ScaRR: Scalable Runtime Remote Attestation for Complex Systems

The introduction of remote attestation (RA) schemes has allowed academia and industry to enhance the security of their systems. The commercial products currently available enable only the validation of static properties, such as applications fingerprint, and do not handle runtime properties, such as control-flow correctness. This limitation pushed researchers towards the identification of new approaches, called runtime RA. However, those mainly work on embedded devices, which share very few common features with complex systems, such as virtual machines in a cloud. A naive deployment of runtime RA schemes for embedded devices on complex systems faces scalability problems, such as the representation of complex control-flows or slow verification phase. In this work, we present ScaRR: the first Scalable Runtime Remote attestation schema for complex systems. Thanks to its novel control-flow model, ScaRR enables the deployment of runtime RA on any application regardless of its complexity, by also achieving good performance. We implemented ScaRR and tested it on the benchmark suite SPEC CPU 2017. We show that ScaRR can validate on average 2M control-flow events per second, definitely outperforming existing solutions.Comment: 14 page

Statin-associated muscle symptoms (SAMS) in primary prevention for cardiovascular disease in older adults:A protocol for a systematic review and meta-analysis of randomised controlled trials

IntroductionAlthough statins are commonly used for prevention of cardiovascular disease, there is limited evidence about statin-related adverse effects in older people. Statin-related adverse events (AEs), especially the statin-associated muscle symptoms (SAMS), are the most common reasons for their discontinuation. Therefore, it is important to determine the risk of SAMS in the older population. We will undertake a systematic review and meta-analysis primarily focusing on the risk of SAMS and secondarily targeting myopathy, rhabdomyolysis, AEs and serious AEs, dropouts due to SAMS in run-in period, related permanent discontinuation rate of statins and creatine kinase level, among older people who received statins for primary prevention.Methods and analysisThis study has been developed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocols statement. We will include randomised controlled trials in which statin was compared with placebo with at least 1 year follow-up among older adults aged ≥65. This review is an update of a Cochrane systematic review that included the articles published before 2012. Cochrane Central Register of Controlled Trials, Medline OvidSP and Embase electronic database searches will be performed to identify relevant articles, limiting the publication date from 1 January 2012 to 13 February 2017. There will be no language limitation. Two independent reviewers will screen titles and abstracts and full text in duplicate. Risk of bias and evidence quality will be assessed using the Cochrane Collaboration’s tool and the Grading of Recommendations Assessment, Development and Evaluation approach, respectively. A meta-analysis using pooled data will be undertaken, if appropriate. We will also perform metaregression and subgroup analyses to identify sources of heterogeneity.Ethics and disseminationThis study is exempt from ethics approval due to the anonymous and aggregated data used. The outcomes will be disseminated by conference presentations and published in a peer-reviewed journal.Trial registration numberCRD42017058436.</jats:sec

Theoretical evidence for efficient p-type doping of GaN using beryllium

Ab initio calculations predict that Be is a shallow acceptor in GaN. Its thermal ionization energy is 0.06 eV in wurtzite GaN; the level is valence resonant in the zincblende phase. Be incorporation is severely limited by the formation of Be_3N_2. We show however that co-incorporation with reactive species can enhance the solubility. H-assisted incorporation should lead to high doping levels in MOCVD growth after post-growth annealing at about 850 K. Be-O co-incorporation produces high Be and O concentrations at MBE growth temperatures.Comment: revised Feb 24 199

A Global Database of Domestic and International Tourist Numbers at National and Subnational Level

We present a new, global data base on tourist destinations. The data base differs from other data bases in that it includes both domestic and international tourists; and it contains data, for the most important destinations, data at national level as well as at lower administrative levels. Missing observations are interpolated using statistical models. The data are freely accessible on the internet.Tourism, Data

Volume oscillations slow down a rising Taylor bubble

A gas volume rising in a vertical tube is called a Taylor bubble when its equivalent spherical diameter is greater than the diameter of the tube. Continuity dictates that the rising velocity of such bullet-shaped bubbles must be such that the drainage flow in the liquid film separating the gas from the tube wall equals the rate at which space is vacated by the bubble tail on its rise. The numerical simulations presented here show that, if the volume of the bubble is made to execute small-amplitude oscillations, this drainage flow can be markedly decreased so that the bubble slows down so much as to very nearly stop. The mechanism is a subtle nonlinear interplay between the upward flow imposed by the bubble expansion and the inertia of the falling liquid. Two manners of excitation are considered. In the first one the liquid column above the bubble is forced to oscillate sinusoidally, e.g. by a piston. In the second one, an oscillating pressure is imposed on the top liquid surface. With the first arrangement the bubble slows down during its entire ascent by an amount depending on the oscillation frequency and amplitude. With the second one, for a given frequency, the bubble slows down only in the neighbourhood of a certain resonant depth at which the volume oscillations are maximized, but is little affected at deeper and shallower depths