Noise and the quality of sleep in two hospitals in the city of Belo Horizonte, Brazil

Male patients of two hospitals in Belo Horizonte completed a questionnaire during an interview on the day of discharge in order to evaluate sleeping conditions related to noise during the previous night and were retested 24 h later. Patients had a worse perception of sleep at the noisier hospital, the University Hospital of the Federal University of Minas Gerais (N = 13), whose internal mean nocturnal noise level was Leq = 53.7 db(A), than at the quieter hospital, Baleia (N = 22), whose internal mean nocturnal noise level was Leq = 45.5 db(A). Noise was the only sleep-disturbing factor which was statistically significant.

Effect of external carbon dioxide concentration on electric organ dischargge frequency by the gymnotiform fish Apteronotus albifrons

A model is described for the instantaneous frequency (F) of electric organ discharge in Apteronotus albifrons: F=H/(aH + b), where a and b are linear parameters and H, hydrogen ion concentration, pH from 7.10 to 4.89 was modified by increasing external carbon dioxide concentrations. With the increase in pH from 5.17 to 7.40, corresponding to a decrease of carbon dioxide concentration, the equation was as follows: F=(logH)/(a ,log H=b). The model search consisted of the adjustment of a simple linear regression using fucntion transformation for the most adequate residue analysis by the Durbin-Watson test. The parallelism was checked by comparing regression lines with homogeneous variances and using other tests for non-homogeneous variances