## Friday, December 25, 2009

### Steam Tables in Matlab, Octave, OpenOfficeOrg, and Excel

Anyone who's taught undergrad chemical thermodynamics understands the important role that steam "tables" play in many calculations.

Here is an amazing website which provides an open-source freely available version of the steam tables in various formats. I mirrored the user-guide and the actual program on Scribd, just in case.

The program is saved as XSteam.m.txt, which you will have to rename as XSteam.m after downloading, for Octave or Matlab to recognize it natively.

Water and steam properties according to IAPWS IF-97
By Magnus Holmgren, www.x-eng.com
The steam tables are free and provided as is. We take no responsibilities for any errors in the code or damage thereby. You are free to use, modify and distribute the code as long as authorship is properly acknowledged. Please notify me at magnus@x-eng.com if the code is used in commercial applications.

## Monday, December 21, 2009

### Wolfram Alpha is amazing!

In all the commotion surrounding Microsoft's Bing, the demise of Yahoo Search, and Google's counter-attack by announcing a light-weight OS, something really useful to me, did not get as much play as it should have.

Wolfram Alpha is an amazingly intelligent search engine/parser/magic genie, for anything mathematical in particular. I have using it quite regularly, not quite as a substitute for Google yet, but even something as unthinkable as that could happen.

In the academic realm, it is a killer resource.

Here are just a few illustrative screenshots from my search today. You may have to zoom in a little bit for clarity.

## Friday, December 18, 2009

### Thoughts on getting an MBA

This article (old but still completely valid) by an insider provoked me to re-articulate, what I've advised many friends and family.

A disclaimer is warranted, upfront. Many of my friends and family, who have MBAs, are extremely talented and smart individuals. By strange coincidence, all of them were extremely talented and smart individuals, before they got their MBAs.

I've never really thought too highly of the content of most MBA programs. In my opinion, there are only a handful of good reasons to enroll in one. Like most opinions, this is probably worthless, but here you go anyway:

1. You want to change your career path. You're stuck, and don't like what you do. You seek growth, you seek something different! In short, you want to hit the reset button.
2. Networking. You go to a great school, which attracts smart people, you build a network. And the value of a good network is quite obvious, especially if you like climbing career ladders. A strong network is like an elevator. It can get you there faster.

Note that I am intentionally not putting "learning" as one of the reasons. In my opinion, you don't learn anything, that you can't read directly from books for 1/100th the cost.

When I took financial economics at Michigan, the instructor who also taught the same class to business students, often used to joke: "in the evening class, we stop here," before introducing something important and mathematical. And Michigan has a good B-school.

Sure you learn how to use useless buzz words (which the linked article describes) without understanding jack. Reminds me of Dilbert's "leveraging synergies across alternative technology platforms!", whatever that means!

I know people say case studies, group interaction etc. But c'mon those things are best picked up on the job. Basically, if you are smart enough, can read books without being threatened, cajoled, or bribed, make friends easily, are happy with your job, and can think independently an MBA is precisely what you don't need.

## Monday, December 14, 2009

### Where are the QuickStar and Amway guys?

When I was in Ann Arbor, MI, my friends and I would bump into these Amway/QuickStar folks all the time (coffee shops, bookstores, grocery store etc.) I was talking to my wife last week, and it seems like we haven't been "approached" even once in three years, since coming to Florida.

It's surprising, but of course, I am not complaining.

It got me thinking about an old incident.

* * *

Once, while still at Michigan, I got a call from this guy - Mr. X - who claimed to be a friend of a friend. He had just moved into the Detroit area. We talked on the phone over multiple weekends, and to be honest, the conversations themselves were quite entertaining.

Then one day, he asked if we could meet, and since we had become "pally" by then, I said yeah.

At his place, I talked with him and his wife, over a cup of tea and cake. He asked me more about what I was doing. At that particular point, I was in grad school wondering whether I should go to industry or academia, and more susceptible to suggestion, than I would have liked.

In short, I was a great bakra.

After about 20 minutes of small talk, I thought I should leave, and got up to say bye. All of a sudden, both Mr. and Mrs. X stood up, and asked me to have more tea.

"Hmmmm. Fisshhhy!", I thought to myself. Something was amiss.

They didn't waste any more time. He started talking about "the business", and "financial independence", "asset creation", and "who wants to be a millionaire?".

When I did not react with the overflowing enthusiasm that was expected, he must have thought, I was the nerdy type, and needed a different approach. Very skillfully, he started spewing out an alphabet soup consisting of "B2B, ..., B2P, ... P2P...", essentially connecting random letters with a "2".

I said, "I am a chemical engineer, and don't know what all this means." It was a rare, but honest concession of ignorance.

He said, I should go to this amazing "once-in-a-lifetime" seminar in Southfield the following weekend. I said I was busy, and he said, "but it will change your life."

## Saturday, December 5, 2009

### Phew! What a week!

I heard back this week about the fate of two of my manuscripts that were grinding through the peer-review process. I should have a really thick skin by now, but I don't think I do. I was getting ready to wind down gracefully in preparation of the upcoming India vacation, when this sweet-and-spicy-tornado hit.

The first one, on ring polymers, got summarily rejected with a editorial note:
Your paper has been reviewed with the aid of two independent reviewers. Their comments are shown below for your consideration. Unfortunately, you will see that they are advising against publication of your work. I am afraid your paper has not been accepted.
which is a polite way of saying buzz off. One reviewer said it was the wrong journal (which I partially agree with), while the other made a few valid, and a few completely addressable scathing attacks. However, I think I am going to check my natural belligerent instinct, and sleep on this one through December.

My other solo-manuscript, on using Bayesian inference as a tool for solving inverse rheology problems, got flattering reviews (the best I have ever received yet!). The more glowing of the two reviews started with:
This is really a breakthrough paper! [...] In fact, my main criticism of the paper is that it does not lay out as well as it should, the possible future uses of this approach for inferring structure from rheology.
I'll take that kind of criticism any day. With mustard and ketchup.

The other review said:
The paper should certainly be published, since it is proposing something that has not been done before in this important problem
So overall, although its 1-1, I feel really good. Great, in fact!

I had mulled over the ideas in the second paper actively for a year (and passively for nearly six). My resolution last year was to undertake two high-risk/high-reward ideas in 2009, and one of them panned out. It sets a clear agenda for 2010 - to polish the rough corners.

