Friday, October 30, 2009

My new favorite physics book

I am reading Absorption and Scattering of light by small particles by Craig Bohren and Donald Huffman and in Chapter 2, when they are talking about Maxwell equations and the relevant assumptions they say:

"Now it is well known (to those who know it well) that the response of a mechanical system to a periodic driving force is a sensitive function of the frequency". (Emphasis added)

Haha, now, THAT is freaking awesome. I can't remember how many times I've read books or journal articles that argue that something is well known, just to find out that I am one of those for whom it isn't "well" known.

I am only in chapter 2 so far, but what I've read so far is really well written. I had a feeling at the beginning that this would be a good book, but now after finding the above-mentioned quote it just became one of my favorites.

Do you have any other funny physics book quotes?

Tuesday, October 27, 2009


That would be me, but apparently not him.

Of all the things (whatever many or few they are) a former president could do, I never thought he would become a motivational speaker.

Oh well...

Monday, October 26, 2009

Welcome to the jungle!!!

I hadn't thought of it until today, but I think the intro song for Monk could almost apply to academia.

Don't be fooled, the limited number of grants plus the pressure of continuously publish make academia a really tough place as far as competition goes.

Massimo wrote a very nice post on one of the ways (dirty) competition happens in academia. I bet many non-academics were not aware of this type of shit going on. Ha, welcome to the jungle!!!!

NOTE: I realize I could also give some credit to Guns n' Roses. I can't really remember all the lyrics and thus I am not sure they apply at this time. I will come back and update the post when I have the time to check that song out again.

Monday, October 12, 2009

Is that my job?... are you sure?

I read PiT's post on the education debate and the comments are, of course, on different sides of the aisle.

The topic is a complicated one because it has many sides and there is also (at least in the US) money involved, and while I am sure it will take a long time to settle the matter, PiT's post comes not so long after I experience a situation related to education in the classroom. I find this time appropriate to tell you about it.

As a grad student I've had to TA for many different courses with many different professors. Some professors were bad, some were good, some were really bad but no one had been really good. I had never taken classes with them, I only had the professor-TA interaction until in my last TA job when I was assigned to a professor with whom I had taken a graduate class. The class I took with him was a special topic class in his area of expertise, and he made it very closely related to his research. I found the class to be very enjoyable, but most importantly useful since I thought I actually learned a lot from him. So, when I got my TA job I was very excited, this could be finally the time where I get to TA for a guy who the students might like (It is awkward to TA for a prof that the students hate and keep making bad comments about).

When the semester started I was a little thrown back because his choice of teaching style was different than the one he used in the class I took with him. I don't particularly like that style but supposedly it has been shown to work better and I wasn't going to tell him to teach it differently. At least not yet.

Everything was going "fine" until the first test came. It was a relatively difficult test and the grades were low. Lower than expected. Something was odd. We talked about it and that's when I said that maybe he should try other teaching styles. It might not be that the style is bad, just that it may not be for him. I knew he was not a bad teacher, I'd had him as one and he was very good. I was "sure" it was the use of a different style. It had to be, right?

Well, the reply was where I got a little disappointed. He wasn't going to change, because 1) when he was a TA that's the way he always did it and 2) changing to the traditional, or any other style, involves work that he didn't want or had no time to put it.

The two points have issues with them in my opinion. Having always done it that way doesn't mean it has always worked. Doesn't even mean that it has worked at all. And changing the style meaning more work, well sure it is a lot of work, but if you want the students to actually learn from you you need to find your style.

When you, as a student, are faced with situations like this, don't you deserve more? I understand that professors have a lot of other things to do that undergrads are usually not aware of, but if you took the job as a professor, with teaching load involved, why not try to be better at it?

You can certainly ask, when do you stop being better? when everyone passes? when you've tried 2 or 3 methods? Those are valid questions, and some for which I don't have an answer. I do think it is unrealistic for 100% of the students to pass a class with perfect grades. It is also unrealistic to try every single teaching method. I just think it is also the professor's responsibility to do his/her best before deciding that some students don't deserve to pass because they didn't work as hard as they should.

