Using Provenance for Quality Assessment and Repair in Linked Open Data

As the number of data sources publishing their data on the Web of Data is growing, we are experiencing an immense growth of the Linked Open Data cloud. The lack of control on the published sources, which could be untrustworthy or unreliable, along with their dynamic nature that often invalidates links and causes conflicts or other discrepancies, could lead to poor quality data. In order to judge data quality, a number of quality indicators have been proposed, coupled with quality metrics that quantify the “quality level” of a dataset. In addition to the above, some approaches address how to improve the quality of the datasets through a repair process that focuses on how to correct invalidities caused by constraint violations by either removing or adding triples. In this paper we argue that provenance is a critical factor that should be taken into account during repairs to ensure that the most reliable data is kept. Based on this idea, we propose quality metrics that take into account provenance and evaluate their applicability as repair guidelines in a particular data fusion setting

Updating DL-Lite ontologies through first-order queries

In this paper we study instance-level update in DL-LiteA, the description logic underlying the OWL 2 QL standard. In particular we focus on formula-based approaches to ABox insertion and deletion. We show that DL-LiteA, which is well-known for enjoying first-order rewritability of query answering, enjoys a first-order rewritability property also for updates. That is, every update can be reformulated into a set of insertion and deletion instructions computable through a nonrecursive datalog program. Such a program is readily translatable into a first-order query over the ABox considered as a database, and hence into SQL. By exploiting this result, we implement an update component for DLLiteA-based systems and perform some experiments showing that the approach works in practice.Peer ReviewedPostprint (author's final draft

Get my pizza right: Repairing missing is-a relations in ALC ontologies (extended version)

With the increased use of ontologies in semantically-enabled applications, the issue of debugging defects in ontologies has become increasingly important. These defects can lead to wrong or incomplete results for the applications. Debugging consists of the phases of detection and repairing. In this paper we focus on the repairing phase of a particular kind of defects, i.e. the missing relations in the is-a hierarchy. Previous work has dealt with the case of taxonomies. In this work we extend the scope to deal with ALC ontologies that can be represented using acyclic terminologies. We present algorithms and discuss a system

Methinks: Enabling Sophisticated Comment Management in the Social Web

User reviews, comments and votes on the Social Web form the modern version of word-of-mouth communication, which has a huge impact on people’s shopping habits, businesses and the overall market. Despite that, systems have so far limited practical success in helping consumers and businesses analysing, managing and understanding Social Web content. In this paper, we present a new tool that leverages a combination of techniques from Semantic Web, Computational Argumentation and Crowdsourcing to support this activity, through an intuitive and functional user interface

Existence of Monetary Steady States in a Matching Model: Indivisible Money

Existence of a monetary steady state is established for a random matching model with divisible goods, indivisible money, and take-it-or-leave-it offers by consumers. There is no restriction on individual money holdings. The background environment is that in papers by Shi and by Trejos and Wright. The monetary steady state shown to exist has nice properties: the value function, defined on money holdings, is increasing and strictly concave, and the measure over money holdings has full support.

Θεωρία Κατηγοριών και Θεμέλια των Μαθηματικών

130 σ.Η διπλωματική καταπιάνεται με την μελέτη των στοιχειωδων εννοιών της Θεωρίας Κατηγοριών και της θεωρίας Τόπων καθώς και με την διαπραγμάτευση των θεμελιωδών φιλοσοφικών προβλημάτων που εγείρονται από αυτην σε σχέση με τα θεμέλια των Μαθηματικών.This thesis is on the basic facts about Category and Topos Theory and axamine the foundamental philosophical problems which couse in the fields of the foundations of mathematics.Ζαχαρίας Μ. Φλουρή

Analysis of the dynamic air conditioning loads, fuel consumption and emissions of heavy-duty trucks with different glazing and paint optical properties

