Dogs are less likely to follow bad advice from humans, according to a new study which found that, in contrast to kids, the canines only copy a person's actions if they are absolutely necessary for solving the task at hand.
"Children tend to copy all of a teacher's actions, regardless of whether they are necessary or not," said Laurie Santos, director of the Canine Cognition Centre at Yale University in the US.
In a previous study, children watched a demonstrator solve a puzzle by first moving a lever and then lifting a lid to pull out a prize.
Although the lever was completely irrelevant for solving the puzzle, children repeatedly performed both actions, even when they were in a race to solve the puzzle as quickly as possible.
The new study shows that dogs will leave out irrelevant actions when there is a more efficient way to solve a problem, even when a human repeatedly demonstrates these actions.
"Although dogs are highly social animals, they draw the line at copying irrelevant actions," said lead author Angie Johnston, PhD student at Yale.
"Dogs are surprisingly human-like in their ability to learn from social cues, such as pointing, so we were surprised to find that dogs ignored the human demonstrator and learned how to solve the puzzle on their own," Johnston said.
Researchers designed a dog-friendly puzzle box in which the only relevant action for getting the treat was lifting a lid on top of the box.
However, just as in the previous experiment with children, when researchers showed dogs how to use the box, they first demonstrated a lever on the side of the box before lifting the lid to get the treat.
Once dogs learned how to open the box, they stopped using the irrelevant lever.
In fact, the researchers found that dogs were just as likely to stop using the lever as undomesticated canines, wild Australian dingoes.
"One reason we're so excited about these results is that they highlight a unique aspect of human learning," said Johnston.
"Although the tendency to copy irrelevant actions may seem silly at first, it becomes less silly when you consider all the important, but seemingly irrelevant, actions that children are successfully able to learn, such as washing their hands and brushing their teeth," she said. The study was published in the journal Developmental Science.
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Having a few drinks may help people with clinical depression feel better, say scientists who have found that alcohol produces same neural changes as rapidly effective antidepressants. "Because of the high comorbidity between major depressive disorder and alcoholism there is the widely recognised self-medication hypothesis, suggesting that depressed individuals may turn to drinking as a means to treat their depression," said Kimberly Raab-Graham, associate professor at Wake Forest Baptist Medical Centre in the US.
"We now have biochemical and behavioural data to support that hypothesis," she said. However, this does not suggest that alcohol can be an effective treatment for depression, researchers said. "There is definitely a danger in self-medicating with alcohol. There is a very fine line between it being helpful and harmful, and at some point during repeated use self-medication turns into addiction," Raab-Graham added.
Using an animal model, researchers found that a single dose of an intoxicating level of alcohol, which has been shown to block NMDA receptors - proteins associated with learning and memory - worked in conjunction with the autism-related protein FMRP to transform an acid called GABA from an inhibitor to a stimulator of neural activity.
In addition, they found that these biochemical changes resulted in non-depressive behaviour lasting at least 24 hours. This study demonstrated that alcohol followed the same biochemical pathway as rapid antidepressants in the animals, while producing behavioural effects comparable to those observed in people.
In recent years, single doses of rapid antidepressants such as Ketamine have proven capable of relieving depressive symptoms within hours and lasting for up to two weeks, even in individuals who are resistant to traditional antidepressants. The study appears in the journal Nature Communications.
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Breastfeeding may not only be beneficial for babies, but also for their mothers - protecting them from premature death and serious diseases such as cancer, diabetes and heart disease, a new study has claimed.
Breastfeeding as recommended - for a total of one year and exclusively for six months - could protect babies and their moms from premature death and serious diseases, researchers said.
The study underscores the importance of policies that make it possible for women to breastfeed, according to study senior author Alison Stuebe from the University of North Carolina in the US.
Researchers said their findings highlight the importance of providing women with the support they need to breastfeed their babies, beginning at birth.
"Breastfeeding is far more beneficial in preventing disease and reducing costs than previously estimated," said lead author Melissa Bartick, assistant professor of medicine at Harvard Medical School in the US.