I want to make it clear that what I just told you is by no means proof that every professor out there is in that position. But, at least in my case, it did make me wonder how many profs think like that and now don't make an effort.

Monday, October 5, 2009

How science moves forward...

This is awesome advice!!! He should be awarded a Nobel prize!!!!

It really doesn't get any easier, right?

Sorry about the quality of the video. I couldn't find a better one online.

Sunday, October 4, 2009

The flu vs. non-experts!

I just found out this article online. The story comes down to this: We have a vaccine for H1N1, but many people don't want to get it because it's unsafe, or so they say. Here are a few quotes from the article:

"Experts stressed that the vaccine was made the same way it is every year and there is no reason to think it will pose any greater risk. Serious side effects involving the seasonal vaccines are extremely rare."

Then, a few paragraphs below:

"We are concerned that the H1N1 vaccine is too new and too untested to be given to such a young child," said Jenn Lewis, an attorney who lives in the District and has a 9-month-old daughter. "We would prefer that our child not be a 'guinea pig' for the vaccine."

All that comes to my mind after reading the article is a quote from PiT:


Since when do people know so much about virology and medicine? The article doesn't mention whether or not the people that are against H1N1 vaccine also refuse to get the seasonal flu vaccine every year. If they do get it every year, then they really have some (wrong) preconceptions about the flu vaccine. Every year, a group of knowledgeable people (in the field of course) make a guess as to what strain of the flu will go around and that's what they put in the vaccine. Some years they guess right (or close enough) that the seasonal flu vaccine is a success, and some other years they miss miserably and it maybe would've made little difference not to get it.

Do you know the difference this year? The H1N1 vaccine is 100% dead on the virus strain. That means that, as long as the virus doesn't mutate (at least significantly), if you get the vaccine you will NOT get the "swine flu".

"From what I've read and what I've heard, all it causes is just a mild case of the flu," said Laura Reavis of Buford, Ga., who has no plans to go for shots herself and no inclination to inoculate her 2-year-old daughter, Rebecca, and 6-month-old son, Woodrow. Her husband, Daniel, plans to pass, too. "You get sick for a few days or maybe a week, get over it, and life goes on." (Emphasis added by me)

This response wouldn't be so bad if most people who thought like this and got sick would just stay home and contain the spreading. The problem is they will go to work (who, other than grad students and professors :D, can afford to not work these days, right?) and cough everywhere and really make no effort to stop passing it on to others. That is why vaccines are so important. That's exactly why vaccines are ranked high up in medical advancements.

For those who are against vaccines, really go learn (from unbiased) sources about how vaccines are made and about immunity (in particular herd immunity).

Wednesday, September 30, 2009

Not bad news at all

I just found out this news article. Very good news for Texas A&M, but also good news for the whole state. I was usually amazed at the fact that Texas, being the largest state in contiguous US (I had written continental US but Wikipedia told me it included Alaska, :S) would have very few large universities and before the 90s, had only two Nobel prize winners in physics or chemistry. It is not the case anymore and you can see more and more articles being published by places other than Univ. of Texas at Austin, Rice and Texas A&M. A sign that having important people in your department definitely helps.

One good thing about Texas is that it has a lot of money: many texans that made a lot of money and are really proud of their state. Obviously, people like George Mitchell, are really good for science and we need more of them. By the way, this is not the first time it happens for A&M in recent years (Think Dudley Herschbach). The Univ. of Texas at Dallas also got Alan MacDiarmid in 2002. Unfortunately for them, and for science, he died in 2007.

Texas also has its own problems when it comes to science, but so far it has managed to not fall for alternative, non-scientific theories, being put in science curricula. Despite these sour incidents, I think we'll be seeing a lot of investments, like the one by Texas A&M , in the coming years in the state of Texas. I do not own a house anywhere in the US (or the world for that matter) but talking to friends that went to grad school in many different states in the US, the ones that have gone to Texas usually feel they can afford more for the same buck. This will probably help recruit talented young scientists and if donors like Mitchell continue to do their part we'll definitely see a lot of scientific competition coming from Texas.

