In a study in the Proceedings of the Royal Society B, Duke University grad student Eleanor Caves reports that African songbirds frequently victimized by brood parasitic cuckoos have taken to creating elaborate patterns on their eggs to help them recognize the forgeries.
“We don’t know at what stage of this evolutionary ‘arms race’ we’re seeing these species,” Caves said, but her study found that birds that are heavily parasitized are able to “sign” their eggs with color and pattern traits in unpredictable combinations.
The hundreds of eggs used in her study had been meticulously collected and cataloged by a retired British military officer on his ranch in southern Zambia over a 35-year period.
One female songbird will lay one pattern type with just a little variability her whole career. The colors and patterns are created in the shell gland of the mother bird hours before the egg is laid. The parasitic cuckoos produce a wide variety of egg patterns in an attempt to mimic the variety of their hosts. But a parasitic bird isn’t always careful to lay in a nest that closely matches the pattern the songbird is producing, so rejections are common. duke.edu
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N.C. State team creates nano-conductors that can stretch
Researchers from N.C. State have created stretchable, transparent conductors that work because of the structures’ “nano-accordion” design. The conductors could be used in a wide variety of applications, such as flexible electronics, stretchable displays or wearable sensors.
“There are no conductive, transparent and stretchable materials in nature, so we had to create one,” said Abhijeet Bagal, a Ph.D. student in mechanical and aerospace engineering at N.C. State and lead author of a paper in the journal Materials Horizons that describes the work.
“Our technique uses geometry to stretch brittle materials, which is inspired by springs that we see in everyday life,” Bagal said.
The researchers begin by creating a three-dimensional polymer template on a silicon substrate. The template is shaped like a series of identical, evenly spaced rectangles. The template is coated with a layer of aluminum-doped zinc oxide (the conducting material), and an elastic polymer is applied to the zinc oxide. The researchers then flip the whole thing over and remove the silicon and the template.
What’s left behind is a series of symmetrical, zinc oxide ridges on an elastic substrate. Because both zinc oxide and the polymer are clear, the structure is transparent. And the ridges of zinc oxide allow the structure to expand and contract, like the bellows of an accordion. ncsu.edu
Clemson study: Tweak GPS to combat driver fatigue
National statistics show drowsy drivers are five times more likely to be involved in an accident, or a near-crash incident, than alert drivers. But biometric measurements – including driver eye movements, muscle activity and changes in heart rate – are inaccurate at times.
Researchers at Clemson University have determined that a reliable, less intrusive way to detect fatigue or drowsiness in a driver is to monitor vehicle behavior rather than the biometrics of the person behind the wheel: GPS.
The Clemson study tested volunteers whose attentiveness was measured in a vehicle simulator during a 26-hour stretch without sleep. Driving performance was measured for lateral lane position, lane heading and vehicle heading.
“By employing more accurate GPS technology to pinpoint the vehicle’s orientation on the road, the driver could be notified if their driving is getting dangerous,” said Drew Morris, a human factors psychology Ph.D. student.
The research was published in the journal Accident Analysis & Prevention. clemson.edu