"The results should compel all hospitals to develop programs aimed at helping new mothers learn to breastfeed their babies," said Bartick.
Researchers modelled two groups for the study. The 'optimal group', in which the majority of mothers breastfed as recommended and the 'suboptimal group', in which mothers breastfed at current rates in the US, which are less than the recommended guidelines.
Using existing research and government data, they projected the rates and costs of diseases that breastfeeding is known to reduce, along with the rates and costs of early deaths from those diseases.
Children's diseases included in the evaluation were acute lymphoblastic leukaemia, ear infections, Crohn's disease, ulcerative colitis, gastrointestinal infections, lower respiratory tract infections, obesity, necrotising enterocolitis and Sudden infant death syndrome (SIDS).
For mothers, the study included breast cancer, pre-menopausal ovarian cancer, diabetes, hypertension and heart attacks.
The researchers found that suboptimal breastfeeding was associated with more than 3,340 premature deaths in the US each year, costing the country 3 billion dollars in medical costs, 1.3 billion dollars in indirect costs and 14.2 billion dollars in costs related to premature deaths.
The majority of the excess death and medical costs - nearly 80 per cent - were maternal.
"Breastfeeding has long been framed as a child health issue, however it is clearly a women's health issue as well," said Eleanor Bimla Schwarz from University of California, Davis, in the US.
"Breastfeeding helps prevent cancer, diabetes and heart disease, yet many women have no idea breastfeeding has any of these benefits," said Schwarz.
The study appears in the journal Maternal & Child Nutrition.
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Most of the Earth's life-giving carbon may have come from a collision about 4.4 billion years ago between our planet and an embryonic planet similar to Mercury, scientists, including one of Indian origin, have found.
Rajdeep Dasgupta from Rice University in the US and his colleagues studied how carbon-based life developed on Earth, given that most of the planet's carbon should have either boiled away in the planet's earliest days or become locked in Earth's core.
"The challenge is to explain the origin of the volatile elements like carbon that remain outside the core in the mantle portion of our planet," said Dasgupta.
"We had published several studies that showed that even if carbon did not vapourise into space when the planet was largely molten, it would end up in the metallic core of our planet, because the iron-rich alloys there have a strong affinity for carbon," Dasgupta said.
"One popular idea has been that volatile elements like carbon, sulphur, nitrogen and hydrogen were added after Earth's core finished forming," said Yuan Li, who was a postdoctoral researcher at Rice at the time of the study.
"Any of those elements that fell to Earth in meteorites and comets more than about 100 million years after the solar system formed could have avoided the intense heat of the magma ocean that covered Earth up to that point," said Li, who is now at Chinese Academy of Sciences.
"The problem with that idea is that while it can account for the abundance of many of these elements, there are no known meteorites that would produce the ratio of volatile elements in the silicate portion of our planet," Li said.
In late 2013, Dasgupta's team decided to conduct experiments to gauge how sulphur or silicon might alter the affinity of iron for carbon.
"We began exploring very sulphur-rich and silicon-rich alloys, in part because the core of Mars is thought to be sulphur-rich and the core of Mercury is thought to be relatively silicon-rich," Dasgupta said.
Experiments showed that carbon could be excluded from the core - and relegated to the silicate mantle - if the iron alloys in the core were rich in either silicon or sulphur.
The team mapped out the relative concentrations of carbon that would arise under various levels of sulphur and silicon enrichment, and the researchers compared those concentrations to the known volatiles in Earth's silicate mantle.
"One scenario that explains the carbon-to-sulphur ratio and carbon abundance is that an embryonic planet like Mercury, which had already formed a silicon-rich core, collided with and was absorbed by Earth," Dasgupta said.
"Because it's a massive body, the dynamics could work in a way that the core of that planet would go directly to the core of our planet, and the carbon-rich mantle would mix with Earth's mantle," he said.
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Gravitational waves are formed around 10 million years after two galaxies collide and their central black holes merge - about 100 times faster than previously thought, a new study has found.