CORRECTION: Initially I wrote "only one" when referring to the number of Nobel Laureates, in either physics of chemistry,working at a Texas university. I made a mistake and there were actually 2 before the 90s. One is at a medical school and I, wrongly, assumed he won it for medicine. You can see the list of the Nobel laureates currently in the state of Texas. A total of 8.

Friday, September 18, 2009

Bouncing water droplets!!!

I have always liked table-top experiments. In my opinion, those who can come up with those ideas really, and I mean really, understand what they are doing. Plus, they usually come up with nice videos (it's funny, now that I think about it, it is mostly fluid dynamics people that get nice videos. Here's one for example).

In the newest issue of Nature, Howard Stone from Harvard has a reeeeeeeeeally cool result. First, let me show you the experimental setup. The tank consists of water at the bottom and then oil on top. The oil (a poor electrical conductor) and the water are connected to electrodes of opposite sign that provide a high voltage. Once everything is turned on, they manually put a drop of water at the top using a pipette.

Initially, the water droplet is attracted towards the upper electrode by dielectrophoretic forces but when the drop actually comes in contact with the top electrode it acquires a positive charge and then it is repelled towards the bottom (the drop is very small and gravity doesn't really play a role here). You would think that when the droplet moves low enough to touch the water reservoir at the bottom it will just merge and become part of the reservoir. It should do that normally, but in this case it should be even better because the drop is positively charged and the water at the bottom is negatively charged and, as we all know, opposite sign charges attract. What's the big deal? Sounds easy enough,right? Well not quite, what Stone and friends found was that the behavior of the droplet actually depends on the voltage applied between electrodes.

When the voltage is low enough, what I quickly described above will happen. But when the voltage is high enough the result is different. Initially, the positively charged droplet moves toward the negatively charged water at the bottom but when they come in contact (just a tiny contact as you can see here) the water in the reservoir transfer negative charge to the droplet and now they will repel. This means the droplet moves up, towards the positively charged electrode that now is creating an electrical attraction between the two. Eventually the drop will touch the upper electrode and again a charge transfer happens, charging the drop positively and therefore the whole cycle repeats. You can watch a video of this "bouncing" here.

Pretty cool, uh?

Wednesday, September 16, 2009

Hours worked vs. taxes paid

Sean at Cosmic Variance just put up a post on the Laffer Curve. Very interesting concept. But as Sean mentions, who knows whether the assumptions that come into the general Laffer Curve theory or those made by the study referred to in Sean's article are correct.

By reading the comments over at CV, I have a question. If you could keep more of the money you earn i.e. lower taxes, and assuming that you could chose how many hours a day you could work, would you work longer hours to increase your personal income, work the same hours which after all means more income anyways (though not as much as the first option)? or would you work less hours (enough to match your current income)?

Monday, September 14, 2009

Is it good for science?

As a TA I have taught labs and also some discussion sections for the courses. Most of them have been for engineers or science (including pre-med majors) but in one occasion I had to TA for a class designed for liberal arts majors. This was a whole new experience for me, it's not like engineers or science majors other than physics really enjoy taking a physics course (I'll leave my rant about why they should like and learn physics for a later time), but (these) liberal arts majors really, really came into the course hating physics. It didn't help that the professor that was teaching it taught it the exact same way that he teaches plasma physics to his graduate students: by showing lots of math and little explanations into the concepts.

As the semester moved on, my office hours started getting more and more students who looked for a different style and hopefully a chance at passing the course. I should mentioned here that I completely disagree with non-science/engineering majors having the requirement of taking science courses (at least in the traditional way). Don't get me wrong, as a scientist I definitely think the non-scientists also need to know about science, they play an important role in politics, economics and religion (just a few of the areas that heavily affect the funding and spreading of science) but do they really need to know how to solve boring textbook problems in order to appreciate science? I think not. I actually think by forcing non-science majors to take our courses we are doing science a disfavor: not only are they not learning science but they are hating it even more.

