117 research outputs found

    Damage detection via shortest-path network sampling

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    Large networked systems are constantly exposed to local damages and failures that can alter their functionality. The knowledge of the structure of these systems is, however, often derived through sampling strategies whose effectiveness at damage detection has not been thoroughly investigated so far. Here, we study the performance of shortest-path sampling for damage detection in large-scale networks. We define appropriate metrics to characterize the sampling process before and after the damage, providing statistical estimates for the status of nodes (damaged, not damaged). The proposed methodology is flexible and allows tuning the trade-off between the accuracy of the damage detection and the number of probes used to sample the network. We test and measure the efficiency of our approach considering both synthetic and real networks data. Remarkably, in all of the systems studied, the number of correctly identified damaged nodes exceeds the number of false positives, allowing us to uncover the damage precisely

    Router-level community structure of the Internet Autonomous Systems

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    The Internet is composed of routing devices connected between them and organized into independent administrative entities: the Autonomous Systems. The existence of different types of Autonomous Systems (like large connectivity providers, Internet Service Providers or universities) together with geographical and economical constraints, turns the Internet into a complex modular and hierarchical network. This organization is reflected in many properties of the Internet topology, like its high degree of clustering and its robustness. In this work, we study the modular structure of the Internet router-level graph in order to assess to what extent the Autonomous Systems satisfy some of the known notions of community structure. We show that the modular structure of the Internet is much richer than what can be captured by the current community detection methods, which are severely affected by resolution limits and by the heterogeneity of the Autonomous Systems. Here we overcome this issue by using a multiresolution detection algorithm combined with a small sample of nodes. We also discuss recent work on community structure in the light of our results

    2017 HRS/EHRA/ECAS/APHRS/SOLAECE expert consensus statement on catheter and surgical ablation of atrial fibrillation: executive summary.

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    2017 HRS/EHRA/ECAS/APHRS/SOLAECE expert consensus statement on catheter and surgical ablation of atrial fibrillation: executive summary.

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    Inferring persistent interdomain congestion

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    There is significant interest in the technical and policy communities regarding the extent, scope, and consumer harm of persistent interdomain congestion. We provide empirical grounding for discussions of interdomain congestion by developing a system and method to measure congestion on thousands of interdomain links without direct access to them. We implement a system based on the Time Series Latency Probes (TSLP) technique that identifies links with evidence of recurring congestion suggestive of an under-provisioned link. We deploy our system at 86 vantage points worldwide and show that congestion inferred using our lightweight TSLP method correlates with other metrics of interconnection performance impairment. We use our method to study interdomain links of eight large U.S. broadband access providers from March 2016 to December 2017, and validate our inferences against ground-truth traffic statistics from two of the providers. For the period of time over which we gathered measurements, we did not find evidence of widespread endemic congestion on interdomain links between access ISPs and directly connected transit and content providers, although some such links exhibited recurring congestion patterns. We describe limitations, open challenges, and a path toward the use of this method for large-scale third-party monitoring of the Internet interconnection ecosystem

    Treat-and-Extend Versus Pro re nata Regimens of Ranibizumab and Aflibercept in Neovascular Age-Related Macular Degeneration: A Comparative Study from Routine Clinical Practice

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    Introduction Anti-vascular endothelial growth factor (VEGF) is generally given using pro re nata or “treat-and-extend” (T&E) regimens for neovascular age-related macular degeneration (nAMD). Randomized clinical trials have reported that T&E is superior to Pro re nata (PRN), but results from clinical trials may not always be replicated in clinical practice. Real-world data comparing T&E and PRN regimens for nAMD are limited. The objective of this work was to report 24-month outcomes of PRN versus T&E regimens for ranibizumab and aflibercept to treat nAMD in routine clinical practice. Methods We conducted a retrospective analysis of data from a prospectively designed observational outcomes registry, the Fight Retinal Blindness! Project (FRB). Treatment-naïve eyes starting nAMD treatment with at least three injections using a T&E or PRN regimen were tracked by using the FRB. The primary outcome was the mean change in visual acuity (VA) measured by the number of letters read on a logarithm of the minimum angle of resolution chart at 2 years versus baseline. The secondary outcome was the number of injections at 2 years. Results From January 1, 2015 to January 31, 2019, 3313 eyes from 2948 patients with nAMD were included: 1243 eyes from 1065 patients were classified as PRN and 2070 eyes from 1935 patients started a T&E regimen. At 24 months, patients on the T&E regimen experienced significantly greater mean (95% confidence interval) improvement in VA than those on PRN (+ 4.2 [3.1, 5.2] vs. + 1.3 [0.1, 2.6] letters; p < 0.001), with more injections (14.9 standard deviation(SD) 4.3) vs. 9.8(SD 4.3); p < 0.001). Conclusions Eyes treated with a T&E regimen had better VA outcomes from VEGF inhibitors than eyes treated PRN. This large real-world data assessment supports previous data from randomized clinical trials that the T&E regimen delivers better outcomes than PRN. Plain Language Summary This study focused on comparing two methods of treating neovascular age-related macular degeneration, a common eye condition. The treatments used were ranibizumab and aflibercept. We looked at the reactive “pro re nata” method, where treatment is given sporadically and only when the condition reactivates, and the proactive “treat-and-extend” method, which aims to keep the disease inactive with the fewest treatments at regular intervals. The main aim was to determine which method provides the best vision outcomes over a 24-month period and the frequency of treatment required. We found that the treat-and-extend method resulted in a greater improvement in vision than the pro re nata method, although it did require more injections. This study highlights the effectiveness of the treat-and-extend method for neovascular age-related macular degeneration, suggesting it gets better outcomes despite requiring more injections

    Mechanical, antibacterial and bond strength properties of nano-titanium-enriched glass ionomer cement

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    The use of nanoparticles (NPs) has become a significant area of research in Dentistry. Objective The aim of this study was to investigate the physical, antibacterial activity and bond strength properties of conventional base, core build and restorative of glass ionomer cement (GIC) compared to GIC supplemented with titanium dioxide (TiO2) nanopowder at 3% and 5% (w/w). Material and Methods Vickers microhardness was estimated with diamond indenter. Compressive and flexural strengths were analyzed in a universal testing machine. Specimens were bonded to enamel and dentine, and tested for shear bond strength in a universal testing machine. Specimens were incubated with S. mutans suspension for evaluating antibacterial activity. Surface analysis of restorative conventional and modified GIC was performed with SEM and EDS. The analyses were carried out with Kolmogorov-Smirnov, ANOVA (post-hoc), Tukey test, Kruskal-Wallis, and Mann Whitney. Results Conventional GIC and GIC modified with TiO2 nanopowder for the base/liner cement and core build showed no differences for mechanical, antibacterial, and shear bond properties (p>0.05). In contrast, the supplementation of TiO2 NPs to restorative GIC significantly improved Vickers microhardness (p<0.05), flexural and compressive strength (p<0.05), and antibacterial activity (p<0.001), without interfering with adhesion to enamel and dentin. Conclusion GIC supplemented with TiO2 NPs (FX-II) is a promising material for restoration because of its potential antibacterial activity and durable restoration to withstand the mastication force
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