This week science has shown that clean shaven is not always best, and that brief periods of stress are actually good for you. We've seen modified bacteria literally nuke cancer cells, and British scientists propose a good old space harpoon as the way to clear Earth's orbit of some 6,000 tonnes of space debris. All that and more in another exciting edition of Week in Science.
Stop shaving to boost your attractiveness - It turns out the rough gets more love than the smooth. A new study has shown that a man's attractiveness to both men and women peaks with "heavy" or 10-day stubble. During a test, both heterosexual men and women were asked to rate pictures of men with varying levels of beard growth. Men with full beards and clean shaven faces were rated with similar health and attractiveness, while bearded men were perceived to have higher levels of parenting skills.
However, 10-day stubble were ranked as the most desirable, possibly due to the connotations of masculinity and maturity without looking aggressive. Five-day stubble was ranked lowest, possibly due to its patchy nature, which shows that you need a certain amount of hair on your face before the stubble effect kicks in. Next time you go out on a date, maybe reach for the beard trimmer instead of the razor. [Evolution and Human Behaviour]
Radioactively-labelled bacteria literally nuke cancer cells - Bacteria are both our friends and our enemies. One particular bacterium, that can cause diseases such as meningitis, may finally become useful. Scientists using a modified strain of Listeria monocytogenes, labelled with a radioactive antibody, found that the bacteria specifically attack cancer cells, entering them and delivering the radioactive payload, killing them off.
Normal healthy cells were pretty much untouched, because our immune system took care of the bacteria easily. Tumour cells prevent your immune system from operating in their vicinity, leaving them open to attack by the bacteria. Testing in mice showed a 90 per cent reduction in metastasised cancer cells, and a tumour reduction of up to 64 per cent after treatment with the bacteria. Further research is needed to work on safety factors and various different forms of radioactive labelling agents, but this kind of targeted bacteria-led treatment shows huge potential in the war against cancer. [Cancer Research]
Circumcision changes the ecosystem of your penis - It's well known that circumcised men have a significantly reduced likelihood of contracting certain sexually transmitted diseases, such as HIV. While we don't specifically know the mechanism of this resistance, a new study shows that the bacterial load of the penis is significantly altered when a man is circumcised.
Research from Uganda monitored their microbial species on the penises of 156 uncircumcised men, then randomly circumcised half of the men before retesting them a year later. The results showed a substantial decrease in the amount of bacteria found after circumcision. How this translates into resistance against viral infection is unclear - however it could be through reduced skin irritation by anaerobic bacteria or another effect of bacterial colonisation that's caused by the warm, moist pocket of foreskin. Whatever the reason, it's clear that circumcision could actually benefit a man's sexual hygiene. [mBio]
Stress isn't all bad - Stress is one of the biggest, non-disease-related killers of our generation, with chronic stress, whether work or emotional, known to cause significant wear and tear on our bodies, ageing us prematurely and damaging our DNA. However, a new study has shown that brief periods of stress can actually be beneficial to our cells, but only if you're not chronically stressed beforehand.
The cellular mechanisms that underpin the findings are, as yet, unknown, but significantly lower levels of cellular damage were discovered in a test group consisting of generally relaxed people put under brief periods of stress. The results suggest that being totally relaxed all the time isn't quite as healthy for you as brief periods of stress. [Psychoneuroendocrinology]
Breakthrough might make solar power finally viable - Solar power has always been the holy grail of limitless, pollution-free, renewable energy. It's fuelled plants for millennia, but it's never been particularly useful on a large scale for humans because the energy efficiency of man-made solar cells has always been terrible. Now an organic dye called pentacene promises to change that, generating two electrons for every photon that's absorbed, effectively doubling the power generation of solar cells using only a narrow band of visible light.
As a coating for silicon photovoltaic cells, it could boost total energy efficiency up to 30 per cent or more, a 5 per cent boost on the best solar cells currently available. This leap, combined with more efficient energy storage solutions like the gimballed flywheel could finally make solar energy a viable replacement for fossil fuel or nuclear power. [Science]
Marathon runners generate electricity with nothing but their feet - We've been hearing about electricity generation from simple human movement for a while, but now Pavegen Systems, a manufacturer of electricity generating floor tiles, has shown just how much juice can be generated from our pounding feet. It laid a 25m-wide stretch of its power generating pavement slabs across the Avenue des Champs Élysées for the Paris marathon to test how much electricity they could generate. In the space of about five hours the 176 tiles generated enough energy to light a 5W LED for 40 days, or about 4.7kilowatt-hours of juice.
The tiles use a combination of piezoelectric and induction electricity generation to feed into a battery or directly to things like lights, laptops or anything with a low-voltage plug. With that amount of power generated from such a small stretch, pavement-pounding electricity could soon be seen in places like shopping centres, train stations or anywhere people walk about, powering all sorts of things. It's practically free energy. [Scientific American]
Space harpoons are go - There's so much junk sitting in orbit around our planet that it's almost a full-time job just keeping track of it. Every space launch has to avoid some 6,000 tonnes of garbage left over from other operations that could easily ruin a mission or even kill the people on board. Now scientists from the UK have proposed a solution: Harpoon space junk and drag it back into the atmosphere to burn up.
The plan is to use a manoeuvrable satellite to knock the debris out of the sky and clear up Earth's orbit, something that's badly needed. Currently they've worked out an efficient targeting system, have modelled the debris burn-up, and are looking to launch the plan with approval in the next couple of years. [Al Jazeera]
The cinnamon challenge really could kill you - Doctors have been out in force this week warning of the dangers of the cinnamon challenge. A report from hospitals across the US has found a worrying trend of hospitalised challenge takers that have ended up with anything from chocking into unconsciousness to a collapsed lung.
The challenge, which pits the participant against a teaspoonful of cinnamon powder, without water, has been labelled as dangerous and should be avoided at all costs. Best not to try it, even if you are trying to make the world laugh with your struggling efforts on YouTube. [Sky]
Harvard can guess your age with just a few mouse clicks - Not even the internet is able to hide our age it seems. Researchers working on human-computer interaction have released a very clever test that can tell how old you are simply from a few clicks of your mouse.
Tracking your movements, the accuracy of your clicks, and the time it takes you to complete the test, combined with some simple information concerning your sex and where you live, the test can then compute your age with terrifying accuracy. It's all to do with your precision and speed, which sadly decreases as we get older. Try it for yourself and tell us how close it gets in the comments. [Harvard]