“Yasanka is of a very rare breed in my industry and I was truly lucky to spot him and hire him at the right time for CAKE LABS. He comes with an amazing conceptual knowledge on computing, coupled with a high mathematical aptitude and analytical ability. And to top it all off, he comes with a great friendly personality too. During his time with the Data & Analytics team at CAKE, he made significant contributions to our data solutions where he got the chance to get his hands dirty on bigdata related open source tools and technologies. Yasanka is able to work independently without zero supervision and he can fast adapt to any kind of challenges in a very short time span. He is a very good communicator and can effectively work in a team setting. I consider it an honour to have work with you Yasanka. I would not hesitate to recommend Yasanka to any organizations.”
Sameera Horawalavithana
Seattle, Washington, United States
2K followers
500+ connections
About
I am a Staff Scientist at Pacific Northwest National Laboratory. I received my Ph.D. in…
Activity
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DOE's congressionally mandated report on data center energy usage by Berkeley Lab is out, and it's already making the rounds with industry partners.…
DOE's congressionally mandated report on data center energy usage by Berkeley Lab is out, and it's already making the rounds with industry partners.…
Liked by Sameera Horawalavithana
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Today, our team at OMB is releasing the consolidated AI Use Case Inventory for 37 federal agencies, collecting more than 1700 publicly reportable use…
Today, our team at OMB is releasing the consolidated AI Use Case Inventory for 37 federal agencies, collecting more than 1700 publicly reportable use…
Liked by Sameera Horawalavithana
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I am excited to share that our article “Foundation models for the electric power grid” https://lnkd.in/dRJhauE8 was featured on the cover of Joule…
I am excited to share that our article “Foundation models for the electric power grid” https://lnkd.in/dRJhauE8 was featured on the cover of Joule…
Liked by Sameera Horawalavithana
Experience
Education
Licenses & Certifications
Volunteer Experience
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ACM Ambassador
Association for Computing Machinery
- Present 9 years 7 months
Science and Technology
Local Ambassador to perform ACM activities
Publications
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Twitter is the Megaphone of Cross-Platform Messaging on the White Helmets
International Conference on Social Computing, Behavioral-Cultural Modeling, & Prediction and Behavior Representation in Modeling and Simulation
This work provides a quantitative analysis of the cross-platform disinformation campaign on Twitter against the Syrian Civil Defence group known as the White Helmets. Based on four months of Twitter messages, this article analyzes the promotion of urls from different websites, such as alternative media, YouTube, and other social media platforms. Our study shows that alternative media urls and YouTube videos are heavily promoted together; fact-checkers and official government sites are rarely…
This work provides a quantitative analysis of the cross-platform disinformation campaign on Twitter against the Syrian Civil Defence group known as the White Helmets. Based on four months of Twitter messages, this article analyzes the promotion of urls from different websites, such as alternative media, YouTube, and other social media platforms. Our study shows that alternative media urls and YouTube videos are heavily promoted together; fact-checkers and official government sites are rarely mentioned; and there are clear signs of a coordinated campaign manifested through repeated messaging from the same user accounts.
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Mentions of Security Vulnerabilities in Reddit, Twitter and GitHub,
IEEE/WIC/ACM International Conference on Web Intelligence
Activity on social media is seen as a relevant sensor for different aspects of the society. In a heavily digitized society, security vulnerabilities pose a significant threat that is publicly discussed on social media. This study presents a comparison of user-generated content related to security vulnerabilities on three digital platforms: two social media conversation channels (Reddit and Twitter) and a collaborative software development platform (GitHub). Our data analysis shows that while…
Activity on social media is seen as a relevant sensor for different aspects of the society. In a heavily digitized society, security vulnerabilities pose a significant threat that is publicly discussed on social media. This study presents a comparison of user-generated content related to security vulnerabilities on three digital platforms: two social media conversation channels (Reddit and Twitter) and a collaborative software development platform (GitHub). Our data analysis shows that while more security vulnerabilities are discussed on Twitter, relevant conversations go viral earlier on Reddit. We show that the two social media platforms can be used to accurately predict activity on GitHub.
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Behind the Mask: Understanding the Structural Forces that Make Social Graphs Vulnerable to De-anonymization.
IEEE Transactions on Computational Social Systems (TCSS)
The tradeoff between anonymity and utility in the context of the anonymization of graph data sets is well acknowledged; for better privacy, some of the graph structural properties must be lost. What is not well understood, however, is what forces shape this tradeoff. Specifically, for the data practitioner who wants to publish an anonymized graph data set, it is unclear what graph structural properties can be preserved and what are the anonymity costs associated with preserving them. This…
The tradeoff between anonymity and utility in the context of the anonymization of graph data sets is well acknowledged; for better privacy, some of the graph structural properties must be lost. What is not well understood, however, is what forces shape this tradeoff. Specifically, for the data practitioner who wants to publish an anonymized graph data set, it is unclear what graph structural properties can be preserved and what are the anonymity costs associated with preserving them. This article proposes a framework that examines the interplay between graph properties and the vulnerability to deanonymization attacks. We demonstrate its applicability via extensive experiments on thousands of graphs with controlled properties generated from real data sets. In addition, we show empirically that there are structural properties that affect graph vulnerability to reidentification attacks independent of degree distribution.
