Wednesday, June 22, 2016
So does tapping a can of fizzy pop REALLY stop it from exploding? Scientist finally reveals the truth - and the answer may surprise you
Have you gotten into the habit of tapping the top of your can of pop because someone told you it stopped it from exploding when you open it?
It's a bizarre ritual that many people just can't seem to shake off, but experts say there may well be method in the madness.
Indeed, scientist Christopher Arthur Edward Hamlett explains that tapping the top of the can may well reduce the bubbles.
In his essay for The Conversation he explained: 'Before the can is opened, microscopic gas bubbles attach to the inside of it (nucleation). When the can is opened, these bubbles increase in size, due to the decrease in the solubility of CO2.'
He goes on to explain that when these bubbles reach a certain size, buoyancy causes them to rapidly rise to the top of the can - where you open it - and displace liquid (the fizz) as they do so.
So what part could tapping the top of the can play in this process? He goes on: 'Bubbles in an unopened can nucleate at the walls, so tapping the can before opening could dislodge some of the bubbles, enabling them to float to the top of the liquid.'
He goes on to explain his theory in more depth, saying that when a can is opened, the bubbles expand with those deeper within the liquid travelling further than those near the surface, which can cause the explosion effect many fear.
'A "tapped" can will have fewer of these "deep" bubbles and so less liquid will be dislodged – and possibly sprayed out – than an "untapped" can,' he concluded.
So, next time someone questions your seemingly strange ritual, you can use science to back it up.
Sunday, June 19, 2016
Albert Perry carried a secret in his DNA: a Y chromosome so distinctive that it reveals new information about the origin of our species. It shows that the last common male ancestor down the paternal line of our species is over twice as old as we thought.
One possible explanation is that hundreds of thousands of years ago, modern and archaic humans in central Africa interbred, adding to known examples of interbreeding – with Neanderthals in the Middle East, and with the enigmatic Denisovans somewhere in southeast Asia.
Perry, recently deceased, was an African-American who lived in South Carolina. A few years ago, one of his female relatives submitted a sample of his DNA to a company called Family Tree DNA for genealogical analysis.
Geneticists can use such samples to work out how we are related to one another. Hundreds of thousands of people have now had their DNA tested. The data from these tests had shown that all men gained their Y chromosome from a common male ancestor. This genetic “Adam” lived between 60,000 and 140,000 years ago.
All men except Perry, that is. When Family Tree DNA’s technicians tried to place Perry on the Y-chromosome family tree, they just couldn’t. His Y chromosome was like no other so far analysed.
Michael Hammer, a geneticist at the University of Arizona in Tucson, heard about Perry’s unusual Y chromosome and did some further testing. His team’s research revealed something extraordinary: Perry did not descend from the genetic Adam. In fact, his Y chromosome was so distinct that his male lineage probably separated from all others about 338,000 years ago.
“The Y-chromosome tree is much older than we thought,” says Chris Tyler-Smith at the Wellcome Trust Sanger Institute in Hinxton, UK, who was not involved in the study. He says further work will be needed to confirm exactly how much older.
“It’s a cool discovery,” says Jon Wilkins of the Ronin Institute in Montclair, New Jersey. “We geneticists have been looking at Y chromosomes about as long as we’ve been looking at anything. Changing where the root of the Y-chromosome tree is at this point is extremely surprising.”
Digging deeper, Hammer’s team examined an African database of nearly 6000 Y chromosomes and found similarities between Perry’s and those in samples taken from 11 men, all living in one village in Cameroon. This may indicate where in Africa Perry’s ancestors hailed from.
Older than humanity
The first anatomically modern human fossils date back only 195,000 years, so Perry’s Y chromosome lineage split from the rest of humanity long before our species appeared.
What are the implications? One possibility is that Perry’s Y chromosome may have been inherited from an archaic human population that has since gone extinct. If that’s the case, then some time within the last 195,000 years, anatomically modern humans interbred with an ancient African human.
There is some supporting evidence for this scenario. In 2011, researchers examined human fossils from a Nigerian site called Iwo Eleru. The fossils showed a strange mix of ancient and modern features, which also suggested interbreeding between modern and archaic humans. “The Cameroon village with an unusual genetic signature is right on the border with Nigeria, and Iwo Eleru is not too far away,” says Hammer.
Chris Stringer at the Natural History Museum, London, was involved in the Iwo Eleru analysis, and says the new Y chromosome result highlights the need for more genetic data from modern-day sub-Saharan Africans. “The oldest known fossil humans in both West Africa at Iwo Eleru and Central Africa at Ishango [in Democratic Republic of the Congo] show unexpectedly archaic features, so it certainly looks like we have a more complex scenario for the evolution of modern humans in Africa.”
Journal reference: American Journal of Human Genetics, doi.org/kp4
Saturday, June 18, 2016
An invaluable help in reading for my PhD was a speed-reading course I did with Laurie Enticknap. It has also been immensely useful to me over the last fifty years of professional life.
