Ioannis Anagnostopoulos

Ioannis Anagnostopoulos
University of Thessaly | UTH · Department of Computer Science and Biomedical Informatics

Assoc. Professor

About

188
Publications
65,610
Reads
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2,640
Citations
Citations since 2016
53 Research Items
1528 Citations
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2016201720182019202020212022050100150200250
2016201720182019202020212022050100150200250
2016201720182019202020212022050100150200250

Publications

Publications (188)
Article
Full-text available
In our era of big data and information overload, content consumers utilise a variety of sources to meet their data and informational needs for the purpose of acquiring an in-depth perspective on a subject, as each source is focused on specific aspects. The same principle applies to the online social networks (OSNs), as usually, the end-users mainta...
Chapter
Full-text available
Text classification is the task of assigning a class to a document. Machine Learning enables the automation of Text Classification Tasks, amongst others. Recent advances in the Machine Learning field, such as the introduction of Recurrent Neural Networks, Long Short Term Memory and Gated Recurrent Units, have greatly improved classification results...
Article
Full-text available
The descriptive concepts of “semantic” taxonomies are assigned to content items of the publishing domain for supporting a plethora of operations, mostly regarding the organization and discoverability of the content, as well as for recommendation tasks. However, either not all publishers rely on such structures, or in many cases employ their own pro...
Article
Full-text available
Over the last decade, learning theory performed significant progress in the development of sophisticated algorithms and their theoretical foundations. The theory builds on concepts that exploit ideas and methodologies from mathematical areas such as optimization theory. Regularization is probably the key to address the challenging problem of overfi...
Preprint
Full-text available
The extensive use of online social media has highlighted the importance of privacy in the digital space. As more scientists analyse the data created in these platforms, privacy concerns have extended to data usage within the academia. Although text analysis is a well documented topic in academic literature with a multitude of applications, ensuring...
Chapter
The extensive use of online social media has highlighted the importance of privacy in the digital space. As more scientists analyse the data created in these platforms, privacy concerns have extended to data usage within the academia. Although text analysis is a well documented topic in academic literature with a multitude of applications, ensuring...
Article
Full-text available
Text has traditionally been used to train automated classifiers for a multitude of purposes, such as: classification, topic modelling and sentiment analysis. State-of-the-art LSTM classifier require a large number of training examples to avoid biases and successfully generalise. Labelled data greatly improves classification results, but not all mod...
Article
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The appearance of images in social messages is continuously increasing, along with user engagement with that type of content. Analysis of social images can provide valuable latent information, often not present in the social posts. In that direction, a framework is proposed exploiting latent information from Twitter images, by leveraging the Google...
Conference Paper
In this paper, we propose a framework that uses latent information from Twitter images by employing the Google Cloud Vision API platform aiming at enriching social analytics with semantics and textual information. Our study reveals that user-generated content, linked data as well as hidden concepts and textual information from social images can be...
Article
This article presents LinkZoo, a web-based, linked data enabled tool that supports collaborative management of information resources. LinkZoo addresses the modern needs of information-intensive collaboration environments to publish, manage, and share heterogeneous resources within user-driven contexts. Users create and manage diverse types of resou...
Article
Full-text available
Sentiment analysis usually refers to the analysis of human-generated content via a polarity filter. Affective computing deals with the exact emotions conveyed through information. Emotional information most frequently cannot be accurately described by a single emotion class. Multilabel classifiers can categorize human-generated content in multiple...
Article
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The discovery of influential entities in all kinds of networks (e.g. social, digital, or computer) has always been an important field of study. In recent years, Online Social Networks (OSNs) have been established as a basic means of communication and often influencers and opinion makers promote politics, events, brands or products through viral con...
Conference Paper
In this paper we describe a methodology for measuring the influence and impact of Twitter accounts, by combining their activity, social degree and disseminated content. Experimental results show that the accuracy of our methodology is comparable to an established commercial service, while the distribution of the assigned influence values and their...
