A New Data Deletion Scheme for a Blockchain-based De-duplication System in the Cloud

Almost all Cloud Service Providers (CSP) takes a principled approach to the storage and deletion of Customer Data. Most of them have engineered their cloud platform to achieve a high degree of speed, availability, durability, and consistency. Their systems are designed to be optimized for these performance attributes and must be carefully balanced with the necessity to achieve accurate and timely data deletion.many researchers have turn their focus toward data storage and how it will be a challenging task for CSPs in term of storage capacity, data management and security, a considerable number of papers has been published containing new models and technique that will allow data De-duplication in a shared environment but few of them have discussed data deletion.In this paper we will be discussing a new approach that will allow a smart deletion of data stored in the file system as well as its reference in the Blockchain since, by its nature, Blockchains does not allow deletion without violating the Blockchain’s consistency, a preexisting de-duplication system will be our base platform on which we will be working to achieve an accurate and secure data deletion using Blockchain technology while preserving its consistency

Diagnostic des systèmes temps réel modélisés par des automates à entrées sorties temporisées

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal

Web application for school libraries

La lectura en la etapa escolar es supremamente importante, y la biblioteca cumple una especial labor en la enseñanza y el aprendizaje, pues ésta ejerce una influencia sobre el logro académico en los estudiantes. Las bibliotecas sirven para propiciar, favorecer y estimular la lectura. Por todo lo anterior, hemos decidido implementar nuestra aplicación web para las bibliotecas escolares cuyos usuarios serán los bibliotecarios y los encargados de todo lo relativo a la gestión del catálogo de la biblioteca. Para llevar a cabo el desarrollo de este software hemos seguido un desarrollo iterativo, una iteración inicial para un estudio global del problema y las tecnologías a utilizar, seguida de siete iteraciones donde al inicio de cada una, seleccionamos las funcionalidades que más valor aportan a nuestro sistema, de manera que al final de cada iteración obtenemos una versión funcional y demostrable. Para la implementación, hemos optado por utilizar Spring Framework por su modularidad, flexibilidad y facilidad a la hora de implementar aplicaciones empresariales. Otro aspecto técnico es la utilización de MySQL como gestor de bases de datos

Blockchain & Multi-Agent System: A New Promising Approach for Cloud Data Integrity Auditing with Deduplication

Recently, data storage represents one of the most important services in Cloud Computing. The cloud provider should ensure two major requirements which are data integrity and storage efficiency. Blockchain data structure and the efficient data deduplication represent possible solutions to address these exigencies. Several approaches have been proposed, some of them implement deduplication in Cloud server side, which involves a lot of computation to eliminate the redundant data and it becomes more and more complex. Therefore, this paper proposed an efficient, reliable and secure approach, in which the authors propose a Multi-Agent System in order to manipulate deduplication technique that permits to reduce data volumes thereby reduce storage overhead. On the other side, the loss of physical control over data introduces security challenges such as data loss, data tampering and data modification. To solve similar problems, the authors also propose Blockchain as a database for storing metadata of client files. This database serves as logging database that ensures data integrity auditing function

Efficient Method Based on Blockchain Ensuring Data Integrity Auditing with Deduplication in Cloud

With the rapid development of cloud storage, more and more cloud clients can store and access their data anytime, from anywhere and using any device. Data deduplication may be considered an excellent choice to ensure data storage efficiency. Although cloud technology offers many advantages for storage service, it also introduces security challenges, especially with regards to data integrity, which is one of the most critical elements in any system. A data owner should thus enable data integrity auditing mechanisms. Much research has recently been undertaken to deal with these issues. In this paper, we propose a novel blockchain-based method, which can preserve cloud data integrity checking with data deduplication. In our method, a mediator performs data deduplication on the client side, which permits a reduction in the amount of outsourced data and a decrease in the computation time and the bandwidth used between the enterprise and the cloud service provider. This method supports private and public auditability. Our method also ensures the confidentiality of a client's data against auditors during the auditing process

La particularité de la pratique d’intelligence économique dans les PME marocaines : Cas d’une société de bourse marocaine

