I haven’t updated my blog in a few days due to travel but I’m back just in time for this monthly feature. Just four of them this month and they’re all about biology.
- First up, here’s this bit about the first known use of gene therapy to cure a patient of sickle cell anemia. The doctors harvested stem cells from the patient’s bone marrow, altered the DNA so that they would produce normal hemoglobin, used chemotherapy to kill off the remaining stem cells and then inserted the new ones. This makes it a case of genetic engineering on a human patient in vivo, instead of altering an embryo so that it would develop differently.
- This next article is also about DNA engineering. In this case, scientists have created wholly artificial chromosomes for yeast cells. The chromosomes are not only synthetic but edited to remove what is believed to be rubbish code in the original DNA and to alter the code’s punctuation to eliminate one letter from the usual stop code. The hope is that the yeast cells can still live normally after these modifications and the freed letters can open up more space for more extensive changes in the future.
- Dinosaur aficionados were up in arms earlier this month as a new paper proposes a radical redrawing of the family tree. Historically, dinosaurs have been classified according to whether they are “bird-hipped” or “reptile-hipped”. But as more data has been gathered, this classification system has become ridden with inconsistencies so a new paper now proposes that it be thrown away entirely. It may not seem like much to many people but it does matter to children who grew up memorizing names of their favorite dinosaurs and some of them may no longer be properly recognized as being dinosaurs at all!
- Finally here’s a cool bit about a couple of researchers who tried to put hard numbers on how many spiders there are around the world and how much they eat. They conclude that there are around 25 million tonnes of spiders on Earth, a number that is hard to put in context. But a more comprehensible figure is the 400 million tonnes of other animals that they consume a year because that is also the approximate mass of the total number of human beings living on the planet.
A solid selection of articles this time around, with findings that are a lot more significant than the boring stuff last month.
- Let’s just get NASA’s huge announcement out of the way first. As I’m sure all of you have heard by now, this is the discovery of a system that contains at least seven planets that are approximately the same size as our Earth orbiting around a single star. The system is less than 40 light years away from us and the planets seem to be packed in an astonishingly small volume of space, which makes it appropriate that it’s being called TRAPPIST-1 although it really refers to the telescope that found the system. Obviously we still know very little about them but the most exciting thing that we do know is that since they’re packed so close together, it should be possible to view the other planets if you’re on the surface of one of them. Their skies must have an amazing view.
- Moving on to animal behavior, this study talks about how monkeys and dogs can engage in social evaluations as humans do. The animals were allowed to observe humans interacting with each other, specifically a human actor making a request of another and the other one either cooperating or refusing. The scientists found that when the second person helped, they were equally likely to accept food from either person. But when the other person refused, the animal was more likely to accept food from the first person.
- Next are the workings in human society and I was fascinated to read this study about school voucher programs in the United States. It finds that a lot of this funding has gone on to schools that are affiliated with religions but instead of making the education more religious it seems to have made the schools more secular instead as they strive to welcome more students. Combined with the drop in attendance of church services as seen everywhere, the funding seems to also be displacing traditional tithes as a major source of funding for churches.
- Then there’s this study which tries to explain the unusually high life expectancy of Israeli men by linking it to obligatory military service. Apparently Israeli men live for around 7 years longer than men in other countries under similar conditions. The military service which is theorized to impose physical fitness on men doesn’t explain all of the additional lifespan but it does seem to explain about half of it.
- Finally here’s an article that is less about what was discovery than about how it was made. The finding is that about 2,500 years ago, the Earth’s magnetic field was briefly 2.5 times stronger than it is usually. It was possible to know this by studying ceramic pots that were made during that time. The dates on which they are made can be precisely dated because the bureaucracy of that era required that they carry administrative stamps. The clay used include ferromagnetic minerals that once fired and then cooled down, lock in information about the magnetic patterns at that time, allowing scientists to make inferences about the strength of the Earth’s magnetic field.
Like everyone else, my usual routines have been severely disrupted by the Chinese New Year holiday season. As far as I can tell, interesting science news is down this month as well as there are few really noteworthy announcements. The ones that I read this month probably belong more in the entertaining and sensational science news category.
- First, we have this bit about vampire bats in Brazil which ordinarily prey on birds having learned to drink blood from humans. This is significant as they have been previously been observed to starve rather than feed on pigs or goats and is probably an instance of natural selection in action as human encroachment in their habitat leads to a drop in the availability of their usual prey.