Laurie was one of those people that you find in many psychology departments who seem to be involved in a low-key way with just about everything that is happening in the department. He didn’t push himself forward, but his opinion was often sought and he often assisted with other people’s projects as well as conducting many of his own. In his career he worked and published in areas as diverse as perception, electronics, statistics, ageing, child welfare and speech.
In the mid sixties there were a number of speed-reading courses being heavily advertised – particularly to university students. Laurie Enticknap ran a series of experiments to determine if any of those courses did improve reading speed and accuracy as advertised and if so which was the most effective.
The courses used a number of techniques to teach people how to read faster. Some instructed the reader to look only at the beginning of each line, some to look only at the middle. Some suggested reading only the first few words of each paragraph. Some even had a mechanical device, which allowed only one line of text to be in view, and ran down the page at a fixed speed. Each course favoured a particular method and had its own hype to explain how it worked and why it was superior.
Laurie asked separate groups of students to engage in each of the different speed reading courses and assessed the results with two measures. The time taken to read a standard number of words was the speed measure in words per minute (wpm). The comprehension measure was the percentage of correct answers to a series of questions about the content of each test paragraph.
The courses took several weeks and progress was measured at standard intervals.
I was fortunate to be in the control group. A control group is used in experiments to see what effect “going through the motions” has. It usually comprises an activity that seems like the experimental condition but lacks the vital ingredient that is supposed to produce the effect.
In Laurie’s experiment the control group was given the same exercises as the experimental groups, but with none of the techniques that were supposed to teach you how to read faster. Instead subjects were issued with a rather bland Zen like instruction “read faster”.
Laurie found no difference between the groups with regards to improvement in either speed of reading or comprehension. This may lead you to believe that none of those speed-reading courses worked and in one sense this is true. Differences in technique did not make any difference. On the other hand the reading speed and comprehension of all the subjects improved. Even those in the control group!
In my case my speed improved from around 200wpm (which is average) to well over 1000wpm (which is well above average). At the same time my comprehension improved to above 80%.
So the conclusion I would draw from these results is that improvement in speed and comprehension are not dependent on technique, but are probably simply a result of the intention to read faster.
So it’s probably a waste of money to buy a speed-reading course. If you want to read faster, just…read faster.
Of course it is very handy to have a set of test passages and comprehension questions so you can get some feedback as to how you are progressing. You can find those for free on the net and I have listed some of them in the references section for this chapter. Be warned though that some of these are on websites that will eventually try to sell you a speed-reading course.
For interest’s sake as I was preparing this chapter I took the speed reading test at “Reading test online” at http://www.readingsoft.com/ and was surprised to find after all these years that my speed is still a respectable 725wpm and my comprehension is at 82%. Although I have used speed-reading a lot in the last fifty years I haven’t made any attempt to practice reading faster and yet my scores are still well above my starting point. This is obviously a skill that holds up well with age.
Over the years I have used speed reading to absorb the content of journal articles, books, technical and clinical reports, hospital charts, DIY instructions, and the dust jackets of novels. It saves a lot of time and I find I can still absorb the information at speed.
There is a very large downside to speed-reading when it comes to reading for pleasure. I soon found that reading poetry and novels was eerily bland. Speed-reading enabled me to acquire all the information in a novel, but none of the color. I could read a novel in half a day and be quite clear about the plot and characterisation, but I got none of the emotional connection with the characters and story that I enjoy so much when reading novels.
I eventually worked out that the emotional connection takes time and I would have to slow down to get it. It took me quite some time to learn to control the speed of my read and eventually developed two “gears”, one for work and one for pleasure.
Thursday, June 16, 2016
A little scrap of life was rescued from great danger by great love
A young mother has told how she risked her own life saving her premature baby from a fire which destroyed her family home.
Rachel Smeeth, from Accrington, Lancashire, ran into the flaming building after her partner's fourth failed attempt and managed to find her way to her son Matthew's cot.
Recalling the chain of events, the 23-year-old said: 'The neighbours were all screaming at me to stay outside, but all I could think about was my baby.
'I felt my way to the cot and he was lifeless - not crying - and I was sure he was dead. 'I scooped him up with a blanket over his face.
'By this time, the firemen were outside and I was able to follow the lights from their torches to make my way down the stairs.'
Rachel's partner Danny Casson, 27, who was disorientated by the smoke, jumped from a bedroom window.
The family was rushed to hospital and treated for smoke inhalation. Rachel - also mother to Katie-Louise, three, and three-month-old Matthew - said: 'The doctors said it was a miracle that Matthew was alive.
'My throat was badly burned and we were all in shock. I lost my voice and the doctors have said I may have some permanent damage but that doesn’t matter at all.
