Should miaow-miaow be banned

The "legal high" mephedrone – also known as M-Cat, plant food, and miaow miaow – is getting a lot of attention because a series of deaths have been linked to the drug. Most recently, two teenaged men in the UK died after taking it on Sunday night, although the results of medical tests to determine the causes of their deaths will not be known for several weeks.

It has become the fourth most popular drug in the UK behind cannabis, ecstasy and cocaine over the past year. The British government's official drug advisers are expected to recommend that it be banned, but some drugs policy experts say criminalisation could do more harm than good. Now New Scientist cuts through the hype.

What is mephedrone?

The leaves of the khat plant, Catha edulis, are chewed for the stimulant, amphetamine-like properties of its active ingredients cathinone and cathine, mostly in east Africa and in migrant groups elsewhere. Mephedrone – more properly 4-methylmethcathinone – is the best known of a family of synthetic or substituted cathinones. It is commonly sold as a white powder or in capsules and is usually snorted or swallowed.

Where does it come from?

The vast majority is produced by Chinese chemical companies, which sell it for around £4,000 a kilogram, mostly to European dealers who sell it online for £10 to £15 per gram or less for larger quantities.

Point of nuclear weapons on instant alert

The NPR is expected to state that the US will not use its nukes to attack a country that does not itself have nuclear weapons - as long as that country complies with the Nuclear Non-Proliferation Treaty - and it may renounce nuclear weapons as a response to chemical or biological attack. It may also say 2500 "spare" US nuclear warheads will be destroyed.

But it is not expected to pledge that the US will never be first to launch a nuclear strike, nor that nuclear weapons are only for deterrence or response to nuclear attack. This policy means that the US, along with Russia, will continue to keep 1000 to 1200 nuclear missiles "on alert". For those who support the elimination of nuclear weapons that is a cause for concern. "De-alerting is the key problem," says Ivan Oelrich of the pressure group Federation of American Scientists.

To deter or respond to an attack, nations don't need to keep weapons on alert, says Oelrich. No country could take out all US missiles in a first strike, so a reprisal would not need to be speedy. The only reason to have so many on alert would be to pre-empt a large imminent attack by Russia, says policy analyst James Acton of the Carnegie Endowment for International Peace, a Washington DC-based think tank.

Missiles on alert are a worry, partly because a malfunction could lead to accidental launch, or they could be hijacked - but mostly because they could be launched by misinformed or pressurised military leaders or politicians during a fast-evolving situation, Oelrich says.

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Insect semen kills rival sperm

If you've only got one shot, you better make it count. For some social insects, with only one chance to impregnate their queen, things can get nasty, but it's not the males that try to harm each other: it's their ejaculate.

Some female insects, such as honeybeesMovie Camera and leafcutter ants, have sex on only one day in their life. But what a day: they mate with multiple males and store enough sperm to fertilise eggs throughout their lives.

Now it seems that when honeybees and leafcutter ants inseminate the queen, their seminal fluid is harmful to rival sperm. Researchers looking at sexual selection often focus on the all-important sperm, says Boris Baer of the University of Western Australia. The seminal fluid tends to be discounted as merely a sugary liquid which provides energy, he says.

Baer and colleagues from the University of Copenhagen, Denmark, exposed the sperm of honeybees and leafcutter ants to their own seminal fluid, and the secretions of other males of the same species. The seminal fluid killed more than 50 per cent of the rival sperm within 15 minutes. "The males seemed to use the seminal fluid to harm the sperm," says Baer.