## Of Cheese, Mice, Men, and Mars

02/23/2013

I just read about a cool experiment that you can do at home. You can follow the link, but in a nutshell the experiment involves cutting a piece of cheese into cubes of different sizes. When you place these cheese cubes in a conventional preheated oven you find that the smaller cheese cubes melt first. However, if you place these cheese cubes in a microwave oven it is the larger cubes that melt first! How can this be?

The explanation has to do with something called the surface to volume ratio. If you calculate the surface area of a cube and divide this by the volume of that cube, you will find that the smaller cubes have a greater surface to volume ratio than the larger cubes. So when you place the cheese cubes in a conventional oven, the heat enters the smaller cubes much faster (because they have more surface area relative to their volumes) than it enters the larger cubes. Most people that have tried to heat food in a conventional oven have experienced this. The center of bulky pieces of food may remain cold while the outside is hot, whereas smaller pieces heat up faster.

But just in the same way that heat gets in faster into a small cheese cube that has a high surface to volume ratio, it is also true that heat can get out equally fast (dissipate) from such cubes. The microwave oven generates heat inside the cubes. In the larger cubes the heat has trouble moving out (because of the lower surface to volume ratio) and accumulates, heating the cube and melting it, whereas in the smaller cubes the heat escapes much faster and the cube doesn’t get as hot.

The interesting thing is that this principle also applies to living things. Mice have a very high surface to volume ratio compared to a human being, and tend to lose heat very fast just like the small cheese cubes. This is why mice have a very high metabolic rate (expressed on a per body mass basis) to compensate for this large heat loss. If a mouse had the metabolic rate of a human it would die from hypothermia (lack of heat). Conversely if a person had the metabolic rate of a mouse, he/she would die from over-heating because the heat generated in the large volume of the human body would have trouble getting out through the limited surface area, just like in the large cheese cubes. If an elephant had the metabolic rate of a mouse it would (in theory) boil!

But even more interesting is that we owe our very existence to the principle of the surface to volume ratio. Compare our planet teeming with life to the barren wasteland that is Mars. The Earth is larger than Mars and therefore has a lower surface to volume ratio and cools slowly (like the large cheese cubes). All the heat that gets trapped inside the Earth as a result of this has melted its core, and the spinning of this core generates a magnetic field. This magnetic field protects the Earth against the solar wind, which would otherwise strip away our atmosphere. Unlike the Earth, Mars is smaller (has a high surface to volume ratio) and, like the small cheese cubes, it has cooled faster. As a result of this, its core solidified and stopped spinning a long time ago. When this happened, Mars lost its magnetic field and its atmosphere was stripped away by the solar wind.

So there you have it. Who needs expensive labs or particle accelerators? Here is a fundamental physical principle responsible for life that holds true from mice to planets and that you can put to the test in your kitchen. Isn’t that cool?

Now next time you get served cheese cubes and crackers at a cocktail party you can impress everyone by talking about the principle of the surface to volume ratio and heat transfer. Please remember to reference this blog!

Mouse & Cheese Photo credit: Darny / Foter.com / CC BY-NC-ND
Mars Photo credit: NASA Goddard Photo and Video / Foter.com / CC BY

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## It doesn't get more insignificant than this!

02/08/2013

A follow up to my Pale Blue Dot post during the past holidays.
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## Spotlight on Interesting Factoids: A Tale of Two Mountains

01/19/2013

I just learned an interesting factoid that I want to share with you. The image below is a picture of the tallest mountain in the world. Do you know which is it?

If you answered Mount Everest you are correct. This mountain is over 29,000 feet high and has a lot of name recognition in the world. But let me ask the above question in a different way. When measured from the center of the Earth, which is the tallest mountain in the world? Or alternatively, the summit of which mountain is closer to outer space? Surprisingly the answer is not “Everest” but rather the mountain in the picture below. Do you know its name?

This is a volcano in Ecuador called Chimborazo and it is 20,564 feet tall when measured from sea level. However, when measured from the center of the Earth, Chimborazo is 1.35 miles taller than Everest and therefore also closer to outer space! In fact, when measured in this manner, Everest is the fifth highest mountain in the world with the second, third, and fourth positions occupied by the mountains Huascaran in Peru, Cotopaxi also in Ecuador, and Kilimanjaro in Tanzania, respectively.