Gravitational waves were detected for the first time earlier this year, over a century after Albert Einstein predicted the phenomenon in his General Theory of Relativity.
Until now, it was not possible to conclusively predict the point at which gravitational waves are triggered and spread throughout space when galaxies merge.
An international team of astrophysicists from the University of Zurich, the Institute of Space Technology in Pakistan, the University of Heidelberg in Germany and the Chinese Academy of Sciences has now calculated this for the first time using an extensive simulation.
Every galaxy has a supermassive black hole at its core, which can exhibit millions or even billions of solar masses.
In a realistic simulation of the universe, the merging of two roughly 3-billion-year-old galaxies lying relatively close to one another was simulated.
With the aid of supercomputers, researchers calculated the time the two central black holes with around 100 million solar masses needed to emit strong gravitational waves after the galaxies collided.
"The merging of the two black holes already triggered the first gravitational waves after 10 million years – around 100 times faster than previously assumed," said Lucio Mayer from the University of Zurich.
The computer simulation, which took more than a year, was conducted in China, Zurich and Heidelberg. The project required an innovative computational approach with various numerical codes on different supercomputers.
In the process, each supercomputer was responsible for calculating a certain phase of the orbital convergence of the two massive black holes and their parent galaxies.
Compared to previous models, the relation between the orbits of the central black holes and the realistic structure of the parent galaxies was factored into the present simulation.
"Our calculations therefore allow a robust forecast for the merging rate of supermassive black holes in the early stage of the universe," said Mayer.
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The upper depths of the oceans of the Earth have warmed significantly over the last 20 years causing an increase in the number of severe hurricanes, storm surges, loss of ice and change in global weather patterns, according to a new report.
The report which was presented at the IUCN World Conservation Congress in Hawaii yesterday has found the upper depths of the world's oceans have warmed significantly since 1995.
A chapter of the study, led by Professor Grant Bigg and Professor Edward Hanna from the University of Sheffield's Department of Geography, has disclosed how this increase in sea temperatures has changed global weather patterns.
The scientists have shown that the rise in ocean temperatures has caused an increase in the number of severe hurricanes and typhoons, such as Hurricane Katrina, which devastated New Orleans in 2005, and Typhoon Haiyan, which caused massive destruction in the Philippines in 2013.
Hurricanes have even been observed in the South Atlantic for the first time since satellite records began in the 1970s.
The area was traditionally viewed as an unlikely region for hurricane formation because of its cooler sea surface temperatures, however in 2004 conditions were more favourable than normal due to warmer ocean temperatures, spawning Hurricane Catarina off the coast of Brazil.
The report also shows that warmer seas have resulted in a significant loss of ice in the Arctic region.
The atmosphere in the polar regions has warmed at about twice the average rate of global warming with Arctic coasts experiencing a rise in the occurrence of storm surges.
This increase in storm surges can have a detrimental effect on fragile ecosystems in the area, such as low relief tundra, underlain by permafrost, according to the report.
Warmer oceans have also caused a distinct change in El Nino events – the warmer currents associated with the cycle have now been observed towards the central Pacific rather than the west, according to the Sheffield scientists.
Professor Grant Bigg, from the University's Department of Geography, said: "Many people may associate warmer seas with the pleasant weather conditions they're used to experiencing while on holiday, but the fact of the matter is that an increase in sea temperatures is having a huge impact on the world's weather.
"Our study has shown that severe hurricanes, storm surges, melting ice in the Arctic region and changes to El Nino are all being caused by sea temperatures rising across the planet. These are all things that can have a devastating impact on the way we live our lives," he said.
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Scientists have for the first time discovered tiny magnetic particles from air pollution lodged in human brains - which could be a possible cause of Alzheimer's disease.
Researchers at Lancaster University in the UK found abundant magnetite nanoparticles in the brain tissue from 37 individuals aged three to 92-years-old who lived in Mexico City and Manchester.
This strongly magnetic mineral is toxic and has been implicated in the production of reactive oxygen species (free radicals) in the human brain, which are associated with neurodegenerative diseases including Alzheimer's disease.
