Providing the world with electricity

How much would it cost to provide every person on Earth with electricity and clean-combusting cooking fuels by the year 2030? According to a multinational team of researchers led by Shonali Pachauri of the International Institute for Applied Systems Analysis, Austria, about 75 billion U.S. dollars per year.

Currently, over 20% of the world’s population do not have electricity. You can imagine how much less productive a society is if it must cease most types of work or learning at sunset. The lack of clean cooking fuels is an even bigger problem. The time and energy spent collecting traditional fuels (wood or coal) drains local economies. Even worse, the smoke from these stoves is known to cause illness and premature death, particularly in children. 


A traditional outdoor cookstove - a chulla - in rural Tamil Nadu fired, as you can see, by any readily available material, here branches pulled from the rapidly deforesting barren lands, some salvaged scrap wood, dried dung cakes and coconut shells. 
Credit: McKay Savage 8/30/2012

Because of these issues, the United Nations has set the ‘International Year of Sustainable Energy for All’ goal of achieving universal access to modern energy by the year 2030. Using 2005 as a base year, the researchers created models with different scenarios of public support in order to calculate what sorts of investment and policy changes would be required to get to that goal. For example, in some cases, the energy changes have to be achieved without changing existing polices, in others, western countries come together to offer low-cost financing and grants.

Not surprisingly, if the affluent parts of the world refuse to offer substantial assistance, the rest of world will not have electricity by 2030. In fact, without infrastructure assistance in the form of subsidized fuel prices, microloans and grants, there will be even more people without access to clean fuels in the future. On the other hand, an investment of about $75 billion per year could very well provide everyone on Earth with modern energy. Remember, that would be a global contribution, it wouldn't have to all come from one country.

Needless to say, this is an estimate. Even if the models are accurate, we can’t predict which if any policy changes are going to be implemented to push the U.N.’s agenda along. 

By the way, contrary to first impression, giving more people access to modern energy should not increase carbon emissions. This is because petroleum products give off less carbon than wood or other traditional cooking fuels. Also, modern stoves and lighting apparatuses are more efficient than traditional cookstoves. And if newly built energy grids focus much more heavily on renewable resources like wind or solar, the gains will be that much greater.

Pachauri, S., van Ruijven, B., Nagai, Y., Riahi, K., van Vuuren, D., Brew-Hammond, A., & Nakicenovic, N. (2013). Pathways to achieve universal household access to modern energy by 2030 Environmental Research Letters, 8 (2) DOI: 10.1088/1748-9326/8/2/024015.

Genetic mosaicism may affect genome studies

There are so many things I love about this story, not the least of which is that the senior author on the paper is named Hudson Freeze. Kudos to his parents. More importantly, this study exposes a hitherto unsuspected problem with genomic studies. Not all the cells within a person contain the same genes.

To be clear, it’s not the phenomenon of having cells of different genotype that’s novel. Scientists have known about the existence of genetic ‘mosaics’ for over eighty years. Occasionally when cells divide, DNA replication or chromosome division goes slightly awry and you end up with two daughter cells that are not genetically identical.

The drawing below illustrates mosaicism (don’t worry about the name of the specific gene or syndrome in the captions, they’re from a different article). 

What is new is the realization that mosaicism may have to be taken into account when doing genomic studies. Case in point, three young children with glycoyslation disorders. Briefly, these kids have mutations that prevent their cells from attaching the right sugars in the right places to their proteins. Sugar placement is surprisingly critical for a whole host of functions, including cognitive ability.

Here’s the interesting part: only some of these kids’ cells contained the relevant mutation. This made it difficult to accurately diagnose them, because genetic studies came up negative or inconclusive. The scientists realized that they were dealing with mosaicism. That is, only a subset of the kids’ cells were defective.

Going forward, Freeze and his colleagues suggest that researchers be cautious about how much credence they pay to whole genome studies. Those studies obviously involve only a tiny fraction of a person’s cells and could possibly be misleading.

By the way, this study dealt with ‘somatic mosaicism’. The children with this condition had originated from a single fertilized egg and some of their cells had subsequently mutated. This is a common enough occurrence that some researchers believe we may all be somatic mosaics. Under rare circumstances, two fertilized eggs will fuse into one embryo (the reverse of identical twinning) and the resulting baby will have some cells that are derived from each of those eggs.

Ng, B., Buckingham, K., Raymond, K., Kircher, M., Turner, E., He, M., Smith, J., Eroshkin, A., Szybowska, M., Losfeld, M., Chong, J., Kozenko, M., Li, C., Patterson, M., Gilbert, R., Nickerson, D., Shendure, J., Bamshad, M., & Freeze, H. (2013). Mosaicism of the UDP-Galactose Transporter SLC35A2 Causes a Congenital Disorder of Glycosylation The American Journal of Human Genetics, 92 (4), 632-636 DOI: 10.1016/j.ajhg.2013.03.012.