## Thursday, December 3, 2009

### Can US census data help guide a dating strategy?

Perhaps.

But I will leave most of that to you.

I recently saw a fascinating blog entitled "An Older Woman, A Younger Man" by mathematician Tanya Khovanova. She uses US Census data to figure out what her dating outlook is, since she is 50-year old single woman seeking to enter the circuit again.

She starts out with a thesis:
We know that boys are born more often than girls, and men die earlier than women. Somewhere around age 30 the proportion in [the] population switches from more boys to more girls. And it gets more skewed with age. So there’s a deficit of older men. In addition, a big part of the population is married, making the disproportions in singles group more pronounced. So I decided to look at the numbers to see how misshaped the dating scene is.
I plotted the ratio of single men to women from the table she diligently assembled for easier visualization, as below.

You can do all sorts of "data-mining" with these figures. For example, she uses the data to figure out that if she dates a randomly chosen single man, she has a 3/4 chance of picking someone younger than her (you need the absolute numbers from her entry to figure that out).

This means that if I am a 30 year old man trying to marry someone my age, I face a much harder scene, than if I were a 50 year old man trying to do the same.

Also, a woman under 40 years of age, looking to marry someone younger than her, and a man over the age of 40, looking to marry someone older than him have statistics loaded in their favor.

## Wednesday, December 2, 2009

### When Math Software Fails!

You may already have heard of an embarrasing problem with MS Excel 2007. It was reported on groups.google, a couple of years ago, in a simple email:
I heard about it when someone posted a printout of the following essay ("Arithmetic is Hard - To Get Right") on a bulletin board right outside the kitchen in my department.

A couple of days ago, I heard about a serious problem with Matlab R2009b. Apparently, when you try to solve this simple 2x2 linear system:
A=[ 0 2 ; 1 0 ];
b=[ 2 ; 0 ];
A'\b

ans =
0
1  
which is clearly wrong (A' is the transpose of A). Apparently, older versions of Matlab and the wonderful FOSS program which I use a lot, GNU Octave, do not have the same problem. They yield the correct solution

ans=
0
2

## Tuesday, December 1, 2009

### OpenFOAM - a nice open-source CFD tool!

Having used Fluent and COMSOL in the past, I recently switched to an open-source CFD package called OpenFOAM. Although I use the label "CFD" software, it really allows you to solve PDEs.

It has basic meshing functionality (blockMesh), and integrates well into a reasonably well-developed visualization tool called ParaView. However, the pre- and post-processing steps can be carried out using any of your favorite programs - free or commercial. There are all sorts of converters available to translate data to and from these applications to something that OpenFOAM understands.

What is great about the program, and the primary reason I am attracted to it, is the flexibility of the solver. It allows one to extend standard solvers to consider a new constitutive relation, or a new multi-physics problem, relatively easily.

As bonus, it has great parallel efficiency, and is of course free!

Unlike most of the other FOSS software that I use, I like OpenFOAM more for the "open-source" part, than the "free" part, since writing/changing source code is critical to solve my problem.

I've started working on an interesting problem of the flow of a nanotube filled polymer resin in a relatively simple geometry, where the constitutive relation depends on the density and orientation of the nanotubes, which is in turn governed by the flow field, and hence, the constitutive relation.

Here are a few links that I found useful, while trying to ascend the relatively gradual learning curve (I am still climbing!)

1. The official OpenFOAM website.
2. The OpenFOAM wiki site - especially the compile and build section.
3. Nice course materials on OpenFOAM by Hakkan Nilson at Chalmers.
4. Lecture notes on CFD in general.
5. The discussion group on OpenFOAM at CFD-Online.

## Friday, November 27, 2009

### Three "timepass" links!

Timepass links for the weekend.

1. Life (via this and this place)

2. Fox News needs a math lesson? (via FlowingData)

3. A fascinating blog on the "meandering of rivers". One very interesting tidbit towards the end of the article is "self-similarity". Apparently some universality underlies the meandering of rivers and streams.

It seems that the wavelength "lambda" is approximately 11*w and the "radius" is approximately 2.3*w, where "w" is the width of the stream

## Wednesday, November 25, 2009

### I love craigslist

I once owned eBay stock, and they were scared of craigslist.

Similar to Microsoft's fear of the open-source movement.

This inspiring article from Wired magazine, tells you why it would be great to work for this company, and why its competition just can't figure it out.
... what you see at the most popular job-search site: another wasteland of hypertext links, one line after another, without recommendations or networking features or even protection against duplicate postings. Subject to a highly unpredictable filtering system that produces daily outrage among people whose help-wanted ads have been removed without explanation, this site not only beats its competitors—Monster, CareerBuilder, Yahoo's HotJobs—but garners more traffic than all of them combined. Are our standards really so low?
But if you really want to see a mess, go visit the nation's greatest apartment-hunting site, the first likely choice of anybody searching for a rental or a roommate. On this site, contrary to every principle of usability and common sense, you can't easily browse pictures of the apartments for rent. Customer support? Visit the help desk if you enjoy being insulted. How much market share does this housing site have? In many cities, a huge percentage. It isn't worth trying to compare its traffic to competitors', because at this scale there are no competitors.
Each of these sites, of course, is merely one of the many sections of craigslist, which dominates the market in facilitating face-to-face transactions, whether people are connecting to buy and sell, give something away, rent an apartment, or have some sex. With more than 47 million unique users every month in the US alone—nearly a fifth of the nation's adult population—it is the most important community site going and yet the most underdeveloped. Think of any Web feature that has become popular in the past 10 years: Chances are craigslist has considered it and rejected it. If you try to build a third-party application designed to make craigslist work better, the management will almost certainly throw up technical roadblocks to shut you down.
This is a great article, and reads really well.

### Why can't Apple figure the mouse out?

In terms of usability, Apple products like the iPhone and iPod are design icons. Elegance, utility and simplicity rolled into beautiful compact devices.

Many years earlier, in 1984, Apple did something similar to the computing world, and brought the GUI and mouse to life (thanks to Xerox). Since those paleolithic days, it has always stuck with a "single-button" mouse, the defense being more buttons are "confusing to novice users", or some crap like that.

