Nabin K. Malakar, Ph.D.

I am a computational physicist working on societal applications of machine-learning techniques.

Research Links

My research interests span multi-disciplinary fields involving Societal applications of Machine Learning, Decision-theoretic approach to automated Experimental Design, Bayesian statistical data analysis and signal processing.


Interested about the picture? Autonomous experimental design allows us to answer the question of where to take the measurements. More about it is here...


I addition to the research, I also like to hike, bike, read and play with water color.

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Friday, August 6, 2010

Packing for Mars?

This is definitely not a book review, just my wild speculations into travel into Mars.

When you travel for cross Atlantic travel, how cozy was it? Seating at one confined place while waiting for long destination has so many side effects. Physical, psychological so and so.
Well, we are talking about months of isolations and painful travel. This should shakedown your enthusiasm for space travel. :P  
How about adding some humor to the pain? 
It is said that
"Pain + time = humor".

Packing for Mars: The Curious Science of Life in the Void

"Packing for Mars: The Curious Science of Life in the Void" by Mary Roach should be a good read. I would definitely love to have a chance to read it. Actually, I have added it to my wish list@Amazon. ;) Reviews are saying that there are a lot of LOL moments in the book.

I know the saying, "No pain, no gain". However, I am curious why send humans to the deep space? The recent advancement in robotics allows us to do the same thing at less cost and less insurance value than pushing humans to such harsh environments and posing fatal risks involved.

Side note:
Download the pdf to have some idea on how tricky it is to travel to sister planet Mars:

Thursday, August 5, 2010

Bayes' Theorem in \LATEX

I am learning Latex. Using Texnic Center and other similar softwares. I wish that Kile was available on Windows...
Anyways, everytime I start a new file, I have to search for the barebone of the file which needs to be there before anything can be done.
So, here I am collecting some skeleton for latex files:
I think they are free from any (c).

\usepackage{amsmath} % need for subequations
\usepackage{hyperref} % use for hypertext links, including those to external documents and URLs
\title{Your Title Here}
\author{Your Name here \thanks{Email:}
Abstract goes here...
\tableofcontents{} % comment: just in case... it can be commented
Here we start...
Oh, why not start by writing Bayes Theorem in Latex ?
... we use Bayesian method to infer the model parameters in question. We learn from the available data. The process of arriving at the posterior from the prior in the light of given data can be accomplished by using Bayes' theorem.
As a general statement, we can state Baye's theorem as follows\\
P(\theta|\textbf{D}) = P(\theta ) \frac{P(\textbf{D} |\theta)}{P(\textbf{D})} ~~~~~|| I,
where we have adopted Skilling--Gull convention of writing $I$ as the generally accepted term in the conditionals. The data are represented by \textbf{D} and parameters are represented by $\theta$.

Thanks to the Blogger platform which do not convert latex command into symbols. (That was a satire :P )
Note to self: I believe I have seen Gull using the conditional out of bracket... where, where ???

Sunday, August 1, 2010

Bus Resistance of a Code or Program

Last year I was on a training for a operating computations on grid at Cornell. Our instructor from Texas threw a Joke: "Do you know the bus resistance of your code?"
Everyone was surprised to hear the question. The Joke is interesting because it indicates one thing and tells you something else. While some people were thinking of how the string of 1's and 0's that travel through the computer data bus might come across such bus resistance, he explained in a funny way.

Here we go:
Imagine one fine friday evening you are grabbing a beer and walking down the road, and you are hit by a bus. What happens to your code? The next day the project manager decides to give your code to your colleague to continue the project. If your code is not properly commented, he will be completely lost in there. 
So, the bus resistance is given by the amount of comments in a code and the readability of your code by someone else.
Let us wish that this happens to no one. However, for the continuity of the project in your lab, your code must have very high bus resistance value.
The moral is: comment your code as much as you can.
Beginning C++ Through Game Programming, Second EditionPython Programming: An Introduction to Computer Science 2nd EditionC Programming Language (2nd Edition)

Are your codes bus resistant?

Wednesday, July 28, 2010

Congratulations to recent Nepali Physics PhD graduates

Wishing all the best to the recent Physics PhD graduates.

Dr. Hikmat BC
New Mexico State University 

Dr. Shyam Badu
University at Albany

Dr. Madhav Neupane
Boston College

Dr. Pashupati Dhakal 
Boston College

Dr. Mukti Aryal
UT Dallas 

Locating Nepali Physicists on Google map LINK here:

Please join us to congratulate Nepali Physicists graduating with PhD degree. The Google group of Nepal Physical Society LINK here.

Tuesday, July 20, 2010

Collective Behavior in Animals

Feel like yawning? Look around, someone near you might also be yawning!

The so called collective behavior such as yawning might be an urban myth but a recent studies have attempted to model such collective behavior. The modal system they considered consists of an example of collective behavior of cows. Such theories have not been tested it in the real cows, however one should not be surprised to see such studies to be verified in near future.

In a recent work, published in arxiv,  Sun et. al. study the collective behavior of animals such as cows.  Animals are coupled oscillators. They simply model the cow as coupled oscillator. By considering the discrete states of such animals and by considering such couplings, they study the collective decision bearing of such system.
Specifically, they consider three states of cows: standing, sitting and grazing; say "1", "2" and "3" just for sake of easy symbolization. By coupling the states, they assume that behavior of one is going affect the behavior of nearby ones. So, there is more tendency of uniform state such as 1,1,1,1,1 than 1,2,3,2,1 or 1,2,1,2,3. However, for larger cow population there can be some nice oscillatory behavior between the stable states.
The paper is interesting! Have a look.

Acknowledgements are due to the first author for suggests in the draft version of the post and allowing to use the figures.

Fig: Coupled cows.

On the lighter side:
One can see the influence of "spherical cow" on the coupling diagrams. See Jackson, J.D. Third Edition Ch3 problem#15.