I mentioned that traditional science courses for non-majors do not stand very highly in my eyes, but every time I tried to explain my position to someone I ended up getting into many many details that, while true, were so specific many people didn't think they were as bad as I did. A few days ago I found a two-sentence answer that summarizes my view. It was Shinya Inoue who said it during an interview:

"I continue to worry about science being learned as a collection of facts and theories. One needs to have a certain body of knowledge -- but in addition, one needs to understand how the knowledge is acquired-- that really is at the heart of science."

I agree 100% percent. It is a simple phrase that contains important ideas. Just standing in front of a room reciting every equation or theory we can remember is a horrible way of teaching science. Science majors will (hopefully) eventually pick up the lost knowledge, but non-science majors will go through life thinking that science is just a bunch of non-sense stuff.

Is knowing that when we let go of something it will fall that complicated? Really? Can no one do better than integrating the acceleration twice on the board? I hope science professors and teachers soon catch up with the idea that not everyone is as passionate about science as they are and that science is more than just equations and theorems.

Wednesday, September 9, 2009

Nice prevention idea... maybe?

I don't know much (or anything) about regular gatherings of religions except for catholic masses but at least in these ones I see many weak points in terms of disease-spreading prevention. For example, before communion everyone recites Our Father while holding their neighbors' hands. Then they give the peace (shake hands with everyone around them) and a little later the go up for the communion. During communion, the priest puts the Host (sacramental bread) on the parishioners' hands, who then proceed to put it in their mouths. Afterwards, they drink the sacred wine from a common cup that is "cleaned" with a piece of cloth after each person that drinks from it. These are four actions that can spread diseases among the parishioners. With H1N1 flu looking like it is easily transmitted I wonder if churches can still provide the spiritual fulfillment to their people while being proactive as far as infection prevention goes. I am sure it is doable; when the "swine flu" first broke in Mexico, churches there encouraged their attendees not to shake hands and when things got worse they actually closed the churches (or any public gathering for that matter) for some time.

Just this past weekend I was talking to a family member about what churches (specifically in the US) will do to reduce the risk of H1n1 flu spreading among their members and now I find this article. Funny and maybe well intentioned (both because it makes an attempt to stop spreading disease and also because by offering "fortified" wine they might increase the number of people that attend, mmm maybe we should do that in science? ha) but will it actually work? Could they just stop doing that particular thing (drinking the wine from a common cup) for a while? At least while scientists figure out how to best combat H1N1?

I've actually been wanting to post about the real advantage (if any) of alcohol-based hand sanitizers (HS) in preventing getting the flu but I am definitely not an expert in virology or communicable diseases and finding good information on journals/books about this has proven more difficult than I thought so I've put it off. Health agencies, on the other hand, seem to be pretty convinced that using HS on a regular basis (if regular hand-washing is not available) is a good idea. Don't get me wrong, I think Health agencies are really trying their best to prevent any more spreading of diseases but I wonder if their suggestion of using HS is because it actually deactivates the virus or just to people are aware and think before putting their hand in their mouth or nose. You'd be surprised as to how effective not touching your face and covering your sneezes and coughs actually is. I will keep looking and will post about it if I do find out.

In the meantime, we should thank the Swedish for providing us with a great reason (excuse) to drink!

Tuesday, September 8, 2009

Stop the pain!!!!

Some time ago, Savage and I had a talk in which the concept of pain came up. I won't go into the details of the conversation but I will say that at the end we both sort of agreed that pain is a very important issue in human life. I don't think there are many people out there who like pain. And once you start thinking about pain, you start thinking about pain killers (e.g. acetaminophen, ibuprofen, acetylsalicylic acid). Many people are also sort of used to having these pills at hand, after all they are sold over the counter (OTC), but I have a feeling that just a very little number of them actually know how they work. This post is about that, about how they stop the pain.

