Fisheries management is a laborious task that relies on data analysis using complex models and fi... more Fisheries management is a laborious task that relies on data analysis using complex models and finegrained software over several sources of information in order to deduce certain facts with the overall aim of improving the sustainability of fisheries. It includes the usually manual process of identifying and combining different parts of information, which is an extremely time-consuming and error-prone process. The key indicators for efficient fisheries management are stocks and fisheries. Stocks refer to groups or individuals of a species occupying a well-defined spatial range (e.g. swordfish in the Mediterranean Sea). Fisheries describe the activities leading to the harvesting of the fish within a particular area, using a particular method or equipment and purpose of activity (e.g. the Atlantic cod fishery in the area of East and South Greenland). The knowledge of the status and the trends of stocks and fisheries at regional, national and local levels is the key factor for highly r...
This paper elaborates on the problem of provenance for both physical and digital objects. In part... more This paper elaborates on the problem of provenance for both physical and digital objects. In particular it discusses provenance according to OAIS (ISO 14721: 2003) and how it relates with the conceptualization of CIDOC CRM ontology (ISO 21127: 2006). ...
Abstract: One of the distinctive features of Information Retrieval systems comparing to Database ... more Abstract: One of the distinctive features of Information Retrieval systems comparing to Database Management systems, is that they offer better compression for posting lists, resulting in better I/O performance and thus faster query evaluation. In this paper, we ...
The capability for long term preservation of earth science data is a key requirement to support o... more The capability for long term preservation of earth science data is a key requirement to support on-going research and collaboration within and between many earth science disciplines. A number of critically important current research directions (e.g. understanding climate change, and ensuring sustainability of natural resources) rely on the preservation of data often collected over several decades in a form in which it can be accessed and used easily. In many branches of the earth sciences the capture of key observational data may be difficult or impossible to repeat. For example, a specific geological exposure or subsurface borehole may be only temporarily available, and deriving earth observation data from a particular satellite mission is clearly often a unique opportunity. At the same time such unrepeatable observations may be a critical input to environmental, economic and political decision making. Another key driver for strategic long term data preservation is that key researc...
One of the distinctive features of Information Retrieval systems comparing to Database Management... more One of the distinctive features of Information Retrieval systems comparing to Database Management systems, is that they offer better compression for posting lists, resulting in better I/O performance and thus faster query evaluation. In this paper, we introduce database representations of the index that reduce the size (and thus the disk I/Os) of the posting lists. This is not achieved by redesigning the DBMS, but by exploiting the non 1NF features that existing Object-Relational DBM systems (ORDBMS) already offer. Specifically, four different database representations are described and detailed experimental results for one million pages are reported. Three of these representations are one order of magnitude more space efficient and faster (in query evaluation) than the plain relational representation.
Fisheries management is a laborious task that relies on data analysis using complex models and fi... more Fisheries management is a laborious task that relies on data analysis using complex models and finegrained software over several sources of information in order to deduce certain facts with the overall aim of improving the sustainability of fisheries. It includes the usually manual process of identifying and combining different parts of information, which is an extremely time-consuming and error-prone process. The key indicators for efficient fisheries management are stocks and fisheries. Stocks refer to groups or individuals of a species occupying a well-defined spatial range (e.g. swordfish in the Mediterranean Sea). Fisheries describe the activities leading to the harvesting of the fish within a particular area, using a particular method or equipment and purpose of activity (e.g. the Atlantic cod fishery in the area of East and South Greenland). The knowledge of the status and the trends of stocks and fisheries at regional, national and local levels is the key factor for highly r...
This paper elaborates on the problem of provenance for both physical and digital objects. In part... more This paper elaborates on the problem of provenance for both physical and digital objects. In particular it discusses provenance according to OAIS (ISO 14721: 2003) and how it relates with the conceptualization of CIDOC CRM ontology (ISO 21127: 2006). ...
Abstract: One of the distinctive features of Information Retrieval systems comparing to Database ... more Abstract: One of the distinctive features of Information Retrieval systems comparing to Database Management systems, is that they offer better compression for posting lists, resulting in better I/O performance and thus faster query evaluation. In this paper, we ...
The capability for long term preservation of earth science data is a key requirement to support o... more The capability for long term preservation of earth science data is a key requirement to support on-going research and collaboration within and between many earth science disciplines. A number of critically important current research directions (e.g. understanding climate change, and ensuring sustainability of natural resources) rely on the preservation of data often collected over several decades in a form in which it can be accessed and used easily. In many branches of the earth sciences the capture of key observational data may be difficult or impossible to repeat. For example, a specific geological exposure or subsurface borehole may be only temporarily available, and deriving earth observation data from a particular satellite mission is clearly often a unique opportunity. At the same time such unrepeatable observations may be a critical input to environmental, economic and political decision making. Another key driver for strategic long term data preservation is that key researc...
One of the distinctive features of Information Retrieval systems comparing to Database Management... more One of the distinctive features of Information Retrieval systems comparing to Database Management systems, is that they offer better compression for posting lists, resulting in better I/O performance and thus faster query evaluation. In this paper, we introduce database representations of the index that reduce the size (and thus the disk I/Os) of the posting lists. This is not achieved by redesigning the DBMS, but by exploiting the non 1NF features that existing Object-Relational DBM systems (ORDBMS) already offer. Specifically, four different database representations are described and detailed experimental results for one million pages are reported. Three of these representations are one order of magnitude more space efficient and faster (in query evaluation) than the plain relational representation.
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Papers by Yannis Marketakis