Professor Barbara Maher, from Lancaster Environment Centre, used spectroscopic analysis to identify the particles as magnetite.
Unlike angular magnetite particles that are believed to form naturally within the brain, most of the observed particles were spherical, with diameters up to 150 nanometres (nm), some with fused surfaces, pointing to high-temperature formation - such as from vehicle engines or open fires.
The spherical particles are often accompanied by nanoparticles containing other metals, such as platinum, nickel, and cobalt.
"The particles we found are strikingly similar to the magnetite nanospheres that are abundant in the airborne pollution found in urban settings, especially next to busy roads, and which are formed by combustion or frictional heating from vehicle engines or brakes," said Maher.
Other sources of magnetite nanoparticles include open fires and poorly sealed stoves within homes.
Particles smaller than 200 nm are small enough to enter the brain directly through the olfactory nerve after breathing air pollution through the nose.
"Our results indicate that magnetite nanoparticles in the atmosphere can enter the human brain, where they might pose a risk to human health, including conditions such as Alzheimer's disease," said Maher.
"This finding opens up a whole new avenue for research into a possible environmental risk factor for a range of different brain diseases," said David Allsop, of Lancaster University's Faculty of Health and Medicine.The findings were published in the journal PNAS.
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The reddish polar region on Pluto's largest moon, Charon, is an effect of methane gas escaping from the icy dwarf planet's atmosphere, say scientists who solved the mystery behind the coloured region first spotted by NASA's New Horizons spacecraft last year.
Methane gas escapes from Pluto's atmosphere, becomes "trapped" by the moon's gravity and freezes to the cold, icy surface at Charon's pole, researchers said.
This is followed by chemical processing by ultraviolet light from the Sun that transforms the methane into heavier hydrocarbons and eventually into reddish organic materials called tholins, they said.
"Who would have thought that Pluto is a graffiti artist, spray-painting its companion with a reddish stain that covers an area the size of New Mexico?" said Will Grundy, a New Horizons co-investigator from Lowell Observatory in the US.
"Nature is amazingly inventive in using the basic laws of physics and chemistry to create spectacular landscapes," Grundy said.
The team combined analyses from detailed Charon images obtained by New Horizons with computer models of how ice evolves on Charon's poles.
Mission scientists had previously speculated that methane from Pluto's atmosphere was trapped in Charon's north pole and slowly converted into the reddish material, but had no models to support that theory.
Researchers dug into the data to determine whether conditions on the moon (with a diameter of 1,212 kilometres) could allow the capture and processing of methane gas.
The models using Pluto and Charon's 248-year orbit around the Sun show some extreme weather at Charon's poles, where 100 years of continuous sunlight alternate with another century of continuous darkness.
Surface temperatures during these long winters dip to minus 257 degrees Celsius, cold enough to freeze methane gas into a solid.
"The methane molecules bounce around on Charon's surface until they either escape back into space or land on the cold pole, where they freeze solid, forming a thin coating of methane ice that lasts until sunlight comes back in the spring," Grundy said.
But while the methane ice quickly sublimates away, the heavier hydrocarbons created from it remain on the surface.
The models also suggested that in Charon's springtime the returning sunlight triggers conversion of the frozen methane back into gas.
However, while the methane ice quickly sublimates away, the heavier hydrocarbons created from this evaporative process remain on the surface.
Sunlight further irradiates those leftovers into reddish material - called tholins - that has slowly accumulated on Charon's poles over millions of years.
New Horizons' observations of Charon's other pole, currently in winter darkness - and seen by New Horizons only by light reflecting from Pluto, or "Pluto-shine" - confirmed that the same activity was occurring at both poles.
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Pregnant women may be up to 1.5 times more likely to develop gestational diabetes during the summer months, a new study has found.
Seasonality in the onset of type-1 diabetes is well documented, with some studies showing higher winter incidence associated with higher circulating virus levels and lower vitamin D status.
However, less is known about the seasonality in the diagnosis of type-2 and gestational diabetes (GDM).
