Knowledge Update

​London, June 17 (IANS) Unable to retain your memory? A new study suggests that physical exercise four hours after learning can significantly improve long-term memory and memory traces.

The findings showed that students who exercised four hours after learning retained the information for two days in comparison to those who exercised either immediately or not at all. 

Exercise after the stipulated time was associated with more precise representations in the hippocampus -- a brain region important for learning and memory.

"It shows that we can improve memory consolidation and long term memory by doing sports after learning," said Guillen Fernandez from Radboud University in the Netherlands.

"The study suggests that appropriately timed physical exercise can improve long-term memory and highlights the potential of exercise as an intervention in educational and clinical settings," Fernandez noted.

The study, published in the journal Current Biology, involved 72 students, who were made to learn 90 picture-location associations for 40 minutes. 

After that, they were randomly assigned to one of three groups: first group performed the exercise immediately after learning. The second group performed the exercise four hours later and the third did not perform any exercise.

The exercise consisted of 35 minutes of interval training on an exercise bike at an intensity of up to 80 per cent of participants' maximum heart rates.

​London, June 17 (IANS) Being overweight during adolescence can put men at significantly higher risk of developing severe liver disease later in life, says a study.

The findings are based on 40 years follow-up of study of nearly 45,000 Swedish men.

The study showed that adolescent males with a body mass index (BMI) above 25 are at a 64 per cent increased risk of developing severe liver diseases and liver cell cancer in their late lives. 

Even for one kg/m2 increase in BMI, obese males can face a five per cent increased risk, the study said.

"It is possible that this increased risk is caused by a longer exposure to being overweight, compared to becoming overweight or obese later in life and that individuals with a longer history of being overweight have an increased risk of severe liver disease," said lead investigator Hannes Hagstrom from Karolinska University in Sweden.

In addition, overweight and obesity are associated with a worse prognosis in several liver diseases, such as non-alcoholic fatty liver disease (NAFLD), hepatitis B and C as well as alcoholic liver disease.

The increased risk of a high BMI for the development of severe liver disease later in life is already present from an early age, commented the researchers.

"The increased prevalence of overweight and obesity has also contributed to the worldwide rise in liver diseases," Hagstrom added.

It has been estimated that if current trends continue, there will be more than two billion overweight and over one billion obese individuals worldwide by 2030, said the paper published in the Journal of Hepatology. 

The researchers examined approximately 45,000 Swedish men, over a period of 40 years, to investigate if the body mass index (BMI) in adolescence developed severe liver diseases in later life. 

The results of the follow-up revealed 393 men diagnosed with severe liver diseases and being overweight was a risk factor for developing severe liver disease after adjusting for a variety of confounding factors, including alcohol and tobacco. ​

​New York, June 16 (IANS) Shedding new light on why extra weight is so difficult to shed permanently, researchers have found that overeating reduces levels of a hormone that signals the feeling of fullness in the brain, potentially promoting more eating.

Through earlier studies on colon cancer, Thomas Jefferson University researchers led by Scott Waldman noticed that a hormone called uroguanylin also appeared to play a role in obesity. 

Their studies had shown that in non-obese mice, uroguanylin would travel to the brain, where it produced a feeling of fullness. But it was unclear what happened to this signaling in the obese state.

In the current study, the researchers looked at mice who were overfed, and saw that the small intestines of these mice had stopped producing uroguanylin. 

The receptors for uroguanylin that reside in the brain were intact, and had even increased in number, but hormone itself was no longer being made, suggesting that overeating had caused its production to shut down. 

However, when the animals were put on a diet, the guanylin production resumed.

"What's interesting is that it didn't matter whether the mice were lean and overfed, or obese and overfed - urogaunylin production stopped in both groups of animals when they got too many calories," Waldman said.

The research was published in the journal Nutrition & Diabetes.

"Taken together, these experiments show that excess calories - either from fat or carbohydrates - stress small intestinal cells so that they stop producing uroguanylin, which helps people feel full after eating," Waldman said. 

"What we don't know is how much is too much and what molecular sensor makes that decision," he pointed out.​

New York, June 15 (IANS) Both lack or excess of sleep can lead to health risks like hypertension, obesity, diabetes and depression among children and teenagers, warns a research team led by an Indian-origin scientist.

The findings showed that insufficient hours of sleep could increase the risk of accidents and injuries as also lead to self-harm, suicidal thoughts or suicide attempts among teenagers.

Conversely, sleeping for longer hours may also be associated with adverse health outcome such as hypertension, diabetes, obesity and mental health problems.

"Sleep is essential for a healthy life, and it is important to promote healthy sleep habits in early childhood," said Shalini Paruthi from the American Academy of Sleep Medicine, Springfields, Illinois.

A good sleep pattern can lead to better health outcome like improved attention, behaviour, learning, memory, emotional regulation, quality of life, mental and physical health.

"Adequate sleep is essential for the children who are in the critical years of early development," added Nathaniel Watson, President at the American Academy of Sleep Medicine.

