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In this thesis, we address the problem of data outsourcing in presence of access control policies. Due to the emergence of Database-as-a-Service paradigm, secure data outsourcing has become one of the crucial challenges which strongly imposes itself. Indeed, data owners place their data among Cloud Storage Service Providers (CSSP) in order to increase flexibility, optimize storage, enhance data manipulation and decrease processing time. In spite of that, access control is considered as a major barrier to cloud computing and data outsourcing arrangements. Hence, the central challenge identified in this context is: How access control policies of data owner are preserved when data is moved to the cloud?From a security perspective, preserving access control policies means that if an access was prohibited initially by the owner's access control policies, it should be also prohibited when data is externalized to Cloud Storage Service Providers. Also, the policy in the Cloud Storage Service Providers level should protect data against indirect access via inference channels. This inference channel is derived from the combination of legitimate answers received from the system with semantic constraints. Furthermore, to maintain data utility, an optimal data placement decision should be considered when this latter is moved to the cloud.In this manuscript, on the basis of vertical partitioning, we propose a graph-based approach to preserve owner's access control policies efficiently when data is externalized to the Cloud Storage Service Providers. To do that, our proposed approach runs through the following steps: Firstly, it relies on semantic relatedness measure between users roles and schema attributes to derive an optimal vertical partitioning. Optimal partitioning is the minimization of the number of distributed queries issued from a user role in order to provide higher performance and speedup. Secondly, by reasoning about functional dependencies as source of inference, we propose a set of algorithms to detect inference ...

PurposeThe study seeks to reduce the blurriness remaining around the value that HRM can bring to innovation in the specific context of start‐ups, it advocates that the early adoption of appropriate HRM practices, can act as a catalyst for innovation because they constitute a powerful means to systematically promote and facilitate employees' innovative behaviours.Design/methodology/approachIn the aim of complementing the existing quantitative work, this paper employs a multiple case study approach to explore the role of HRM in fostering employees' innovative work behaviour in four Tunisian tech companies.FindingsThe study found substantial support for the importance of establishing a work environment for learning where employees can build their innovative capacities by upgrading their knowledge and skills through both formal and informal methods. Work autonomy and freedom are found to be essential parts of this environment. Workspace design that takes into account employees' comfort and the collaborative nature of their work, also stands out as a major contributor to innovative work behaviour.Originality/valueThe adopted qualitative approach enabled a grasp of the less apparent aspects underpinning the HRM and innovation relationship in start‐ups. "Ownership of space" is revealed as a key element of the innovation-supportive work environment. By having a feeling of control on the workspace, employees can develop a sense of ownership towards the organisation which enhances their eagerness to exert innovation efforts. It also demonstrated that developing an overly creative workforce can turn into a source of stagnation which can be mitigated by cultivating "an environment for idea ownership".

POVOAR is a not-for-profit association whose main goal is to explore, improve and decentralize the artistic and cultural sector in countries where the latter is underestimated, unequal and underdeveloped. POVOAR came to light with the concern of the centralized and neglective systems that rule many countries and limit the flourishing and diversification of the cultural and artistic fields. As a response to such issues, a pilot project was created based on the mapping of artistic and cultural expressions over the regions of Portugal. The country was chosen to initiate the project as it represents a good example of a culturally rich but poorly invested territory. The first steps of the project rely on an on-site campaign of data gathering of the cultural and artistic expressions of one of the poorest regions of the country: Beja. The findings of the research then become available on an online platform, through a digital map accessible to anyone. In the long-term, the association intends to expand its research to other countries by pairing projects and relating people and activities from different communities, based on their similarities, with the aim of creating a worldwide cultural network. At the core of POVOAR there is a quest for connections: human, artistic, heritage, and geographical relations drive us towards the future, and have been driving us to where we are today. The project was born from a shared interest in human encounters, a passion for tales of tradition, and a need for preserving what is getting forgotten in every community. POVOAR has the power to bring visibility and opportunities to the people of the cultural sector, raise awareness of the importance of arts and culture, encourage an alternative form of tourism - more committed and sustainable - and provide the governments with a database of diversified useful information to develop truly effective cultural policies. ; info:eu-repo/semantics/publishedVersion