OTC pain killers fall into a category called Non-Steroidal Anti-Inflammatory Drugs or NSAIDs. Acetaminophen (better known as Tylenol) is usually (and unofficially) considered in this category even though it is not really an anti-inflammatory drug. The main reason is that although it doesn't prevent inflammation, the mechanism of action is somewhat similar to that of ibuprofen (Advil, Motrin) or acetylsalicylic acid (aspirin), or at least that's the assumption. We'll talk about this later and you'll see how little it's known about acetaminophen.

So what is this mechanism? It is the inhibition of a class of enzymes called cyclooxygenase (COX for short). The COX enzymes are involved in the production of prostaglandin and thromboxane. Prostaglandin is the carrier of the message of damage (and the body's reaction is to let you know by creating pain) while thromboxane is involved in clot formation. So, by blocking the COX enzymes, the pain killers make it difficult for the body to know it's hurt and also prevent blood from clotting (this is why in many cases doctors cannot operate on you if you are taking aspirin until your body is free of it).

You can get into more detail and notice that there are several COX enzymes: COX-1, COX-2 and COX-3 and as you can imagine they have different roles. COX-1 is actually a regulator of many physiological processes and serves as a protector of the stomach lining. COX-2 is the one that raises the levels of prostaglandin when there is inflammation of tissue. This is the one that when blocked, produces the wanted effects of pain killers. COX-3 has just recently been discovered and the role is still unknown. Since NSAIDs block COX-1 too, you can now see why ibuprofen or aspirin can cause stomach ulcers, you are basically left without the protective element when you take those pills. Some attempts have been made at developing an specific COX-2 inhibitor and leaving the other ones unaffected but the results have been at least highly controversial, aside from the fact that lab tests show that although specific to COX-2 inhibition these drugs still cause stomach lining damage, the side effects of these new drugs seem to be very serious (think Celebrex or Vioxx).

Ibuprofen blocks both COX-1 and COX-2, while aspirin seems to have a larger effect on COX-1 than COX-2. That is why aspiring "thins" out the blood more than the others. What about acetaminophen?

Well, remember that at the beginning I said acetaminophen was considered an NSAID even though it didn't prevent inflammation? This in turn would indicate that it doesn't block COX-2 and since it doesn't affect blood clotting much then it should mean that COX-1 is also unaffected to a good extend by acetaminophen. So, why is it thrown together with NSAIDs and what the hell does it do to make pain go away? The reason it is put together with NSAIDs is because it seems that acetaminophen also blocks COX enzymes but the real mechanism of action is still debated. Some people argue it is actually COX-3 that is being blocked but the explanations as to how acetaminophen blocks pain without reducing inflammation are still speculative at best. For example, one idea is that acetaminophen cannot do its job in an environment where there is inflammation. This implies that acetaminophen actually in the central nervous system which seems to fit the observed effects. The bottom line is that very little is known about the most popular OTC pain medication.

Also, remember that while pain is awful and one would like to avoid it, overdosing (even just a single time) on NSAIDs or acetaminophen can cause acute liver damage. The chances of surviving this are rather slim so be conscious when consuming these medicines. Just because they work and are sold without much hassle doesn't mean that we understand them well nor that they come with no side effects.

Thursday, August 20, 2009

Sir... you're gonna need to keep the noise down!!!!

As cities grow, their governments and citizens need to start worrying about their environmental effects. Everyone is familiar with air or water pollution and it is indisputable when it exists. There is however, a different but just as important pollution type, that not many people are aware of: noise pollution.

I started to think about this for two reasons, 1) the research group I work in can be loud, no I mean really loud and 2) I have an infant son who's woken up when the fucking neighbor and his motorcycle arrive or leave. It is amazing the possible negative health effects that noise pollution can have (from Wikipedia: annoyance and aggression, hypertension, high stress levels, tinnitus, hearing loss, sleep disturbances). Not fun at all. And that is only in humans. Animal environments suffer probably even more when noise is introduced into their area.

One big problem when it comes to regulating noise pollution is that a general agreement as to what sounds constitute pollution is not easy to be reached. I suspect my neighbor reeeeeeeeeeally likes his bike when it annoys me big time. Here's an area where scientists can really make an impact on society. By performing all kinds of studies and making those results available we could, maybe, change people's understanding of noise and its detrimental effect.