That unrelenting stubbornness continues to this day.

In 2006, I bought a MacBook Pro at work, with a single button mouse as shown above. For the most part, I like my Mac, although I prefer a similarly priced Linux machine running Ubuntu.

I never really liked the one button mouse, but out of the compromise that is this life, I forged a working relationship with it.

In other parts of the world, the number of buttons on "mice" have increased, as shown by the five button mouse here (from wikipedia).

Last month, my wife got a new Mac from her workplace, after her old Mac gave her repeated battery problems.

To my surprise and utter disgust, in these spanking new machines, they got rid of the only button left!

And replaced that with a trackpad, instead. So her computer looks like the picture below.

No buttons. See!

The whole trackpad is the button. WTF?

To add to the insult, it now has all the cool features such as zooming using two fingers, borrowed from their iPhone. Personally, I find it extremely annoying, since every time I try to select some text using two fingers (and there is no button to anchor one of the fingers, remember), it thinks I want to zoom.

To think that they wanted to stick with a single button because novice users would be confused.

Heck, I've been using computers for 20+ years, and I am confused with this crap!

## Sunday, November 22, 2009

### The Forer Effect

I came across "the Forer effect" on this blog (via Abi). As Abi points out on his blog, you should send this "to all your friends/family members/associates who believe in astrology".

The story runs thus:

A psychologist named B. R. Forer apparently gave a bunch of his students a personality test (like a Myers-Briggs test, or one of those stupid Cosmo' surveys), and asked each person taking the test to rate the accuracy of the customized "individual profile" between 0 and 5, ranging from the least to the most accurate.

Unknown to the participants, there was really only one common profile (independent of the choices on the personality test), which read:
You have a great need for other people to like and admire you. You have a tendency to be critical of yourself. You have a great deal of unused capacity which you have not turned to your advantage. While you have some personality weaknesses, you are generally able to compensate for them. Your sexual adjustment has presented problems for you. Disciplined and self-controlled outside, you tend to be worrisome and insecure inside. At times you have serious doubts as to whether you have made the right decision or done the right thing. You prefer a certain amount of change and variety and become dissatisfied when hemmed in by restrictions and limitations. You pride yourself as an independent thinker and do not accept others' statements without satisfactory proof. You have found it unwise to be too frank in revealing yourself to others. At times you are extroverted, affable, sociable, while at other times you are introverted, wary, reserved. Some of your aspirations tend to be pretty unrealistic. Security is one of your major goals in life.

This average score on this and similar studies (repeated a gazillion times) was around 4.2 (pdf original research article, on Scribd).

Our gullibility is shocking, huh?

Here's an YouTube video, for those who don't like to read, or, for those who also like to watch. It's an entertaining video, which shows how little gender, culture, and other elements matter.

If this study was included as a foreword in Linda Goodman's books, I wonder if they would have sold nearly as well.

This has direct implications, not only for "psychic" disciplines, but also on personality test batteries, such as Myers-Briggs.

## Friday, November 20, 2009

### Buzzwords and Data Visualization

I stumbled upon two interesting links via this blog that I follow:

1. A PhD comics take on buzzwords in scientific literature.

2. Top 10 worst data visualizations in scientific literature. Some of it may be nit-picking, and I am sure like all top-10 lists (or US News college rankings, for that matter) this list is flawed in terms of the "top"-10. But it makes for an interesting read nevertheless.

The "discussion" on each graph is enlightening, particularly since I must have committed some of the same mistakes myself.

One interesting thing I learned was how bad pie charts were. Apparently, we are much better at comparing lengths than areas. I never knew that.

There are some good links on how to present data wisely at the bottom of this link.

## Wednesday, November 18, 2009

### The Tipping Point

I know I am late to the party, since this popular book by Michael Gladwell was published almost a decade ago. The book attempts to present a synthesis of many disparate ideas to ponder over the question: "Why do some ideas catch fire?", or as he would probably like it phrased "What makes an idea tip?"

The book itself is enjoyable, as it talks about Paul Revere's midnight ride, the Mavens, the Connectors, and the Salesmen, the fascinating rule of 150, Bernie Goetz and how cleaning up graffiti on subway walls reduced crime in New York, Hush Puppies, the stickiness of Sesame Street and Blue's Clues, Peter Jennings demeanor during Ronald Reagan's candidacy, six degrees of separation etc.

He cites a number of interesting social and psychological research studies, and being the master storyteller that he is, beautifully integrates them into his narrative.

I think he makes a great journalist.

However, I think he would make a bad scientist.

This is pure extrapolation from the one data point I am familiar with. The six degrees of separation reference to Stanley Milgram is bad science. He repeats some of the same stuff in his famous article "Six Degress of Lois Weisberg".

The myth suggests that Milgram gave 160 people in Omaha, Nebraska a package that had to be delivered to a stockbroker who worked in Boston, through the smallest number of intermediaries. He found that "chains varied from two to 10 intermediate acquaintances, with the median at five" in his 1967 paper - which apparently is the basis for the "six degrees" supposition. The big problem for me as a scientist was that only 24 of the original 160 chains was completed - and hence the conclusion probably suffers from a heavy survivorship bias.

Milgram carried out an earlier study where starters were from Wichita, Kansas and were supposed to reach a divinity student on the east coast, and the completion statistics there were more miserable. The measurement error must have been quite large to suggest such a strong conclusion.

Sure, we might indeed be separated by six degrees. But Milgram's study does not definitively prove it.

In fact there are other glaring problems with Milgram's study as this very interesting and more academically rigorous article points out.

PS: I swear I wrote this blog a long time ago, and thought that I would publish it later. In the meantime, I bumped into this article by Steve Pinker (via nanopolitan). It is amazing that he comes to the same conclusion towards the end of his book-review:
Readers have much to learn from Gladwell the journalist and essayist. But when it comes to Gladwell the social scientist, they should watch out for those igon values.

## Monday, November 16, 2009

### Society of Rheology meeting - Madison, WI.

I was in Madison, WI  for my annual pilgrimage to the Society of Rheology annual meeting. Of the several meetings I go (or, have gone) to, this is easily my favorite. It is very focused - I learn a lot, and always come back with ideas to try, things to check, and papers to read.

It is small, fun, very good value for money, and has plenty of good food and drink.

