Handling Confidential Data on the Untrusted Cloud: An Agent-based Approach

Cloud computing allows shared computer and storage facilities to be used by a multitude of clients. While cloud management is centralized, the information resides in the cloud and information sharing can be implemented via off-the-shelf techniques for multiuser databases. Users, however, are very diffident for not having full control over their sensitive data. Untrusted database-as-a-server techniques are neither readily extendable to the cloud environment nor easily understandable by non-technical users. To solve this problem, we present an approach where agents share reserved data in a secure manner by the use of simple grant-and-revoke permissions on shared data.Comment: 7 pages, 9 figures, Cloud Computing 201

Can Severe Fiscal Contractions be Expansionary? Tales of Two Small European Countries

According to conventional wisdom, a fiscal consolidation is likely to contract real aggregate demand. It has often been argued, however, that this conclusion is misleading as it neglects the role of expectations of future policy: if the fiscal consolidation is read by the private sector as a signal that the share of government spending in GDP is being permanently reduced, households will revise upwards their estimate of their permanent income, and will raise current and planned consumption. Only the empirical evidence can sort out which of these two contending views about fiscal policy is more appropriate -- i.e how often the contractionary effect of a fiscal consolidation prevails on its expansionary expectational effect. This paper brings new evidence to bear on this issue drawing on the European exercise in fiscal rectitude of the 1980s, and focusing, in particulars on its two most extreme cases -- Denmark and Ireland. We find that at least in the experience of these two countries the expectations' view has a serious claim to empirical relevance.

Living City, A Collaborative Browser-Based Massively Multiplayer Online Game

This work presents the design and implementation of our Browser-based Massively Multiplayer Online Game, Living City, a simulation game fully developed at the University of Messina. Living City is a persistent and real-time digital world, running in the Web browser environment and accessible from users without any client-side installation. Today Massively Multiplayer Online Games attract the attention of Computer Scientists both for their architectural peculiarity and the close interconnection with the social network phenomenon. We will cover these two aspects paying particular attention to some aspects of the project: game balancing (e.g. algorithms behind time and money balancing); business logic (e.g., handling concurrency, cheating avoidance and availability) and, finally, social and psychological aspects involved in the collaboration of players, analyzing their activities and interconnections

Potencial use of ionic liquids in tribology

228 p.Los líquidos iónico son una categoría de sales fundida con un punto de fusión relativamente bajo, lo que las haces especialmente interesantes desde un punto de vista de aplicaciones tecnológicas. En los últimos años, se les ha dedicados grande atención en muchos sectores por las buenas propiedades que presentan: baja presión de vapor, buena estabilidad térmica, elevada conductividad eléctrica, etc. Además de estas características, lo que mas de todo resulta muy atractivo de los líquidos iónicos es la posibilidad de combinar fácilmente propiedades del anión con propiedades del catión para obtener estructuras que presentan las características deseadas. En esta tesis, se han estudiado las propiedades tribológicas de diferentes tipos de líquidos iónicos y se han intentado explicar los procesos que llevan al desarrollo de tribo-capas protectoras y los fenómenos de degradación de los lubricante

A Framework for Designing 3d Virtual Environments

The process of design and development of virtual environments can be supported by tools and frameworks, to save time in technical aspects and focusing on the content. In this paper we present an academic framework which provides several levels of abstraction to ease this work. It includes state-of-the-art components we devised or integrated adopting open-source solutions in order to face specific problems. Its architecture is modular and customizable, the code is open-source.\u

iPrivacy: a Distributed Approach to Privacy on the Cloud

The increasing adoption of Cloud storage poses a number of privacy issues. Users wish to preserve full control over their sensitive data and cannot accept that it to be accessible by the remote storage provider. Previous research was made on techniques to protect data stored on untrusted servers; however we argue that the cloud architecture presents a number of open issues. To handle them, we present an approach where confidential data is stored in a highly distributed database, partly located on the cloud and partly on the clients. Data is shared in a secure manner using a simple grant-and-revoke permission of shared data and we have developed a system test implementation, using an in-memory RDBMS with row-level data encryption for fine-grained data access controlComment: 13 pages, International Journal on Advances in Security 2011 vol.4 no 3 & 4. arXiv admin note: substantial text overlap with arXiv:1012.0759, arXiv:1109.355

Searching for Non-Monotonic Effects of Fiscal Policy: New Evidence

Data revisions and the availability of a longer sample offer the opportunity to reconsider the empirical findings that suggest that in the OECD countries national saving responds non-monotonically to fiscal policy. The paper confirms that the circumstance most likely to give rise to a non-monotonic response of national saving to a fiscal impulse is a “large and persistent impulse”, defined as one in which the full employment surplus, as a percent of potential output, changes by at least 1.5 percentage points per year over a two-year period. This particular circumstance remains the only statistically significant one even when we allow for non-monotonic responses to arise when public debt is growing rapidly or interest rate spreads are widening. We find that non-monotonic responses are similar for fiscal contractions and expansions. In particular, an increase in net taxes has no effect on national saving during large fiscal contractions or expansions. For government consumption there is a large, albeit in some specifications less then complete, offset during expansions or contractions.Fiscal policy, national saving