Thanks to Gabriel Iglesias for the title.

Thursday, August 6, 2009

How can no one complain?

Well, it is because they probably aren't aware of the problem. I don't know about you, but I find a bit funny and at the same time confusing the rules for college grading the US.

First of all, how can anyone guarantee that translating a number into a letter grade will be done uniformly across disciplines and also professors. As much as people claim that Chemistry is harder than History, or that Physics is harder than anything else, :P , an A in one class should mean the same in another: that the student has learned everything (or most, since the A-grade represents a range) that was expected. For all I can tell, getting an A means being in the ~10% of your class, even if the top student only has a max numeric grade of 80-85. I don't think I will ever understand this idea of curving, but if everyone plays by the same rules then I can see not many people complaining and having a more or less fair process. Maybe not representative of the true learning done by the students but at least fair.

There is, however, another issue that only came to my attention after I was on the other side of the line, not as a student but as TA and that really, really troubles me: If my final letter grade will depend on how everyone else does in the class, I better fucking know how everyone else in the class did.

Case in point: One student, who didn't show up for class in a regular basis, gets a final numeric grade of 77. Another student, who religiously attended lecture gets a 74. According to the letter grade breaks, both of them got a B but since the professor knew the 74 student and thought this person put enough effort, he bumped the student's grade up to an A (which given that semester's distribution was a 79 and above).

This, unfair actions in my opinion, will continue to happen because students are not allowed to know the other students grades. The B student might just think he/she was too far away from an A and leave it at that. I know I would be bothered by the idea that someone else who did by the quantifiable standards worse than I did got a better grade because the professor thought better of them than he did of me. I'd like to complain, but if I can't see that someone who did worse than me got a better grade then I have no proof and will always lose the battle.

I really don't know how often this type of situation happens but I have the feeling that it occurs way more often than I think it should. Plus, it just doesn't make sense that in a highly subjective grading scheme showing all the data (in this case grades) is forbidden by law.

I get it that some people might feel bad if their peers find out they got a failing, or barely passing, grade and they need some sort of "protection". But I am sure no one intended having these privacy laws to abuse the system.

Wednesday, August 5, 2009

Why Science?

There is no one in my family nor high school friends that has studied any scientific major. Some friends are engineers yes, but not scientists. No one has gone to grad school to pursue a PhD degree either. As such, every time I go back home and meet with them I always get questions about what I do. I try to explain in layman terms my research and I think I do a good job at painting the big picture.

The last time I went home, I was asked a different question: Why do you (as in Charro, not any person) study science? I gave a standard answer: because it is really important for the future of the human race to keep make scientific discoveries and given that my research could have some relevance in the medical field I might (directly or indirectly) save a few lives, who knows. A few hours later I thought about the question again and I couldn't come up with an honest, awesome reason.

I could've say that it is because I can't see myself doing anything else, but that is a lie. Although I like doing science, I actually enjoy other activities to the point were I could've majored on those fields. So, ultimate passion is not the reason. I could say that I do it for the money, but anyone in science can tell you that average science salaries are not that high. You can definitely make more money in some of those other areas that I like. Money is out too. I kept thinking and came up with few other "potential" reasons but at the end they also didn't really make sense to me.

After several days of putting thought into it, I think I found the answer. It is not convincing for many people nor is it a cool answer but it seems to be the truth. I do science because I knew nothing else when I was growing up. No I was/am not a genius and knew science facts since I was a kid, on the contrary my "knowledge" was purely empirical but somehow discovery and experimentation were always present during my childhood. I owe this to my grandpa. As I mentioned already, no one in my family has any science, or engineering, education but my grandfather was a poor farm boy that had to learn how to fix whatever stuff broke at home. This taught him many tricks of course, but I think even more importantly it taught him not to be afraid about a problem, but to get your hands on it as soon as you can and look for the solution.

When I was a kid both of my parents worked and my grandparents took care of me during the day. I had the opportunity to learn from my grandpa how to fix stuff around the house. I am sure many people have opportunities like this, but what (probably) made the difference in my case was that whenever we had a "project" he would show me a way to go about fixing the problem but always ended by saying: This is not the best way to do it, why don't you think about it and try to come up with a better solution.