Here are some pictures I took in Madison, when my colleague and I went for a run from our hotel near the state capitol to the University. It is always great to catch fall in the northern states, especially having been away from Michigan for a while.

## Friday, November 13, 2009

### Interesting Economics/Finance Links

Three interesting links for the weekend.

1. A fascinating article in Vanity Fair on the state of Harvard's endowment (Rich Harvard, Poor Harvard). It's hard for me to really feel sorry, although I know it hurts a lot of innocent bystanders. From the article:
Only a year ago, Harvard had a $36.9 billion endowment, the largest in academia. Now that endowment has imploded, and the university faces the worst financial crisis in its 373-year history. Could the same lethal mix of uncurbed expansion, colossal debt, arrogance, and mismanagement that ravaged Wall Street bring down America’s most famous university? 2. This NYT article (free sign up required) recounts how the governor of India's Reserve Bank, Y. V. Reddy, played it tough during the bubble years, and saved the country from a financial crisis. He seems like the anti-thesis of former Fed-chairman Alan Greenspan, both in action and in popularity. From the article: Unlike Alan Greenspan, who didn’t believe it was his job to even point out bubbles, much less try to deflate them, Mr. Reddy saw his job as making sure Indian banks did not get too caught up in the bubble mentality. About two years ago, he started sensing that real estate, in particular, had entered bubble territory. One of the first moves he made was to ban the use of bank loans for the purchase of raw land, which was skyrocketing. Only when the developer was about to commence building could the bank get involved — and then only to make construction loans. (Guess who wound up financing the land purchases? United States private equity and hedge funds, of course!) Seeing inflation on the horizon, Mr. Reddy pushed interest rates up to more than 20 percent, which of course dampened the housing frenzy. He increased risk weightings on commercial buildings and shopping mall construction, doubling the amount of capital banks were required to hold in reserve in case things went awry. He made banks put aside extra capital for every loan they made. In effect, Mr. Reddy was creating liquidity even before there was a global liquidity crisis. 3. An interesting email conversation (pdf) between Buffett and Raikes, regarding Microsoft and Berkshire (via Reflections on Value Investing). ### Dicey puzzle: Solution The full puzzle statement may be found here. In short "What are the odds that n=2 v/s n=3 dice are rolled, given that the sum is 7?" Solution: For n=2, there are 6 ways of rolling a 7 (1+6, 2+5, 3+4, 4+3, 5+2, and 6+1), out of a total of 6^2=36 total outcomes. Therefore p(sum = 7 | n = 2) = 6/36 = 36/216. For n = 3, there are 15 ways of rolling a 7 (1+1+5, 1+2+4, 1+3+3, 1+4+2,1+5+5, 2+1+4, 2+2+3, 2+3+2, 2+4+1, 3+1+3, 3+2+2, 3+3+1, 4+1+2, 4+2+1, 5+1+1), out of a total of 6^3 = 216 total outcomes. Therefore p(sum = 7 | n = 3) = 15/216. Thus, the odds of n = 2 v/s n = 3 are 36/15. That is it is about 2.5 times more likely that n = 2. What happened? There were more ways of getting a 7 with n = 3? ## Wednesday, November 11, 2009 ### LaTeX equations in Google Documents I found out from here that I can now type LaTeX equations into Google Documents, and they look pretty nifty too. I find the look of equations using Microsoft Equation Editor to be truly hideous. Of course you can buy MathType, but why? The native equation editor in OpenOffice is efficient to use, but I still don't like how they look in the document. Despite its age, LaTeX typesets equations beautifully - and there is no reason to discard something good, just because it is old. Previously, I wrote about how I currently use a plugin called OOOLaTeX, which lets me combine the beauty of LaTeX with the unbeatable price and portability of OpenOffice. Back to the topic of the post. It really is easy to use. Just go to Insert->Equation and you can enter LaTeX code directly, or choose symbols from the dialog boxes above. Here are a couple of screenshots: and I can easily visualize myself using this for presentations. ## Sunday, November 8, 2009 ### Advice from a scientist I found this article via this blog that I follow. The advice is commonsensical, which, ironically, makes it a must-read. Some of my favorite excerpts: Now for the matter of drive. You observe that most great scientists have tremendous drive. I worked for ten years with John Tukey at Bell Labs. He had tremendous drive. One day about three or four years after I joined, I discovered that John Tukey was slightly younger than I was. John was a genius and I clearly was not. Well I went storming into Bode's office and said, How can anybody my age know as much as John Tukey does?'' He leaned back in his chair, put his hands behind his head, grinned slightly, and said, You would be surprised Hamming, how much you would know if you worked as hard as he did that many years.'' I simply slunk out of the office! My own PhD advisor, Ron Larson, is this (Tukey) type of person. Towards the end of my PhD, I realized that I had to do something he wasn't interested in. Barring luck, it is hard to directly compete with him. He is smarter, and works longer hours. Another quote from the speech: What Bode was saying was this: Knowledge and productivity are like compound interest.'' Given two people of approximately the same ability and one person who works ten percent more than the other, the latter will more than twice outproduce the former. The more you know, the more you learn; the more you learn, the more you can do; the more you can do, the more the opportunity - it is very much like compound interest. I don't want to give you a rate, but it is a very high rate. Given two people with exactly the same ability, the one person who manages day in and day out to get in one more hour of thinking will be tremendously more productive over a lifetime. There's another trait on the side which I want to talk about; that trait is ambiguity. It took me a while to discover its importance. Most people like to believe something is or is not true. Great scientists tolerate ambiguity very well. They believe the theory enough to go ahead; they doubt it enough to notice the errors and faults so they can step forward and create the new replacement theory. If you believe too much you'll never notice the flaws; if you doubt too much you won't get started. It requires a lovely balance. But most great scientists are well aware of why their theories are true and they are also well aware of some slight misfits which don't quite fit and they don't forget it. ## Friday, November 6, 2009 ### Eric Drexler and Science Education in India Eric Drexler (a nanotechnologist) wrote an interesting article on his blog about how the subset of visitors to his site from India, chose to visit the more technically meaty topics. A comment on his post, which I sympathize with, provoked a second article, which sought to understand the previous post in a more nuanced manner. During the course of reading these articles, I also stumbled upon this interesting YouTube presentation. I have my own thoughts on this matter, having been a student and educator in both the US and in India, but I will save those for a separate post, later. ## Thursday, November 5, 2009 ### Install LAMMPS with FFTW on your Desktop Earlier I wrote about how to install LAMMPS and AtomEye on a Desktop without FFTW. The following document now shows how to download, compile and build the freely available fftw library with LAMMPS to consider electrostatic effects. Building LAMMPS with FFTW ### How to embed a pdf document in blogger? The idea is like embedding a YouTube video as I remarked earlier. By trial and error, I have come to the personal conclusion that this is going to be my method of choice, from here on. The steps are simple: 1. Get a Scribd account. 2. Upload your document there, where it is converted into an iPaper format. 