Just for fun: 2013 Best Illusion of the Year

Once again, it's time for the Best Illusion of the Year contest, sponsored by the Vision Sciences Society.

The top prize went to this video, made by Jun Ono, Akiyasu Tomoeda and Kokichi Sugihara of Meiji University.



This illusion concerns apparent rotation generated by pure translation. Square patterns consisting of four segments appear to rotate when they move straightly at a constant speed across the grid background. More surprisingly, the rotations in opposite directions can be generated by exactly the same square patterns. This illusion might be explained by well-known inchworm illusion; inchworm illusion arises at the four segments one after another resulting in the impression of rotation. This illusion is new in the sense that the rotation is generated by pure
translation.


Full disclosure, it took me a bit of staring to see all the rotation patterns. You can judge for yourself.

I loved the second prize winner, by Arthur Shapiro and Alex Rose-Henig from American University, but unfortunately I could not embed it here. Check it out and be prepared to spend some time playing with it.

Finally, here's one I liked by Guy Wallis and David Lloyd from the University of Queensland.



You can see the other finalists here.

Does antimatter fall or rise?

Mass can be explained in two ways: by the amount of force required to accelerate an object (inertial mass) and by that object’s attraction for other objects (gravitational mass). For ordinary matter, these two measurements are equal. What about for antimatter? While we can’t yet answer this question definitively, we now have the first observations of anti-atoms within a gravitational field.

Where ordinary hydrogen is composed of one electron and one proton, antihydrogen is composed of a positron (anti-electron) and an anti-proton. Note that even though protons and positrons both have positive charges, they do not occupy the same roles. Despite their opposite charges, it’s the protons and antiprotons that have the same positions within their respective atoms. The same is true of positrons and electrons. So anti-atoms are just like regular atoms except with opposite charges. Oh, and there’s the fact that when anti-atoms meet normal atoms the two annihilate each other.

Physicists working with CERN’s ALPHA, an international collaboration with the purpose of studying antimatter, have succeeded in producing and capturing antihydrogen. The anti-atoms are trapped within the ALPHA apparatus until the scientists are ready to release them. Within a few milliseconds of this release, the anti-hydrogens annihilate against the regular matter wall of the trap. The position at which this annihilation occurs can then be detected. From this, the researchers can determine any gravitational effects.

Early experiments show that the gravitational mass of antihydrogen is not more than 100 times that of its inertial mass. Remember, these two numbers are equal for regular hydrogen and could also be equal for anti-hydrogen. At this stage, these initial experiments are not much more than proof-of-concept tests. However, the physicists are confident that they will crack this puzzle in the coming years.

Amole, C., Ashkezari, M., Baquero-Ruiz, M., Bertsche, W., Butler, E., Capra, A., Cesar, C., Charlton, M., Eriksson, S., Fajans, J., Friesen, T., Fujiwara, M., Gill, D., Gutierrez, A., Hangst, J., Hardy, W., Hayden, M., Isaac, C., Jonsell, S., Kurchaninov, L., Little, A., Madsen, N., McKenna, J., Menary, S., Napoli, S., Nolan, P., Olin, A., Pusa, P., Rasmussen, C., Robicheaux, F., Sarid, E., Silveira, D., So, C., Thompson, R., van der Werf, D., Wurtele, J., Zhmoginov, A., & Charman, A. (2013). Description and first application of a new technique to measure the gravitational mass of antihydrogen Nature Communications, 4 DOI: 10.1038/ncomms2787.

Tracking the progression of Huntington’s Disease

Huntington’s Disease (HD) is one of those rare diseases for which we know the exact genetic cause. If either of your parents bequeathed to you a huntingtin gene with extra CAG repeats, you will one day succumb to this terrible illness. This means that if you have a family history of HD, you can choose to have yourself tested and thus learn your inevitable fate, at least with regards to HD.

Graphic showing the excessive repetitions of the cytosine-adenine-guanine (CAG) nucleotide sequence in a gene from a Huntington's disease patient (bottom) compared to a gene from a person without the neurodegenerative disorder (top). Credit: National Institute of General Medical Sciences, National Institutes of Health

There is one more implication of being able to test for HD. It means that doctors can now follow the progression of an illness in people who are completely asymptomatic but who will one day have that disease. This kind of certainty is very unusual in medicine. Even with the best family histories, you can’t know for sure if someone will one day succumb to Alzeimer’s or cancer.