The reason for this surprising fact is that the Earth is not a perfect sphere. Due to the Earth’s rotation, the land and the sea around the equator bulge outward. Someone standing at sea level on the Earth’s poles is about 13 miles closer to the center of the Earth than someone standing at sea level on the equator. Because Chimborazo is located 1 degree south of the equator it sits on top of this bulge, whereas Everest which is 28 degrees north of the equator is not “pushed up” as much.

The Death Zone is found in high mountains above an elevation of 26,000 feet. At this altitude the abundance of oxygen is only 1/3 of that found at sea level and the human body is incapable of adapting effectively. The death zone is one of the reasons Everest is so hard to climb and also why the route to the top in this area of the mountain is littered with the bodies of dead climbers. I reasoned that if Chimborazo is closer to outer space than Everest, then it should also have a death zone. As it turns out this is not the case because the Earth’s atmosphere also bulges out around the equator. As a result of this, the summit of Chimborazo is safely below the death zone and the human body can function in the thin atmosphere of the summit if allowed the time for adaptation to high altitudes.

So there you have it. Now next time someone says that Everest is the tallest mountain, you can impress everyone by saying, “Wait a minute…” and proceed to set the record straight. Remember to reference this blog as your source. Thanks!

Everest photo credit: Rupert Taylor-Price / Foter.com / CC BY
Chimborazo photo credit: apgwhite / Foter.com / CC BY-NC-ND

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## The Funny in Your Mind

12/01/2012

Have you ever asked yourselves what makes something funny? Why do we laugh when something is funny? What goes on in our brain when we hear something funny? Why do we seek the funny? Well, as it turns out neuroscientists have been hard at work in this area for a while using the most up to date technologies to answer these questions. One way to study these questions is to look at the areas of the brain that increase in activity while subjects listen to jokes. For this, scientists have used a technique called functional magnetic resonance imaging (fMRI) that can identify those regions of the brain that become more active in response to a stimulus.

In a recent study, scientists imaged the brain of volunteers who listened to jokes or non-jokes. The scientists also asked the subjects to complete a questionnaire to rate the level of "funniness" of what they heard. The results indicate that funny is not something that is localized to one structure in the brain. When what the subjects heard was funny, several dispersed structures in the brain were activated. Some of the structures like the amygdala, ventral striatum, and midbrain, are associated with the experience of positive reward. This means that "getting a joke" produces pleasure. The extent to which these areas were activated correlated with the subjective ratings of funniness that the participants ascribed to the jokes. The researchers could tell whether a person thought something was funny just by evaluating the increases in activity in these brain areas.

One interesting aspect of this study was the evaluation of jokes with semantic ambiguity. There is an area of the brain called the inferior frontal gyrus (IFG) that increases in activity when subjects are exposed to funny things. The IFG also becomes active when a person encounters semantic ambiguity. For example:

"What was the problem with the other coat? It was difficult to put on with the paint roller."

This sentence activates your IFG briefly because of the ambiguity associated with the word "coat" (a garment vs. a layer of paint). The IFG is a brain structure involved in resolving ambiguities. Now consider the following joke:

"Why don't cannibals eat clowns? Because they taste funny!"

When you listen to this joke, your IFG also becomes active in response to the ambiguity regarding the meaning of the word "funny" (odd or bad vs. amusing), but in this case the resolution of the ambiguity is more difficult than with the example about the coat. As a result of this your IFG remains active for a longer time. The authors of the study found that this increased activity of the IFG was an important component associated with the funniness of jokes with semantic ambiguity.

This study evaluated the neurological complexity behind something as seemingly mundane as finding a joke funny. Of course, when scientists study these processes they try to simplify things as much as possible to make them amenable to research. One aspect that was not evaluated is whether we find a joke funny when we are the object of the joke. For example if an author received a review of their book that stated:

"Your book was both good and original. Unfortunately the part that was good was not original and the part that was original was not good."

Would the author find that funny? I can't even begin to imagine how the brain scan would look!

What do you think? (Image courtesy of smokedsalmon)

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## Mumbo Jumbo?

