The ultrasonic detection of an isolated craniosynostosis

The prenatal detection of scaphocephaly, an isolated form of craniosynostosis, is presented. The diagnosis was made at 34 weeks of gestation in a woman with polyhydramnios. The ultrasound appearance and postnatal follow-up are presented.     

Does colour matter? The importance of colour in avoidance learning, memorability and generalisation

Aposematic species exploit the ability of predators to associate, for example, conspicuous colouration with the unprofitability of prey. We tested the importance of colour for avoidance learning, memory and generalisation in wild-caught great tits (Parus major). First, we determined the birds’ initial colour preferences for red, yellow, orange and grey artificial prey items. The birds showed some preferences, as they were more willing to eat grey prey as their first choice, but these were not strong preferences. We then trained birds to discriminate red, yellow or variable (red and yellow) signals from grey where colours signalled palatable and unpalatable food. In general, the birds learned the discrimination task equally well, irrespective of which colours signalled unpalatability, and subsequently remembered the distinction between previously palatable and previously unpalatable colours in the memorability test. We did not find strong evidence that variability in the signal affected learning or memory. Our results suggest that, in a task where birds must discriminate between palatable and unpalatable prey, it does not matter which specific colour signals unpalatability, although this might be context-dependent. To study whether training also affects responses to unconditioned stimuli, we included orange prey items in the memorability test. Although orange had been palatable in the initial preference test, the birds ate fewer orange prey items after they had been trained to avoid red, yellow or both colours (variable signal) as unpalatable prey, but did not change their preference when trained that these colourful signals were palatable. This indicates that generalisation occurred more readily after a negative experience than a positive experience, a situation that would potentially allow imperfect mimicry to occur.     

The effect of lignin and sugars to the aerobic decomposition of solid wastes

A series of experimental runs were conducted from 1995 to 1999 in Madison (WI, USA) with the goal to investigate the biodegradation process of seven (7) solid waste components and mixtures of them under near optimal aerobic conditions. It was shown that substrates with high initial lignin contents or high initial HWSM contents were observed to have relatively low and high degradation extents, respectively. Two linear equations were derived that correlate degradation extent (as indicated by the volatile solids reduction) to initial lignin and initial HWSM contents separately. The lignin equation was compared to a similar equation previously developed for anaerobic environments by Chandler et al. (Predicting methane fermentation biodegradability. In: Biotechnology and Bioengineering Symposium No. 10 (1980) New York: John Wiley & Sons). With comparison to the Chandler formula, lignin was found to be less inhibitory to the overall substrate decomposition in aerobic environments compared to anaerobic ones. Cellulose loss contributed to a higher than 50% to the overall dry mass loss for all substrates studied. In addition, the cellulose to lignin (C/L) ratio appeared to be a relatively accurate compost maturity indicator, since it reduced to a value less than 0.5 for most substrates that had reached their degradation extent.     

Objections to the use of polyvinyl fluoride in smogchamber experiments

The interference of low molecular weight additives in polyvinyl fluoride film (PVF; “Tedlar”) used for the construction of smogchambers has been investigated by means of irradiation experiments, chemical modelling and analytical techniques. The results indicate that PVF is unsuitable as a wall material for smogchambers, owing to interference in hydrocarbon measurements, possibly NO_x-measurements, and in the formation of ozone and peroxyacetyl nitrate. This information is thought to be of interest to present and future workers in air pollution research.