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Datalog is a rule-based formalism that can axiomatise recursive properties such as reachability and transitive closure. Datalog implementations often materialise (i.e., precompute and store) all facts entailed by a datalog program and a set of explicit facts. Queries can thus be answered directly in the materialised facts, which is beneficial to the performance of query answering, but the materialised facts must be updated whenever the explicit facts change. Rematerialising all facts ‘from scratch’ can be very inefficient, so numerous materialisation maintenance algorithms have been developed that aim to efficiently identify the facts that require updating and thus reduce the overall work. Most such approaches are variants of the counting or Delete/Rederive (DRed) algorithms. Algorithms in the former group maintain additional data structures and are usually applicable only if datalog rules are not recursive, which limits their applicability in practice. Algorithms in the latter group do not require additional data structures and can handle recursive rules, but they can be inefficient when facts have multiple derivations. Finally, to the best of our knowledge, these approaches have not been compared and their practical applicability has not been investigated. Datalog is becoming increasingly important in practice, so a more comprehensive understanding of the tradeoffs between different approaches to materialisation maintenance is needed. In this paper we present three such algorithms for datalog with stratified negation: a new counting algorithm that can handle recursive rules, an optimised variant of the DRed algorithm that does not repeat derivations, and a new Forward/Backward/Forward (FBF) algorithm that extends DRed to better handle facts with multiple derivations. Furthermore, we study the worst-case performance of these algorithms and compare the algorithms' behaviour on several examples. Finally, we present the results of an extensive, first-of-a-kind empirical evaluation in which we investigate the robustness and the scaling behaviour of our algorithms. We thus provide important theoretical and practical insights into all three algorithms that will provide invaluable guidance to future implementors of datalog systems.

Background: Community-acquired pneumonia (CAP) has a potential complication of bacteremia. The objective of this study was to define the clinical outcomes of patients with CAP and bacteremia treated with and without a macrolide. Materials and methods: Secondary analysis of the Community-Acquired Pneumonia Organization database of hospitalized patients with CAP. Patients with a positive blood culture were categorized based on the presence or absence of a macrolide in their initial antimicrobial regimen, and severity of their CAP. Outcomes included inhospital all-cause mortality, 30-day mortality, length of stay, and time to clinical stability. Results: Among 549 patients with CAP and bacteremia, 247 (45%) were treated with a macrolide and 302 (55%) were not. The primary pathogen was Streptococcus pneumoniae (74%). Poisson regression with robust error variance models were used to compare the adjusted effects of each study group on the outcomes. The unadjusted 30-day mortality was 18.4% in the macrolide group, and 29.6% in the non-macrolide group (adjusted relative risk (aRR)0.81; 95% confidence interval (CI)0.50-1.33; P = 0.41). Unadjusted in-hospital all-cause mortality was 7.3% in the macrolide group, and 18.9% in the non-macrolide group (aRR 0.54, 95% CI 0.30-0.98; P = 0.043). Length of stay and time to clinical stability were not significantly different. Conclusions: In-hospital mortality, but not 30-day mortality, was significantly better in the macrolide group. Our data support the use of a macrolide in hospitalized patients with CAP and bacteraemia.

Rewriting is widely used to optimise owl:sameAs reasoning in materialisation based OWL 2 RL systems. We investigate issues related to both the correctness and efficiency of rewriting, and present an algorithm that guarantees correctness, improves efficiency, and can be effectively parallelised. Our evaluation shows that our approach can reduce reasoning times on practical data sets by orders of magnitude., This is the technical report supporting the AAAI 2015 Conference submission with the same title

We present a novel approach to parallel materialisation (i.e., fixpoint computation) of OWL RL Knowledge Bases in centralised, main-memory, multi-core RDF systems. Our approach comprises a datalog reasoning algorithm that evenly distributes the workload to cores, and an RDF indexing data structure that supports efficient, ‘mostly’ lock-free parallel updates. Our empirical evaluation shows that our approach parallelises computation very well so, with 16 physical cores, materialisation can be up to 13.9 times faster than with just one core.