Thinking about how to fix things better somehow made me think about the factors that mattered the most: use a longer lever to unscrew a stuck screw, use the ground friction to loosen up a tire's screws before lifting it up, unplug the oven before touching the wires (just kidding), etc... you get the point. All of it was empirical, I couldn't explain that the reason why it was better was the torque increases with the lever arm for example. I guess when I had the opportunity to go to college there was only one thing I could do: Physics. It just made sense. Now I can explain all of those tricks I learned when I was a kid. I can even draw fancy diagrams and intimidating (for my family) equations explaining different phenomena.

That is why I do science. Although my grandpa is not with me anymore, I keep trying to come up with better ways to solve problems (I can't let him down, right?). But it doesn't have to be the only reason why someone goes into science. Maybe sometimes I wish I had absolute passion, it might make the journey more enjoyable. Anyways, even though I could have done many things with my life I do not regret the experiences I've had in science. Plus, I save a lot of money fixing everything at home.

So... next time someone asks I'll have an honest answer

Friday, July 17, 2009

Man vs. Ape

I just found this interview in NPR. It's called "Cooking sets up apart from apes".

Cooking? really? what about the following video setting us apart from apes?

Ha. More seriously, it is a very interesting interview. The main idea is that humans have a difficult time staying healthy by eating only raw foods. Richard Wrangham goes on to explain why it is easier to extract nutrients from food when it is cooked. Go listen to it, it is only 5 minutes long.

Wednesday, July 15, 2009

Confirm or Deny?

- Feynman lectures

When I read the books on the life of Feynman, he became my physics' hero. It might be because there just aren't enough books about the lives of many other physicists (Einstein being the exception of course), but I think it goes even beyond that. His approach to physics and his ability to form mental images that were 1) complete and 2) simple enough to work with is what does it for me.

I found these lectures by Feynman in New Zealand and I've never seen anyone explain physics like him. Also, it seems Microsoft made some Feynman lectures available online.

I hope you all enjoy them!

Monday, July 6, 2009

- Reporting under the influence!

This guy does journalism under the influence. Must be fun...

Thursday, July 2, 2009

- Questions...

I think I should stop trying to answer all the questions on my own...

- What you learn in grad school....

This is how it feels right now

Monday, June 29, 2009

- Immigration and science

Immigration reform is a hugely controversial topic these days. You just need to read the comments to online posts to see how strong and different the feelings are. Most of this discussion centers around illegal immigration and the effects it has on the economy and crime. These are complicated issues and I am not qualified to talk about them nor have the intention of posting my view on them. However, there is a whole other side to immigration reform and it has to do with legal immigration. Legal immigration requires a visa and there are many visa categories depending on the purpose of the foreign person. Many of these visas, for example F (students) and J (exchange visitors) visas, do not allow the person to remain in the US once they finish their program. Work visas (H-1B) do allow for permanent immigration but the number of visas per year is capped and the process is expensive, lengthy and not guaranteed for everyone.

Now you might be wondering why legal immigration is important or relevant to science and the answer is nicely presented by Tom Friedman in his Invent, Invent, Invent article. All you need is to visit a science department at your closest university to find out how many foreigners do science and are willing to stay in the US and be productive both economically and scientifically. There are also plenty of scientists and engineers abroad that would like to come to the US and enjoy the technology and research culture any day. Of course, there are many American citizens in the same departments doing science, but point is that the US needs to have policies that not only keeps in, but also invites the best of the best in the world to come to this country. Friedman makes a great point when he says that these scientists will create more jobs than they take and that will benefit every one.

Getting it done requires an immigration reform too and it seems to be neglected/forgotten with the illegal part. Hopefully soon people will get over their fears and politicians over their stupidity and stubbornness and we'll have a decent proposal approved.

Wednesday, June 24, 2009

- Stopping cracks!

