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

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

Validation of a dose warping algorithm using clinically realistic scenarios

OBJECTIVE: Dose warping following deformable image registration (DIR) has been proposed for interfractional dose accumulation. Robust evaluation workflows are vital to clinically implement such procedures. This study demonstrates such a workflow and quantifies the accuracy of a commercial DIR algorithm for this purpose under clinically realistic scenarios. METHODS: 12 head and neck (H&N) patient data sets were used for this retrospective study. For each case, four clinically relevant anatomical changes have been manually generated. Dose distributions were then calculated on each artificially deformed image and warped back to the original anatomy following DIR by a commercial algorithm. Spatial registration was evaluated by quantitative comparison of the original and warped structure sets, using conformity index and mean distance to conformity (MDC) metrics. Dosimetric evaluation was performed by quantitative comparison of the dose–volume histograms generated for the calculated and warped dose distributions, which should be identical for the ideal “perfect” registration of mass-conserving deformations. RESULTS: Spatial registration of the artificially deformed image back to the planning CT was accurate (MDC range of 1–2 voxels or 1.2–2.4 mm). Dosimetric discrepancies introduced by the DIR were low (0.02 ± 0.03 Gy per fraction in clinically relevant dose metrics) with no statistically significant difference found (Wilcoxon test, 0.6 ≥ p ≥ 0.2). CONCLUSION: The reliability of CT-to-CT DIR-based dose warping and image registration was demonstrated for a commercial algorithm with H&N patient data. ADVANCES IN KNOWLEDGE: This study demonstrates a workflow for validation of dose warping following DIR that could assist physicists and physicians in quantifying the uncertainties associated with dose accumulation in clinical scenarios

Analyzing the Evolution of Vocabulary Terms and Their Impact on the LOD Cloud

Vocabularies are used for modeling data in Knowledge Graphs (KGs) like the Linked Open Data Cloud and Wikidata. During their lifetime, vocabularies are subject to changes. New terms are coined, while existing terms are modified or deprecated. We first quantify the amount and frequency of changes in vocabularies. Subsequently, we investigate to which extend and when the changes are adopted in the evolution of KGs. We conduct our experiments on three large-scale KGs: the Billion Triples Challenge datasets, the Dynamic Linked Data Observatory dataset, and Wikidata. Our results show that the change frequency of terms is rather low, but can have high impact due to the large amount of distributed graph data on the web. Furthermore, not all coined terms are used and most of the deprecated terms are still used by data publishers. The adoption time of terms coming from different vocabularies ranges from very fast (few days) to very slow (few years). Surprisingly, we could observe some adoptions before the vocabulary changes were published. Understanding the evolution of vocabulary terms is important to avoid wrong assumptions about the modeling status of data published on the web, which may result in difficulties when querying the data from distributed sources

Direct measurement of local oxygen concentration in the bone marrow of live animals

Characterizing how the microenvironment, or niche, regulates stem cell activity is central to understanding stem cell biology and to developing strategies for therapeutic manipulation of stem cells1. Low oxygen tension (hypoxia) is commonly thought to be a shared niche characteristic in maintaining quiescence in multiple stem cell types2–4. However, support for the existence of a hypoxic niche has largely come from indirect evidence such as proteomic analysis5, expression of HIF-1 and related genes6, and staining with surrogate hypoxic markers (e.g. pimonidazole)6–8. Here we perform direct in vivo measurements of local oxygen tension (pO2) in the bone marrow (BM) of live mice. Using two-photon phosphorescence lifetime microscopy (2PLM), we determined the absolute pO2 of the BM to be quite low (<32 mmHg) despite very high vascular density. We further uncovered heterogeneities in local pO2, with the lowest pO2 (~9.9 mmHg, or 1.3%) found in deeper peri-sinusoidal regions. The endosteal region, by contrast, is less hypoxic as it is perfused with small arteries that are often positive for the marker nestin. These pO2 values change dramatically after radiation and chemotherapy, pointing to the role of stress in altering the stem cell metabolic microenvironment

Contra aquam remigare*: Reimagining humanistic paideia through comparative-historical analysis of education

This article attempts a reading of Andreas M. Kazamias’s work and method as a persistent and firmly grounded attempt to “go against the tide” of an empirical/instrumentalist comparative education and toward a “modernist episteme.” Kazamias has been explicitly critical of the social-scientific-cum-positivist comparative education, while at the same time acknowledging the limitations of the traditional historical-philosophical-humanistic approach. His “revisionist” comparative-historical analysis seeks to combine history with social science toward an “anthropocentric” comparative education, “concerned with the great problems—political, social but also ethical—which ‘mankind’ faces.” Consistent with his rejection of instrumental/“techno-scientific” approaches to comparative education, Kazamias argues for a promethean humanistic education (i.e., paideia, liberal education, culture générale, bildung) cultivating the soul and the mind, aiming at both the Platonic/Socratic psyche and the Aristotelian phronesis. © Taylor & Francis Group, LLC

Assessing the strength of democratic institutions associated with modern universities: the case of the Greek university

This paper proposes the establishment of a systematic framework for measuring dimensions of democracy within a university. It is shown that certain indicators internationally established and validated for the measurement of the institutional characteristics of democracy can, through appropriate adaptation, be transferred to the university field. A new model of mapping these characteristics to the university field was built using all available knowledge from international surveys, valid databases and researches conducted using questionnaires and structured interviews, specifically for the purposes of this paper. Chord diagrams, capable of providing meaningful dynamic graphical representations, were employed as a novel evaluative tool that highlights the existence and degree of significant interrelations between democracy indicators and democratic characteristics of the university. As a case study, we have chosen to analyze, compare and contrast the three most representative laws governing the operation of Greek universities for the last 35 years using the proposed model. Its operation, validity and capabilities were verified, after encapsulating the complex interdependencies among its variables, for a large time period, influenced by adverse social and economic changes. Thus, it can be used as an effective tool for comparisons among different universities, with respect to their democratic constitution. © 2020, The European Higher Education Society