Researchers at Lund University and Skane University Hospital in Sweden examined seasonal patterns in glucose tolerance and in the diagnosis of GDM.
A total of 11,538 women who had agreed to take part underwent a universally applied standard 75-gramme oral glucose tolerance test (OGTT) in the 28th week of pregnancy during 2003-2005 in southern Sweden.
OGTT results from a three-year study period were grouped together into months and seasons.
Statistical modelling was used to calculate differences in GDM across months and seasons, and to examine whether month or season were associated with the diagnosis of GDM.
Information on mean monthly temperatures during the study period was obtained from the Swedish Meteorological and Hydrological Institute.
A total of 487 women (4.2 per cent) were diagnosed with GDM during the study period. The monthly frequency of GDM ranged from 2.9 per cent in March to 5.8 per cent in June.
The seasonal frequency ranged from 3.3 per cent in spring to 5.5 per cent in summer. The differences were statistically significant for both month and season.
Mean monthly temperature ranged from minus 0.6 degrees Celsius in the winter to 17.7 degrees Celsius in the summer.
When adjusted for age, the data showed that the summer months (June-August) were associated with an increased glucose level and a 51 per cent (or 1.5 times) increased frequency of GDM compared with the other seasons.
These associations were no longer apparent when also adjusting for mean monthly temperature, suggesting that temperature could be part of the reason for the differences.
"Our findings suggest seasonal variations in the glucose concentration and in the proportion of women diagnosed with GDM with a peak in the summer. A positive association with the ambient temperature was demonstrated," researchers said.
They add that a potential mechanism for this relationship is that hypothetically, temperature-induced changes in peripheral blood flow may affect the composition of capillary blood, representing a mixture of arterial and venous blood, explaining the increased glucose levels during the warmer summer months.
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Hard, oxygen-poor tumours trigger a biological switch that causes cancer stem cells to invade other tissues, and could offer a promising treatment target to stop the disease from spreading, scientists have found.
Scientists from Princeton University and the Mayo Clinic Cancer Centre in the US suggests that the biological switch is critical to a tumour's ability to invade other tissue, a process called metastasis.
"Our study suggests that to combat cancer, we should be developing treatments that target the stiff, hypoxic regions of tumours," said lead author Celeste Nelson, professor at Princeton.
"We were surprised to see just how important these two properties in the tumour microenvironment - stiffness and hypoxia - were for regulating cancer stem cells," Nelson said.
The specific cells triggered by stiffness and hypoxia are called cancer stem cells. These cells represent only a small proportion of the total cells in a tumour, but researchers believe they play a key role in spreading the disease.
As normal stem cells help form an embryo, or aid in repairing muscles, cancer stem cells specialise in generating new malignant cells.
In addition to spreading cancer, just 10 to 100 leftover cancer stem cells are needed to regenerate a tumour after it has been removed.
Using cultures of human breast-cancer cells and mouse mammary-cancer cells, researchers discovered an association between a protein called integrin-linked kinase and the creation of cancer stem cells.
Normally, integrin-linked kinase assists cells with a variety of important cellular tasks. But in dense, oxygen-poor tumours, the protein's function goes awry.
Researchers created a range of human and mouse breast-cancer cultures reflecting different tissue conditions.
They showed that stiff hypoxic cultures did indeed promote cancer stem cells.
However, when they eliminated the integrin-linked kinase from those samples, they found that the cancer stem cells stopped forming.
Conversely, when they forced abnormal levels of integrin-linked kinase in samples containing softer or less hypoxic tissue, cancer stem cells formed.
They also confirmed a significant association between tumour stiffness, integrin-linked kinase and cancer stem cell presence in samples from human breast-cancer patients.
The findings suggest that stiffness and hypoxia cause integrin-linked kinase to behave abnormally, which in turn triggers cancer stem-cell formation.
There are likely other features in tumours that cause cancer stem cells to form, but the findings indicate that stiff, hypoxic conditions and their effects on integrin-linked kinase are two of the most prominent ones.The study appears in the journal Cancer Research
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