Early Helladic pottery traditions in western Greece: the case of Kephalonia and Ithaca

Pelikata on northern Ithaca was a rare known settlement dating to the Early Helladic period in the Ionian Islands, until recent rescue excavations on Kephalonia brought to light substantial architectural remains on the EKO property at the southern entrance to the modern town of Sami. The analytical results from a total of 55 samples indicate that the Early Helladic pottery production is heavily based on local resources. The raw materials are transformed into durable clay pastes by clay mixing and tempering, as these islands (notably Ithaca) are characterised by sediments which are not suitable for pottery making if unprocessed. Imports were not identified within the analysed assemblage, suggesting the existence of a very strong local tradition and possibly the rather introvert character of Early Helladic Ionian pottery production

Exhumed hydrocarbon-seep authigenic carbonates from Zakynthos island (Greece): Concretions not archaeological remains

In Zakynthos Island (Greece), authigenic cementation of marine sediment has formed pipelike, disc and doughnut-shaped concretions. The concretions are mostly composed of authigenic ferroan dolomite accompanied by pyrite. Samples with >80% dolomite, have stable isotope compositions in two groups. The more indurated concretions have δ 18O around +4‰ and δ 13C values between -8 and -29‰ indicating dolomite forming from anaerobic oxidation of thermogenic methane (hydrocarbon seep), in the sulphate-methane transition zone. The outer surfaces of some concretions, and the less-cemented concretions, typically have slightly heavier isotopic compositions and may indicate that concretion growth progressed from the outer margin in the ambient microbially-modified marine pore fluids, inward toward the central conduit where the isotopic compositions were more heavily influenced by the seep fluid. Sr isotope data suggest the concretions are fossil features, possibly of Pliocene age and represent an exhumed hydrocarbon seep plumbing system. Exposure on the modern seabed in the shallow subtidal zone has caused confusion, as concretion morphology resembles archaeological stonework of the Hellenic period

Proceedings of the 21st Conference on Formal Methods in Computer-Aided Design – FMCAD 2021

The Conference on Formal Methods in Computer-Aided Design (FMCAD) is an annual conference on the theory and applications of formal methods in hardware and system verification. FMCAD provides a leading forum to researchers in academia and industry for presenting and discussing groundbreaking methods, technologies, theoretical results, and tools for reasoning formally about computing systems. FMCAD covers formal aspects of computer-aided system design including verification, specification, synthesis, and testing

Design and performance study of algorithms for consensus in sparse, mobile ad-hoc networks

PhD ThesisMobile Ad-hoc Networks (MANETs) are self-organizing wireless networks that consist of mobile wireless devices (nodes). These networks operate without the aid of any form of supporting infrastructure, and thus need the participating nodes to co-operate by forwarding each other’s messages. MANETs can be deployed when urgent temporary communications are required or when installing network infrastructure is considered too costly or too slow, for example in environments such as battlefields, crisis management or space exploration. Consensus is central to several applications including collaborative ones which a MANET can facilitate for mobile users. This thesis solves the consensus problem in a sparse MANET in which a node can at times have no other node in its wireless range and useful end-to-end connectivity between nodes can just be a temporary feature that emerges at arbitrary intervals of time for any given node pair. Efficient one-to-many dissemination, essential for consensus, now becomes a challenge: enough number of destinations cannot deliver a multicast unless nodes retain the multicast message for exercising opportunistic forwarding. Seeking to keep storage and bandwidth costs low, we propose two protocols. An eventually relinquishing (}RC) protocol that does not store messages for long is used for attempting at consensus, and an eventually quiescent (}QC) one that stops forwarding messages after a while is used for concluding consensus. Use of }RC protocol poses additional challenges for consensus, when the fraction, f n, of nodes that can crash is: 1 4 f n < 1 2 . Consensus latency and packet overhead are measured through simulation indicating that they are not too high to be feasible in MANETs. They both decrease considerably even for a modest increase in network density.Damascus University

