Week In Science

Birds and Bees

Androstenone, a compound produced from testosterone, has been identified as a pheromone in pigs. But is it a human pheromone as well? Related research results were discussed in a Nature article titled Some smell it sour, some smell it sweet, (published online: 16 September 2007; doi:10.1038/news070910-15).

Reactions to androstenone vary. To some the compound smells foul and has been compared to sweat or urine. However, for others the same substance smells sweet- like flowers. Why is there such a stark contrast in human perception of the same chemical? The answer may lie with varying receptor properties different people have.

The cited study focused on a particular receptor known as OR7D4. There were two common gene variants found associated with OR7D4. One of them is linked to a sense of sweetness and the other to a foul odour. A third, but less common variation, is associated with an inability to detect androstenone.

A suggested follow-up study would entail linking possible physiological effects to OR7D4. That would help resolve the question of whether or not androstenone is a human sex pheromone.

A Geometrical Model for Straight and Curly Hair?

Hair tangles- hair groupings that resist combing- are a familar problem. It may be more familar to some than others. But why is that? Straight hair seems to engender more tangles than curly hair and according to Jean-Baptiste Masson it may be due to the angles at which individual hairs interact with other hairs. Velcro-like products are a suggested means of dealing with the problem.

A Test to Determine Whether Some Singularities are Naked?

Arlie Petters, a Duke professor of mathematics and physics and Marcus Werner, Cambridge graduate student in astrophysics, may have found a means of determining if some singularities are naked. Singularities have been thought to be hidden from view within an event horizon. Naked singularities could be visible but do they exist and is there a test which would reveal visibility? Since the detection of black holes is dependent on indirect evidence, identifying properties of their singularities would appear a more challenging task. Petters' expertise in gravitational lensing may have provided the insight needed to take on the challenge.

Singularities have a property known as angular momentum- they spin. Some may spin at rates that exceed 1,000 times per second. Petters and Werner concluded that a naked singularity would be possible if its angular momentum exceeds its mass which would signify a spin of thousands of rotations per second for a black hole having about 10 times more gravitational force than the Sun. The naked singularity's gravitation would split light of stars or galaxies in ways that could be detected with astronomical instruments.

Improving the Ecology through Dumping

Stimulating algae growth by dumping large amounts of iron into the ocean may become a novel way of reducing the amount of carbon dioxide in the atmosphere or at least it is a topic of conference discussion. Iron is a nutrient consumed by phytoplankton. The idea is that when these organisms die, their organic matter sinks to ocean depths carrying carbon dioxide with it.