A statistical mixture model for estimating the proportion of unreduced pollen grains in perennial ryegrass (Lolium perenne L.) via the size of pollen grains

The size of pollen grains is commonly used to indicate the ploidy level of pollen grains. In this paper observations of the diameter of pollen grains are evaluated from one diploid accession of perennial ryegrass (Lolium perenne L.), which was expected to produce diploid (unreduced) pollen grains in addition to haploid pollen grains. The considerable overlap of the diameter distributions of haploid and diploid pollen grains severely hampers the accurate estimation of the proportion of diploid pollen grains. To overcome this problem we develop in this paper a statistical normal mixture model and we describe a method to test for the production of diploid pollen grains from a diploid parent, and to estimate the proportion of diploid pollen grains.

Eating without a nose: Olfactory dysfunction and sensory-specific satiety

Odor stimuli play an important role in the perception of food flavor. Olfactory dysfunction is thus likely to affect eating behavior. In the present study, we hypothesized that dysfunctional olfactory perception promotes sensory-specific satiety, a decrease in pleasure derived from a certain test food during and shortly after its consumption relative to other unconsumed control foods. A total of 34 hyposmic/anosmic participants were compared with 29 normosmic control participants. All participants repeatedly consumed a fixed portion of one and the same food item, a procedure known to induce sensory satiation. We found evidence for sensory-specific satiety (SSS) regardless of olfactory function. It thus appears that olfactory deficits have no major effect on SSS

Beer à no-go: Learning to stop responding to alcohol cues reduces alcohol intake via reduced affective associations rather than increased response inhibition

Aims Previous research has shown that consistently not responding to alcohol-related stimuli in a go/no-go training procedure reduces drinking behaviour. This study aimed to examine further the mechanisms underlying this go/no-go training effect. Design, setting and participants Fifty-seven heavy drinkers were assigned randomly to two training conditions: in the beer/no-go condition, alcohol-related stimuli were always paired with a stopping response, while in the beer/go condition participants always responded to alcohol-related stimuli. Participants were tested individually in a laboratory at Maastricht University. Measurements Weekly alcohol intake, implicit attitudes towards beer, approachavoidance action tendencies towards beer and response inhibition were measured before and after the training. Findings Results showed a significant reduction in both implicit attitudes (P = 0.03) and alcohol intake (P = 0.02) in the beer/no-go condition, but not in the beer/go condition. There were no significant training effects on action tendencies or response inhibition. Conclusions Repeatedly stopping pre-potent responses towards alcohol-related stimuli reduces excessive alcohol use via a devaluation of alcohol-related stimuli rather than via increased inhibitory control over alcohol-related responses

Impulsivity in obese women

In our obesogenic environment, self-control might be necessary in order to prevent overeating. Impulsivity is supposed to make it more difficult to resist the temptation to eat too much and can thereby contribute to overweight. In the present study, the hypotheses is tested that obese individuals are more impulsive. Thirty-one obese and 28 lean women, sampled from the normal population, are tested on a behavioural measure and three self-report measures of impulsivity. The obese women appeared more impulsive on the last part of the behavioural task, but not on the self-report measures. Implications of the results are discussed

Food liking, food wanting, and sensory-specific satiety

Sensory-specific satiety refers to a temporary decline in pleasure derived from consuming a certain food in comparison to other unconsumed foods. It has been argued that such a reduction may not be limited to food liking but extends to food wanting as well. Animal research suggests that sensory-specific satiety reflects a reduction in both food liking and food wanting and in the present study it was investigated whether this also holds true for humans. Participants had to consume a certain amount of chocolate milk and afterwards approximately half of the participants played a game to obtain more chocolate milk, whereas the other half played a game to obtain crisps. Participants showed a decline in subjective liking of taste and smell of the chocolate milk in comparison to crisps. Furthermore, they showed less motivation (i.e. wanting) to obtain more chocolate milk. It is concluded that sensory-specific satiety in humans reflects a decrease in both food liking and food wanting