Biomedical subjects

R P Fahey

Publications and source records attributed to R P Fahey.

3 recordsLinked to original sources

PubMed2000

Characterization of obesity phenotypes in Psammomys obesus (Israeli sand rats).

Psammomys obesus (the Israeli sand rat) has been well studied as an animal model of Type 2 diabetes. However, obesity phenotypes in these animals have not been fully characterized. We analyzed phenotypic data including body weight, percentage body fat, blood glucose and plasma insulin concentration for over 600 animals from the Psammomys obesus colony at Deakin University to investigate the relationships between body fat, body weight and Type 2 diabetes using regression analysis and general linear modelling. The body weight distribution in Psammomys obesus approximates a normal distribution and closely resembles that observed in human populations. Animals above the 75th percentile for body weight had increased body fat content and a greater risk of developing diabetes. Increased visceral fat content was also associated with elevated blood glucose and plasma insulin concentrations in these animals. A familial effect was also demonstrated in Psammomys obesus, and accounted for 51% of the variation in body weight, and 23-26% of the variation in blood glucose and plasma insulin concentrations in these animals. Psammomys obesus represents an excellent animal model of obesity and Type 2 diabetes that exhibits a phenotypic pattern closely resembling that observed in human population studies. The obesity described in these animals was familial in nature and was significantly associated with Type 2 diabetes.

Adipose Tissue↗

PubMed1996

Perception of back vowels: effects of varying F1 - F0 Bark distance.

In a study of vowel height perception using front vowels, Hoemeke and Diehl [J. Acoust. Soc. Am. 96, 661-674 (1994)] found that F1 - F0 distance was the best predictor of perceived vowel height for the phonological distinction [+/- high], while for two other vowel height distinctions F1 alone was the best predictor. Further, the [+/- high] identification function was defined by a sharp boundary located at 3- to 3.5-Bark F1 - F0 distance. One hypothesis offered was that F1 - F0 distance had cue value for the [+/- high] distinction because of an underlying quantal region on the F1 - F0 distance dimension. However, the results are also predicted if it is supposed that F1 - F0 distance is a cue for vowel height only for pure height distinctions. The present study further tested these possibilities, using back vowels. The results allowed us to reject both as general explanations of vowel height perception. However, the results were consistent with a third possible explanation, namely, that phonetic quality is determined by the tonotopic distances between any adjacent spectral peaks (e.g., F3 - F2, F2 - F1, and F1 - F0), with greater perceptual weight accorded to smaller distances.

Humans↗

PubMed1996

The missing fundamental in vowel height perception.

Traunmüller (1981) suggested that the tonotopic distance between the first formant (F1) and the fundamental frequency (F0) is a major determinant of perceived vowel height. In the present study, subjects identified a vowel-height continuum ranging in formant pattern from /I/to/epsilon/, at five F0 values. Increasing F0 led to an increased probability of /I/responses (i.e., the phoneme boundary shifted toward the /epsilon/ end of the continuum). Various conditions of filtering out the lower harmonics of the stimuli caused only marginal shifts of the phoneme boundary. The experiments provide evidence against interpretations of Traunmüller's (1981) results that claim that vowel height is determined by the distance between F1 and the lowest harmonic that is present in the basilar membrane excitation pattern.

Adult↗