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Contrary to intuition, adding pockets of water to solids can actually make them stronger. This finding, the result of research by Yale scientists, offers “a new knob to turn” for engineers, the researchers say. Engineers will be able to add exciting new properties to composite materials–such as electromagnetism–by embedding droplets of liquid, and, on a purely scientific level, the research provides valuable insight into the nature of the material properties at small and large scales–how the relative strengths of a material at one size can be opposite to that at another size.

“This is a great example of how different types of physics emerge at different scales,” Dr. Eric Dufresne, associate professor of mechanical engineering and materials science at Yale and principle investigator of the study, told The Speaker. “Shrinking the scale of an object can really change how it behaves.”

Usually, replacing parts of a solid with liquid–generally considered a soft material–makes the material weaker, but this is not always the case. The researchers strengthened solids with liquids by the virtue of the surface tension of liquid droplets.

“Surface tension is a force that tries to reduce the surface area of a material,” Dufresne told us. “It is familiar in fluids–it’s the force that pulls water into a sponge, makes wet hair clump together and lets insects walk on water. Solids have surface tension too, but usually the ‘elastic force’ of the solid is so strong that surface tension doesn’t have much of an effect. The ‘elastic force’ of a solid is what makes a solid spring back to its originial shape after you stop pushing on it.

Because the tendency of a liquid is to have as small a surface as possible, embedding small drops of liquid–about a micron in diameter–strengthen solids because the surface tension of the water provides stiffness to the composite.

Dufresne commented on what would be, in his words, “a new knob to turn” for engineers, who can achieve greater control over the properties of composite materials by including fluids.

“As the solid gets stiffer, the liquid droplets need to be smaller in order to have this stiffening or cloaking effect. By embedding the solid with droplets of different materials, one can give it new electrical, optical or mechanical properties.

“On the simple scale, they could lower the cost be replacing expensive polymers with simple liquids. More excitingly, embedded droplets could provide an electromagnetic handle to actuate structures.”

In the recent research, the team embedded the small drops of liquid into silicone and then stretched the silicone. Silicone embedded with large drops of water deformed easily–the material was weakened by the liquid. Silicone with small droplets resisted deformation–the material was strengthened.

The team found that a composite up to 30 percent stronger than pure silicone could be created by embedding a large amount of small liquid droplets.

Dufresne explained how the current work came about.

“A few years back, we discovered, on accident, some surprises on how liquid droplets sit on top of solid surfaces,” said Dufresne. “In the course of that work, we realized people needed to pay attention to solid surface tension. Since then, we have been looking for other examples where solid surface tension might be an important and neglected component of the behaviour of materials. These experiments were inspired by ongoing efforts in ‘metamaterials’ where engineers tune the microstructure of a material to give it new properties.”

“It turns out that the importance of surface tension is inversely proportional to the size,” Dufresne said of the study. “So what’s just a negligible force for big things becomes a strong force for very small things–which in turn can strongly affect the material as a whole.”

The report, “Stiffening solids with liquid inclusions,” was completed by Drs. W. Style, Rostislav Boltyanskiy, Benjamin Allen, Katharine E.Jensen, Henry P. Foote, John S. Wettlaufer, and Eric R. Dufresne, and was publishe in December’s Nature Physics.

Photos: all belong to the work of the Yale team

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Women feel what is happening to their partners over three times as much as men do. According to new research, the difference between the empathy felt by women and men was the biggest of many factors analyzed.

“In our work, we were trying to measure how partners affect each other’s mental health through life events,” Dr Cindy Mervin, research fellow at Griffith University’s Centre for Applied Health Economics and lead author of the study, told The Speaker. “[O]ur work showed that negative and positive things that happen to individuals not only affect them but also affect their family.”

Mervin explained the research team’s findings about the levels of empathy felt by women and men, most notably, that women’s levels of empathy for their partners–at 24 percent of what they would have felt had an event happened to themselves–are over 300 percent of men’s levels.

“We can interpret the 24 percent by saying that on average women will be affected by the events happening to their partner by about 24 percent of the degree to which they are affected by their own,” Mervin told us. “In other words, women are affected about four times as much by the events happening to them than events happening to their partners.”

