"Males and females differ in their biobehavioural response to stress, where males exhibit a heightened sympathetic response to stress compared with females. Specifically, Taylor et al. 1 propose that the classic "fight-or-flight" response to stress is adaptive for males, whilst females engage in a so-called "tend-and-befriend" response to stress. We propose that the Y-chromosome gene, SRY (sex-determining region on the Y chromosome), provides a genetic basis for the heightened sympathetic reactivity to stress and thus predominance of "fight-flight" response in males. Our idea is based on studies that demonstrate (i) the presence of SRY in brain regions and peripheral tissues abundant in catecholamines, (ii) the regulation of catecholamine synthesis and breakdown by SRY, and (iii) the role of SRY in voluntary movement and blood pressure in males"
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Dog owners often compare their pets to toddlers; many even treat their pooches like kids. It's easy to label such comparisons sentimental. But a new study suggests that the owners are right. A team of scientists has discovered that dogs behave surprisingly like 10-month-old infants on a classic psychological test--though there is one important difference.
In 1967, Simon Kochen and Ernst Specker proved mathematically that even for a single quantum object, where entanglement is not possible, the values that you obtain when you measure its properties depend on the context. So the value of property A, say, depends on whether you chose to measure it with property B, or with property C. In other words, there is no reality independent of the choice of measurement.
It wasn't until 2008, however, that Alexander Klyachko of Bilkent University in Ankara, Turkey, and colleagues devised a feasible test for this prediction. They calculated that if you repeatedly measured five different pairs of properties of a quantum particle that was in a superposition of three states, the results would differ for the quantum system compared with a classical system with hidden variables.
That's because quantum properties are not fixed, but vary depending on the choice of measurements, which skews the statistics. "This was a very clever idea," says Anton Zeilinger of the Institute for Quantum Optics, Quantum Nanophysics and Quantum Information in Vienna, Austria. "The question was how to realise this in an experiment."
Now he, Radek Lapkiewicz and colleagues have realised the idea experimentally. They used photons, each in a superposition in which they simultaneously took three paths. Then they repeated a sequence of five pairs of measurements on various properties of the photons, such as their polarisations, tens of thousands of times.
A beautiful experiment
They found that the resulting statistics could only be explained if the combination of properties that was tested was affecting the value of the property being measured. "There is no sense in assuming that what we do not measure about a system has [an independent] reality," Zeilinger concludes.
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Great introduction to emergence, including several simulations you can play with. Simulations include the classic "Life," Brian's brain, and one that tends towards chaotic patterns.