At least 12 to 16 hours of sleep per day is imperative for infants (four to 12 months), the researchers recommended.

For children between one to two years of age, 11 to 14 hours sleep is essential, and for those who are three to five years, 10 to 13 hours is needed.

Nine to 12 hours for children between six to 12 years and eight to 10 hours of sleep for teenagers from 13 to 18 years is good for them and their overall health. 

"Making sure there is ample time for sleep is one of the best ways to promote a healthy lifestyle for a child," Paruthi noted.

For the study, published in the Journal of Clinical Sleep Medicine, the team conducted a 10-month project and reviewed 864 published scientific articles addressing the relationship between sleep duration and health in children.​

​New York, June 15 (IANS) Type 2 diabetes may lead to significant changes in the brain's grey matter volume in teenagers, says a study involving an Indian-origin researcher.

Grey matter is the brain region involved in muscle control and sensory perception such as seeing and hearing, memory, emotions, speech, decision-making and self-control.

"Previous studies suggested that youth with Type 2 diabetes have changes in brain structure and poorer cognitive function scores compared to their peers," said Amy Sanghavi Shah, Physician-Scientist at Cincinnati Children's Hospital Medical Centre in the US. 

The findings showed that adolescents with Type 2 diabetes have six regions with significantly less grey matter and three with significantly more. 

Also, a relationship was found between less grey matter volume in the brain and the ability to pronounce and sound out unfamiliar words.

"Preventing Type 2 diabetes in adolescents is important to prevent possible complications in the future," added lead author Jacob Redel from Cincinnati Children's Hospital.

"Our results do not show cause and effect. But studies in adults with Type 2 diabetes with longer duration of disease also show brain volume differences, brain vascular changes and cognitive decline," Redel noted, stressing that the team only found an association between the two.

For the study, the team analysed 20 teenagers with Type 2 diabetes and compared them to 20 teenagers without diabetes who were similar in age, race and sex. 

All participants in the study had high-resolution MRIs. Neither group had prior neurological nor psychological disease or prior abnormal MRIs.

The study was presented at the American Diabetes Association's Scientific Sessions in New Orleans in the US, recently.​

​New York, June 15 (IANS) While a conclusive answer to why women have a longer lifespan as compared to men still eludes scientists, a host of factors - from differences in hormones to immune system variations - could be at work, suggests new research.

In a perspective piece published in the journal Cell Metabolism, researchers from the University of Alabama at Birmingham explored what gives women the survival advantage.

"Humans are the only species in which one sex is known to have a ubiquitous survival advantage," the authors wrote in their research review covering a multitude of species. 

"Indeed, the sex difference in longevity may be one of the most robust features of human biology," the researchers said.

Though other species, from roundworms and fruit flies to a spectrum of mammals, show lifespan differences that may favour one sex in certain studies, contradictory studies with different diets, mating patterns or environmental conditions often flip that advantage to the other sex. 

With humans, however, it appears to be all females all the time.

The differences may be due to hormones, perhaps as early as the surge in testosterone during male sexual differentiation in the uterus. 

Longevity may also relate to immune system differences, responses to oxidative stress, mitochondrial fitness or even the fact that men have one X chromosome (and one Y), while women have two X chromosomes, the researchers said.

Evidence of the longer lifespans for women includes the Human Mortality Database, which has complete lifespan tables for men and women from 38 countries that go back as far as 1751 for Sweden and 1816 for France. 

"Given this high data quality, it is impressive that for all 38 countries for every year in the database, female life expectancy at birth exceeds male life expectancy," authors Steven Austad and Kathleen Fischer wrote.

Longer female survival expectancy is seen across the lifespan, at early life (birth to five years old) and at age 50. 

It is also seen at the end of life, where Gerontology Research Group data for the oldest of the old show that women make up 90 percent of the supercentenarians, those who live to 110 years of age or longer, the study pointed out.​

Washington, June 16 (IANS) For the second time in history, an international team of scientists and engineers have detected gravitational waves -- ripples in the fabric of space-time -- and a pair of colliding black holes.

Using the twin, US-based Advanced Laser Interferometer Gravitational-wave Observatory (LIGO) detectors, the second detection occurred on December 26 last year and is named as the "Boxing Day event" (after the holiday celebrated in Britain).

LIGO's first detection of gravitational waves and merging black holes occurred on September 14, 2015 -- an event that made headlines worldwide, confirming a major prediction of Albert Einstein's 1915 general theory of relativity.

"Scientifically, these black holes are important because it shows binary black holes exist as a population, with a range of masses, forming from a range of different stars," said Vicky Kalogera, director of Northwestern University's centre for interdisciplinary exploration and research in astrophysics (CIERA).

Gravitational waves carry information about the origins of black holes and about the nature of gravity that cannot otherwise be obtained.

Physicists have concluded that these gravitational waves were produced during the final moments of the merger of two black holes -- 14 and eight times the mass of the sun -- to produce a single, more massive spinning black hole 21 times the mass of the sun.

In comparison, the black holes detected on September 14, 2015, were 36 and 29 times the sun's mass, merging into a black hole of 62 solar masses.

