Propellant Sneeze: How Far Does Your Sneeze Travel?

When a person coughs or sneezes, you can see the droplets. However, you do not see the gas clouds associated with coughs and sneezes. This invisible gas phase helps extend the distance of the individual droplets, particularly the small ones. A recent study has shown that coughs and sneezes have associated gas clouds that keep their potentially infectious droplets aloft over much greater distances than previously anticipated.

Researchers at the Massachusetts Institute of Technology (MIT) used high-speed imaging as well as laboratory simulations and mathematical modelling to analyse coughs and sneezes in terms of fluid-mechanics. The results suggest that smaller droplets travel further than larger ones which researchers previously assumed to be reversed as larger droplets tend to have more momentum. This would be true if each droplet were unconnected. However, the gas cloud emitted with a cough or sneeze tend to cause the smaller droplets to be swept around and resuspended, causing them to settle more slowly and travel further. Essentially, the smaller droplets can be carried a greater distance by the gas cloud while the larger droplets fall out.

The study showed that droplets 100 micrometers in diameter travelled five times farther than previously estimated, while droplets 10 micrometers in diameter travelled 200 times farther. The tendency of these droplets from coughs or sneezes, referred to as a ''multiphase turbulent buoyant cloud'', to remain airborne means that ventilation systems may be more prone to transmitting potentially infectious particles than previously suspected.

So, the next time you feel a cough or sneeze coming on, raise your elbows to cover up and warn people to take cover from the multiphase turbulent buoyant cloud you're about to expel.

Dark Chocolate to Fight Obesity and Type-2 Diabetes?

Dark chocolate has recently been associated with health benefits. From increasing satiety to lowering blood pressure, ingredients of chocolate have been shown to have a positive impact on health and the potential health benefits continue to pile up. Researchers have now found a particular ingredient that may even help prevent obesity as well as type-2 diabetes.

Cocoa, the main ingredient in chocolate, is rich in flavanols. Flavanols, a type of antioxidant found in grapes and tea, have been reported to aid weight loss and prevent type-2 diabetes. However, flavanols exist in different forms. Cocoa contains several different kinds of these compounds.

Groups of mice were fed different diets, including high-fat and low-fat diets, and high-fat diets supplemented with different kinds of flavanols. Researchers found that adding one particular set of these compounds, known as oligomeric procyanidins (PCs), to the food made the biggest difference in keeping the mice's weight down if they were on high-fat diets. It also improved glucose tolerance, which could potentially help prevent type-2 diabetes.

ORIGINAL RESEARCH: Effect of Interactive behaviour on blood glucose changes following a Carbohydrate load

Objectives: Benefits of physical activity on maintenance of blood glucose within an acceptable range are well documented. This study explores the possible beneficial effect of animated conversation and mental activities on blood glucose levels following dietary carbohydrate loading.

Design and Participants: Blood glucose changes were examined in 18 non-diabetic individuals following the consumption of two doughnuts providing ~48g of carbohydrate. The participants acted as their own controls and were studied twice. On the first occasion they maintained quiet/passive behaviour, on the second they conversed and participated in structured mental activities e.g. reading and solving puzzles.

Measurements: Using the Freestyle Freedom Lite glucose metre, baseline, then post-fasting blood glucose concentrations were evaluated every 30 minutes over a 2 hour period after the consumption of doughnuts.

Results: ANOVA repeated measures analysis of the results showed that time (P<0.001), activity (P<0.01) and time*activity interaction (P<0.05) all had a significant effect on the blood glucose levels. Compared with active intervention, the mean blood glucose levels during quiet/passive behaviour period remained ~30-40% higher and this difference was most significant at 30 minutes (1.40 vs 0.87 mmol/L, P<0.05)) and 60 minutes (1.53 vs 0.91mmol/L, P<0.01) measurements.

Conclusion: The results of this preliminary study indicate that simple non-exercise related activities involving mental activity and conversation have a significant influence on reducing blood glucose levels. This may be of value when individuals are unable to engage in regular exercise due to personal and environmental constraints.