Chapter
Full-text available
Scientific projects that require human computation often resort to crowdsourcing. Interested individuals can contribute to a crowdsourcing task, essentially contributing towards the project’s goals. To motivate participation and engagement, scientists use a variety of reward mechanisms. The most common motivation, and the one that yields the fastes...
Chapter
Vehicular ad hoc networks have attracted a lot of research recently, because of the multiple possible applications. Blockchain is a new approach to designing distributed storage infrastructures. In this paper the implementation of a blockchain infrastructure on top of vehicular ad hoc networks is presented. The main motive is to create a peer to pe...
Article
Full-text available
Recently there has been an exponential growth of the number of publicly available legal resources. Portals allowing users to search legal documents, through keyword queries, are now widespread. However, legal documents are mainly stored and offered in different sources and formats that do not facilitate semantic machine-readable techniques, thus ma...
Article
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Nowadays, social networks incessantly influence the lives of young people. Apart from entertainment and informational purposes, social networks have penetrated many fields of educational practices and processes. This review tries to highlight the use of social networks in higher education, as well as points out some factors involved. Moreover, thro...
Chapter
During the last decades, the classification of images constitutes a typical method for diagnosing many abnormalities and diseases. The application of an efficient classification method is considered essential in modern diagnostic medicine in order to increase the number of analyzed patients and decrease the analysis time. The significant storage ca...
Article
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Background: The application of Health Information Technologies (HITs) can be an effective way to advance medical research and health services provision. The two-fold objective of this work is to: (i) identify and review state-of-the-art HITs that facilitate the aims of evidence-based medicine and (ii) propose a methodology for HIT assessment. Met...
Chapter
In this paper, we propose a model conceptualization (Linked Open Economy - LOE) capable of exploiting the massive amount and variety of open economic data that are gradually becoming available by governments and open source communities. The main aim is to unleash the power of open data and open source systems and create a common ground to serve as...
Article
The Web has been identified to consist of a large portion of content that cannot be crawled by general-purpose search engines because it is only generated after a valid submission to a search interface. Accessing such content, however, requires the location and identification of search interfaces. Towards the automation of this task, many approache...
Article
The increasing availability of diverse multidimensional data on the web has led to the creation and adoption of common vocabularies and practices that facilitate sharing, aggregating and reusing data from remote origins. One prominent example in the Web of Data is the RDF Data Cube vocabulary, which has recently attracted great attention from the i...
Article
Full-text available
Information flows are the result of a constant exchange in Online Social Networks (OSNs). OSN users create and share varying types of information in real-time throughout a day. Virality is introduced as a term to describe information that reaches a wide audience within a small time-frame. As a case, we measure propagation of information submitted i...
Conference Paper
HEVC has emerged as the new video coding standard promising improved compression ratios (for the same quality) by up to 50% compared to H.264/AVC. To achieve this performance HEVC requires increased computational overhead compared to its predecessor. For this reason parallelism is used, usually at a coarse grained level, e.g., per slice or tile. In...
Article
Full-text available
Our work examines the risks and benefits stemming from the evolution of Social Network Services (SNSs) in the healthcare domain. More specifically, we study the impact of specific health-oriented social networks such as PatientsLikeMe. Social networks evolved to a ubiquitous part of daily life and WEB 2.0 paved the way for the internet to be used a...
Article
Full-text available
"Public legal information from all countries and international institutions is part of the common heritage of humanity. Maximizing access to this information promotes justice and the rule of law". In accordance with the aforementioned declaration on free access to law by legal information institutes of the world, a plethora of legal information is...
Article
Full-text available
Towards the provision of medical research and eHealth services, several Health Information Technology (HIT) platforms are blended with communication and software technologies (i.e. mobile and Web applications, wireless sensor networks, Internet of Things and cloud computing). However, an important research issue is whether and to what degree these...
Chapter
Full-text available
Healthcare provision is a set of activities that demands the collaboration of several stakeholders (e.g. physicians, nurses, managers, patients etc.) who hold distinct expertise and responsibilities. In addition, medical knowledge is diversely located and often shared under no central coordination and supervision authority, while medical data flows...