We present RDFox—a main-memory, scalable, centralised RDF store that supports materialisation-based parallel datalog reasoning and SPARQL query answering. RDFox uses novel and highlyefficient parallel reasoning algorithms for the computation and incremental update of datalog materialisations with efficient handling of owl: sameAs. In this system description paper, we present an overview of the system architecture and highlight the main ideas behind our indexing data structures and our novel reasoning algorithms. In addition, we evaluate RDFox on a high-end SPARC T5-8 server with 128 physical cores and 4TB of RAM. Our results show that RDFox can effectively exploit such a machine, achieving speedups of up to 87 times, storage of up to 9.2 billion triples, memory usage as low as 36.9 bytes per triple, importation rates of up to 1 million triples per second, and reasoning rates of up to 6.1 million triples per second.

Datalog-based systems often materialise all consequences of a datalog program and the data, allowing users' queries to be evaluated directly in the materialisation. This process, however, can be computationally intensive, so most systems update the materialisation incrementally when input data changes. We argue that existing solutions, such as the well-known Delete/Rederive (DRed) algorithm, can be inefficient in cases when facts have many alternate derivations. As a possible remedy, we propose a novel Backward/Forward (B/F) algorithm that tries to reduce the amount of work by a combination of backward and forward chaining. In our evaluation, the B/F algorithm was several orders of magnitude more efficient than the DRed algorithm on some inputs, and it was never significantly less efficient.

DataGrid is project funded by the European Commission to develop and deploy distributed computing components for reference applications in the domains of Particle Physics, Earth Observation and Bioinformatics. The software development is shared among nine contractual partners, in seven different countries, and is organized in work-packages covering different areas. In this paper, we discuss how combination of Concurrent Version System, GNU autotools and other tools and practices was organised to allow the development, build, test and distribution of the DataGrid Workload Management Sys-tem. This is the product of one speci_c work-package that is not only characterised by rather high internal geographic and administrative dispersion (four institutions with de-velopers at nine different locations in three countries), but by the fact we had to integrate and interface to dozen of third-party code packages coming from different sources, and to the software products coming from other three development work-packages internal to the project. high level of central co-ordination needed to be maintained for project-wide steering, and this had also to be re_ected in the software development infrastructure, while maintaining ease-of-use for distributed developers and automated procedures wherever possible.

Materialisation precomputes all consequences of a set of facts and a datalog program so that queries can be evaluated directly (i.e., independently from the program). Rewriting optimises materialisation for datalog programs with equality by replacing all equal constants with a single representative; and incremental maintenance algorithms can efficiently update a materialisation for small changes in the input facts. Both techniques are critical to practical applicability of datalog systems; however, we are unaware of an approach that combines rewriting and incremental maintenance. In this paper we present the first such combination, and we show empirically that it can speed up updates by several orders of magnitude compared to using either rewriting or incremental maintenance in isolation., All proofs contained in the appendix. 7 pages + 4 pages appendix. 7 algorithms and one table with evaluation results

We present a novel approach to parallel materialisation (i.e., fixpoint computation) of datalog programs in centralised, main-memory, multi-core RDF systems. Our approach comprises an algorithm that evenly distributes the workload to cores, and an RDF indexing data structure that supports efficient, 'mostly' lock-free parallel updates. Our empirical evaluation shows that our approach parallelises computation very well: with 16 physical cores, materialisation can be up to 13.9 times faster than with just one core.

