Ever wondered how to calculate the day of of the week for any date in the past or future? Turns out, it's quite easy. Full details over here.

Technorati Tags: arithmetic

There is a bit of a myth surrounding Thanksgiving: the Thanksgiving coma, which is basically when everyone nods off after the big meal. So what causes it?

It's quite an elaborate story, even with scientific roots. According to general wisdom, turkey meat contains an amino acid called tryptophan (true), and in the body tryptophan is used for making serotonin (true), a hormone associated with sleep (also true). So the myth tells us that turkey has a lot of tryptophan, and eating lots of it makes your body produce a lot of serotonin, and you feel sleepy. Right? Nope; it's nonsense!

You see, turkey contains as much tryptophan as a similar piece of chicken or beef. In fact, all meats contain a little bit of tryptophan, and we don't dose off after eating chicken, now do we? Also, heavy meals full of fat and carbohydrates tend to make us sleepy anyway, regardless if they contained turkey or not.

And if life wasn't turkey enough (sorry for the pun), tryptophan has been implicated in helping people sleep sometimes. For example, last year, Dutch researchers reported on a small and (very) short study that suggested a link between better sleep and tryptophan. But don't rush and buy tryptophan supplements just yet: in 1989, a link between consuming supplements containing very high levels of tryptophan and Eosinophilia Myalgia Syndrome (EMS), which resulted in 38 deaths was uncovered in the USA. As of 2001, the FDA is still worried about dietary supplements containing tryptophan.

So, really, why do you feel sleepy after a heavy meal? It's because of the fatty and starchy meal you just ate, so the blood is diverted to your digestive system to help absorb all the nutritional goodies. This diversion makes you feel tired and lethargic, but only temporarily. Sorry, no magic involved.

Technorati Tags: thanksgiving, thanksgiving coma, turkey, sleep, tryptophan

This post is a bit of a bookmark for me, but I thought I'd share it. If you have a random burning question you'd like to answer, there are some websites that let you post your questions and let (millions) others answer it. What's nice is that the questions can be very diverse, deep, relating to technical issues, everyday life... well, anything!

By far, the best such service out there is Yahoo! Answers. Yahoo promoted this service heavily, and the end result is that millions of people use it, both asking questions and anwering them. You can also subscribe to RSS feeds for the categories or even searches. It's all free too. Very cool.

Update: Google Answers is no more. Google has a similar offering, called Google Answers. You have to pay to get answers. Personally, I don't like the interface (typical of the spartan Google designs). It should be your second port of call.

If found another service today, called Quick Answers. They don't have a science category (gasp!), but cover pretty much everything else. You have to pay a minimum of $20 for a question.

Technorati Tags: questions, answers, online

Science explains the root of all good and evil.

What happens to people when they have money? Results published in the journal Science found that by possessing or merely thinking money, people are less likely to ask for help in solving a problem, or offer help to another person, or make donations. Even worse, people with money physically distanced themselves from others. This pattern of behaviour is called 'self-sufficiency'.

Mouse model suggests potential treatment of age-related diseases.

International researchers looking at a compound called resveratrol found that it reversed the adverse effects of a high calorie diet in mice. They studied three groups of mice:

• Lean Mice: living on a normal diet
• Untreated Mice: living on a high calorie diet; these mice became obeses
• Treated Mice: living on a high calorie diet; treated with resveratrol

The paper published in Nature talks about the observed changes associated with longer life-span, and reversal of most changes in genetic pathways found in mice on high calorie diets, including some associated with diabetes, and heart disease. All in all, the risk of death was cut by 31% for mice treated with resveratrol, living as long as lean mice. Not just that, treated mice performed better on motor skills tests than untreated obese mice, to the point that treated mice and lean mice were indistinguishable.

So where does resveratrol come from? Resveratrol is found in grapes and red wines but is produced by a variety of plants when put under stress. It was first discovered in 2003 and has since been found to extend the lifespan of diverse species, from worms, to fruit flies, and now, mice. We do know the protein it affects in the cells (a protein called Sir2). Incidentally, Sir2 is also implicated in effects of calorie-restricted diets.

The next steps are clear now: we need studies on humans to figure out the exact effects, and hopefully move towards a drug. We also need more studies on Sir2 since clearly it's an important player in this area of living. Maybe we can find more compounds that affect its function.

Technorati Tags: resveratrol, diet, calories, mice, health, diabetes, heart disease

Still reversible though.