Preprint
Full-text available
"Public legal information from all countries and international institutions is part of the common heritage of humanity. Maximizing access to this information promotes justice and the rule of law". In accordance with the aforementioned declaration on Free Access to Law by Legal information institutes of the world, a plethora of legal information is...
Conference Paper
During the last years, a lot of research has been conducted in the field of Decentralized Online Social Networks (DOSNs). Due to limited dependency on a dedicated central-based infrastructure, such kind of social networking enhances the privacy of users' personal data and information in case of local attacks, yet on the other hand suffers in terms...
Conference Paper
HEVC has emerged as the new video standard to replace H.264/AVC. Although the new standard is able to achieve significantly higher compression ratios compared to the older one, it entails high computational demands. To alleviate the problem, parallelism opportunities are offered by the standard at different levels namely, slice, tile and wave front...
Conference Paper
The number of freely available legal data sets is increasing at high speed. Citizens can easily access a lot of information about regulations, court orders, statutes, opinions and analytical documents. Such openness brings undeniable benefits in terms of transparency, participation and availability of new services. However, legal information overlo...
Conference Paper
As the volume data grows exponentially, more and more big data handling approaches are also applied in the linked data cloud. Thus, semantic triplets which are nucleus of the Resource Description Framework (RDF) must be harmonized to the demanding needs of the 4 Vs. This paper presents the architecture and the main components of a big linked data r...
Conference Paper
In this paper, we propose an iterative algorithm towards the automatic labeling of Twitter accounts in respect to thematic categories derived from DBpedia properties. We describe the rationale behind the selection of these thematic categories, and discuss their evaluation assessment. Finally, we propose and analyze two generic and adaptable methodo...
Conference Paper
The healthcare domain is mission critical and vast research efforts keep being funded in order to improve life quality of people. Health management consists of specific cooperation intensive activities, while medical knowledge and systems are spatially and functionally distributed. Also, medical data flows are inefficient for dynamic data delivery...
Conference Paper
“Public legal information from all countries and international institutions is part of the common heritage of humanity. Maximizing access to this information promotes justice and the rule of law.” In accordance with the aforementioned declaration on Free Access to Law by Legal information institutes of the world (http:// www. worldlii. org/ worldli...
Conference Paper
For decades, valuable economic data was out of reach for most of the people. Gradually, public budgets and tenders are becoming openly available and global initiatives promote financial transparency and data innovation. But, yet the poor quality of open data undermines their potential to answer interesting questions (e.g. efficiency of public funds...
Article
Full-text available
In every environment of information exchange, Information Quality (IQ) is considered one of the most important issues. Studies in Online Social Networks (OSNs) analyze a number of related subjects that span both theoretical and practical aspects, from data quality identification and simple attribute classification to quality assessment models for v...
Article
On daily basis, millions of Twitter accounts post a vast number of tweets including numerous Twitter entities (mentions, replies, hashtags, photos, URLs). Many of these entities are used in common by many accounts. The more common entities are found in the messages of two different accounts, the more similar, in terms of content or interest, they t...
Article
Full-text available
Today, an enormous amount of data is being continuously generated in all walks of life by all kinds of devices and systems every day. A significant portion of such data is being captured, stored, aggregated and analyzed in a systematic way without losing its “4V” (i.e., volume, velocity, variety, and veracity) characteristics. We review major drive...
Conference Paper
Full-text available
Multidimensional data are published in the web of data under common directives, such as the Resource Description Framework (RDF). The increasing volume and diversity of these data pose the challenge of finding relations between them in a most efficient and accurate way, by taking into advantage their overlapping schemes. In this paper we define two...
Preprint
For decades, information related to public finances was out of reach for most of the people. Gradually, public budgets and tenders are becoming openly available and global initiatives promote fiscal transparency and open product and price data. But, the poor quality of economic open data undermines their potential to answer interesting questions (e...
Conference Paper
In this paper, we propose an ontology schema towards linking semantified Twitter social analytics with the Linked Open Data cloud. The ontology is deployed over a publicly available service that measures how influential a Twitter account is by combining its social activity in Twitter. According to our knowledge this is the first work that combines...