The research involved questionnaire data from the Australian study Household, Income and Labour Dynamics in Australia (HILDA) on over 20,000 people across the country. The team looked at partners in both straight and same-sex relationships who did not separate during the observed panel, which amounted to just under 11,000 individuals and over 53,000 person-year observations.

The research led the team to conclude that while women’s empathy toward their partners was the strongest found in their study, men on average were found to not be empathetic in any significant way.

“We estimated this coefficient for different types of respondents–women vs men, parents vs their counterparts, and individual from high-income households vs. those from low-income households,” stated Mervin. “The highest value we found was for women when compared to men. For men, we found a value around seven percent and therefore found that men were not significantly affected by things happening to their partner.”

Mervin clarified that the findings do not mean that men are unemotional or uncaring, but that their care does not extend to their partner the way women’s care does.

“Although the degree measured for women and men is different, it does not mean that men are unemotional as they are quite strongly affected by what happens to themselves,” said Mervin. “They are just not very emotional when it comes to their feelings of their partner.”

The report, “Is shared misery double misery,” was authored by Drs Merehau Cindy Mervin and Paul Frigters of University of Queensland’s School of Economics, and was published in the journal Social Science and Medicine.

By James Haleavy

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A drink before bed? Around 50 million adults in the US take a drink to help them fall asleep, but that drink is being advised against by researchers at the University of Missouri School of Medicine. Their research has found that alcohol actually disrupts sleep–even if it causes people to nod off. It disrupts sleep differently from what is commonly believed, however. Rather than the circadian rhythm, alcohol actually affects the body’s homeostatic system.

“Based on our results, it’s clear that alcohol should not be used as a sleep aid,” Dr. Pradeep Sahota, chair of the MU School of Medicine’s Department of Neurology and an author of the study, said in the press release.

Around one-third of our people’s lives are spent sleeping, and around 20 percent of America’s 250 million adults use alcohol. This is relevant to the nation’s health and economy, the researchers pointed out. They cited research that has found alcohol-related sleep disorders cost the US  at least $18 billion per year.

The MU team have spent five years studying the interaction between sleep and alcohol, and have concluded in their most recent report that alcohol disturbs sleep, but in a way that may surprise scientists and readers alike.

“The prevailing thought was that alcohol promotes sleep by changing a person’s circadian rhythm–the body’s built-in 24-hour clock,” said Dr Mahesh Thakkar, another author of the study. “However, we discovered that alcohol actually promotes sleep by affecting a person’s sleep homeostasis–the brain’s built-in mechanism that regulates your sleepiness and wakefulness.”

The body has two systems that both play a role in sleep. The homeostatic system builds up pressure to sleep the longer a person stays awake, and the circadian system is an internal clock regulated by the body’s perception of light and dark.

A person might drink a lot of coffee and power through a night without sleeping. In the morning they would feel increased pressure to sleep from their homeostatic system, but their circadian clock would tell them it was time to be awake.

Alcohol does something of the opposite, the researchers found. It promotes sleepiness through the homeostatic system while leaving the circadian rhythm unaffected. While a person may nod off more quickly, it will be likely that they will not sleep through the whole night.

“Alcohol disrupts sleep and the quality of sleep is diminished. Additionally, alcohol is a diuretic, which increases your need to go the bathroom and causes you to wake up earlier in the morning,” Sahota pointed out.

The researchers advised other options that could be pursued by people having difficulty getting a good night’s rest.

“If you are experiencing difficulty sleeping, don’t use alcohol,”said Thakkar. “Talk to your doctor or a sleep medicine physician to determine what factors are keeping you from sleeping. These factors can then be addressed with individualized treatments.”

The report, “Alcohol Disrupts Sleep Homeostasis,” was completed by Drs Mahesh Thakkar, Pradeep Sahota and Rishi Sharma, and was published in the international biomedical journal Alcohol.

By Cheryl Bretton

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A unique study of landscape factors–in particular, mines–as regional sources of stress has been conducted by Michigan State University researchers. The study involved waterways in 33 U.S. states and 22,000 fish community samples. The researchers were themselves surprised by the results: even a single mine can damage fish habitats in larger rivers downstream, and the effects can reach streams not even directly connected to a mine. 

