In this work, we perform a comprehensive empirical study of smart contracts deployed on the ethereum blockchain. The objective of the analysis is to provide empirical results on smart contracts features, smart contract transactions within the blockchain, the role of the development community, and the source code characteristics. We collected a set of more than 10 000 smart contracts source codes and a dataset of meta-data regarding their interaction with the blockchain from etherscan.io. We examined the collected data computing different statistics on naming policies, smart contract ether balance, number of smart contract transactions, functions, and other quantities characterizing the use and purpose of smart contracts. We found that the number of transactions and the balances follow power-law distributions and the software code metrics display, on average, values lower than corresponding metrics in standard software but have high variances. Focusing the attention on the 20 smart contracts with the topmost number of transactions, we found that most of them represent financial smart contracts and some of them have peculiar software development stories behind them. The results show that blockchain software is rapidly changing and evolving and it is no longer devoted only to cryptovalues applications but to general purpose computation.

Summary This article proposes a blockchain oriented platform to guarantee the origin and provenance of food items in a Smart Tourism Region context. Local food and beverage, in fact, can become a good combination to attract tourist and to promote the area provided that their provenance is clearly certified. We designed and developed a blockchain‐based system to manage an agri‐food supply chain for tracking food items. By using smart contracts the platform guarantees transparency, efficiency and trustworthiness. Our system is particularly suitable to manage cold chain since the system interfaces with IoT network devices providing detailed information about data monitoring food such as storage temperature, environment humidity, and GPS data. All involved actors can share data and information in a more efficient, transparent, and tamper proof way than traditional systems. The final consumer can access with transparency to all the agri‐food chain of the purchased product and verify provenance by retrieving all detailed information registered in the blockchain public ledger. The proposed system has been designed according to the ABCDE method, an agile development process recently conceived, to obtain a higher software quality to design a general blockchain system by means software engineering practices. A real case study applied to local products from Sardinia, Italy, is proposed at the end of the article.

The use of teledermatology in primary care has been shown to be reliable, offering the possibility of improving access to dermatological care by using telecommunication technologies to connect several medical centers and enable the exchange of information about skin conditions over long distances. This paper describes the main points of a teledermatology project that we have implemented to promote and facilitate the diagnosis of skin diseases and improve the quality of care for rural and remote areas. Moreover, we present a blockchain-based approach which aims to add new functionalities to an innovative teledermatology platform which we developed and tested in the Sardinian Region (Italy). These functionalities include giving the patient complete access to his/her medical records while maintaining security. Finally, the advantages that this new decentralized system can provide for patients and specialists are presented.

Temporary work is an employment situation useful and suitable in all occasions in which business needs to adjust more easily and quickly to workload fluctuations or maintain staffing flexibility. Temporary workers play therefore an important role in many companies, but this kind of activity is subject to a special form of legal protections and many aspects and risks must be taken into account both employers and employees. In this work we propose a blockchain-based system that aims to ensure respect for the rights for all actors involved in a temporary employment, in order to provide employees with the fair and legal remuneration (including taxes) of work performances and a protection in the case employer becomes insolvent. At the same time, our system wants to assist the employer in processing contracts with a fully automated and fast procedure. To resolve these problems we propose the D-ES (Decentralized Employment System). We first model the employment relationship as a state system. Then we describe the enabling technology that makes us able to realize the D-ES. In facts, we propose the implementation of a DLT (Decentralized Ledger Technology) based system, consisting in a blockchain system and of a web-based environment. Thanks the decentralized application platforms that makes us able to develop smart contracts, we define a discrete event control system that works inside the blockchain. In addition, we discuss the temporary work in agriculture as a interesting case of study.Index Terms-blockchain, temporary employment, smart contracts, discrete event model 1 | P a g e arXiv:1711.09758v1 [cs.CY]

Abstract. An Initial Coin Offering (ICO) is an innovative way to raise funds and launch a startup. It is also an opportunity to take part in a project, or in a DAO (Decentralized Autonomous Organization). The use of ICO is a global phenomenon that involves many nations and several business categories: ICOs collected over 5.2 billion dollars only in 2017. The success of an ICO is based on the credibility and innovativeness of project proposals. This fund-raising tool contains however some critical issues, such as the use of tokens that have no intrinsic value and do not generate direct liquidity, and the role of investors in the management of the startup. We analyzed if the Lean Startup methodology is helpful to face this critical aspects and we examined some ICOs in which the proposing team states explicitly that a lean startup approach is used.

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The Instagram is a social network for smartphones created in 2010 and acquired by Facebook in 2012. It currently has more than 300 million registered users and allows for the immediate upload of images (square, inspired by Polaroid), to which users can associate hashtags and comments. Moreover, connections can be created between users that share the same interests. In our work, we intend to analyze the hashtags entered by users: the use of such hashtags, as it happens in other social networks like Twitter, generates a folksonomy, that is a user-driven classification of information. We intend to map that folksonomy as a complex network to which we can associate all the typical analysis and evaluations of such a mathematical model. Our purpose is to use the resulting complex network as a marketing tool, in order to improve brand or product awareness.