I am currently a research scientist at Laboratory for Computational Physiology (LCP) at MIT. My research interests include searching, mining, and detection of clinically significant events in biomedical time series databases. I completed my Ph.D. from Massachusetts Institute of Technology in June 2005. I received my Master’s degrees in Computer Science and also in Management in 1992, both from Georgia Institute of Technology.

My Ph.D. thesis is on modeling and prediction of network latencies in large-scale distributed systems. I developed a fully decentralized network coordinate system for robust and fault-tolerant Internet distance prediction by modeling network distances in a D-dimensional geometric space. My thesis supervisor is Professor Steven Lerman, former director of Project Athena and Professor of the Civil & Environmental Engineering Department at MIT. My thesis committee members are Professor Hari Balakrishnan from MIT CSAIL and Professor Kevin Amaratunga from MIT Department of CEE.

I was a research assistant at the MIT Laboratory for Computer Science (LCS) from 1996 to 1999. My former advisor at MIT/LCS was Dr. David Tennenhouse, now VP and Director of Intel Research. I worked on the Active Networks project under his supervision. While I was a research assistant at MIT Laboratory for Computer Science, I researched protocol design issues for programmable routers that leverage the mobile code technologies. I developed a reliable multicast system, Active Reliable Multicast (ARM), which embeds active routers in a multicast tree to handle loss recovery. The result is a robust, scalable system for reliable multicast that shows significant benefits even when less than half the routers within the multicast tree can perform ARM processing.

My home department is the Department of Civil and Environmental Engineering (CEE). My research in large-scale distributed systems is an integral part of the Information Technology thrust within the CEE department to develop distributed sensing technology for environmental monitoring and intelligent infrastructure. My advisor, Professor Steven Lerman, is the class of 1922 Professor of the Department of Civil and Environmental Engineering. From 1983-1988, he was the director of Project Athena at MIT during the development of the X Window System and the Kerberos authentication system. He served as the Chair of MIT Faculty from 1999-2001. He is currently the director of the Center for Educational Computing Initiatives.

Prior to joining MIT, I was a researcher at the NSF Engineering Research Center for Computational Science and Engineering at Mississippi State University. I was the principal scientist in a collaborative project with the MIT AthenaMuse software consortium in developing Internet Services for a distributed multimedia system, AthenaMuse2. I have co-authored several funded proposals in collaboration with faculty members at Mississippi State University for projects in multimedia and computer-based distance learning technology.

· Honors & Career Highlights

· Summary of Research Accomplishments

· Thesis Abstract

· Publications

· Teaching Experiences

· Experiences in Computer Systems Development

· Personal Interests

Honors & Career Highlights

· Best Poster Presentation Award, Computers in Cardiology Conference, September 2007.

· Recipient of Schoettler Fellowship, awarded to outstanding incoming graduate students, MIT.

· Paper “Active Reliable Multicast” in IEEE INFOCOM’98 received over 180 citations.

· Technical report “PALM: Predicting Internet Network Distances Using Peer-to-Peer Measurements,” 2004, selected as a feature paper in a systems seminar at the Computer Science Department, Cornell.

· Appointed as Head TA for 1.00, Introduction to Computers and Engineering Problem Solving, an MIT course comprising 200 students and 18 student teaching staff, 2001.

· MIT class awards: (1) algorithm & implementation in C++ won 2nd place in final project contest in MIT course 1.124; (2) voted one of the top 3 term papers in MIT course 6.853, Computer Systems.

· Invited talk, "Integrating AthenaMuse 2 and the World-Wide Web," at the Nationalization of the NEEDS Coalition meeting sponsored by the National Science Foundation, September 16, 1994.

Summary of Research Accomplishments

During my doctoral studies at MIT, I worked on several projects in computer networks and distributed systems. Research topics I worked on include: programmable routers, mobile code technologies that dynamically customize network services, multicast protocols, network topology inference and discovery, decentralized algorithms for modeling and prediction of network latencies in large-scale distributed systems. Here is a summary of my major research accomplishments.

· Developed one of the first Active Networks applications, Active Reliable Multicast (ARM), with Dr. David Tennenhouse. ARM embeds active routers in a multicast tree to handle loss recovery. The result is a robust, scalable system for reliable multicast that shows significant benefits even when less than half the routers within the multicast tree can perform ARM processing. Paper “Active Reliable Multicast” in IEEE INFOCOM’98 received over 120 citations. Research was cited and described as one of the active networks applications that demonstrate significant benefits over conventional approaches in a feature article “Activating Networks: A Progress Report” by Jonathan Smith et al. in IEEE Computer, 1999.