“Mines have a much stronger influence on fishes than has been assumed,” Dr. Wesley Daniel, a research associate at MSU and lead author of the study, said. “It’s important, when considering the location of a new mine, to not just look local–but look way downstream.”

Here Dr Daniel explains the research, which has relevance in every part of the world where mining occurs.

Our study was funded by the US Fish and Wildlife and US Geological Survey as part of efforts to characterize associations between landscape factors, including coal and mineral mines, on stream fish communities in a range of stream sizes in the eastern US.

We wanted to test whether mines operate as a regional source of stress to fish communities over large spatial extents, as has been shown in many previous works examining urban and agricultural land use.

One of the striking results was the clear and consistent negative associations between fish and mines across all three regions, and that these relationships held true for many different groupings of fishes. Examples of groupings include game species (fish species targeted by anglers like trout, bass, catfish), intolerant species that cannot endure much disturbance, fishes that use various habitats for spawning or their life cycle, and tolerant species that are often found to increase in disturbed areas. We found that tolerant species decreased in abundance with increased mine density in the watershed.

We found that a single mine in a small river’s watershed (1000 km² watershed) has the potential to alter the fish community by decreasing the number or diversity of fishes. When considering the effect of mines (current or new), managers need to consider not only the local stream watershed but the downstream impact.

There is an opportunity for management and agencies to use the our results along with the advancements in GIS mapping data we have created to consider mine’s influence as a regional source of stress and improve fisheries through management actions. Mining will continue to be needed until an adequate substitution can be found. As a society, we should be thoughtful on where mines at placed, keeping them out of ecologically or culturally significant watersheds. Since, based on our results, a very low density of mines has the potential to alter the fish community in large areas.

We found strong associations between greater numbers of mines in watersheds and lower numbers and diversity of fishes. We tested both mineral and coal mines together and separately and saw associations with altered fish communities. We did not test specifically for mechanisms by which mines could affect stream fishes, but many other studies that have been conducted at smaller spatial scales have demonstrated specifically how mines can affect stream fishes (mines can be a source of sediments and chemicals into rivers, alter the flow of streams, and alter natural land covers all of which can change stream habitats). What makes our study unique is that it was conducted over a large spatial extent, and we repeated our analyses in each of three regions that cover all or portions of 33 states in the central and eastern US. Also, our associations were based on trends detected using 22,000 fish community samples.

Our results suggest that a single mine has potential to alter fish communities. We cannot provide a unique value for the distance the mines can influence fish communities. The distance downstream that mining can influence fish communities will vary based on stream size, number of mines, and regional variation in natural conditions. There is an opportunity for future studies to build upon our results and try to quantify and characterize distance downstream in various regions that mines influence aquatic communities.

The report, “Characterizing coal and mineral mines as a regional source of stress to stream fish assemblages,” was completed by Drs. Wesley Daniel, MSU associate professor of fisheries and wildlife Dana Infante, Robert Hughes at Amnis Opes Institute, Yin-Phan Tsang, Daniel Wieferich, Kyle Herreman, Arthur Cooper and William Taylor at MSU, Peter Esselman at the U.S. Geological Survey Great Lakes Science Center in Ann Arbor, Mich., and Lizhu Wang of the International Joint Commission Great Lakes Regional Office in Detroit,” was published in the journal Ecological Indicators, and was funded the US Fish and Wildlife and US Geological Survey.

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Leaps of faith? Gambling on Sundays may be more risky than churchgoers are aware, because, according to research by Radboud University, Netherlands scientists, activation of the concept of God in the minds of individuals increases their propensity to take risks.

“Risk taking is influenced by subtle environmental factors. It might not be a good idea to house a church service beside a casino, for example,” lead researcher Dr Kai Qin Chan of RU’s Department of Social and Cultural Psychology, told The Speaker.

Chan’s most recent research indicates that bringing the concept of God to the fore of people’s minds increases risk taking behavior, particularly when there is an incentive for gain.

The premise of the research was a hypothesis based on two fields of current research–recent psychological models that suggest religious belief provides a form of social control, and scientific findings that increased psychological control can lead to the formation fo riskier strategies. It made sense that these two fields of research could be brought together to show that religion could influence risk taking.