'The firemen came to see us and told us we should be dead. They kept saying how brave I was to go back into the house for Matthew, but any mother would do exactly the same.'
Rachel and her partner Danny met two years ago and were thrilled when Rachel fell pregnant last year. Baby Matthew was born at the end of February 2016.
The firemen came to see us and told us we should be dead. They kept saying how brave I was to go back into the house for Matthew
Recalling her son's birth, Rachel said: 'I had suffered five miscarriages after my first baby, and so when Matthew was born it felt like a miracle. He was very precious.'
Born four weeks early, on February 24 this year, little Matthew weighed just 4lbs 7ozs.
He was allowed home a week later - with exhausted parents Rachel and Danny taking turns to do two hourly feeds.
Rachel says: 'Matthew didn’t settle very well with him being premature, so I would try to get him to sleep before we had our evening meal. 'But as a result, we were eating later and later in the evening.'
One evening in March, after settling Matthew, she switched on a pan to cook supper - but as she and Danny waited in the living room, they both drifted off to sleep. She says: 'I didn’t even realise I was so tired but looking back, I was exhausted and I should never have switched on a pan.'
When Danny awoke, 45 minutes later, the house was filled with black smoke. He awoke Rachel who, struggling to breathe, was disorientated and choking.
She says: 'I couldn’t even remember where the door was; it was as if I was in a trance. I was gulping in smoke and I could feel myself going faint and dizzy.
'Danny was trying to tell me that the house was on fire and that we had to get the kids out - and suddenly I snapped to my senses.'
Danny rescued three-year-old Katie first and handed her out to neighbours who had gathered around the house. He ran back into the flames to rescue three week old Matthew - but was forced back by the smoke and heat.
Rachel says: 'Danny went back again and again but the house was thick with smoke and he just couldn’t see a thing. He couldn’t even find his way upstairs.
'After his fourth attempt failed, I realised that Matthew was going to die and I knew I had to act. 'I ran back into the house, following the sounds of Danny’s voice to find my way to Matthew’s room.'
Miraculously the couple and their children have all made a good recovery. However, the fire destroyed their home and they have had to relocate.
Reflecting on their house fire ordeal, Rachel said: 'We have lost everything - even our clothes from that night are in ruins.
'But despite everything, we feel so lucky, just to be alive. 'I could not have faced life without my precious baby - he was a miracle even before this happened. Now, we treasure him all the more.'
Thursday, June 2, 2016
It has mystified historians ever since. After a string of major victories, the Mongol army suddenly retreated from central Europe in 1242.
Some scholars claim Mongolian politics forced the withdrawal, while others credit the strength of fortified towns in present-day Hungary and Croatia. But Europe could have been rescued by its own bad weather, an analysis of tree rings and historical documents concludes.
The Mongol cavalry fed its horses on the grass of the Eurasian steppe, says Nicola Di Cosmo of Princeton University, one of the study’s authors. A warm climate in the early 1200s helped make the grasslands lush and this, in turn, helped the Mongols extend their empire into Russia, he says.
In 1241, the Mongol army reached the plains’ western limit in Hungary. Led by Genghis Khan’s grandson Batu, the Mongols crushed the Polish and Hungarian armies on open, flat terrain that suited their mobile warfare tactics.
“They were familiar with that environment,” says Di Cosmo. “What they didn’t know is how prone to flooding that particular area was.”
Compared with the rest of the steppe, Hungary has a high water table so it floods easily.
Analysing tree rings in the region, Di Cosmo and his colleagues found that Hungary had a cold, wet winter in early 1242. This probably turned Hungary’s central plain into a huge swamp.
Historical documents the team studied back up this claim, recording, for example, that melting snows kept the Mongol army from attacking a Hungarian castle surrounded by marshes.
Lacking pasture for its horses, the Mongols fell back to drier highlands and then to Russia in search of better grass.
While climate wasn’t the only factor in the reteat, it would be a mistake to ignore it, says Di Cosmo. “It’s like saying the winter in Russia had no effect on Napoleon’s army,” he says.
Michael Mann of Pennsylvania State University, University Park, says the study is interesting, but he warns against over-interpreting the influence of climate on historic events. “I’m sceptical that such ‘climate determinism’ holds nearly as universally as some authors seem to think,” he says. The changes in weather the study reported seemed “modest”, he says.
But Aaron Putnam of the University of Maine in Orono says that the study steered clear of determinism, taking into account all potential factors. “I think it’s convincing,” he says. “The previous explanations of the Mongol withdrawal didn’t add up.”
Horse logistics limited the Mongols, Putnam says. “They were incredibly technologically savvy, but they got into a place where horses just didn’t do well.”
Putnam says that natural weather records like tree rings have much more to tell us about the history of premodern civilisations, which depended heavily on environmental conditions. “It’s just an incredible archive.”
Journal reference: Scientific Reports, DOI: 10.1038/srep25606