· Part of the Active Networks team that researched protocol design issues for programmable routers that leverage the mobile code technologies. Designed and implemented a capsule-based network protocol that performs in-network processing and storage using the ANTS (Active Node Transport System) toolkit in Java. Protocol design for capsule-based programmable routers differ from traditional protocol designs; issues examined include: compact code size, light-weight computation for in-network processing, use of soft-state for in-network storage, and minimum assumptions about resource availability of programmable routers for incremental deployment.

· Developed the PALM approach, which is among one of the first to demonstrate the feasibility and performance characteristics of a decentralized approach in network coordinate construction. Technical report “PALM: Predicting Internet Network Distances Using Peer-to-Peer Measurements,” 2004, was selected as one of the feature papers by a systems seminar at the Computer Science Department, Cornell.

· Developed a decentralized network coordinate system PCoord for Internet distance prediction. PCoord constructs network coordinates in a fully decentralized fashion without using a fixed set of landmarks as in most existing approaches. Our results suggest that under an extremely challenging flash-crowd scenario where over one thousand hosts simultaneously join the system, PCoord is able to converge to low-error coordinates within 10 seconds using half the number of samples as Vivaldi, a concurrently-developed decentralized coordinate system.

Publications

· “Searching by Example in Multi-Parameter Time Series Databases,” Lehman LH, Saeed M, Moody GB, Mark RG, Computers in Cardiology, Bologna, Italy, September 2008; in print.

· “Automated De-Identification of Free-Text Medical Record,” Neamatullah I, Douglass M, Lehman LH, Reisner A, Villarroel M, Long WJ, Szolovits P, Moody GB, Mark RG, Clifford GD, BMC Medical Informatics and Decision Making, July 2008; 8:32.

· “A Temporal Search Engine for a Massive Multi-Parameter Clinical Information Database,” Lehman LH, Kyaw TH, Clifford GD, Mark RG, Computers in Cardiology, Durham, North Carolina, September 30th - October 3rd, 2007; 34:637-640.

· “A Decentralized Network Coordinate System for Robust Internet Distance Prediction,” Li-wei Lehman, in Proceedings of the Third International Conference on Information Technology, Next Generation, IEEE Computer Society, Las Vegas, Nevada, April 10 - 12, 2005.

· “PCoord: A Decentralized Network Coordinate System for Internet Distance Prediction,” Li-wei Lehman, Ph.D. thesis, MIT, 2005.

· “Network Position Estimation Using Peer-to-Peer Measurements,” Li-wei Lehman and Steven Lerman, Proceedings of the IEEE Network Computing and Applications, Boston, MA, August 2004.

· “PALM: Predicting Internet Network Distances Using Peer-to-Peer Measurements,” Li-wei Lehman and Steven Lerman, Proceedings of the SMA Symposium 2004, January 2004.

· “Discovering Network Neighborhoods Using Peer-to-Peer Lookups,” Li-wei Lehman and Steven Lerman, Proceedings of the SMA Symposium 2003, January 2003.

· “Active Reliable Multicast,” Li-wei Lehman, Stephen Garland, and David Tennenhouse, Proceedings of the IEEE INFOCOM’98, March 1998.

Technical Reports

· “Inferring Characteristics of Multicast Trees,” Xiaowei Yang and Li-wei Lehman, class project for Computer Networks.

· “Internet Services,” Li-wei Lehman, Chapter in AthenaMuse 2 Design Specification Version 1.4, MIT AthenaMuse Software Consortium, September 14, 1994.

· “Integrating Zipcode and PVM: Towards a Higher-Level Message-Passing Environment,” Li-wei Lehman. Technical Report No. MSSU-EIRS-ERC-94-2, NSF Engineering Research Center, December 10, 1993.

Teaching Experiences

From 1999 to 2002, I was a TA and Recitation Instructor for 1.00, Introduction to Computers and Engineering Problem Solving, at Massachusetts Institute of Technology. I taught weekly recitation sections as a lecturer. I also designed and developed recitation course notes, problem sets and exams. Programming languages taught: C++, C, and Java.

In Spring 2001, I was appointed the head TA for 1.00, which allowed me to play a key leadership role in the overall organization and management of the course, comprising 200 students and 18 student teaching staff. I was responsible for the hiring and supervision of eight graders and two lab TAs. Student evaluation of my teaching: 6.4/7.0.

Experiences in Computer Systems Development

I have some experiences in developing large computer systems in team settings. I worked on two major computer system development projects: (1) AthenaMuse2, a distributed multimedia system development project in C++ consisting of at least 13 developers, and (2) Active Networks, a programmable network development project in Java.

Personal Interests

While studying at MIT, I became interested in a wide variety of life science and biomedical science topics. A few graduate students and I formed a life science study group at MIT back in 1998.