Conference Paper
Full-text available
In nowadays, the majority of health care provision supported by Information Technology (IT) services including Internet, cloud tech, e-commerce, e-health etc. Some emerging issues around the application of these technologies and services are on the one hand their quality assurance, reliability and security. On the other hand research efforts also f...
Conference Paper
Mobile applications (apps) have become part of our everyday life with a constantly increasing market. Of particular interest are apps aiding planning and collaboration among family members, or between co-workers. The architecture of such apps usually involves some Cloud storage medium, through which group members post and retrieve data. Naturally,...
Conference Paper
Full-text available
The topic of Information diffusion has been in the centre of sociology interest for many years. Even before the rise of Online Social Networks (OSNs), social ties and the way the information flows have been studied in traditional real-life social networks. In this paper, we propose the concept of multilayer information flow, by considering every On...
Article
The PSGR project is the first attempt to generate, curate, interlink and distribute daily updated public spending data in LOD formats that can be useful to both expert (i.e. scientists and professionals) and naïve users. The PSGR ontology is based on the UK payments ontology and reuses, among others, the W3C Registered Organization Vocabulary and t...
Article
Full-text available
Legislators, designers of legal information systems, as well as citizens face often problems due to the interdependence of the laws and the growing number of references needed to interpret them. Quantifying this complexity is not an easy task. In this paper, we introduce the "Legislation Network" as a novel approach to address related problems. We...
Conference Paper
Full-text available
Legislators, designers of legal information systems, as well as citizens face often problems due to the interdependence of the laws and the growing number of references needed to interpret them. Quantifying this complexity is not an easy task. In this paper, we introduce the " Legislation Network " as a novel approach to address related problems. W...
Conference Paper
he vast amounts of data generated, exchanged and consumed on a daily basis by contemporary networks and devices renders their analysis a cumbersome procedure with inherent difficulties. On the one hand, the need for efficient Machine Learning algorithms and tools that scale on large datasets is continuously growing. On the other, parallel or distri...
Conference Paper
Full-text available
In this paper we present a preliminary analysis over the largest publicly accessible web dataset: the Common Crawl Corpus. We measure nine web characteristics from two levels of granularity using MapReduce and we comment on the initial observations over a fraction of it. To the best of our knowledge two of the characteristics, the language distribu...
Conference Paper
Full-text available
In this paper, we propose an ontology schema towards semantification provision of Twitter social analytics. The ontology is deployed over a publicly available service that measures how influential a Twitter account is, by combining its social activity and interaction over Twittersphere. Apart from influential quantity and quality measures, the serv...
Article
Virtual Worlds evolution is breaking the barriers of virtual isolation, thus allowing users to participate in geographically dispersed and culturally diverse places. At the same time, mobile agents have been established as a solid programming method for heterogeneous networking and computing environments. Our work focuses on the definition of a dis...
Conference Paper
Full-text available
The main contributions of this paper are an automated approach for applying the ABCDE rules in a digital dermoscopy platform with fixed settings and a new registration method specially designed for aligning and comparing follow-up digital dermoscopy images in order to evaluate the evolution over time parameter E. Experimental evaluations of the reg...
Article
Social graphs can be easily extracted from Online Social Networks. However these networks are getting larger from day to day. Sampling methods used to evaluate graph information cannot accurately extract graph properties. Furthermore Social Networks are limiting the access to their data, making the crawling process even harder. A novel approach on...
Conference Paper
Full-text available
We describe a methodology of rating the influence of a Twitter ac-count in this famous microblogging service. We then evaluate it over real accounts, under the belief that influence is not only a matter of quantity (amount of followers), but also a mixture of quality measures that reflect interaction, awareness, and visibility in the social sphere....
Article
Since 1950, information flows have been in the centre of scientific research. Up until internet penetration in the late 90s, these studies were based over traditional offline social networks. Several observations in offline information flows studies, such as two-step flow of communication and the importance of weak ties, were verified in several on...
Conference Paper
Full-text available
With the advent and rapid spread of microblogging services, web information management finds a new research topic. Although classical information retrieval methods and techniques help search engines and services to present an adequate precision in lower recall levels (top-k results), the constantly evolving information needs of microblogging users...