3. Look for "Embed Code" - and copy the html code snippet under it. 4. In your Blogger entry, select the "Edit HTML" tab, and go to the place where you want to embed the stuff 5. Paste the html code snippet here. You should be good to go. Here is an example. ## Wednesday, November 4, 2009 ### Dicey puzzle Your friend rolls either one, two, or three dice (n=1, n=2 or n=3). Each die is a normal cube with six sides, displaying a number between 1 and 6. She doesn't tell you what n is, but tells you that the sum of the numbers on the dice is 7. For example, she could have rolled 4 and 3 with n=2; or perhaps 5, 1, and 1 with n=3 etc. Obviously, n cannot be equal to one. What are the odds of n=2 v/s n=3 given that the sum is 7? Answer coming up in a week, but this is an example of simple Bayesian analysis. Credits: picture from http://www.pwcphoto.com/studio/studio-07.htm. ## Monday, November 2, 2009 ### Knuth, calculus and O-notation I found an interesting entry on a blog I follow, about a "new" method of introducing calculus, by Donald Knuth. Fundamentally, it involves introducing the big-oh notation to define a "strong derivative", and recovering most results including the Fundamental Theorem of Calculus (see the comments section). The resulting math feels light - like you were doing a back of the envelope calculation. It seems interesting, and although I am not sure whether that is the magic potion that will enable all my students to master the idea of applying calculus in physical problems. Personally, I never had a problem with the traditional approach starting with the definition of a limit. ## Friday, October 30, 2009 ### Can a human being outrun a horse? Apparently over long distances. I was listening to Ira Flatow on NPR, in my car today. Since the New York marathon is tomorrow he was talking about it, and one of his guests claimed that when it comes to long distances, human beings can essentially outrun all other animals - including horses. Since I heard only that snippet (I reached my destination), and I had a few minutes, I googled, and no kidding! Here is a fascinating NYT link on the topic. Some interesting numbers. The fastest marathon was run just under 2:04 hours by Haile Gebrselassie of Ethiopia which translates to an average speed of 12.67 mph, or 4:44 minutes per mile. A horse can gallop at about 25-30 mph over short distances, but like I said before, they often underperform humans in marathons. Over short distances, Usain Bolt of Jamaica ran a 9:58 at the 100m dash, which translates to 23.35 mph, or 2.57 minutes per mile, while a cheetah can go at a top speed of 60mph, which is about three times as fast. We clearly weren't built to outrun such predators. So what tilts the balance in our favor as distance increases? Apparently it has all to do with cooling. When a horse gallops, it produces heat at a rate greater than what it can easily dissipate. Humans are much better at dissipating energy. A simple energy balance tells us that if the input is greater than the output, there is accumulation of heat which leads to a rise in temperature - which is clearly undesirable. The evidence for this hypothesis is the fact that humans have a much better chance of beating animals in marathons when it is hot, sunny, and humid - conditions that make heat dissipation even harder for the poor animals. ## Tuesday, October 27, 2009 ### LaTeX tips: eqnarray and detex. 1. Handling equation numbers in the eqnarray environment If you have an equation array environment and don't want to number certain equations use the \notag command. Thus (click to enlarge), produces where an equation number has only been assigned to the second "equation" in the array. 2. The "detex" command I bumped into this command by chance today. Funny thing was, it was installed by default on both my CentOS box at work, and my Mac OS X which runs BSD. It doesn't preserve formatting, but essentially gets rid of all LaTeX tags. You say: detex file.tex You can then pipe it to a spell check or save it as a simple text file, and do whatever you want with the un-LaTeXed file. This works well if you have command line spell-checker available on your Unix/Linux system. ## Friday, October 23, 2009 ### Interesting Links 1. A visualization of the S&P universe. Color, size, and transparency represent percent change, market capitalization, and moving average, respectively. Percent change relative to the rest of the market determines the speed at which a stock orbits - fast movers so to speak. 2. A new excuse for students. It would definitely work on me. Check out the actual website! 3. A visualization of job losses Via FlowingData: Red means loss and green means gain, and as you can see above, there isn't much green (read that zero) on the map. The larger the circle is, the greater the number of net loss or gain compared to that of the numbers of the year before in the respective metropolitan statistical area. ## Saturday, October 17, 2009 ### Linux/Unix is Sleazy! Rediscovered this on the internet!$ unzip
$strip$ touch
$finger$ mount
$fsck$ more
$yes$ unmount
$sleep Hilarious! ## Thursday, October 15, 2009 ### Active Learning in Science and Engineering According to wikipedia: Active learning is an umbrella term that refers to several models of instruction that focus the responsibility of learning on learners. These days it is a teaching buzzword. Big time. If you are a teacher and not employing active learning techniques, then you are a stubborn, old-school, ineffective, uninspiring, bumbling idiot. There are entire journals dedicated to enhancing student engagement using these "active learning" techniques. To be perfectly honest, I do read this literature and find a lot of it fascinating. This site (Felder's webpage), for example, is chock full of interesting ideas. My problem with it originates from the obsession with employing active learning techniques, especially in science and engineering. In many social science classes, opinion is as important as fact, which facilitates a natural two-way dialogue. For example, what you think of Shakespeare's "Twelfth Night" is perhaps as important as what an expert thinks about it. Both opinions are "valid" - even if they are diametrically opposed to each other. But the same cannot be said of Newton's third law. You can't have an opinion about it. It is what it is. And this very fact reduces the number of meaningful avenues for increasing student participation. Another confession. I actually like teaching, and my courses usually review well, both with students and with peers (which is important because it is easy to win a popularity contest by making a course "easy"). My favorite teachers, themselves, have been old-fashioned role models. A common denominator among them was passion, super-smartness, depth, humor, and genuine love for being challenged by a newbie. Those are things you can't fake just by reading the latest educational literature. Sure one ought to try to make a class interesting. But sometimes, passion + humor + depth automatically transforms into "interesting". ## Friday, October 9, 2009 ### Calvin is funny! We were trying to take passport-size pictures of our daughter recently, and to say it was a circus, is putting it mildly. I remembered the Calvin and Hobbes strip, where Calvin makes all sorts of faces, when his dad wants to get a good picture for their Christmas card. To recall, this is what he gets when he develops his film: Our experience wasn't very different! Thank God for digital cameras. ### How to convert a set of eps pictures to jpg format? If you have a linux system with ImageMagick installed this is easy. While I refer to jpg and eps files in this howto, conversion between any two formats that ImageMagick supports is similar. Let us say you have a directory full of eps files along with non eps files. A simple shell script using "sed" will do the trick for i in *.eps do prefix=echo$i | sed 's/\.eps//'
suffix=".jpg"
newfile=echo "$prefix$suffix"
convert -density 300 -units PixelsPerInch $i$newfile
done

