Search Results for author: Nicolas Kourtellis

Found 18 papers, 9 papers with code

PPFL: Privacy-preserving Federated Learning with Trusted Execution Environments

1 code implementation29 Apr 2021 Fan Mo, Hamed Haddadi, Kleomenis Katevas, Eduard Marin, Diego Perino, Nicolas Kourtellis

We propose and implement a Privacy-preserving Federated Learning ($PPFL$) framework for mobile systems to limit privacy leakages in federated learning.

Federated Learning

The Rise and Fall of Fake News sites: A Traffic Analysis

1 code implementation16 Mar 2021 Manolis Chalkiadakis, Alexandros Kornilakis, Panagiotis Papadopoulos, Evangelos P. Markatos, Nicolas Kourtellis

In this paper, we perform a first of its kind investigation to answer such questions regarding the online presence of fake news websites and characterize their behavior in comparison to real news websites.

Misinformation

User Tracking in the Post-cookie Era: How Websites Bypass GDPR Consent to Track Users

1 code implementation17 Feb 2021 Emmanouil Papadogiannakis, Panagiotis Papadopoulos, Nicolas Kourtellis, Evangelos P. Markatos

As a result, users' choices play very little role with respect to tracking: we measured that more than 75% of tracking activities happened before users had the opportunity to make a selection in the cookie consent banner, or when users chose to reject all cookies.

Computers and Society Cryptography and Security K.4.2

FLaaS: Federated Learning as a Service

no code implementations18 Nov 2020 Nicolas Kourtellis, Kleomenis Katevas, Diego Perino

Indeed, FL enables local training on user devices, avoiding user data to be transferred to centralized servers, and can be enhanced with differential privacy mechanisms.

Federated Learning Object Detection

Not one but many Tradeoffs: Privacy Vs. Utility in Differentially Private Machine Learning

1 code implementation20 Aug 2020 Benjamin Zi Hao Zhao, Mohamed Ali Kaafar, Nicolas Kourtellis

In this work, we empirically evaluate various implementations of differential privacy (DP), and measure their ability to fend off real-world privacy attacks, in addition to measuring their core goal of providing accurate classifications.

Cryptography and Security

I call BS: Fraud Detection in Crowdfunding Campaigns

no code implementations30 Jun 2020 Beatrice Perez, Sara R. Machado, Jerone T. A. Andrews, Nicolas Kourtellis

Donations to charity-based crowdfunding environments have been on the rise in the last few years.

Fraud Detection

Detecting Cyberbullying and Cyberaggression in Social Media

no code implementations20 Jul 2019 Despoina Chatzakou, Ilias Leontiadis, Jeremy Blackburn, Emiliano De Cristofaro, Gianluca Stringhini, Athena Vakali, Nicolas Kourtellis

We also explore specific manifestations of abusive behavior, i. e., cyberbullying and cyberaggression, in one of the hate-related communities (Gamergate).

A Self-Attentive Emotion Recognition Network

1 code implementation24 Apr 2019 Harris Partaourides, Kostantinos Papadamou, Nicolas Kourtellis, Ilias Leontiadis, Sotirios Chatzis

Modern deep learning approaches have achieved groundbreaking performance in modeling and classifying sequential data.

Emotion Recognition

Cookie Synchronization: Everything You Always Wanted to Know But Were Afraid to Ask

no code implementations26 May 2018 Panagiotis Papadopoulos, Nicolas Kourtellis, Evangelos P. Markatos

In this paper, we perform a first to our knowledge in-depth study of CSync in the wild, using a year-long weblog from 850 real mobile users.

The Web of False Information: Rumors, Fake News, Hoaxes, Clickbait, and Various Other Shenanigans

no code implementations10 Apr 2018 Savvas Zannettou, Michael Sirivianos, Jeremy Blackburn, Nicolas Kourtellis

In this work, we pay particular attention to political false information as: 1) it can have dire consequences to the community (e. g., when election results are mutated) and 2) previous work show that this type of false information propagates faster and further when compared to other types of false information.

Social and Information Networks Computers and Society

A Unified Deep Learning Architecture for Abuse Detection

no code implementations1 Feb 2018 Antigoni-Maria Founta, Despoina Chatzakou, Nicolas Kourtellis, Jeremy Blackburn, Athena Vakali, Ilias Leontiadis

Hate speech, offensive language, sexism, racism and other types of abusive behavior have become a common phenomenon in many online social media platforms.

Abuse Detection

Large Scale Crowdsourcing and Characterization of Twitter Abusive Behavior

6 code implementations1 Feb 2018 Antigoni-Maria Founta, Constantinos Djouvas, Despoina Chatzakou, Ilias Leontiadis, Jeremy Blackburn, Gianluca Stringhini, Athena Vakali, Michael Sirivianos, Nicolas Kourtellis

In recent years, offensive, abusive and hateful language, sexism, racism and other types of aggressive and cyberbullying behavior have been manifesting with increased frequency, and in many online social media platforms.

Social and Information Networks 68T06 K.4.2

Measuring #GamerGate: A Tale of Hate, Sexism, and Bullying

no code implementations24 Feb 2017 Despoina Chatzakou, Nicolas Kourtellis, Jeremy Blackburn, Emiliano De Cristofaro, Gianluca Stringhini, Athena Vakali

Over the past few years, online aggression and abusive behaviors have occurred in many different forms and on a variety of platforms.

Mean Birds: Detecting Aggression and Bullying on Twitter

1 code implementation22 Feb 2017 Despoina Chatzakou, Nicolas Kourtellis, Jeremy Blackburn, Emiliano De Cristofaro, Gianluca Stringhini, Athena Vakali

In recent years, bullying and aggression against users on social media have grown significantly, causing serious consequences to victims of all demographics.

Computers and Society Social and Information Networks

VHT: Vertical Hoeffding Tree

no code implementations28 Jul 2016 Nicolas Kourtellis, Gianmarco De Francisci Morales, Albert Bifet, Arinto Murdopo

IoT Big Data requires new machine learning methods able to scale to large size of data arriving at high speed.

Partial Key Grouping: Load-Balanced Partitioning of Distributed Streams

2 code implementations26 Oct 2015 Muhammad Anis Uddin Nasir, Gianmarco De Francisci Morales, David Garcia-Soriano, Nicolas Kourtellis, Marco Serafini

We study the problem of load balancing in distributed stream processing engines, which is exacerbated in the presence of skew.

Distributed, Parallel, and Cluster Computing

Dynamic Matrix Factorization with Priors on Unknown Values

1 code implementation23 Jul 2015 Robin Devooght, Nicolas Kourtellis, Amin Mantrach

In each case, we outrank state-of-the-art matrix factorization methods that do not use a prior on unknown ratings.

Collaborative Filtering

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