Hot on the heals of the publication of the Stern Review, a new paper published in this week's Science magazine plots a gloomy future for wild fish living in oceans: at current trends, by 2050 the researchers predict that wild-living marine species will have collapsed (defined as 90% depleted). The good news is that although the rate of decline is getting faster, the trend is still reversible.

By now you probably have heard of the Stern Review on the economics of climate change, especially if you're living in the UK. Essentially, Sir Nicholas Stern, Head of the UK Government Economic Service, and a former Chief Economist of the World Bank was commissioned to study in a comprehensive manner that effects of a changing environment on the world economy. The report was published a few days ago, and is now available for download.

If you don't read anything from the Review, at least read the Executive Summary. The first sentence is striking:

The scientific evidence is now overwhelming: climate change presents very serious global risks, and it demands an urgent global response.

It gets better:

The evidence shows that ignoring climate change will eventually damage economic growth. Our actions over the coming few decades could create risks of major disruption to economic and social activity, later in this century and in the next, on a scale similar to those associated with the great wars and the economic depression of the first half of the 20th century. And it will be difficult or impossible to reverse these changes. Tackling climate change is the pro-growth strategy for the longer term, and it can be done in a way that does not cap the aspirations for growth of rich or poor countries. The earlier effective action is taken, the less costly it will be. At the same time, given that climate change is happening, measures to help people adapt to it are essential. And the less mitigation we do now, the greater the difficulty of continuing to adapt in future.

You can download the Stern Review final report or buy it from Cambridge University Press.

Technorati Tags: Stern Review, environment, economics, climate change

A video.

One of the most fundamental concepts in biology is what's called the 'central dogma'. It states that DNA carries information between generations, and that the DNA information gets transcribed into RNA inside each cell, which in turn gets translated into proteins that carry out the cell's functions. This basic pathway of DNA-RNA-Proteins is the essential foundation on which all biology rests.

How this happens on a molecular level is a question that has had the attention of molecular biologists for decades. Of course we know a lot about the steps, but explaining it to new biology students is still sometimes a challenge. To this end, a video from 1970 has resurfaced again - on YouTube! - that explains one step of the central dogma, namely RNA to protein translation. THe video uses human chains and groups to animate the process of RNA translation into proteins. It's quite funky and by far the best explanation I've seen about the subject!

I've embedded the video below, but you can also see it on its home page.

Technorati Tags: biology video, central dogma, protein, RNA, translation

Due to aldehyde dehydrogenase gene.

Drinking alcohol is a risk factor for cancers of the oral cavity, pharynx, larynx, and esophagus. Scientists long have suspected that acetaldehyde, a compound produced as the body breaks down the alcohol is the culprit behind alcohol-related cancers. Now researchers in Japan and New York found a molecular link between acetaldehyde and DNA damage - that is, acetaldehyde is a carcinogen.

The experiment is straight forward enough: acetaldehyde causes DNA damage by reacting with the DNA itself, leaving detectable products. Can we find these reaction products in alcoholics? The answer turned out to be a resounding yes, but only in some people.

The key is an enzyme called aldehyde dehydrogenase-2 (ALDH2). ALDH2 is responsible for breaking down most of the acetaldehyde produced from alcohol in the body. As with most genes, there are variants of ALDH2. One variant is called ALDH2*2, which produces a nonfunctional enzyme - that is, the body does not have the critical machinery for clearing acetaldehyde. Millions of people carry the ALDH2*2 variant, but it is mostly found among East Asian; approximately 40% of Japanese carry the nonfunctional ALDH2*2.

So combining the above, the researchers studied 44 alcoholics in Japan, some carrying the normal copy of ALDH2 and some carrying ALDH2*2. They found that acetaldehyde-related DNA damage is significantly higher in people carrying ALDH2*2 than those carrying ALDH2. Summing up their results, the scientists report:

Taken together, the observations from biochemical, epidemiological, and molecular epidemiological studies discussed above, in conjunction with this study, well fit the scenario that acetaldehyde is a primary causative factor for alcohol-induced cancers.

As a side note: have you ever wondered why East Asians turn red when they drink alcohol? This is also due to ALDH2*2. Because they are not breaking down the acetaldehyde fast enough, it accumulates and causes skin flushing.

Technorati Tags: alcohol, acetaldehyde, acetaldehyde dehydrogenase, cancer