Instead of an apple, could a hug-a-day keep the doctor away? According to new research from Carnegie Mellon University, that may not be that far-fetched of an idea.
Led by Sheldon Cohen, the Robert E. Doherty University Professor of Psychology in CMU's Dietrich College of Humanities and Social Sciences, the researchers tested whether hugs act as a form of social support, protecting stressed people from getting sick. Published in Psychological Science, they found that greater social support and more frequent hugs protected people from the increased susceptibility to infection associated with being stressed and resulted in less severe illness symptoms.
Cohen and his team chose to study hugging as an example of social support because hugs are typically a marker of having a more intimate and close relationship with another person.
"We know that people experiencing ongoing conflicts with others are less able to fight off cold viruses. We also know that people who report having social support are partly protected from the effects of stress on psychological states, such as depression and anxiety," said Cohen. "We tested whether perceptions of social support are equally effective in protecting us from stress-induced susceptibility to infection and also whether receiving hugs might partially account for those feelings of support and themselves protect a person against infection."
In 404 healthy adults, perceived support was assessed by a questionnaire, and frequencies of interpersonal conflicts and receiving hugs were derived from telephone interviews conducted on 14 consecutive evenings. Then, the participants were intentionally exposed to a common cold virus and monitored in quarantine to assess infection and signs of illness.
The results showed that perceived social support reduced the risk of infection associated with experiencing conflicts. Hugs were responsible for one-third of the protective effect of social support. Among infected participants, greater perceived social support and more frequent hugs both resulted in less severe illness symptoms whether or not they experienced conflicts.
"This suggests that being hugged by a trusted person may act as an effective means of conveying support and that increasing the frequency of hugs might be an effective means of reducing the deleterious effects of stress," Cohen said. "The apparent protective effect of hugs may be attributable to the physical contact itself or to hugging being a behavioral indicator of support and intimacy."
Cohen added, "Either way, those who receive more hugs are somewhat more protected from infection."
Fireflies used rapid light flashes to communicate. This "bioluminescence" is an intriguing phenomenon that has many potential applications, from drug testing and monitoring water contamination, and even lighting up streets using glow-in-dark trees and plants. Fireflies emit light when a compound called luciferin breaks down. We know that this reaction needs oxygen, but what we don't know is how fireflies actually supply oxygen to their light-emitting cells. Using state-of-the-art imaging techniques, scientists from Switzerland and Taiwan have determined how fireflies control oxygen distribution to light up their cells.
The work is published in Physical Review Letters.
The firefly's light-producing organ is called the "lantern," and it is located in the insect's abdomen. It looks like a series of tubes progressing into smaller ones and so one, like a tree's branches growing into twigs. The function of these tubes, called, is to supply oxygen to the cells of the lantern, which contain luciferase and can produce light. However, the complexity of the firefly's lantern has made it difficult to study this mechanism in depth, and reproduce it for technological applications.
Giorgio Margaritondo at EPFL, Yeukuang Hwu at the Academia Sinica and their colleagues at the National Tsing Hua University in Taiwan have successfully used two sophisticated imaging techniques to overcome the complexity of the firefly lantern and map out how oxygen is supplied to light-emitting cells. The techniques are called synchrotron phase contrast microtomography and transmission x-ray microscopy. They can scan down to the level of a single cell, even allowing researchers to look inside it.
By applying these techniques on live fireflies, the scientists were able to see the entire structure of the lantern for the first time, and to also make quantitative evaluations of oxygen distribution.
The imaging showed that the firefly diverts oxygen from other cellular functions and puts it into the reaction that breaks up luciferin. Specifically, the researchers found that oxygen consumption in the cell decreased, slowing down energy production. At the same time, oxygen supply switched to light-emission.
The study is the first to ever show the firefly's lantern in such detail, while also providing clear evidence that it is optimized for light emission thanks to the state-of-the-art techniques used by the scientists. But Margaritondo points out another innovation: "The techniques we used have an advantage over, say, conventional x-ray techniques, which cannot easily distinguish between soft tissues. By using an approach based on changes in light intensity (phase-contrast) as opposed to light absorption (x-rays), we were able to achieve high-resolution imaging of the delicate firefly lantern."