The Accelerated Ring Protocol: Ordered Multicast for Modern Data Centers

Ordered multicast is an important building block for many distributed applications, and there are many existing protocols providing this service, which is often referred to as total order broadcast or atomic broadcast. However, few of the existing protocols were specifically designed for high-performance in modern data center environments. This thesis introduces a new ordered multicast protocol, called the Accelerated Ring protocol, that provides high throughput and low latency in modern data center environments. Like other token-based protocols, the Accelerated Ring protocol places the protocol participants in a logical ring, and circulates a token around this ring. Each participant is allowed to send new multicasts to the other participants upon receiving the token. The key idea behind the Accelerated Ring protocol is that a participant can begin to send multicasts when it receives the token, but, unlike in other protocols, it may release the token before it finishes multicasting. Each participant updates the token to reflect all messages it will multicast during the current token round before beginning to multicast. It can then pass the token to the next participant at any point during the time it is multicasting. Since the token includes all the information the next participant needs, the next participant can begin multicasting as soon as it receives the token, even if its predecessor on the ring has not yet completed its multicasts. Sending the token before completing all multicasts allows the token to circulate the ring faster. This acceleration of the token improves both throughput and latency. We implemented the protocol as a prototype and evaluated its performance in 1-Gig and 10-Gig networks. We also implemented the full protocol in the open-source Spread Toolkit and evaluated its performance relative to the previous version of the toolkit in a 1-Gig local area network, virtualized 1-Gig local area settings, and a 10-Gig local area network. The results of these evaluations demonstrate the significant benefit of accelerating the token in all of these environments, both in terms of throughput and in terms of latency. The Accelerated Ring Spread implementation achieves throughput over 900 Mbps on a 1-Gigabit network and close to 2.5 Gbps on a 10-Gigabit network. At the highest throughput that both the Accelerated Ring Spread implementation and Spread 4.3 can comfortably sustain on a 1-Gig network (about 600 Mbps), the Accelerated Ring protocol reduces latency by 77% for agreed delivery and by 63% for safe delivery. On a 10-Gig network, the latency reduction is about 49% for agreed delivery and 26% for safe delivery (with throughput at 1.2 Gbps). The implementation of the protocol in Spread is open-source, and the Accelerated Ring protocol is Spread's standard protocol for data center environments and local area networks as of Spread version 4.4

Pioneering food safety:Blockchain's integration in supply chain surveillance

Ensuring food safety in a world facing escalating demand and complex supply chains is a pressing challenge. Despite increasing awareness, obstacles such as information distribution, financial limitations, and insufficient infrastructure impede food safety efforts. Blockchain technology presents a promising solution by improving transparency and traceability in supply chains, which are essential for tackling food safety issues. This study explores the integration of blockchain into food safety frameworks, emphasising its compatibility and potential to transform food production and distribution. Drawing on literature, it identifies key challenges to blockchain adoption, including regulatory frameworks and interoperability issues, and proposes strategies such as government intervention and standardisation to overcome them. Ultimately, blockchain holds immense promise in revolutionizing food safety practices, ensuring safe and nutritious food for all

Cryptocurrencies and beyond: using design science research to demonstrate diverse applications of blockchains

This thesis investigates blockchain technology and whether its mutually cooperative topology and commons-based peer production practices have implications for society because, instead of the traditional top-down, centralised model of governance, blockchains represent an alternative way of collaborating. Much of the literature anticipates the vast potential of the permanent and publicly auditable nature of the propagated values of blockchains. Indeed, writers have supposed that the smart contract capabilities of the technology may prove revolutionary for areas beyond that of the economic domain targeted by the cryptocurrency Bitcoin, which is the first successful use-case of a blockchain. However, few advanced use cases beyond that economic realm have materialised; this research demonstrates such usecases. This thesis asks four research questions. The first asks whether blockchains can help reduce energy consumption. The second asks whether blockchains can help digitise the informal sector. The third asks whether blockchains can help counter fake news. The final question asks whether blockchains can help address criticisms of humanitarian aid. Those topics are four amongst many urgent problems currently facing humankind, and therefore, the overarching research question of this thesis becomes whether blockchains can help humanity. This work advances the supposed potential of blockchains proposed by current literature by using design science research to create software artefacts that propose solutions for incentivising energy efficiency, fighting financial fraud, providing digital provenance and adding trust to humanitarian aid reporting. By demonstrating blockchain-based software solutions in those four topic areas, this thesis concludes that blockchains can help humanity. However, if they are to help society address some of its problems, blockchains have significant technological and organisational barriers to overcome. Furthermore, the idea that blockchains can help humanity is a form of techno-determinism and this research concludes that it is impossible to solve every issue by diversifying technical operations; humankind must also change political, economic, and cultural goals, too. Nevertheless, this thesis has implications for regulators, despite the barriers and false solutionism offered by technology because, rather than the trusted lawmakers and experts that nations used to look up to as oracles of truth, now it may be possible to look to blockchains, instead