## Wednesday, October 7, 2009

### We like cocky!

Check out this New Scientist article. It suggests that the public, at large, likes absolutes uttered by overconfident individuals. Jim Cramer, Dick Cheney, Rush Limbaugh and company, immediately come to mind.

If you are trying to persuade, it probably means that a nuanced, multifaceted argument is probably going to lose out to a black-white pronouncement. This has policy implications as the article points out:
There are times, however, when this link breaks down. With complex but politicised subjects such as global warming, for example, scientific experts who stress uncertainties lose out to activists or lobbyists with a more emphatic message.
On the other hand, one of the reasons I like to listen to Warren Buffett, for example, is also because he can distill complexity into something simple that I can understand.

So I guess, the knife cuts both ways.

### Installing LAMMPS with AtomEye on your Desktop

Recently, I wrote a brief on how to upload files on blogger using a Google docs as the intermediary.

Here I am testing, whether I can upload a presentation (pdf) on how to install LAMMPS and AtomEye for the molecular dynamics class I am teaching this fall.

Update: Need to share it with you :(

Here it is on Scribd.
Getting LAMMPS

## Thursday, October 1, 2009

### Paper or On-screen reading?

I spend a significant fraction of my waking life reading. About ten years ago, most of my reading, and writing for that matter, was paper-based.

I distinctly remember that during my senior thesis, and the first few years in grad school - I couldn't read and think, off a computer screen at all. Writing was even harder, and I used to write stuff down on paper before composing a serious document.

Any technical paper, I had to download, print, and scribble on to really digest.

Here are articles from the Boston Globe and a University of Florida website which support the thesis that reading from paper is better. The latter website claims reading paper is 20-30% faster, more accurate (in terms of the ability to identify grammatical and typographic errors), and less taxing on the eyes.

But things change.

Personally I can now read much better off a screen. With a high-resolution monitor, I prefer it. My main reasons are the following:
1. zoom
2. place my paper online, and read it from any computer.
3. "Go Green"
4. read and create color documents at no additional cost
6. organizing/searching papers is easier
7. search for a word in a long document
In fact, I write much better on a keyboard too. Not only has my speed increased, I can correct spelling errors, and especially because I use a sophisticated word processor invented in the 70s called LaTeX, I worry less about appearance and more about content.

Indeed, a not-so-new paper cited at the end claims that paper and on-screen reading have now become equivalent.

Something that my own experience mirrors.

Reference:
Harrison, B, ‘E-Books and the Future of Reading’, IEEE Computer Graphics and Applications, Volume 20 , Issue 3 (May 2000) , pp. 32 - 39.

## Tuesday, September 29, 2009

### Mechanical Turk

I usually never spend time on stuff like this, but was amazed at how easy it is to earn money these days, doing simple stuff. However, this may not be the best use of your time as this blog suggests.

## Friday, September 25, 2009

### Li Mu Bai

Stumbled upon a quote from the movie "Crouching Tiger, Hidden Dragon" that used to be my on my email signature file once upon a time.
The things we touch have no permanence. My master would say: there is nothing we can hold onto in this world. Only by letting go can we truly possess what is real.

## Monday, September 21, 2009

### Ajoba - a truly remarkable man!

My Ajoba (maternal grandfather) died in his sleep last week. He was 98.

As anybody who met him will say, he was a truly remarkable man.

Remarkable, not simply due to the sheer length of his life which allowed him to witness historical events like World War I and II, the rise and fall of communism,  the emergence of Mahatma Gandhi and the modern Indian nation, the Great Depression, the shift from newspapers to radio to television to the internet etc.

No.

His legacy is not built around being a passive spectator of history as it quickened its pace of change to unprecedented levels over the last century. He was an active participant, a man who made interesting choices in his life - many that directly affect and guide me today.

He was born in a business family in a small town, became enamored with physics, and decided that he wanted to do a PhD, and went to Gottingen, Germany in the early 1930s.

Germany, early 20th century and physics were like Silicon Valley, late 20th century, and computers.

He got to meet and interact with some of the brightest minds of that time (my Aaji - his wife - loves to tell us the story of how she once had Nobel Laureate Milliken for tea). He got out of Germany, and came back to India just as the Nazi regime was taking hold.

He joined the physics staff at the Indian Institute of Science, Bangalore in a department that then included another Nobel Laureate, C.V. Raman. A few years later, in a move I've never really understood even after asking him several times, he came back to his little home town - the same place where I spent the first 18 years of my life.

He immersed himself in science education at the school and college levels. In the meantime, he fathered 9 children - 8 of whom were girls. His education brushed off on all of his children (including my mother). In a time and age when few women ventured out - three of his girls became doctors, four of them got a masters in science, and one of them became a practicing lawyer. He really was far ahead of his times.

He was a voracious reader, and immersed himself in his study for several hours every day. It was a little, quiet, sunny room, with diploma-laden walls, and the scent of old books. He made his own tea and walked almost a kilometer to the college he built and loved, well into his 90s. He led a simple, active, and intellectually full life.