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Diversity, Topology, and the Risk of Node Re-identification in Labeled Social Graphs.
The 7th International Conference on Complex Networks and Their Applications (Complex Networks)
Real network datasets provide significant benefits for understanding phenomena such as information diffusion or network evolution. Yet the privacy risks raised from sharing real graph datasets, even when
stripped of user identity information, are significant. When nodes have associated attributes, the privacy risks increase. In this paper we quantitatively study the impact of binary node attributes on node privacy by employing machine-learning-based re-identification attacks and exploring…Real network datasets provide significant benefits for understanding phenomena such as information diffusion or network evolution. Yet the privacy risks raised from sharing real graph datasets, even when
stripped of user identity information, are significant. When nodes have associated attributes, the privacy risks increase. In this paper we quantitatively study the impact of binary node attributes on node privacy by employing machine-learning-based re-identification attacks and exploring the interplay between graph topology and attribute placement. Our experiments show that the population’s diversity on the binary attribute consistently degrades anonymity -
An Efficient Incremental Indexing Mechanism for Extracting Top-k Representative Queries Over Continuous Data-streams
ACM/IFIP/USENIX Middleware 2015
Top-k publish/subscribe (pub/sub) models have gained traction as an expressive alternative to extend the binary notion of matching. In our study, we focus on the problem of extracting the k-most representative set of publications in the dynamic case where the results are updated over a
stream of matching publications. This can be observed as the minimum independent dominating set problem in graph theory, when streaming publications are represented as dynamic graph spaces. Due to the inherent…Top-k publish/subscribe (pub/sub) models have gained traction as an expressive alternative to extend the binary notion of matching. In our study, we focus on the problem of extracting the k-most representative set of publications in the dynamic case where the results are updated over a
stream of matching publications. This can be observed as the minimum independent dominating set problem in graph theory, when streaming publications are represented as dynamic graph spaces. Due to the inherent complexity of solving this problem over continuous data, an incremental
indexing mechanism is proposed for handling a stream of publications. The proposed mechanism is based on Locality Sensitive Hashing (LSH) to avoid the overhead of recalculating neighborhoods over consecutive sliding windows. The experimental results show that the incremental version of
LSH indexing mechanism reduces the computational cost of naive greedy approach significantly, while producing Top-k representative results at 70% accuracy compared to the naive optimal method.Other authors
Courses
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Artificial Intelligence Methods & Applications
5DV058
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Compilers and Automata Theory
SCS3008
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Computational Pattern Recognition
SCS4019
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Computer System Architecture
SCS3013
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Cryptography Systems
SCS3011
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Data Mining
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Deep Learning
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Distributed Systems
5DV147
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Fundamentals of Artificial Intelligence
5DV121
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Graph Data Processing
CIS6930
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High Performance Computing
SCS4007
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Introduction to Theory of Algorithms
COT6405
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Middleware Architectures
SCS3009
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Networking Technologies
SCS3004
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Operating Systems
COP6611
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Principles of Computer Architecture
EEL6764
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Social Network Analysis
SYA7357
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Special Topics in Theoritical Computing
SCS4009
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System Security
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Wireless Ad-Hoc and Sensor Networks (WASN)
SCS4017
Projects
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Modeling Information Diffusion Processes with Deep Learning Algorithms (SocialSim)
- Present
The principal research objective of the project is to evaluate deep learning methodologies using neural networks for predicting information diffusion processes in various social online environments. While deep learning has been shown to be a valuable tool in recognizing images, it has not been sufficiently explored in the context of dynamic processes on social networks. Yet, we believe, with the right techniques in place, deep learning can contribute significantly to predicting dynamic…
The principal research objective of the project is to evaluate deep learning methodologies using neural networks for predicting information diffusion processes in various social online environments. While deep learning has been shown to be a valuable tool in recognizing images, it has not been sufficiently explored in the context of dynamic processes on social networks. Yet, we believe, with the right techniques in place, deep learning can contribute significantly to predicting dynamic processes on social networks at scale.
In our first phase, we used Long Short Term Memory (LSTM) neural network to model information cascades. We proposed a graph-representational learning framework (aka Cascade-LSTM), and simulate information cascades around communities of popular crypto-currency systems appeared Reddit, Github and Twitter. The crypto-currency systems are highly volatile and evolve quickly. Also, cryptocurrencies are disproportionately used by criminals and hackers, and their use has political and economic implications for the U.S. Thus, understanding, explaining, and anticipating the social behavior and communication patterns in the social environments surrounding cryptocurrencies is crucial to understand this phenomena and devise appropriate responses. -
Structural Anonymization Techniques for Large, Labeled, and Dynamic Social Graphs
- Present
The objective of this work is to provide big data owners with tools to safely share their social networks data with the research community. The project aims to approach graph anonymization via two techniques for graph generation: dK-series techniques, introduced in the context of internet network generation, and Exponential Random Graph Model-based approaches (ERGM). My contribution is related to privacy/ utility measures, and how such graph annonymization techniques could apply on evolving…
The objective of this work is to provide big data owners with tools to safely share their social networks data with the research community. The project aims to approach graph anonymization via two techniques for graph generation: dK-series techniques, introduced in the context of internet network generation, and Exponential Random Graph Model-based approaches (ERGM). My contribution is related to privacy/ utility measures, and how such graph annonymization techniques could apply on evolving graphs.