Background: Understanding the level of patients’ satisfaction with treatment and its determinants have the potential to impact therapeutic management and clinical outcome in chronic conditions such as chronic obstructive pulmonary disease (COPD). Methods: A national, multicenter, longitudinal, observational study of COPD from 20 Italian pulmonary centers to explore patients’ satisfaction to treatment [assessed by the Treatment Satisfaction Questionnaire, 9 items (TSQM-9)] and association with clinical parameters [including dyspnea score, COPD Assessment Test (CAT) score, exacerbation rate], adherence to treatment [Morisky Medication-Taking Adherence Scale (MMAS-4)], illness perception [evaluated by Brief Illness Perception Questionnaire (B-IPQ)] in a 1-year follow up. Results: A total of 401 COPD patients were enrolled [69.4% group B Global Initiative for COPD (GOLD), considering 366 patients with available GOLD 2017 classification at enrollment]. At enrollment, satisfaction with treatment was moderate, being TSQM-9 mean scores for effectiveness 64.2 [95% confidence interval (CI) 62.5–65.9], for convenience 75.8 (95% CI 74.2–77.3), and for global satisfaction 65.7 (95% CI 64.0–67.4). Global satisfaction was negatively associated with disease perception (β = −0.4709, p Conclusions: The results of this real-life study showed that the patients’ satisfaction with treatments is only moderate in COPD. A high grade of patients’ satisfaction is associated mainly with a low perception of the disease, high adherence to treatment and lower level of dyspnea. Trial Registration: Clinicaltrials.gov identifier: NCT02689492 The reviews of this paper are available via the supplemental material section.

Background Bronchial thermoplasty (BT) is a non-pharmacological intervention for severe asthma whose mechanism of action is not completely explained by a reduction of airway smooth muscle (ASM). In this study we analyzed the effect of BT on nerve fibers and inflammatory components in the bronchial mucosa at 1 year. Methods Endobronchial biopsies were obtained from 12 subjects (mean age 47 ± 11.3 years, 50% male) with severe asthma. Biopsies were performed at baseline (T0) and after 1 (T1), 2 (T2) and 12 (T12) months post-BT, and studied with immunocytochemistry and microscopy methods. Clinical data including Asthma Quality of Life Questionnaire (AQLQ) and Asthma Control Questionnaire (ACQ) scores, exacerbations, hospitalizations, oral corticosteroids use were also collected at the same time points. Results A statistically significant reduction at T1, T2 and T12 of nerve fibers was observed in the submucosa and in ASM compared to T0. Among inflammatory cells, only CD68 showed significant changes at all time points. Improvement of all clinical outcomes was documented and persisted at the end of follow up. Conclusions A reduction of nerve fibers in epithelium and in ASM occurs earlier and persists at one year after BT. We propose that nerve ablation may contribute to mediate the beneficial effects of BT in severe asthma. Trial registration Registered on April 2, 2013 at ClinicalTrials.gov Identifier: NCT01839591.

Background Community-acquired pneumonia (CAP) has a potential complication of bacteremia. The objective of this study was to define the clinical outcomes of patients with CAP and bacteremia treated with and without a macrolide. Materials and methods Secondary analysis of the Community-Acquired Pneumonia Organization database of hospitalized patients with CAP. Patients with a positive blood culture were categorized based on the presence or absence of a macrolide in their initial antimicrobial regimen, and severity of their CAP. Outcomes included in-hospital all-cause mortality, 30-day mortality, length of stay, and time to clinical stability. Results Among 549 patients with CAP and bacteremia, 247 (45%) were treated with a macrolide and 302 (55%) were not. The primary pathogen was Streptococcus pneumoniae (74%). Poisson regression with robust error variance models were used to compare the adjusted effects of each study group on the outcomes. The unadjusted 30-day mortality was 18.4% in the macrolide group, and 29.6% in the non-macrolide group (adjusted relative risk (aRR)0.81; 95% confidence interval (CI)0.50–1.33; P = 0.41). Unadjusted in-hospital all-cause mortality was 7.3% in the macrolide group, and 18.9% in the non-macrolide group (aRR 0.54, 95% CI 0.30–0.98; P = 0.043). Length of stay and time to clinical stability were not significantly different. Conclusions In-hospital mortality, but not 30-day mortality, was significantly better in the macrolide group. Our data support the use of a macrolide in hospitalized patients with CAP and bacteraemia.

