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The energy crisis has given rise to a new source of fuel – the Styrofoam cup. Mechanical engineers at Iowa State University in Ames have demonstrated how to boost the power output of biodiesel simply by adding waste plastic to the fuel.
Song-Charng Kong, a co-author of the study, says the experiment – funded in part by the Department of Defense – was conducted to find a way to dispose of trash and generate power under battlefield conditions.
"One can recycle any kind of plastic, but if you are camped in a remote area, recycling is not an option," Kong says. "Turning plastic into fuel is a way to get rid of garbage and generate electricity."
Kong and colleagues dissolved polystyrene – a polymer used to make disposable foam plates and cups – into biodiesel at concentrations ranging from 2 to 20% polystyrene by weight. "A polystyrene cup will dissolve almost instantly in biodiesel, like a snowflake in water," Kong says, although the plastic doesn't break down as well in petroleum-based diesel and other liquid fuels.
Thicker juice
Tests of the mixed fuel in a tractor engine used for electricity generation showed that as polystyrene concentrations increased to 5%, power output increased at roughly the same rate. However, there was a drop off in output for plastic concentrations above 5%.
Kong thinks the change is due to the fuel's increasing viscosity as more and more polystyrene is added. Initially, he says, the thicker fluid creates greater pressure inside the generator's fuel injector causing earlier injection of fuel into the engine and increasing its output.
But eventually the fluid gets so viscous that it doesn't completely combust in the engine and power output decreases. At 15% polystyrene, the fuel is so thick the fuel injection pump overheats.
The new fuel mix is not without its problems, however – as the concentration of polystyrene increases, so do emissions of carbon monoxide, soot, and nitrous oxides.
"You are putting large polymer compounds in, it's hard to burn them completely," Kong says, adding that he hopes to now work on refining the engine's fuel injection system to yield a more complete burn with fewer emissions.
Bulky problem
Robert Malloy of the University of Massachusetts Lowell says as long as emissions can be brought back into line, adding polystyrene into fuel makes sense.
A recent report suggests it's over three times as energy efficient to recycle trash rather than convert it to fuel, but Malloy points out that polystyrene is a special case.
"I think we should try to recycle as much as we can, but there are certain materials that don't lend themselves to recycling in an economic way," he says. Polystyrene is so lightweight and bulky that it's uneconomical to ship to recycling plants. "Technologies like this where you get energy back would be preferable to landfilling," Malloy says.
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BATALLIONS of super-soldiers could be selected for specific duties on the basis of their genetic make-up and then constantly monitored for signs of weakness. So says a report by the US National Academies of Science (NAS).
If a soldier is struggling, a digital "buddy" might step in and warn them about nearby threats, or advise comrades to zap them with an electromagnet to increase their alertness. If the whole unit is falling apart, biosensors could warn central commanders to send in a replacement team.
As advances in neuroscience bring all this into the realms of reality, there are ethical issues to consider. Last week, the NAS released a report assessing the military potential of neuroscience, providing a rare insight into how the military might invest its money to create future armies.
Sponsored by the US army and written by a panel of 14 prominent neuroscientists, the report focuses on those areas with "high-payoff potential" - where the science is sufficiently reliable to turn into useful technologies (see "Where should the money go?").
"A growing understanding of neuroscience offers huge scope for improving soldiers' performance and effectiveness on the battlefield," says the report.
If a soldier is struggling, a digital "buddy" might step in and warn them about nearby threats, or advise comrades to zap them with an electromagnet to increase their alertness. If the whole unit is falling apart, biosensors could warn central commanders to send in a replacement team.
As advances in neuroscience bring all this into the realms of reality, there are ethical issues to consider. Last week, the NAS released a report assessing the military potential of neuroscience, providing a rare insight into how the military might invest its money to create future armies.
Sponsored by the US army and written by a panel of 14 prominent neuroscientists, the report focuses on those areas with "high-payoff potential" - where the science is sufficiently reliable to turn into useful technologies (see "Where should the money go?").
"A growing understanding of neuroscience offers huge scope for improving soldiers' performance and effectiveness on the battlefield," says the report.
Within five years, biomarkers might be used to assess how well a soldier's brain is functioning, and within 10 years, it should be possible to predict how individuals are likely to respond to environmental stresses like extreme heat and cold, or endurance exercises.