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Cloud based publish/subscribe model for Top-k matching over continuous data streams
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Publish/subscribe systems are widely recognized in processing continuous queries over data
streams and are augmented by algorithms coming from the field of data stream processing.
Existing functions which are capable of matching publications & subscriptions in state-of-the-
art publish/subscribe systems are depended on a stateless function which provides only a
Boolean decision on whether a given publication is to be notified to relevant subscriber or not.
But in such systems…Publish/subscribe systems are widely recognized in processing continuous queries over data
streams and are augmented by algorithms coming from the field of data stream processing.
Existing functions which are capable of matching publications & subscriptions in state-of-the-
art publish/subscribe systems are depended on a stateless function which provides only a
Boolean decision on whether a given publication is to be notified to relevant subscriber or not.
But in such systems, the large quantity of received publications may be considered as a sort of
spam, while a system that delivers too few publications might be recognized as non-working.
In our study, we propose an advanced publish/subscribe matching model to control the
unpredictable number of delivered publications over a continuous data-stream, where at a given
time t our model limits the number of delivered publications by parameter k, while ranks them
within a size w of sliding window. A general scoring mechanism is exploited where publications
get scored against personalized user subscription spaces based on the relevancy. We adopt
an inverted-list data structure to index the subscription space to enhance the efficiency of
matching process. Also we focus on the problem of selecting the k-most diverse items from a
relevant result set, in a dynamic setting where Top-k results change over time. We formalize
the above problem of continuous k-diversity as MAXDIVREL which maps to the independent
dominating set problem in graph theory, which is NP-hard. An incremental indexing mechanism
is proposed for handling streaming publications that is based on Locality Sensitive Hashing
(LSH) to diversify Top-k results continuously. Our prototype model is implemented in a cloud
based message broker system and we have designed it to scale on top of Amazon Web Services
(AWS): a scalable cloud-service provider.Other creators
Honors & Awards
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Winner, Grand Challenge, 3rd North American Social Networks Conference (NASN)
International Network for Social Network Analysis
The NASN 2021 Grand Challenge asks researchers to explore a Twitter dataset around COVID disinformation and share their insights.
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Student Travel Grant for PODC '17
ACM SIGACT
Principles of Distributed Computing (PODC) conference held at Washington, DC July 25 - 28th 2017
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ACM Travel Grant for Supercomputing '16
Association of Computation and Machinery
Acceptance Rate 12%
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CINTEC Award for Best Computer Science Thesis 2015
General Convocation - University of Colombo
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Linnaeus Palme Scholarship
International Exchange Programme administered by the International Programme Office for Education and Training and financed by Sida, Swedish International Development Co-operation Agency
I was selected as one of two exchange students (out of 240) to continue education at Umea University, Sweden.
Languages
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English
Native or bilingual proficiency
Organizations
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Association for Computing Machinery (ACM)
SIGHPC Student Member and ACM Professional Member
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Recommendations received
3 people have recommended Sameera
Join now to viewMore activity by Sameera
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Excited to share that AI Snake Oil is one of Nature's 10 best books of 2024! https://lnkd.in/eAJE7hSX The whole first chapter is available online:…
Excited to share that AI Snake Oil is one of Nature's 10 best books of 2024! https://lnkd.in/eAJE7hSX The whole first chapter is available online:…
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Join NAEP's Emerging Professionals Working Group and connect with peers who are passionate about advancing their careers in environmental…
Join NAEP's Emerging Professionals Working Group and connect with peers who are passionate about advancing their careers in environmental…
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This is worth looking at. more here: https://lnkd.in/eHyKHZ95 ↓ Enjoy reading AI papers? Join 100K+ researchers and devs for our weekly summary of…
This is worth looking at. more here: https://lnkd.in/eHyKHZ95 ↓ Enjoy reading AI papers? Join 100K+ researchers and devs for our weekly summary of…
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AND WE'RE OFF! With over 1,800 participants, #Deploy24 is officially underway in Washington, D.C.! Hosted by the U.S. Department of Energy (DOE)…
AND WE'RE OFF! With over 1,800 participants, #Deploy24 is officially underway in Washington, D.C.! Hosted by the U.S. Department of Energy (DOE)…
Liked by Sameera Horawalavithana
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Ive been asked several times recently about using LLMs to evaluate generated texts (LLM as judge). I've written several blogs about this, but…
Ive been asked several times recently about using LLMs to evaluate generated texts (LLM as judge). I've written several blogs about this, but…
Liked by Sameera Horawalavithana
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USDA is proud to release the Agriculture and Forestry Greenhouse Gas Inventory Data Viewer. This interactive visualization tool allows users to…
USDA is proud to release the Agriculture and Forestry Greenhouse Gas Inventory Data Viewer. This interactive visualization tool allows users to…
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