My favorite story about him - something that I derive direct inspiration from - happened on the eve of his 85th birthday. I saw him in his study working out a calculus problem from a graduate textbook. I was puzzled, and asked him why he was doing it. He replied "If I don't practice, I will forget." He worried about forgetting how to integrate a function by parts, when most people his age had trouble remembering their names. His devotion to learning is what kept his mind surprisingly sharp, till a very advanced age. It is only after his eyesight became too weak to read, that the overall deterioration of his health commenced.

The last time I met him in 2008 at Anju mavashi's place - I talked to him about his time in graduate school. He was surprisingly coherent, and laughed often, as he told me stories of his advisor, his defense, and his work.

For almost a full hour.

I never knew, at that time, that this was my last chance to watch, as he vicariously re-lived some of his fondest memories.

Like someone said, "We all die. The goal isn't to live forever, the goal is to create something that will".

And he did.

## Wednesday, September 16, 2009

### Differences between boy and girl (kid) brains?

In one [study], scientists dressed newborns in gender-neutral clothes and misled adults about their sex. The adults described the "boys" (actually girls) as angry or distressed more often than did adults who thought they were observing girls, and described the "girls" (actually boys) as happy and socially engaged more than adults who knew the babies were boys. Dozens of such disguised-gender experiments have shown that adults perceive baby boys and girls differently, seeing identical behavior through a gender-tinted lens.
I always suspected that the "men are from mars and women are from venus" line, as closer to astrology than to science. Evidently
assertions of innate sex differences in the brain are either "blatantly false," "cherry-picked from single studies," or "extrapolated from rodent research" without being confirmed in people. For instance, the idea that the band of fibers connecting the right and left brain is larger in women, supposedly supporting their more "holistic" thinking, is based on a single 1982 study of only 14 brains. Other baseless claims: that women are hard-wired to read faces and tone of voice, to defuse conflict, and to form deep friendships; and that "girls' brains are wired for communication and boys' for aggression." Eliot's inescapable conclusion: there is "little solid evidence of sex differences in children's brains."
Of course the larger picture that the article and the book suggests is that small differences in treatment accumulate to measurable differences eventually.

## Wednesday, September 9, 2009

### Surface Area Required to Power the World

Check out this blog which tries to estimate the surface area required to generate all of the worlds energy requirements using renweable sources.

## Tuesday, September 1, 2009

### How to post a ppt, doc, pdf, odf, etc. file on Blogger?

The main obstacle in doing this is, of course, the lack of "space" to upload your document.

One method to accomplish this is embedding. You can use an utility like Scribd, or slideshare. These websites show you how to do the needful on Scribd, and on slideshare. Essentially, this involves registering on the particular website and uploading your presentation there. The process is very similar to how you would upload movies onto YouTube and link to it from your blog.

Another method, which I guess is obvious to many people, exploits the ubiquity of gmail accounts.

2. Select "Upload" (in the blue band), and upload your file.
3. "Open" the document
4. On the top right corner select "Share -> Get Link to Share"
5. Get the link, and from your blogger site just link to it as you would any other website.

One advantage of this method is that anybody can download the file in whatever format it was uploaded.

## Thursday, August 27, 2009

### Robert Heinlein and Specialization

Having spent my life learning more and more about less and less, and being envious of people who know more and more and more of less and less and less, this Robert Heinlein quote offers refreshing perspective.
A human being should be able to change a diaper, plan an invasion, butcher a hog, conn a ship, design a building, write a sonnet, balance accounts, build a wall, set a bone, comfort the dying, take orders, give orders, cooperate, act alone, solve equations, analyze a new problem, pitch manure, program a computer, cook a tasty meal, fight efficiently, die gallantly. Specialization is for insects.
"Stranger in a Strange Land" by Heinlein is one my all-time favorite SciFi novels. This particular quote is not from that book, however.

## Saturday, August 22, 2009

### Returning to India

One of my friends from IIT Bombay, Kashyap Deorah, who moved back to India a couple of years ago has written a couple of absolutely fascinating essays on the subject. Speaking through metaphors, it dwells one level below the completely abstract, and one level above the completely mundane.

Here is are links to the first, and the second essays.

## Wednesday, August 19, 2009

### OpenOffice Impress + OOoLaTeX = Presentations on Steroids!

Okay, I got carried away with the title, but occasionally things happen, which forever change the way you do many regular tasks. And some irrational exuberance is warranted.

I've successfully weaned myself away from non-free software, over the last decade. So no, I don't use MS Windows, MS Office, Mathematica, SigmaPlot, Material Studio, Fluent, Matlab etc. anymore. Instead, I use Linux, LaTeX+OpenOffice, Maxima, gnuplot+xmgrace, LAMMPS, OpenFOAM, Octave etc. In most cases, my choices are superior, and in some cases, despite their flaws, they are adequate for the types of things I do, and the kind of person I am [I like command lines, can compile things from source, don't mind hacking around a little bit if short term inconvenience ensures long-term peace]. So this entry is heavily biased by my computing habits and temperament.

I've never really liked how equations turn up on MS Office or OpenOffice (without paying for MathType - I'm cheap I told you!). Presentations using a LaTeX class like beamer or seminar, is an option, but most of my presentations unlike my documents don't have too much cross-referencing, structure, etc. What I really miss is professional layout of mathematical formulae. Recently, I started using this plugin called OOOLaTeX. Installing it on OOo 3.0 was a breeze. This is on a Linux machine, on which LaTeX and ghostscript were already installed.

1. Just go to Tools -> Extension Manager -> Get More Extensions here.
2. Search for OOOLaTeX
3. "Get It", which allows to download an "oxt" file.
4. Install it, by choosing "Add" in the extension manager.
5. Download "Bakoma" fonts (which look like the Computer Modern fonts in standard LaTeX documents) and push them into your fonts directory.

You're set. The following is my own document. The one above, obviously, is not mine. I got that from the official Screenshots (the writer is French).

## Saturday, August 15, 2009

### I love IIT Bombay!

Didn't notice this before, but am glad my alma mater is taking a stand!

I have nothing personally against Microsoft, and I am not against commercial software, although I don't use much of it. But I am most certainly for open formats like PDF, ODF, SVG etc.