Genetic testing might also enable recruitment officers to determine which soldiers are best for specialist jobs. For example, by combining psychological testing with genetic tests for levels of brain chemicals, a clearer picture of a soldier's competencies might shine through. "We might say that given this person's high levels of brain serotonin, they're going to be calmer under pressure, so they might make a good sniper," says Paul Zak of Claremont Graduate University in California, who was on the NAS panel. Alternatively, someone with low dopamine might be less likely to take risks, he says, and therefore be better suited as a commanding officer in a civilian area.
Selection by genotype could be fraught with difficulty - applicants rejected for certain jobs might try to sue on the grounds of genetic discrimination, say. Anders Sandberg, a neuroscientist at the University of Oxford's Future of Humanity Institute, says the military also needs to choose the traits it wants to optimise with care. "The battlefield is changing quite a lot right now. Wars are becoming more like computer games, which means that in the future having the genes that make you a good physical fighter might not be so important as having excellent hand-eye coordination."
Perhaps more sinister is the possibility of neuroscientists creating cognitively manipulated warriors, whose emotions have been blunted, for example.
Zak emphasises that the panel was not asked how to turn soldiers into better "killing machines", although "the whole purpose of maximising and sustaining battlefield capacity is to gain superiority over opponents", admits Floyd Bloom of the Scripps Research Institute in La Jolla, California, who chaired the panel.
That's not to say someone won't try it, though. Zak's own work focuses on the role of the hormone oxytocin in trust and empathy. If drugs were developed to block oxytocin, the effect might be to reduce a soldier's ability to empathise with enemy combatants or civilians.
Genetic testing might also enable recruitment officers to determine which soldiers are best for specialist jobs. For example, by combining psychological testing with genetic tests for levels of brain chemicals, a clearer picture of a soldier's competencies might shine through. "We might say that given this person's high levels of brain serotonin, they're going to be calmer under pressure, so they might make a good sniper," says Paul Zak of Claremont Graduate University in California, who was on the NAS panel. Alternatively, someone with low dopamine might be less likely to take risks, he says, and therefore be better suited as a commanding officer in a civilian area.
Selection by genotype could be fraught with difficulty - applicants rejected for certain jobs might try to sue on the grounds of genetic discrimination, say. Anders Sandberg, a neuroscientist at the University of Oxford's Future of Humanity Institute, says the military also needs to choose the traits it wants to optimise with care. "The battlefield is changing quite a lot right now. Wars are becoming more like computer games, which means that in the future having the genes that make you a good physical fighter might not be so important as having excellent hand-eye coordination."
Perhaps more sinister is the possibility of neuroscientists creating cognitively manipulated warriors, whose emotions have been blunted, for example.
Zak emphasises that the panel was not asked how to turn soldiers into better "killing machines", although "the whole purpose of maximising and sustaining battlefield capacity is to gain superiority over opponents", admits Floyd Bloom of the Scripps Research Institute in La Jolla, California, who chaired the panel.
That's not to say someone won't try it, though. Zak's own work focuses on the role of the hormone oxytocin in trust and empathy. If drugs were developed to block oxytocin, the effect might be to reduce a soldier's ability to empathise with enemy combatants or civilians.
"There are lots of stories of soldiers who refuse to shoot other soldiers," says Zak. "If you could get rid of that empathy response you might create a soldier that's more prepared to engage in battle and risk their life."
The panel recognised that such ethical dilemmas might be an inevitable consequence of their work. For this reason, they recommended that the US military should recruit ethicists to examine the ramifications of such developments before they occur. "They need to be explored because at some point someone's going to do them," says Zak. "Controls have to be put in place."
Neuroscience could also help to save lives in a military context. If you could predict which soldiers were particularly susceptible to stress, for example, it might help prevent a tragedy. Last week US army sergeant John Russell was charged with shooting five of his colleagues dead. Russell had completed a 15-month tour of Iraq and was being treated for stress.
Other research has suggested that navy recruits whose hypothalamo-pituitary axes (an area of the brain involved in the stress response) are highly reactive to stress are less likely to complete navy SEAL training. Robert Ursano at the Uniformed Services University in Bethesda, Maryland, and his colleagues have hinted that you might be able to predict individual responses to stress by looking at numbers of serotonin receptors, and levels of p11, a protein linked to depression (Progress in Brain Research, DOI: 10.1016/s0079-6123(07)67014-9).