The European transportation sector employs 10 million people and accounts for 4.6% of the European Union GDP. Due to climate change, this workforce is increasingly affected by high temperatures and radiant loads, particularly during summer. They rely on air conditioning (AC) to minimize heat inside the truck cabins, increasing fuel consumption and tailpipe emissions. Because sustainable transportation is crucial for climate change mitigation, we developed a numerical investigation on the dynamic thermal exchanges of cabins of heavy-duty trucks in realistic conditions of a summer workday, to quantify the potential impact of interventions in the glazing and paint optical properties, over the truck AC loads. We observed that the changes in air temperature and solar irradiation throughout the workday imply substantial variations in the truck's AC loads and, consequently, in its fuel consumption and tailpipe emissions. Furthermore, windshields and side windows with transmissivity of 0.33 instead of typical 0.79 and 0.84, respectively, can reduce AC loads by up to 16%. External paints with reflectivity of 0.70 instead of 0.04 can reduce the AC loads by up to 30%, whereas cumulative changes to glazing and paint can reduce the AC load by up to 40%. These interventions can lower fuel consumption and emissions by up to 0.4%. These results show that important improvements in fuel efficiency and tailpipe emissions are possible, if the research community, policy makers and industry stakeholders successfully promote the adaptation of the European transportation fleet

Instruments to assess secondhand smoke exposure in large cohorts of never smokers: The smoke scales

© 2014 The Authors. Published by PLOS. This is an open access article available under a Creative Commons licence. The published version can be accessed at the following link on the publisher’s website: https://doi.org/10.1371/journal.pone.0085809The objectives of this study were to: (i) to develop questionnaires that can identify never-smoking children and adults experiencing increased exposure to secondhand smoke (SHS+), (ii) to determine their validity against hair nicotine, and (iii) assess their reliability. A sample of 191 children (85 males; 106 females; 7-18 years) and 95 adult (23 males; 72 females; 18- 62 years) never-smokers consented to hair nicotine analysis and answered a large number of questions assessing all sources of SHS. A randomly-selected 30% answered the questions again after 20-30 days. Prevalence of SHS+ in children and adults was 0.52±0.07 and 0.67±0.10, respectively (p16.5 and >16, respectively. Significant Kappa agreement (p0.05). Area under the curve and McNemar's Chi-square showed no pair-wise differences in sensitivity and specificity at the cutoff point between the two different days for SS-C and SS-A (p>0.05). We conclude that the SS-C and the SS-A represent valid, reliable, practical, and inexpensive instruments to identify children and adult never-smokers exposed to increased SHS. Future research should aim to further increase the validity of the two questionnaires. © 2014 Misailidi et al.Published versio

Bone mineral density in vocational and professional ballet dancers

Summary: According to existing literature, bone health in ballet dancers is controversial. We have verified that, compared to controls, young female and male vocational ballet dancers have lower bone mineral density (BMD) at both impact and non-impact sites, whereas female professional ballet dancers have lower BMD only at non-impact sites. Introduction: The aims of this study were to (a) assess bone mineral density (BMD) in vocational (VBD) and professional (PBD) ballet dancers and (b) investigate its association with body mass (BM), fat mass (FM), lean mass (LM), maturation and menarche. Methods: The total of 152 VBD (13 ± 2.3 years; 112 girls, 40 boys) and 96 controls (14 ± 2.1 years; 56 girls, 40 boys) and 184 PBD (28 ± 8.5 years; 129 females, 55 males) and 160 controls (27 ± 9.5 years; 110 female, 50 males) were assessed at the lumbar spine (LS), femoral neck (FN), forearm and total body by dual-energy X-ray absorptiometry. Maturation and menarche were assessed via questionnaires. Results: VBD revealed lower unadjusted BMD at all anatomical sites compared to controls (p < 0.001); following adjustments for Tanner stage and gynaecological age, female VBD showed similar BMD values at impact sites. However, no factors were found to explain the lower adjusted BMD values in VBD (female and male) at the forearm (non-impact site), nor for the lower adjusted BMD values in male VBD at the FN. Compared to controls, female PBD showed higher unadjusted and adjusted BMD for potential associated factors at the FN (impact site) (p < 0.001) and lower adjusted at the forearm (p < 0.001). Male PBD did not reveal lower BMD than controls at any site. Conclusions: both females and males VBD have lower BMD at impact and non-impact sites compared to control, whereas this is only the case at non-impact site in female PBD. Maturation seems to explain the lower BMD at impact sites in female VBD