## Wednesday, August 12, 2009

### Does the human skin sense temperature?

The answer is no, if you are in a hurry. But if you have time, let me pose a puzzle:

"Your body temperature is about 37C or 98F depending on which side of the Atlantic you are. If you are like most people it "feels" quite uncomfortable when the temperature outside is 37C. When asked most people say they like 20-27C (or 65-80F). "

Why?

The basic point is that our body is constantly producing heat. In fact, most of the food we eat is eventually converted to heat. This should explain why the average daily intake of an adult is approximately 2500 calories, while only about 300 of those are consumed by jogging for 30 minutes.

For heat to flow, it needs a temperature difference. Thus, the 10-12 celcius difference that a 25 celcius environment provides, enables us to efficiently dissipate the heat we constantly generate. This leads us to the answer.

Our skin senses heat flow (flux), not temperature.

There are several manifestations which illustrate this point:
• When you sleep, you feel colder because your body processes have slowed down, producing less heat.
• When it is hot your body sweats. Sweat vaporizes, and in doing so takes away a lot of heat from your body (aka latent heat of vaporization).
• When it is windy you feel colder because heat is being convected away from your body faster (the wind chill effect).
Notice, how the outside temperature is only one of the factors which governs how "hot" or "cold" we feel. The mere fact that other things, such as level of activity, humidity, convection, perspiration affect that feeling suggests that we don't sense outside temperature.

## Saturday, August 8, 2009

### Feynman Lectures

I found a this link via Simoleon Sense. It is really a fabulous resource, and I highly recommend it, even if your interest in physics is only marginal.

From the blog:
Apparently, Bill Gates has purchased the rights (to many of the Feynman lectures) and posted them for free on his Microsoft Research Labs “Project Tuva”. I can’t recommend these enough, Feynman had the ability of teaching science in a simple, insightful, and eloquent manner.

Often all it taken to enliven a dull subject is a spectacular teacher, and few can doubt Feynman's charisma. What Warren Buffet is to investing, Feynman is to general physics. They serve their specialties with a hearty dose of common-sense and humor.

The only problem with these lectures is that it requires SilverLight!

## Sunday, August 2, 2009

### Spicy Stuff

One of the blogs I follow, brought my attention to this article, which is an interesting take on the spice: asafoetida or hing. My dad loves the spice, and as kid, I hated it.

With age comes maturity, and a tempering of strong emotions, and these days I don't mind it as much.

Interesting tidbits from the article, which I definitely did not know were:

1. its source:

the farmer digs away the soil around the plant and makes an incision in the top of the thick carrot-like root, which then exudes, for about three months, as much as a kilogram of the milky resin. It hardens on exposure to air and gradually turns brown.
2. that asafoetida means "stinking resin" (very apt!). Sulphides are the culprit, as usual. If you recall, a relative - hydrogen sulphide - is partly responsible for smelly farts, and rotten eggs. By the way, it is also flammable, so don't do it near a campfire or a smoker.
3. This is interesting, even ironical, since,

Not unnaturally, the resin has been thought to have very many medicinal uses. Its most common use is to treat indigestion and flatulence. Even today, a bit of it is pasted on the stomach (belly button) of an infant, with the idea that it relieves “locked” gas and aids in digestion.
Apparently this is one of the reasons why it is usually added to dishes containing lentils and beans.
They contain molecules that disturb the enzyme carbonic anlydrase and thus produce gas. And asafoetida helps in relieving this effect – or so the theory goes.
4. Check out the comments on Guru's blog, if you read the article. I really like the keen observation made in the first comment.

## Sunday, July 26, 2009

### Cartograms

You must have seen some of these before, especially in connection with recent US presidential elections. I picked the image above which depicts the 2008 election (Obama v/s McCain) from this University of Michigan website. Their meaning is obvious: they rescale geography, unlike normal maps, to some metric other than geographic size. In effect, one gets a better appreciation of the particular metric.

Parenthetical remark: Go Blue! I spent 7 amazing years in Ann Arbor. The guy whose website I quote above (Mark Newman of Physics) has done some work with Bob Ziff from chemical engineering on percolation theory. Bob is one of the smartest+nicest professors I have ever met. I took statistical mechanics with him, and it was one of the two career-defining classes I took at UM (the other was my advisor Ron Larson's class, Complex Fluids). End of parenthetical remark.

Another wonderful resource for cartograms which is less US-centric and more global in scope is this site. If you look at the population of the world from year 0001 through now, you realize why the Indian sub-continent and China have the largest populations.

This is interesting to me, because about 6 months ago over a cup of coffee, my colleague Milen Kostov and I were trying to figure out why India and China have large populations, and not, say Egypt or Mesopotamia (modern day Iraq) which were also cradles of ancient civilizations. Looks like something happened between 0001 and 1500 AD, where you can see that their sizes sort of diminished or remained same relative to India-China. Perhaps being in a desert limited how much food could be grown to support a population.

## Thursday, July 23, 2009

### Amateur Science

On my way to work today, I heard a story on NPR about an amateur Australian astronomer Anthony Wesley, who discovered a big crater (the size of earth) near Jupiter's south pole. As soon as I sat in front of my computer, I googled and found almost 600 news articles, and here is a link to one of those stories.

Post World War II, science has gotten bigger, and more expensive. To merely keep up with literature, "to stand on the shoulders of giants", requires exorbitant journal subscriptions, which are beyond the reach of individuals. Some of those things are changing, there is arxiv, and of course, the web is an amazing democratizing force.

To see someone with passion and a telescope discovering something that the biggies missed is real chicken-soup for the soul.

It reminded me of the afternoons as a kid, when my cousins and I tried to mix random stuff in water (soil, talcum powder, herbs etc.) to try and create an invisibility potion. The approach was what modern science would call "Edisonian", which meant "keep trying".

Thank god, we never tried to drink that crap, otherwise we would be invisible for good!

But yeah, the astronomer story moved something in me that hadn't moved in some time. It reminded me why I write grants, papers, and put up with pointless meetings.

Its because the joy of discovery, however small, is still so thrilling. You spend the vast majority of your time connecting dots, and most of the time that produces nothing. Occasionally, you get lucky and something starts emerging. The time interval, between that realization that something is emerging, to the instant when the last dot is connected makes one sing: "I am dancing at the feet of God, all is bliss, all is bliss!"