This is a post inspired in an article about bone plasticity and fracture toughness published in the most recent issue of Physics Today. No, I will not teach you how to break someone's arm or leg (although if I knew how to it would probably be cool to teach, wouldn't it?). What I want to talk about is the concept of fracture toughness and the mechanisms that increase it in materials.

For a crack to be created you need energy. Everyone is familiar with mechanical energy, you can push, bend or throw a cup and it will break. You could also use thermal energy, heat (or cool) certain objects and they will crack. But it is not at the slightest push that an object will break, there is a minimum of energy that you need to create a crack.

A crack is nothing more than breaking chemical bonds and creating more surfaces (think about it, if you break a plate now you have at least 2!! =P). There is an energy associated with keeping a bond and there is an energy associated with an exposed surface. When it is energetically favorable (that is, breaking the bond has less energy than keeping the bond) the object will crack.

So, that's what a crack is and although learning about how cracks originate is an interesting topic, it is not the most interesting part of fracture theory for me. What I find really cool is how a material deals with a crack once this one is formed. Materials possess a quantity called fracture thoughness, which is a measurement of how hard (or easy) it is for a crack to propagate through. The most critical part of a crack is the tip because here is where the higher stresses (or forces if you prefer) concentrate. Just as you need energy to create a crack, you need energy to grow it. However, just as some materials have mechanisms to prevent cracking (for example, a clothes hanger bends significantly before you can break it) some materials have mechanisms to prevent the cracks from growing (in other words, they increase the fracture toughness). Some of these mechanisms can even be artificially engineered, isn't that cool?

Ok, so what are these mechanisms that increase fracture toughness? One of them is crack deflection. The idea here is to change the direction of crack propagation to eliminate (or at least minimize) the force applied at the crack tip. Crack deflection occurs very often in porous materials and at the interfaces in composite materials. Bone being a porous matrix does exhibit crack deflection.

Another way of increasing fracture toughness is by creating microcracks around the crack tip. In this case the effect is double, first when a force is applied to a material containing both a crack and microcracks, the force is distributed among all of them and therefore can reduce the stress concentrated at the main crack tip and inhibit crack growth. The other way in which microcracks help is by expanding the region around the crack and "closing" its size. Radiographs of damaged bone can show multiple microcracks, although in some cases the microcracks are way too small to be seen by eye.

Lastly, crack bridging can also hinder crack growth. Bridging is, by design, the main fracture toughness mechanism in most fiber-reinforced materials but in monolithic ceramics (i.e. alumina) exhibit grain-bridging. In fiber reinforced materials, the idea is that the matrix cracks easier than the fibers, and thus when force is applied the crack will form but the fiber across the crack will remain intact and support the load. Grain-bridging is a much more subtle idea and it consists of grains in the crack rubbing against each other and carrying the applied force instead of the crack.

Any fracture toughness mechanism will show up in what engineers call an R-curve. If this curve rises with crack extension then you can be certain the material possesses some kind of fracture toughness mechanism. Determining which one, on the other hand, is not always that easy. Now to come back to the Physics Today article, it turns out bone has all three of them:deflection, microcracks and bridging. I am not surprised that bone is really hard to break now.

Tuesday, June 23, 2009

- Welcome post

Hello all,

Science under the influence is an experiment where Squashed, The Savage and I will try to regularly write about science-related stuff we know or would like to learn more about and in some cases about general topics that we find interesting too.

Although the three of us do very similar research on a daily basis, we come from very different backgrounds and somehow we hope we can present and discuss topics in a way that is accessible to the average non-science person (at least most of the time) but also with each one's personal touch. Of the three of us, two are males and one is a female.

We'll do our best to tell the science without mistakes, but don't say we didn't tell you that you should read at your own risk. =P

A bit of background on how we decided to start SUI:

The Savage and el Charro were talking about how good of an exercise it would be to write about science and also to have the freedom to write about whatever you want and reach an audience. Somehow the idea of having a blog sounded good and here we are. Squashed, who was in the room at the time, decided to join us in this journey.

We hope you enjoy reading our blog and feel free to comment!!!!