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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Thursday, July 26, 2012

Statistical Physics of Human Mobility: Paper

Statistical physics help understand relating the microscopic properties of atoms and molecules to the macroscopic properties of materials that can be observed in everyday life. As a result, it is able to explain thermodynamics as a natural result of statistics, classical mechanics, and quantum mechanics at the microscopic level. [1]

By looking into the GPS information, from vehicles (collected) in Italy, Gallotti et al have performed a study to apply ideas of statistical physics to describe the properties of human mobility.

The human mobility is an interesting research question. Understanding of human mobility can be useful in urban planning, and to understand spread of epidemic. In addition, the authors suggest that such studies may also be useful to discover possible "laws" that can be related to the dynamical cognitive features of individuals.

The average speed variance (on the left), the distribution (on the right) can be decomposed as a mixture of Gaussian. Two Gaussians with mean speed of around 20 Km/hr and 45 Km/hr emerges. This indicates the distinct behavior of drivers. I find this to be an interesting decomposition.

The left figure shows the statistical distribution of the activity time. The presence of straight line indicates Benford's law. Figure on the right shows "total activity time". With the help of the "down time" i.e. the period for which the GPS is turned off, the authors suggest that at least three distinct peaks for full-time (~9 hrs), part-time (~4 hrs) jobs and night rest (~13 hrs). However, there is also one more peak around 1hr downtime. I guess the down-time for one hour peak shows short-term activities such as shopping behavior.

In the paper, using the travel time as a cost function, the authors show that the distribution between successive trips are indeed driven by an underlying Benford's law. The ranking of the the distribution of the average visitaion frequency may also help to understand how people organize their daily agenda. An interesting feature comes out when the average speed distribution for the recorded trip is decomposed as a mixture of two Gaussians: one with ≤ 5km. I think such characteristics distribution indicate the local constraint on the movements. Obviously, the motion is not free of constraints. The mobility data is strictly constrained by the road structures.
It would be interesting to see if there are such statistical phenomena as "phase transition" in such statistical law of human mobility.
This is an interesting paper. See [2].

At last, Why do we move from one place to another?
If we assume some aggregate effect on social scale; are we different than the gas molecules contained in a box? Moreover, it seems someone has to drive an extra mile since the system demands it!

(Special thanks to Prof. Armando Bazzani for allowing me to use the figures.)
[2] Towards a Statistical Physics of Human Mobility
Riccardo Gallotti, Armando Bazzani, Sandro Rambaldi

Wednesday, July 25, 2012

Google Science Fair Grand Prize goes to Brittany Wenger, 17 For Neural Network based Breast Cancer Diagnosis App Project

The second Google Science Fair Grand Prize goes to Brittany Wenger, 17 For Neural Network based Breast Cancer Diagnosis App Project.
Her project title is:
"Global Neural Network Cloud Service for Breast Cancer"
It is quite a nice idea of enabling cloud-based diagnostics. Read the details in the project page.

In addition, we would also like to congratulate all the finalists for their efforts!

Summary - Science Fair 2012: 

Friday, July 13, 2012

Nepalese Physicists departing from Nepal for Fall 2012

I am sure a lot of people are missing from the list. However, thanks to Narayan G, we have compiled this list for the moment. Please let me know, I will update it.

We would like to wish all the best to the physicists for their success. Please join the Google Group of Nepal Physical Society for lively discussions. We have also created a Google Map showing Nepali Physicists around the globe. If you know someone who is missing from the map, please let us know.
1 Basu Ram Lamichane University of Missouri Science and Technology
2 Bikas Kafle University of Memphis
3 Chet Raj Bhatta Mississippi State University
4 Chinta Mani Aryal University of Akron
5 Deepak Sapkota University of Tennessee
6 Dinesh Thapa University of Idaho
7 Dipendra Adhikari University of Memphis
8 Dipendra Dahal CUNY, New York
9 Durga Raj Siwakoti Mississippi State University
10 Ebin Bastola Bowling Green State University
11 Ganga Prasad Sharma University of Rhode Island
12 Ghadendra B. Bhandari Bowling Green State University
13 Gyanendra Bohara North Texas
14 Indra Mani Ghimire Baylor University
15 Jiwan Katwal University of Houston
16 Kiran Ghimire
17 Kushal Shrestha
18 Lokendra Poudel University of Missouri
19 Medani P. Sangraula Illinois Institute of Technology
20 Min Prasad Khanal Auburn University
21 Mohan Panta University of Houston
22 Nabin Thapa Kent State University
23 Nabina Paudyal Akron University of Ohio
24 Narayan Poudel University of Houston
25 Nawa Raj Dahal Boston College
26 Pauf Neupane Missouri Science and Technology
27 Pawan Pathak University of Naveda
28 Prabodh Dhakal Washington State University
29 Pradip Raj Niraula University of Massachusetts
30 Prakash Upreti Bowling Green State University
31 Rabi Khanal Missouri University of Science and Technology
32 Rajiv Kadel Iowa State University
33 Rishi Ram Paudel University of Delaware
34 Rudra Prasad Pokhrel University of Wyoming
35 Sagar Prasad Paudel Wyane State University
36 Samana Shrestha University of Rhode Island
37 Shanker Aryal University of Southern Illinios
38 Shiva Shran Bhandari Michigan Technology University
39 Sudip Nepal Arkansas University
40 Surendra Maharjan University of Houston
41 Umesh Silwal Mississippi State University
42 Upendra Rijal Bowling Green State University
43 Vijay Khanal University of Naveda
44 Yagya Raj Joshi Florida International

Thanks to Narayan Poudel, Yuba Raj Poudel, Samana Shrestha and others.

Thursday, July 12, 2012

Questions You Wanted to Ask About Physics Graduate School (But Were Afraid to Ask!)

A nice webinar presented by Graduate students and post docs.
 Discusses important issues:

  • Grad School application process (tests and how early should one plan)
  • Financial support
  • Required course work, and qualifying exams
  • About research and advising etc