Using Ontologies for Semantic Data Integration

While big data analytics is considered as one of the most important paths to competitive advantage of today’s enterprises, data scientists spend a comparatively large amount of time in the data preparation and data integration phase of a big data project. This shows that data integration is still a major challenge in IT applications. Over the past two decades, the idea of using semantics for data integration has become increasingly crucial, and has received much attention in the AI, database, web, and data mining communities. Here, we focus on a specific paradigm for semantic data integration, called Ontology-Based Data Access (OBDA). The goal of this paper is to provide an overview of OBDA, pointing out both the techniques that are at the basis of the paradigm, and the main challenges that remain to be addressed

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

A DSP equipped digitizer for online analysis of nuclear detector signals

In the framework of the NUCL-EX collaboration, a DSP equipped fast digitizer has been implemented and it has now reached the production stage. Each sampling channel is implemented on a separate daughter-board to be plugged on a VME mother-board. Each channel features a 12-bit, 125 MSamples/s ADC and a Digital Signal Processor (DSP) for online analysis of detector signals. A few algorithms have been written and successfully tested on detectors of different types (scintillators, solid-state, gas-filled), implementing pulse shape discrimination, constant fraction timing, semi-Gaussian shaping, gated integration

Linear electronics for Si-detectors and its energy calibration for use in heavy ion experiments

Abstract The design and implementation of linear electronics based on small-size, low-power charge preamplifiers and shaping amplifiers, used in connection with Si-detector telescopes employed in heavy ion experiments, are presented. Bench tests and "under beam" performances are discussed. In particular, the energy calibration and the linearity test of the overall system (Si-detector and linear and digital conversion electronics) has been performed with a procedure which avoids the pulse height defect problems connected with the detection of heavy ions. The procedure, basically, consists of using bursts of MeV protons, releasing up to GeV energies inside the detector, with low ionization density

Lung cancer surgery in octogenarians: a meta-analysis of predictors for postoperative complications

Background: Recently, several reports had focused on the feasibility of lung cancer surgery in octogenarians, describing encouraging short and long-term survival. However, the postoperative complication rate remains high. Some papers analyzed the role of potential predictors of post-operative complications, showing discordant results. We aimed at systematically assessing the evidence on risk factors for post-operative complications in octogenarians undergoing lung cancer surgery. Methods: Literature search was performed through PubMed and MEDLINE using the terms “lung cancer”, “non-small cell lung cancer” or “lung cancer surgery” combined with “octogenarian” or “80 years”. Last search was performed on 03/2021. Inclusion criteria were: clinical studies involving octogenarians undergoing lung cancer surgery between 1990 and 2020; studies explicitly appraising risk factors for postoperative complications and providing adjusted risk effect estimates. Studies that did not explicitly investigate predictors of postoperative complications and papers published in other language than English were not included. Risk of bias was assessed using the Quality in Prognostic Factor Studies (QUIPS) tool. More than 20 potential predictors were screened, finally limiting the inferential analysis to the six most frequently reported: performance status (PS), forced expiratory volume in 1 second (FEV1), type of resection, surgical approach, history of tobacco abuse and male gender. Adjusted P values from individual studies were pooled with the Fisher method. A pooled 2-tailed P value ≤0.05 was considered statistically significant. Results: A final set of 13 cohort studies, including 2,596 patients, was considered. Effect estimates were reported for PS by 6 studies (46%), for FEV1 by 10 (77%), for type of resection by 11 (85%), for surgical approach by 4 (31%), for history of tobacco abuse by 6 (46%), and for male gender by 8 (62%). After inferential analysis with the Fisher method, a significant association with post-operative complications was found for PS (P=0.004), major resections (P=0.002) and open approach (P=0.007); male gender showed only a borderline trend (P=0.053). Preoperative FEV1 (P=0.109) and history of tobacco abuse (P=0.399) were not associated with increased postoperative complications. Conclusions: Lung cancer surgery in octogenarian patients represent a viable and useful treatment. According to our analysis, patients should be carefully selected considering that a good preoperative PS is associated with a lower rate of postoperative complications. Similarly, thoracoscopic approach and sublobar resection should be preferred in octogenarian patients if technically and oncologically sound. Interestingly, impaired lung function was not significantly associated to post-operative complications

Tracking dynamics of magma migration in open-conduit systems

Open-conduit volcanic systems are typically characterized by unsealed volcanic conduits feeding permanent or quasi-permanent volcanic activity. This persistent activity limits our ability to read changes in the monitored parameters, making the assessment of possible eruptive crises more difficult. We show how an integrated approach to monitoring can solve this problem, opening a new way to data interpretation. The increasing rate of explosive transients, tremor amplitude, thermal emissions of ejected tephra, and rise of the very-long- period (VLP) seismic source towards the surface are interpreted as indicating an upward migration of the magma column in response to an increased magma input rate. During the 2014 flank eruption of Stromboli, this magma input pre- ceded the effusive eruption by several months. When the new lateral effusive vent opened on the Sciara del Fuoco slope, the effusion was accompanied by a large ground deflation, a deepening of the VLP seismic source, and the cessation of summit explosive activity. Such observations suggest the drainage of a superficial magma reservoir confined between the crater terrace and the effusive vent. We show how this model successfully reproduces the measured rate of effusion, the observed rate of ground deflation, and the deepening of the VLP seismic source. This study also demonstrates the ability of the geophysical network to detect superficial magma recharge within an open-conduit system and to track magma drainage during the effusive crisis, with a great impact on hazard assessment

Mastro: Ontology-Based Data Access at Work (Extended Abstract)

In this paper we present the current version of Mastro, a system for ontologybased data access (OBDA) developed at Sapienza Università di Roma. Mastro allows users for accessing external data sources by querying an ontology expressed in a fragment of the W3C Web Ontology Language (OWL). As in data integration [5], mappings are used in OBDA to specify the correspondence between a unified view of the domain (called global schema in data integration terminology) and the data stored at the sources. The distinguishing feature of the OBDA approach, however, is the fact that the global schema is specified using an ontology language, which typically allows to provide a rich conceptualization of the domain of interest, independently from the source representation