Scopo della comunicazione è studiare la presenza dei politici italiani nei due social network con maggior numero di utenti (Facebook e Twitter). Nel dibattito sviluppatosi negli ultimi anni è stato sottolineato come il passaggio dal web 1.0 al web 2.0 (e ormai quasi 3.0) abbia portato a un avvicinamento fra politici e utenti/elettori/cittadini (in quest’ordine). Nel più generale contesto di “disintermediazione della comunicazione” (Bentivegna 2002), si è pensato (forse ci si è illusi) che il superamento del filtro rappresentato dai media tradizionali avrebbe creato un rapporto diretto fra politici e cittadini, quasi del tipo “dal produttore al consumatore”. Recenti lavori (ad esempio Spina 2012) hanno invece mostrato come, a fronte della massa di messaggi presenti nei profili e nelle pagine dei SN riconducibili a esponenti politici, solo una parte di questi è costituita da scambi bidirezionali fra l’esponente politico e uno (o più utenti). L’ipotesi sviluppata nel contributo è che scopo primario della presenza dei politici sui social network non è tanto quello di creare un contatto bi-direzionale con gli utenti/elettori/cittadini, ma quello di poter gestire la comunicazione mono-direzionale in modo più diretto e immediato, senza il filtro (anche linguistico) dei media tradizionali. Allo scopo di verificare questa ipotesi sono stati monitorati il profilo Twitter e la pagina Facebook di Beppe Grillo e di Matteo Renzi. La scelta di soffermarsi su questi personaggi politici è dettata essenzialmente da due motivi: il primo è che Grillo e Renzi sono i due politici italiani con il maggior seguito sui social network (un milione e mezzo di followers su Twitter e altrettanti seguaci su Facebook Grillo, quasi novecentomila su Twitter e quasi seicentomila su Facebook Renzi); il secondo è che entrambi trovano in rete il terreno loro più congeniale, in quanto conoscono molto bene i meccanismi del web, le sue potenzialità e i suoi limiti, che essi sanno sfruttare a proprio vantaggio. In particolare, l’analisi si è concentrata sui seguenti aspetti: 1) Tipologia dei post (notizie sull’attività politica e su iniziative, commenti su avvenimenti o su dichiarazioni di altri politici, ecc.) 2) Tipologia delle interazioni che vengono a crearsi, distinguendo tra: 2a) le interazioni fra il politico e gli utenti; 2b) le interazioni fra gli utenti 3) Caratteristiche linguistico-testuali dei post, loro grado di coerenza con la “lingua del web” (nei diversi livelli dell’analisi linguitica) e grado di coscienza metalinguistica e metapragmatica per l’(auto)identificazione delle due diverse comunità di utenti La considerazione di questi aspetti contribuisce a delineare le differenti strutture partecipative che caratterizzano l’interazione nei profili e nelle pagine dei due leader politici. Tale definizione costituisce il primo passo per individuare le differenze di carattere linguistico-testuale fra i due esponenti politici e i loro seguaci nei diversi tipi di post e nei diversi tipi di interazione considerati.

Background Friedreich's ataxia (FRDA) is the most common hereditary ataxia among caucasians. The molecular defect in FRDA is the trinucleotide GAA expansion in the first intron of the FXN gene, which encodes frataxin. No studies have yet reported frataxin protein and mRNA levels in a large cohort of FRDA patients, carriers and controls. Methodology/Principal Findings We enrolled 24 patients with classic FRDA phenotype (cFA), 6 late onset FRDA (LOFA), all homozygous for GAA expansion, 5 pFA cases who harbored the GAA expansion in compound heterozygosis with FXN point mutations (namely, p.I154F, c.482+3delA, p.R165P), 33 healthy expansion carriers, and 29 healthy controls. DNA was genotyped for GAA expansion, mRNA/FXN was quantified in real-time, and frataxin protein was measured using lateral-flow immunoassay in peripheral blood mononuclear cells (PBMCs). Mean residual levels of frataxin, compared to controls, were 35.8%, 65.6%, 33%, and 68.7% in cFA, LOFA, pFA and healthy carriers, respectively. Comparison of both cFA and pFA with controls resulted in 100% sensitivity and specificity, but there was overlap between LOFA, carriers and controls. Frataxin levels correlated inversely with GAA1 and GAA2 expansions, and directly with age at onset. Messenger RNA expression was reduced to 19.4% in cFA, 50.4% in LOFA, 52.7% in pFA, 53.0% in carriers, as compared to controls (p