“We measured risk taking using a behavioral task,” Chan told us. “In this task, participants had to pump virtual balloons. With more ‘pumps’ they gave, the risk of explosion increases, but the chances of getting a larger reward increases as well, provided the balloon does not burst before they cashed in on their trial. We found that participants primed with God–for example, seeing the word ‘God’ briefly before doing the task–took more risk–they gave more pumps.”

All of the three studies conducted by the team showed that activating the God concept led to greater risk taking. The study participants were literally “taking a leap of faith,” according to the researchers.

However, this increased risk taking behavior was found to present only when participants felt they were in control of the situation.

“When we made one group of participants feel that they were not in control of things–i.e., we decreased their sense of psychological control–albeit momentarily–we found that these people look less risks, even when primed with God. This implies that priming with God (without any manipulation of psychological control) must have increased psychological control, because when we disrupted this process, risk taking returned to baseline levels.”

Chan’s research enabled him to make some educated guesses about the relationship between religion, morality and risk taking, but he was clear that questions of such relationships were difficult to answer, and that other great research was being done in those areas.

“I think much risk taking literature that examines how religion–e.g., religiosity–is related to lower risk taking may be an artifact of the measurement of risk taking,” said Chan.

“In these studies, sometimes investigators use measurements of risk taking that have an inherent moral component–for example, unprotected sex is risky, but it also has a tinge of one being morally loose. So, there are different domains of risk taking and we need to take them into account. Being risky in one domain does not necessarily translate into being risky in another, and because our notion of religion is so tightly linked with morality, risk-religion research needs to take into account the moral domains of risk taking as well.”

The research, the team found, contradicted certain other survey findings that religious people were less risk seeking than other people.

“Religion sometimes affects us in subtle ways,” observed Chan. “However, I do want to stress that I am not implying that religion is bad. Risk taking itself is not necessarily an evil, and I certainly do not want to say that religion makes people bad risk takers.”

The report, “Taking a Leap of Faith Reminders of God Lead to Greater Risk Taking,” was authored by Kai Qin Chan, Eddie Mun Wai Tong, and Yan Lin Tan of the National University of Singapore.

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Small businesses that fear competing giant neighbors may need to think again. According to research by a joint team of university scientists, having a large competitor nearby may actually boost the sales of small businesses, but this depends on whether a small business can successfully “stick it to the man” in “framing the game.”

“When the owner of Los Angeles’s Coffee Bean & Tea Leaf could not stop Starbucks from moving in next door, he at first admitted defeat,” the team stated. “However, soon after, he was surprised to see his sales shoot up, so much so that he began to proactively locate new stores next to Starbucks.”

The research team, composed of Neeru Paharia of Georgetown University and Jill Avery and Anat Keinan of Harvard University, set out to test a theory that small businesses could benefit from big neighbors.

They examined shopping habits of two groups of participants. One group was told that a small bookstores only competitors were other small bookstores. Another group was told that the small bookstore was in competition with a nearby chain that threatened the future of the small bookstore.

The second group was more likely to buy at the small bookstore.

The team further explored the idea with a second study.

They gave participants a scenario: “Imagine you are in the mood for a cup of coffee. You can either go to Starbucks or an independent coffee shop called Joe’s Java.”

Again, there were two groups involved. The first was told that Joe’s Java and the chain were the same distance away, although in different directions. The second group learned that Joe’s and Starbucks were neighbors.

The second group–believing the two shops were neighbors–was the one that was more likely to patronize Joe’s Java.

The team believes that the results indicate an interest people may have in “sticking it to the man.”

This interest, the researchers argue, has something to do with the “framing-the-game effect.” Consumers, the researchers believe, want to be felt and heard in the marketplace, and do so through their purchase choices. Thus, they may feel motivated to exert their influence upon stores they wish to allow to succeed or fail.

The report, “Positioning Brands against Large Competitors to Increase Sales,” was authored by Neeru Paharia, Jill Avery, and Anat Keinan, and will be published in the upcoming in Journal of Marketing Research.

By Cheryl Bretton