An Empirical Analysis and Evaluation of Internet Robustness

The study of network robustness is a critical tool in the understanding of complex interconnected systems such as the Internet, which due to digitalization, gives rise to an increasing prevalence of cyberattacks. Robustness is when a network maintains its basic functionality even under failure of some of its components, in this instance being nodes or edges. Despite the importance of the Internet in the global economic system, it is rare to find empirical analyses of the global pattern of Internet traffic data established via backbone connections, which can be defined as an interconnected network of nodes and edges between which bandwidth flows. Hence in this thesis, I use metrics based on graph properties of network models to evaluate the robustness of the backbone network, which is further supported by international cybersecurity ratings. These cybersecurity ratings are adapted from the Global Cybersecurity Index which measures countries' commitments to cybersecurity and ranks countries based on their cybersecurity strategies. Ultimately this empirical analysis follows a three-step process of firstly mapping the Internet as a network of networks, followed by analysing the various networks and country profiles, and finally assessing each regional network's robustness. By using TeleGeography and ITU data, the results show that the regions with countries which have higher cybersecurity ratings in turn have more robust networks, when compared to regions with countries which have lower cybersecurity ratings

Studio idrogeologico delle Sorgenti di «Badde Selo» in agro del Comune di Thiesi (Sassari)

Sommario: Premessa; Lineamenti morfologici; Geologia; Caratteristiche climatiche; Idrogeologia

A comparative study of X-ray tomographic microscopy on shales at different synchrotron facilities: ALS, APS and SLS.

Synchrotron radiation X-ray tomographic microscopy (SRXTM) was used to characterize the three-dimensional microstructure, geometry and distribution of different phases in two shale samples obtained from the North Sea (sample N1) and the Upper Barnett Formation in Texas (sample B1). Shale is a challenging material because of its multiphase composition, small grain size, low but significant amount of porosity, as well as strong shape- and lattice-preferred orientation. The goals of this round-robin project were to (i) characterize microstructures and porosity on the micrometer scale, (ii) compare results measured at three synchrotron facilities, and (iii) identify optimal experimental conditions of high-resolution SRXTM for fine-grained materials. SRXTM data of these shales were acquired under similar conditions at the Advanced Light Source (ALS) of Lawrence Berkeley National Laboratory, USA, the Advanced Photon Source (APS) of Argonne National Laboratory, USA, and the Swiss Light Source (SLS) of the Paul Scherrer Institut, Switzerland. The data reconstruction of all datasets was handled under the same procedures in order to compare the data quality and determine phase proportions and microstructures. With a 10× objective lens the spatial resolution is approximately 2 µm. The sharpness of phase boundaries in the reconstructed data collected from the APS and SLS was comparable and slightly more refined than in the data obtained from the ALS. Important internal features, such as pyrite (high-absorbing), and low-density features, including pores, fractures and organic matter or kerogen (low-absorbing), were adequately segmented on the same basis. The average volume fractions of low-density features for sample N1 and B1 were estimated at 6.3 (6)% and 4.5 (4)%, while those of pyrite were calculated to be 5.6 (6)% and 2.0 (3)%, respectively. The discrepancy of data quality and volume fractions were mainly due to different types of optical instruments and varying technical set-ups at the ALS, APS and SLS

Radiation dose optimized lateral expansion of the field of view in synchrotron radiation X-ray tomographic microscopy

Increasing the lateral field of view of tomography-based imaging methods greatly increases the acquisition time. This article presents scanning protocols to obtain high-resolution tomographic scans with large lateral field of view at greatly decreased acquisition time and thus reduced radiation dose while resulting in high-quality three-dimensional tomographic datasets

Salt release from potato crisps

The rate of salt release in-mouth from salted potato crisps was evaluated. It was hypothesised that a slow steady release of sodium would occur on chewing and hydration; to test this a crisp was chewed and held in the oral cavity without swallowing for 60 s. Sodium release was measured over the entire holding period, after 20–30 s a peak in salivary sodium levels was recorded. A similar trend was observed with sensory perceived saltiness by trained panellists. The results suggest that a significant proportion of the crisp’s salt flavouring is released in a pulse-type mechanism which would not be encountered when the crisp is exposed to normal eating patterns and would result in the consumption of a large proportion of unperceived sodium