The difficulty is finding predictive markers that are reliable enough, says Simon Wessely at the King's Centre for Military Health Research in London, who was not involved in the report. "Current predictors are too weak, and while they may work statistically in large groups, they cannot say that Private A is vulnerable and Private B isn't." Moreover, "if you wrongly label someone as vulnerable to breakdown, you are damaging his career and robbing the army of much-needed manpower".
A more likely short-term prospect is monitoring whether an individual soldier's mental performance is deteriorating because of stress or tiredness.
Many errors involve lapses of attention, so finding ways to monitor attentiveness could have big benefits. Recent studies have linked variations in blood flow and oxygenation with occasions when observers miss signals, says the report, so sensors in helmets to monitor these variations could alert the soldier and his unit that his attention was fading.
Another possibility might be to use brain imaging to work out which recruits have understood new training concepts. In a recent study, fMRI was used to compare the brain activity of physics students and other students when they watched film clips of two different-sized balls falling at either the same or different rates.
The students were asked if the film they viewed was consistent with their expectations of how the balls should fall. In the non-physics students, an area of the brain associated with error detection lit up when the large and small balls fell at the same rate. For the physics students, the same area lit up when they fell at different rates - suggesting that they had fully grasped the Newtonian concept that different balls should fall at the same rate, regardless of their size.
Bloom emphasises that while all technologies have the potential to be misused, this is not necessarily a reason for ignoring them. Indeed, military investment could even reap benefits for the wider society. "Investment in such opportunities will be of benefit to the public by improving ways we educate our children and understand ourselves," he says.
The panel recognised that such ethical dilemmas might be an inevitable consequence of their work. For this reason, they recommended that the US military should recruit ethicists to examine the ramifications of such developments before they occur. "They need to be explored because at some point someone's going to do them," says Zak. "Controls have to be put in place."
Neuroscience could also help to save lives in a military context. If you could predict which soldiers were particularly susceptible to stress, for example, it might help prevent a tragedy. Last week US army sergeant John Russell was charged with shooting five of his colleagues dead. Russell had completed a 15-month tour of Iraq and was being treated for stress.
Other research has suggested that navy recruits whose hypothalamo-pituitary axes (an area of the brain involved in the stress response) are highly reactive to stress are less likely to complete navy SEAL training. Robert Ursano at the Uniformed Services University in Bethesda, Maryland, and his colleagues have hinted that you might be able to predict individual responses to stress by looking at numbers of serotonin receptors, and levels of p11, a protein linked to depression (Progress in Brain Research, DOI: 10.1016/s0079-6123(07)67014-9).
The difficulty is finding predictive markers that are reliable enough, says Simon Wessely at the King's Centre for Military Health Research in London, who was not involved in the report. "Current predictors are too weak, and while they may work statistically in large groups, they cannot say that Private A is vulnerable and Private B isn't." Moreover, "if you wrongly label someone as vulnerable to breakdown, you are damaging his career and robbing the army of much-needed manpower".
A more likely short-term prospect is monitoring whether an individual soldier's mental performance is deteriorating because of stress or tiredness.
Many errors involve lapses of attention, so finding ways to monitor attentiveness could have big benefits. Recent studies have linked variations in blood flow and oxygenation with occasions when observers miss signals, says the report, so sensors in helmets to monitor these variations could alert the soldier and his unit that his attention was fading.
Another possibility might be to use brain imaging to work out which recruits have understood new training concepts. In a recent study, fMRI was used to compare the brain activity of physics students and other students when they watched film clips of two different-sized balls falling at either the same or different rates.
The students were asked if the film they viewed was consistent with their expectations of how the balls should fall. In the non-physics students, an area of the brain associated with error detection lit up when the large and small balls fell at the same rate. For the physics students, the same area lit up when they fell at different rates - suggesting that they had fully grasped the Newtonian concept that different balls should fall at the same rate, regardless of their size.
Bloom emphasises that while all technologies have the potential to be misused, this is not necessarily a reason for ignoring them. Indeed, military investment could even reap benefits for the wider society. "Investment in such opportunities will be of benefit to the public by improving ways we educate our children and understand ourselves," he says.