- Also in biology is the mystery of why so many corpse flowers bloomed in the year 2016. These plants bloom unpredictably once every 5 to 10 years and famously give off a smell of decomposing flesh when they do so. There aren’t many of these being cultivated yet somehow many of them bloomed in the same year all across the US and some other countries and botanists have no idea why this is so.
- Finally, here’s an announcement about a nova that should be visible to the naked eye on Earth. The problem is that it’s scheduled for 2022. The star in question is KIC9832227, actually a pair of stars that very close to one another. Astronomers have noted that the smaller of the two stars has been spiralling towards its companion and hence a nova is expected. This is noteworthy because all previous novas have been detected after the fact and this will be the first time that a nova has been predicted in advance.
Pulling the trigger on this one a little earlier than usual to square things with my posting schedule.
- The most headline grabbing announcement of the month is the news that more than 20 years after Jurassic Park, scientists have found a dinosaur tail preserved in amber. The incredible thing about this find that was made in Myanmar is that the tail is feathered and the features show up in wonderful detail, making it a powerful demonstration that dinosaurs really are feathered animals and not the scaly reptiles as envisioned in the film. Analysis indicates that this early form of feather isn’t well adapted for flight and so must have served some other function, regulating body temperature for example, so it’s also a good example of how features that evolved to serve some purpose went on to become adapted for another purpose.
- Biology is probably the theme of this post as the next entry is about elephants. One of the key differences between African and Asian elephants is that all male and female African elephant usually have tusks while only some male Asian elephants have tusks while some female ones have short tusks known as tushes. This article talks about how ivory poaching have caused an increasing number of African elephants to be born tuskless, a clear case of natural selection in action. In one national park, high levels of poaching have even caused 98 percent of female elephants to be born tuskless.
- Next up are horses. No new science here, just a bit of news about how Adolfo Cambioso, apparently the world’s best polo player, used a team of six horses in a high-profile event, all of which were clones of the same mare. I find it sobering how this passes without notice these days indicating that this is now a mature and commonly used technique.
- Still on the subject of animals, this article talks about how a Chinese team fed silkworms mulberry leaves that have been sprayed with a solution containing graphene. The silkworms then went on to produce silk that is twice as tough as normal silk. This seems a bit too easy. How could the researchers be sure that the graphene would be incorporated in silk? But it sure is cool if it’s true.
- Finally, here’s one that’s at least potentially about humans. It talks about disturbing your circadian rhythms can be a cause for liver cancer. The mechanics in mice stems from the fact that disrupted day-night cycles cause the animals to overproduce bile acid. Over time, this damages the liver and leads to cancer. They’re only guessing that the same applies to people and accordingly advise to follow a regular sleeping schedule.
Well, this has certainly been a tumultuous month in terms of politics. In terms of science, though it started out a bit slow, plenty of interesting stuff came out in the past couple of weeks.
- Over the long term and on a global scale, probably the biggest harm the Trump presidency could cause is in rolling back measures to tackle climate change. Fortunately the latest news is that there seems to have been a recent pause in the growth rate of atmospheric carbon dioxide. The upshot is that human industry is emitting more of the stuff than ever before, but it seems that carbon sinks have also been absorbing more of it than expected. It isn’t at all clear what is happening but the leading theory is that plants seem to be increasing their absorption of carbon dioxide in response to higher concentrations of the gas and higher temperatures.
- Also due to the recent elections, Facebook has been in the news due to its dissemination of fake news. This article covers a study in Denmark which shows that quitting Facebook seems to make people happier. Previous papers of this nature have been published before but this one involves a randomized controlled trial of more than a thousand participants recruited via Facebook itself in which half of them were randomly instructed not to use the social network for a week and the other half were instructed to continue their usual browsing habits. The effect was small but those who changed their habits did indeed seem to become happier.
- The most important science article however must be this New York Times feature arguing that growing usage of genetically modified crops seems to not have led to increased yields, nor to reduced usage of pesticides. They came to this conclusion by studying aggregate data about crop yields and pesticide usage in the United States and Canada, where genetically modified crops are common to Europe, where they are generally banned. Many commentators have since pointed out that this isn’t comparing like to like since, as you might expect, agricultural conditions within just the United States itself, vary considerably from place to place. Furthermore, decisions on what to grow come from farmers themselves and there must be good reasons why farmers, when given the choice in North America, tend to choose genetically modified crops even though those seeds are more expensive. Nonetheless, regardless of which side you take, this is an important piece of a conversation that is still ongoing.