03/24/2012

In season 2, episode 5 (The Euclid Alternative) of that great show “The Big Bang Theory,” Penny asks Sheldon why he didn’t get his driving license when he was 16 years old like anybody else. Sheldon, a theoretical physicist with 2 PhDs, replies that it was because he was busy “examining perturbative amplitudes in n=4 supersymmetric theories leading to a re-examination of the ultraviolet properties of multi-loop n=8 supergravity using modern twistor theory.”

Of course the Big Bang Theory is just a sitcom, but the science depicted in the program is often quite accurate and also as cryptic as real science is too. Check for example actual tittles of research published recently in academic journals:

-Vortex dynamics in two-dimensional Josephson junction arrays with asymmetrically bimodulated potential

-Dopaminergic Polymorphisms Associated with Time-on-Task Declines and Fatigue in the Psychomotor Vigilance Test.

- Heavy cluster knockout reaction (16)O((12)C,2(12)C)(4)He and the nature of the (12)C-(12)C interaction potential.

-Countertransference feelings in one year of individual therapy: An evaluation of the factor structure in the Feeling Word Checklist-58

Regular folk are often bewildered by the apparent mumbo jumbo spoken by academics. Like in the Calvin and Hobbes cartoon depicted above some may even wonder if all those big words are nothing more than gobbledygook employed by people who just pretend to know what they are talking about and hide behind an “intimidating and impenetrable fog of writing.”

To address this issue consider the following thought experiment. Imagine that your language is restricted to that employed by a tribe in a remote jungle that has had no contact with civilization. Now imagine trying to survive in our modern society using only this language. How are you going to express yourself and be understood when you deal with computers, microwave ovens, the internet, television, CDs, DVDs, cell phones, cars, airplanes, trains, robots, atomic bombs, or genes?

Our degree of technological advance has led to the production or discovery of many entities that are just not part of the immediate reality that this tribal language describes. If you incorporated these words into the tribal language and used them in front of the members of the tribe they would think you are talking nonsense. That is the same situation with academics.

This is not to say that some individual academics may not attempt to hide their ignorance behind a wall of jargon. But by and large all researchers in different fields eventually encounter entities that cannot be described by words existing in our regular language. This is why new words are created. In some areas these words eventually filter into the day to day reality of the common folk, but in other areas they make sense only to those who study the field.

So no, it’s not mumbo jumbo, and some of these words may end up being part of the vocabulary of your children or your children’s children in the future.

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## Alerting all females! Males who do not get sex become alcoholics!

03/15/2012

OK all you femmes out there. It’s official! Here is at last rock-solid scientific evidence you cannot dispute! If males don’t get enough sex they take up booze. Deny them access to your affection and they will turn into alcoholics. And nobody wants that, right?

That is, if you are a fruit fly.

Researchers from the University of California and the Howard Hughes Medical Institute have published a paper in the journal Science where they found that male fruit flies that were denied sex increased their alcohol consumption.

The authors took two groups of male fruit flies. They exposed one group to sexually receptive virgin females while the other group was exposed to sexually non-receptive females that rejected their advances. The two groups of males were then given access to two sources of sweet fluids one of which contained 15% alcohol. They found that males that were rejected, and thus didn’t get any sex, drank more of the fluid that contained alcohol.

While any drunk in any bar in America could have told them that, the researchers found something else. They found that the males that were denied sex had 50% lower levels in their brain of a chemical called NPF (neuropeptide F). The authors proceeded to manipulate the levels of NPF by other means than sex, increasing them in the rejected males and decreasing them in the males that had mated, and they were able to reverse the behavior of the flies. Thus the sequences of events seems to be less sex > less NPF > more alcohol, more sex > more NPF > less alcohol.

But don’t you ladies think for a moment that this is a curiosity only limited to fruit flies. There is a protein in the brains of mammals that is similar to NPF, it is called neuropeptide Y (NPY). Lower levels of NPY in the brain of rats leads to higher alcohol and drug consumption. People with depression and post-traumatic stress disorder (conditions that make them prone to alcoholism) have lower levels of NPY in their brains, and certain variants of the receptor for the NPY are associated with greater alcohol and drug dependence.

