Monthly Archives: August 2015

Why does running make us happy?

The joy of running. That sense of well-being, freedom and extra energy that runners often experience is not just a matter of endorphins. A study at the University of Montreal Hospital Research Centre (CRCHUM) shows that the “runner’s high” phenomenon is also caused by dopamine, an important neurotransmitter for motivation.

“We discovered that the rewarding effects of endurance activity are modulated by leptin, a key hormone in metabolism. Leptin inhibits physical activity through dopamine neurons in the brain,” said Stephanie Fulton, a researcher at the CRCHUM and lead author of an article published in the journal Cell Metabolism.

 

Secreted by adipose tissue, leptin helps control the feeling of satiety. This hormone also influences physical activity. “The more fat there is, the more leptin there is and and the less we feel like eating. Our findings now show that this hormone also plays a vital role in motivation to run, which may be related to searching for food,” explained Stephanie Fulton, who is also a professor at Université de Montréal’s Department of Nutrition.

Hormone signals that modulate feeding and exercise are in fact believed to be closely linked. Endurance running capacity in mammals, particularly humans, is thought to have evolved to maximize the chances of finding food. This study suggests that leptin plays a critical role both in regulating energy balance and encouraging behaviours that are “rewarding” for the person’s metabolism, i.e., engaging in physical activity to find food.

The researchers studied voluntary wheel running in mice in cages. These mice can run up to seven kilometres a day. In a laboratory, the physical activity of normal mice was compared with that of mice who underwent a genetic modification to suppress a molecule activated by leptin, STAT3 (signal transducer and activator of transcription-3). The STAT3 molecule is found in the neurons that synthesize dopamine in the midbrain. This “mesolimbic dopaminergic pathway” is a like a motivational highway in the brain.

“Mice that do not have the STAT3 molecule in the dopaminergic neurons run substantially more. Conversely, normal mice are less active because leptin then activates STAT3 in the dopamine neurons, signalling that energy reserves in the body are sufficient and that there is no need to get active and go looking for food,” explained Maria Fernanda Fernandes, first author of the study.

And is leptin as important for motivation to be active in humans? Yes. “Previous studies have clearly shown a correlation between leptin and marathon run times. The lower leptin levels are, the better the performance. Our study on mice suggests that this molecule is also involved in the rewarding effects experienced when we do physical exercise. We speculate that for humans, low leptin levels increase motivation to exercise and make it easier to get a runner’s high,” summed up Stephanie Fulton.

Mice, humans and mammals in general are thought to have evolved to increase the return on effective food acquisition behaviours. Ultimately, hormones are sending the brain a clear message: when food is scarce, it’s fun to run to chase some down.

Nasa starts year-long isolation to simulate life on Mars

Six Nasa recruits have shut themselves inside a dome in Hawaii to begin a year-long isolation programme that will simulate life on Mars to help the US space agency prepare for the pioneering mission to the red planet.

The group began the isolation experiment on August 28, and now face 365 days without fresh air, food or privacy.

The exterior of the HI-SEAS habitat on the northern slope of Mauna Loa in Hawaii

The group consists of a French astrobiologist, a German physicist and four Americans; a pilot, an architect, a doctor/journalist and a soil scientist.

They are living in a self-contained solar-powered dome, which measures only 11 metres in diameter and is six metres tall.

It is estimated that the first human mission to Red Planet could last between one to three years.

The participants will each have a small sleeping cot and a desk inside their rooms and will be eating food such as powdered cheese and canned tuna, ‘Ibtimes.co.uk’ reported.

The group has limited access to the internet, and must wear a spacesuit if they

Evidence suggests subatomic particles could defy the standard model

The Standard Model of particle physics, which explains most of the known behaviors and interactions of fundamental subatomic particles, has held up remarkably well over several decades. This far-reaching theory does have a few shortcomings, however–most notably that it doesn’t account for gravity. In hopes of revealing new, non-standard particles and forces, physicists have been on the hunt for conditions and behaviors that directly violate the Standard Model.

Now, a team of physicists working at CERN’s Large Hadron Collider (LHC) has found new hints of particles–leptons, to be more precise–being treated in strange ways not predicted by the Standard Model. The discovery, scheduled for publication in the September 4, 2015 issue of the journalPhysical Review Letters, could prove to be a significant lead in the search for non-standard phenomena.

 

The team, which includes physicists from the University of Maryland who made key contributions to the study, analyzed data collected by the LHCb detector during the first run of the LHC in 2011-12. The researchers looked at B meson decays, processes that produce lighter particles, including two types of leptons: the tau lepton and the muon. Unlike their stable lepton cousin, the electron, tau leptons and muons are highly unstable and quickly decay within a fraction of a second.

According to a Standard Model concept called “lepton universality,” which assumes that leptons are treated equally by all fundamental forces, the decay to the tau lepton and the muon should both happen at the same rate, once corrected for their mass difference. However, the team found a small, but notable, difference in the predicted rates of decay, suggesting that as-yet undiscovered forces or particles could be interfering in the process.

“The Standard Model says the world interacts with all leptons in the same way. There is a democracy there. But there is no guarantee that this will hold true if we discover new particles or new forces,” said study co-author and UMD team lead Hassan Jawahery, Distinguished University Professor of Physics and Gus T. Zorn Professor at UMD. “Lepton universality is truly enshrined in the Standard Model. If this universality is broken, we can say that we’ve found evidence for non-standard physics.”

The LHCb result adds to a previous lepton decay finding, from the BaBar experiment at the Stanford Linear Accelerator Center, which suggested a similar deviation from Standard Model predictions. (The UMD team has participated in the BaBar experiment since its inception in 1990’s.) While both experiments involved the decay of B mesons, electron collisions drove the BaBar experiment and higher-energy proton collisions drove the LHC experiment.

“The experiments were done in totally different environments, but they reflect the same physical model. This replication provides an important independent check on the observations,” explained study co-author Brian Hamilton, a physics research associate at UMD. “The added weight of two experiments is the key here. This suggests that it’s not just an instrumental effect–it’s pointing to real physics.”

“While these two results taken together are very promising, the observed phenomena won’t be considered a true violation of the Standard Model without further experiments to verify our observations,” said co-author Gregory Ciezarek, a physicist at the Dutch National Institute for Subatomic Physics (NIKHEF).

“We are planning a range of other measurements. The LHCb experiment is taking more data during the second run right now. We are working on upgrades to the LHCb detector within the next few years,” Jawahery said. “If this phenomenon is corroborated, we will have decades of work ahead. It could point theoretical physicists toward new ways to look at standard and non-standard physics.”

With the discovery of the Higgs boson–the last major missing piece of the Standard Model–during the first LHC run, physicists are now looking for phenomena that do not conform to Standard Model predictions. Jawahery and his colleagues are excited for the future, as the field moves into unknown territory.

“Any knowledge from here on helps us learn more about how the universe evolved to this point. For example, we know that dark matter and dark energy exist, but we don’t yet know what they are or how to explain them. Our result could be a part of that puzzle,” Jawahery said. “If we can demonstrate that there are missing particles and interactions beyond the Standard Model, it could help complete the picture.”

In addition to Jawahery and Hamilton, UMD Graduate Assistants Jason Andrews and Jack Wimberley are co-authors on the paper. The UMD LHCb team also includes Research Associate William Parker and Engineer Thomas O’Bannon, who are not coauthors on the paper.

The LHCb experiment is supported by funding from a consortium of international collaborating agencies and institutions. United States participation in the LHCb collaboration is supported by the National Science Foundation. The content of this article does not necessarily reflect the views of these organizations.

 

 

 

Source- sciencedaily.com