This time, the gravitational waves released by the violent black hole merger resulted in a longer signal, or chirp, providing more data.

The new chirp lasted one second; the September 14 chirp lasted just one-fifth of a second. The higher-frequency gravitational waves from the lower-mass black holes better spread across the LIGO detectors' sweet spot of sensitivity.

Gravitational waves are not sound waves, but researchers have converted the gravitational wave's oscillation and frequency to a sound wave with the same frequency, producing a "chirp" people can hear.

The discovery, accepted for publication in the journal Physical Review Letters, was made by the international LIGO Scientific Collaboration (which includes the GEO Collaboration and the Australian Consortium for Interferometric Gravitational Astronomy) and the Virgo Collaboration using data from the two LIGO detectors.

Northwestern alumnus David Reitze, now at Caltech and the executive director of the LIGO Laboratory, was one of three scientific leaders to announce the discovery at the summer meeting of the American Astronomical Society (AAS) in San Diego.

Scientists now have a small population of black holes from which to learn more about the universe.

As Advanced LIGO becomes more and more sensitive, the number of detected black holes will only grow, producing a broad mass spectrum of black holes in nature.

"We expect black holes with a range of masses, which we now are seeing, showing us that black holes form ubiquitously in the universe," Kalogera added.

This second detection also proves the first was not a fluke -- the gravitational waves truly came from cosmic sources.

"It is very significant that these black holes were much less massive than those in the first detection," said Gabriela Gonzalez, spokesperson of the LIGO Scientific Collaboration.

Because of their lighter mass, they spent more time -- about one second -- in the sensitive band of the detectors.

"It is a promising start to mapping the populations of black holes in our universe," she noted.

During the merger, which occurred approximately 1.4 billion years ago, a quantity of energy roughly equivalent to the mass of the sun was converted into gravitational waves.

The detected signal comes from the last 27 orbits of the black holes before their merger.

Scientists from Rochester Institute of Technology and University of Maryland physicists also contributed to the identification of second gravitational wave event.​

​New York, June 16 (IANS) The same behavioural skills that are commonly taught to fight depression can also help unemployed people land a job, new research has found.

These skills included identifying negative thoughts and countering them with more positive responses and planning enjoyable activities to improve the mood.

This study is the first to show that cognitive behavioural (CB) skills not only predict changes in depression symptoms, but also real life functioning, said co-author of the study Daniel Strunk, associate professor of psychology at The Ohio State University in the US.

"Searching for a job is difficult in any circumstance, but it may be even more difficult for people who are depressed," Strunk said.

"But we found that there are specific skills that can help not only manage the symptoms of depression but also make it more likely that a person will receive a job offer," Strunk noted.

The study involved 75 unemployed people, aged 20 to 67, who participated in two online surveys taken three months apart.

About a third of the sample reported symptoms that would put them in the moderately to seriously depressed category, although they were not formally diagnosed. 

The remaining two-thirds had scores that ranged from mild depression to no symptoms.

The results showed that participants who reported more use of cognitive behavioural skills were more likely to show an improvement in depressive symptoms in the three months between the surveys -- and were more likely to report they had received a job offer.

The findings appeared in the Journal of Clinical Psychology.

"The people who got jobs in our study were more likely to be putting into practice the skills that we try to teach people in cognitive therapy," Strunk explained.​

New York, June 16 (IANS) Wearing a specifically designed compression collar around the neck may prevent or reduce the devastating effects of head collisions in sports, researchers have found.

Inspired by woodpeckers and bighorn sheep, the neck device, called a Q-Collar, is designed to press gently on the jugular vein to slow blood outflow increasing the brain's blood volume.

The resulting effect of the increased blood volume helps the brain fit tighter within the skull cavity, reducing the energy absorbed by the brain during collisions.

The analysis of neurophysiological and neuroanatomical data from the brain showed athletes in the non-collar wearing group had significant functional and structural changes to white matter regions of the brain but these changes were not evident in those who did wear the Q-Collar during play, findings from two studies showed.

"White matter of the brain essentially connects all the pathways including structure and function,” explained lead author of both studies Greg Myer, director of sports medicine research at Cincinnati Children's Hospital Medical Center in Ohio, US.

In the preliminary study published in Frontiers in Neurology, 15 high school hockey players took part. 

Half wore the collar for the hockey season and the other half did not. 

Each of the helmets for the athletes was outfitted with an accelerometer to measure every head impact. 

Results from the imaging and electrophysiological testing indicated that athletes in the non-collar wearing group had a disruption of microstructure and functional performance of the brain. 

Athletes wearing the collar did not show a significant difference despite similar head impacts.

In a follow-up study published in the British Journal of Sports Medicine, 42 football players from two Greater Cincinnati high schools participated. 

While half of the participants wore the collar, the other half did not. 

The results of this larger study showed similar protective effects of collar wear during the football season.

"The results of the studies demonstrate a potential approach to protecting the brain from changes sustained within a competitive football and hockey season, as evidenced by brain imaging," Myer said. ​