- Moving on to better news, here’s one about the discovery that rates of dementia in the United States seem to be falling despite the fact that some of the risk factors associated with the disease, such as diabetes, are increasing. Researchers have no idea why dementia rates are falling and can only speculate that it might be linked to more education or higher cognitive demands being placed on the brain. Some commentators have instantly named this as another kind of Flynn effect.
- The most exciting news of course is the one about the EM drive. I’ve talked about it before, but to recap, it’s a reactionless space drive that requires no propellant and so seemingly violates Newton’s Third Law. A NASA team has just published a peer reviewed paper confirming that they’ve managed to detect the device generating net thrust in a vacuum. This is huge but most commentators are still skeptical and this Reddit discussion thread provides a decent summary of some of the objections. On balance, it’s still likely that this is due to experimental error but if this checks out, quite a bit of known physics will need to be redone.
- Finally, here’s a paper with a very politically incorrect conclusion. Please note that this is a non-peer reviewed paper that has been released for discussion only. It examines upward mobility of Asian Americans, showing that the group suffered plenty of discrimination, both institutional and otherwise, and yet by the 1970s or 1980s had caught up to white Americans in terms of income. The argument is that market forces subverted the discrimination as the wages of Asian Americans, despite work performance at similar levels as white Americans, were artificially depressed by the discrimination so that whichever company hired them would gain a competitive advantage. Over time, this eroded the discrimination itself. The corollary then is that black Americans did not experience similar convergence of income levels because their skills and abilities in the workplace truly aren’t, for whatever reason, as valuable, hence in their case the discrimination is exacerbated by market forces.
A little early this month due to some kinks in my posting schedule but as I have a full roster of these articles already, so why not.
- Let’s start with this discovery of a new plant species in Japan. Named Gastrodia kuroshimensis, this highly unusual plant does not use photosynthesis at all. Instead it gets all of its nutrition from the fungi that it hosts. At the same time, it produces flowers but they never bloom. Instead through a process called cleistogamy, the flowers self-fertilize within the closed buds. Perhaps the most surprising bit about this announcement is that such a strange plant can still be discovered for the first time in an area of a developed country that has already been thoroughly investigated, reminding us that new scientific findings can pop up in the most unexpected of places.
- Next is an article in a field that isn’t often featured here: chemistry! It’s about scientists discovering a new process that turns carbon dioxide into ethanol in a single step. There isn’t a lot of detail about it except that the reaction takes place in some fancifully engineered nano-structures but the claim is that the process takes little energy, low enough that it occurs at room temperature. Needless to say, if this checks out and can be scaled up, the impact would be immense as we would be turning a common pollutant into a source of energy.
- These days I often browse FiveThirtyEight for its politics coverage, but here’s a science article on the site. It talks about a statistical analysis of breast cancer data and finds that regular mammograms appears to be of little effectiveness. The study found that as mammograms became more frequent, the rate of finding small tumors increased, which is to be expected. However the incidence of larger tumors decreased by a much smaller amount, suggesting that finding tumors early does little to prevent them from growing. Most importantly the incidence of metastatic cancer was flat, meaning that early screening didn’t seem to reduce it at all. In the meantime, mortality rates from breast cancer has indeed fallen but this seems attributable to better treatment and not early screening. This result falls in line with a recent change in thinking that early screening for cancer mainly finds small tumors that would have disappeared on their own anyway and don’t need to be treated.
- Finally here’s an article from The Economist about sexual cannibalism in spiders. Most of us already know about how female black widows eats their male partners after eating, but how many of you know about the dark fishing spider, who males spontaneously die after mating and so ensure that they will be eaten? Even more strangely, the offspring of females who ate their male partners in this way were larger and more numerous even than those from females who were given a cricket of comparable size to eat rather than their male partners. This suggests that there is something especially nutritious in the bodies of the male spiders that helps the offspring and that this is the result of evolution.
I’ve long wanted to take a course about electricity since it’s one of the most mysterious parts of physics to me despite it being essential to everyday life. There doesn’t seem to be anything available on it on Coursera. I’ve been aware of the competing edX platform for a while now but hadn’t taken the time to explore it. So when I saw that it does indeed have a course on this topic, I immediately made an account.
This one is taught by Jason Hafner of Rice University and consists of five weeks worth of material. Being part one of a two part course, the coverage only stretches from the concept of charge to circuits, so don’t expect to be fiddling with complex electronics here. I consider the course to be quite difficult, especially because of the mathematics involved. There is plenty of calculus in the later weeks. Due to this, I could only follow along so far and eventually just settled on watching the lecture videos as I had no hope of completing the weekly exercises, let alone the final exam.
Continue reading Electricity and Magnetism, Part 1