Les PME sont aujourd’hui confrontées à trois changements majeurs ; la révolution des NTIC, la mondialisation de l’économie et la prédominance des normes juridiques et techniques. L’ensemble de ces facteurs oblige les PME à adopter une nouvelle démarche de gestion et de planification stratégique en réponse à ces défis nouveaux. En effet, les PME sont bousculées dans leur quotidien et souvent forcées de remettre en cause leurs habitudes, de repenser leurs stratégies et d’adopter une démarche anticipative et non plus réactive pour ne pas disparaître ou être avalées. Des dangers comparables à ceux encourus par des grandes entreprises les guettent : prédation, détournement d’informations, L’efficacité de cette transformation de stratégie repose sur le développement de véritables systèmes d’intelligence économique qui établissent la gestion stratégique de l’information comme un outil d’anticipation, de protection du patrimoine immatériel ainsi que d’influence. A l’heure où la course mondiale à la compétitivité est déjà bien établie, la plupart des entreprises et notamment les PME marocaines, sont encore loin d’intégrer les enjeux de l’intelligence économique. En effet, notre étude de cas s’intéresse à la proposition d’une stratégie de l’intelligence économique à une catégorie des PME notamment les sociétés de bourse. &nbsp

Effects of copper mineralogy and methanobactin on cell growth and sMMO activity in <i>Methylosinus trichosporium</i> OB3b

Controls on in situ methanotroph activity are not well understood. One potentially important parameter is copper (Cu) because it is the metal-centre of particulate methane monooxygenase (pMMO), the most active enzyme for oxidizing methane to methanol. Further, Cu-to-cell ratios influence the relative expression of pMMO versus the alternate soluble MMO (sMMO) in some species. However, most methanotroph studies only have assessed readily soluble forms of Cu (e.g. CuCl₂) and there is a dearth of Cu-related activity data for Cu sources more common in the environment. Here we quantified sMMO activity (as a practical indicator of Cu availability) and growth kinetics in <i>Methylosinus trichosporium</i> OB3b, an organism that expresses both pMMO and sMMO, when grown on Cu-minerals with differing dissolution equilibria to assess how mineral type and methanobactin (mb) might influence in situ methanotroph activity. Mb is a molecule produced by <i>M. trichosporium</i> OB3b that has a high affinity for Cu, reduces Cu toxicity, and may influence Cu availability in terrestrial systems. CuCO₃.Cu(OH)₂ and CuO were chosen for study based on modelling data, reflecting more and less soluble minerals, respectively, and were found to affect <i>M. trichosporium</i> OB3b activity differently. Cells grew without growth lag and with active pMMO on CuCO₃.Cu(OH)₂, regardless of the amount of mineral supplied (<500 μmoles Cu-total l^&minus;1). The organism also grew well on CuO; however, significant sMMO activity was retained up to 50 μmoles Cu-total l^&minus;1, although sMMO activity was suppressed by supplemental mb and-or direct cell-mineral contact. Mb addition increased growth rates (<i>p</i> < 0.05) with both minerals. Results show mb broadly stimulates growth, but Cu mineralogy and mb dictate whether sMMO or pMMO is active in the cells. This explains why sMMO activity has been seen in soils with high Cu and also has implications for predicting dominant MMO activity in terrestrial bioremediation applications

A four-helix bundle stores copper for methane oxidation

Methane-oxidising bacteria (methanotrophs) require large quantities of copper for the membrane-bound (particulate) methane monooxygenase (pMMO). Certain methanotrophs are also able to switch to using the iron-containing soluble MMO (sMMO) to catalyse methane oxidation, with this switchover regulated by copper. MMOs are Nature’s primary biological mechanism for suppressing atmospheric levels of methane, a potent greenhouse gas. Furthermore, methanotrophs and MMOs have enormous potential in bioremediation and for biotransformations producing bulk and fine chemicals, and in bioenergy, particularly considering increased methane availability from renewable sources and hydraulic fracturing of shale rock. We have discovered and characterised a novel copper storage protein (Csp1) from the methanotroph Methylosinus trichosporium OB3b that is exported from the cytosol, and stores copper for pMMO. Csp1 is a tetramer of 4-helix bundles with each monomer binding up to 13 Cu(I) ions in a previously unseen manner via mainly Cys residues that point into the core of the bundle. Csp1 is the first example of a protein that stores a metal within an established protein-folding motif. This work provides a detailed insight into how methanotrophs accumulate copper for the oxidation of methane. Understanding this process is essential if the wide-ranging biotechnological applications of methanotrophs are to be realised. Cytosolic homologues of Csp1 are present in diverse bacteria thus challenging the dogma that such organisms do not use copper in this location

Methanobactin and MmoD work in concert to act as the ‘copper‐switch’ in methanotrophs

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/100314/1/emi12150.pd