Utilisation of bubble resonance phenomena to improve gas–liquid contact

 In several branches of science and technology a gaseous phase is dispersed into a liquid in the form of bubbles, a gaseous component then dissolves into the liquid and subsequently undergoes chemical reaction. The overall process performance can be improved substantially when the area of gas–liquid contact is increased. By subjecting the liquid phase to low frequency vibrations, the bubbles are shown to suffer significant breakage, induced by resonance. When the vibration is properly tuned, the interfacial area is found to increase by a factor of 1.8–2.4, depending on the properties of the liquid. Resonance-induced bubble breakage phenomena have a great potential for improving the rates of chemical processes involving fast reactions, with minimal energy input. Received: 7 July 2000 / Accepted in revised form: 28 August 2000     

Flavonoid wing pigments increase attractiveness of female common blue (Polyommatus icarus) butterflies to mate-searching males

 Common blue butterflies (Polyommatus icarus) sequester flavonoids from their larval host plants and allocate these UV-absorbing pigments to the wings. In field experiments using dummies constructed from female butterflies, mate-searching males inspected flavonoid-rich dummies more intensively than those with little or no flavonoids. Flavonoid content as signalled by UV-wing pattern may indicate ontogenetically determined female quality or enhance detectability to males. Received: 21 March 2000 / Accepted in revised form: 17 May 2000     

Urban Flood Damage and Greenhouse Scenarios - The Implications for Policy: An Example from Australia

Urban flooding is often used as an illustration of the potentially adverse effects of greenhouse-induced climate change on extreme events. There is however, a paucity of studies that convert climate scenarios into changes in flood damage. This account summarises the use of modelling techniques, for three flood prone urban catchments in south eastern Australia, to assess changes to urban flood losses for the 'most wet' and 'most dry' scenarios for the year 2070. The most wet scenario indicates that annual average flood damage could increase within the range of 2.5 to 10 times, under the most dry scenario flood regimes would be similar to those experienced at present. The socio-economic scenarios based on the changes to flood losses are used to consider policy responses. It is unlikely that many local government authorities will respond because of lack of interest and because of major changes to the climate scenarios proposed over the last decade. Any response is likely to be incremental and accord with the 'no regrets' and the precautionary principle'.     

The association between alpha-fetoprotein and βhcg levels prior to and following chorionic villus sampling in cases that spontaneously miscarried

Maternal serum alpha-fetoprotein (AFP) and beta-human chorionic gonadotropin (βhCG) measurements taken prior to chorionic villus sampling (CVS) in 21 patients who subsequently miscarried were compared with measurements in a control group of 113 patients with uneventful pregnancies. Patients with AFP levels of 10 iu/ml or more prior to the CVS had a 4·3 times greater risk of miscarriage (95 per cent confidence interval 1·3–13·6). AFP levels obtained 1 week after the CVS in the 13 patients with late miscarriages were higher than in the control group (P = 0·06). Patients miscarrying had a greater rise in AFP (P = 0·06) and a greater fall in βhCG levels (P = 0·04) following the CVS procedure, compared with the control subjects. Each 10-unit change in the difference between AFP or βhCG levels prior to and 1 week following the CVS was associated with a significantly increased risk for late miscarriage. Elevated maternal serum AFP levels early in pregnancy and changes in AFP and βhCG levels following CVS may predict an increased risk for subsequent miscarriage.