So there you have it. If you ladies want to keep us away from the bottle please, oh please, pleeeeeease grant us access to your lovely charms (especially when we resort to pathetic whining). Let’s work together to keep those NPY levels in our brains elevated!

; ^ )

***

06/29/2011

A study recently published in the American Journal of Epidemiology may mean bad news for writers. The study analyzed the relationship between time spent sitting, physical activity, and mortality. About 50,000 women and 70,000 men participated. The subjects were free of disease at the time of enrollment in the study and their level of physical activity and time spent sitting were gauged by questionnaire. The authors of the study followed the subjects for 14 years recording a total of about 11,000 deaths in the men and 8000 deaths in the women.

The authors found that the least active of the women and men that also sat for more than 6 hours a day, were 94% and 48%, respectively, more likely to die compared to the most active women and men that also sat more than 6 hrs a day. In other words, physical activity decreases your chance of dying. However, the authors also found that, physical activity being equal, women and men that spent 6 or more hours a day sitting were 35% and 18%, respectively, more likely to die compared to those that sat for less than 3 hours a day. The cause of death that was associated the strongest with the mortality was cardiovascular disease.

So like other previous studies, this study confirmed, that physical activity decreases your odds of dying. However, the novel finding is that sitting more than 6 hours a day, regardless of your level of physical activity, can increase your odds of dying compared to people with a similar level of physical activity that sit for less than 3 hours a day. In other words, time spent sitting was independently associated with total mortality.

Since we writers spend a lot of time sitting down this may mean we are at increased risk of dying.

But such are the risks we take for the pleasures that come with the act of creation.

## Why Aren't Anti-Cancer Drugs like Antibiotics?

06/25/2011

A friend asked me why anti-cancer drugs have so many side effects. Why can't anti-cancer drugs be like, for example, antibiotics? This is a question that few scientists consider because it is so basic, but it is one that a layperson may feel curious about and the answer is very interesting.

Cancer is like a car losing its brakes. Cells normally have brakes in place that prevent them from multiplying. When cells lose these brakes they start multiplying like crazy. When bacteria infect our body they also start multiplying like crazy, but there is one key difference. Bacteria are recognized by our immune system as foreign objects and they are attacked. Cancer cells, on the other hand, are by and large ignored by our immune system because they are identified as self, not as a foreign body.

And because bacteria have a physiology and a biochemistry that is very different from that of our own cells, scientist can use these extreme differences as unique targets to come up with drugs (antibiotics) designed to exclusively affect bacteria. As a result of this, antibiotics don't affect us at all most of the time. Additionally, bacteria also have to deal with the immune system. Thus, the double whammy of antibiotics and immune system normally wipes them out. In fact, many antibiotics don't kill bacteria, they just delay their growth while the immune system catches up and does the killing.

Cancer cells however, are so similar to healthy cells that scientist have very few unique differences that they can exploit to come up with drugs that will only affect the cancerous cells. The difference that is most often employed is the fact that cancer cells multiply very fast while most of our cells don't. But that is the key word, "most". We do have a significant number of cell types in our body that multiply very fast: For example, in our bone marrow, in our intestines, and the cells that make our hair. This is why most anti-cancer drugs also cause damage to the body.

Hence, scientists administering a cancer drug are faced with a balancing act. They must deliver a dose of the drug that is effective against the cancer, but they can't give too much or else they can cause significant toxicity to the patient. Many times the doses necessary to kill the cancer are too high for the patient to withstand, and this is especially true in the case of advanced cancers that have spread. This is why the best way to deal with cancer is to get screened and increase the chance of detecting it early. Mammograms, pap smears, prostate exams, colonoscopies and other such procedures are instrumental to this process.

So you see, in these technologically advanced times the old adage "an ounce of prevention is worth a pound of cure" is still true!

## Time to Quit Smoking?

06/14/2011

My father told me the story of how he quit smoking. A doctor friend of his took him to the hospital's morgue and showed him the lungs from a smoker and those from a non-smoker. From that day on he did not smoke again. Of course not everyone has a friend who is a doctor with access to a morgue, but I hope the following short video does the same for you.

## Phantomimic

I am a tinker, tailor,
soldier, sailor,
rich man, poor man,
beggar-man, thief!