equilibrium moisture content (EMC) of wood must be determined according to the place where wood is to be used. Moisture content can be determined from wood samples exposed to environmental conditions of temperature and relative humidity in the field, a laboratory equipped with environmental chambers, or by mathematical model calculations. The EMCs of angelim vermelho (Dinizia excelsa Ducke), guariúba (Clarisia racemosa) and tauarí vermelho (Cariniana micrantha Ducke) were determined in a environmental chamber at two temperatures and three relative humidity conditions. Differences were found between the EMC estimated by the Simpsons equation (1971) and the real value determined in environmental chamber. Large discrepancies, averaging 26,6%, were found at 25oC and 40% relative humidity. The minimum discrepancies, averaging 2,1%, were determined on angelim vermelho at 35oC and 80% relative humidity. In general, the Simpsons equation overestimated the EMC values for the three species.