Sarah Tabrizi of the University College London and her colleagues, including TRACK-HD (a multinational prospective observational study of HD) investigators, chose to take advantage of this circumstance. They enrolled close to 400 volunteers who had the HD genetic marker but who were asymptomatic. The subjects were followed for thirty-six months. During that time, they were tested for cognitive and motor skills and had periodic brain scans to detect any loss of white or gray matter. Not surprisingly, the subjects showed steady declines in many of these areas. More importantly, the doctors could use the data to construct a sequence of expected failings.

At first glance, this may seem like the world’s most depressing clinical study. Actually, it still seems that way after multiple glances. However, it’s important to keep in mind that the better HD is understood, the more chance there is for a cure. These data could also help doctors learn how to postpone or ameliorate the worst of the symptoms. Barring that, knowing the way the disease progresses could at least give people a more accurate assessment of their futures.

Tabrizi, S., Scahill, R., Owen, G., Durr, A., Leavitt, B., Roos, R., Borowsky, B., Landwehrmeyer, B., Frost, C., Johnson, H., Craufurd, D., Reilmann, R., Stout, J., & Langbehn, D. (2013). Predictors of phenotypic progression and disease onset in premanifest and early-stage Huntington's disease in the TRACK-HD study: analysis of 36-month observational data The Lancet Neurology DOI: 10.1016/S1474-4422(13)70088-7.

Human-caused climate change--Now even realer

John Cook from the University of Queensland and his colleagues have now put to rest the idea that there’s no consensus on global warming. Global warming is real, and it’s caused by humans. So say over 97% of peer-reviewed climate studies.

The researchers pored through nearly 12,000 published papers on climate science and separated them into ones that explicitly endorse anthropogenic (human-caused) global warming, those that explicitly reject that premise, and those that offer no position on the matter. Of the papers that expressed any judgment at all on global warming, 97.1% clearly stated that humans were the cause. When the authors of the papers were asked to rate their own positions on global warming, that number increased slightly to 97.2%.

For perspective, Greg Laden points out that, among scientists, there's as much credence paid to the notion that humans are not causing global warming as there is to the existence of Big Foot.

The scientific community has spoken. Global warming is real and we caused it. It’s up to us to fix it if we can.  

Cook discusses his results below.

Still not convinced? By all means, check the results for yourself. Study author Dana Nuccitelli suggests you visit Skeptical Science's Consensus Project where you can sign up to review abstracts and make up your own mind. 

Cook, J., Nuccitelli, D., Green, S., Richardson, M., Winkler, B., Painting, R., Way, R., Jacobs, P., & Skuce, A. (2013). Quantifying the consensus on anthropogenic global warming in the scientific literature Environmental Research Letters, 8 (2) DOI: 10.1088/1748–9326/8/2/024024.

Can early reading and math skills predict future earning?

How well do early reading and math ability correlate with success later in life? Better than you might think, according to Stuart Ritchie and Timothy Bates from the University of Edinburgh. They found that reading and math achievement at age seven predicted socioeconomic status (SES) thirty-five years later. 

The study participants included over 18,000 children born the same week in 1958. In 1965, when the kids were seven years old, their parents filled out surveys to determine their childhood SES. The parents provided information on their type of job (professional, skilled or unskilled), whether the family rented or owned their home and how many rooms it contained. 

Also at age seven, the children were rated for math and reading ability, both on standardized tests and by their teachers’ personal evaluations. At age eleven, the kids were given intelligence tests, and at age 16, they were asked about their motivation and perceived ability to do well in school.

Finally, at age 42, the participants were asked how much education they had ultimately completed and to provide their current SES by the same measures indicated above. 

There was a definite correlation between both math and reading ability and SES at age 42. This was true even after accounting for childhood SES and intelligence. If achieving a high SES is your top priority, you'd better hope you were paying attention in second grade.

As usual, I have a few comments about this data. First, correlation is not causation, and Ritchie is the first to point this out. Second, even if the association between early academic skills and future earning potential turns out to be true, this doesn’t mean that there aren’t other paths to success. Finally, there’s nothing magical about age seven. Kids in Finland don’t even start formal education until that age, and they have the best educated students in the world. I wonder what the results would have been if reading and math skills at a later age were included. In other words, would reading proficiency at age 12 correlate more or less strongly with future SES than reading ability at age 7?

While I agree that proficiency in math and reading are extremely important, I hope this study won’t be used to further stigmatize students who are not doing well. If this news galvanizes schools to make a greater effort to help students who are struggling, that’s all to the good.


Ritchie, S., & Bates, T. (2013). Enduring Links From Childhood Mathematics and Reading Achievement to Adult Socioeconomic Status Psychological Science DOI: 10.1177/0956797612466268.