On the security of NoSQL cloud database services

Processing a vast volume of data generated by web, mobile and Internet-enabled devices, necessitates a scalable and flexible data management system. Database-as-a-Service (DBaaS) is a new cloud computing paradigm, promising a cost-effective and scalable, fully-managed database functionality meeting the requirements of online data processing. Although DBaaS offers many benefits it also introduces new threats and vulnerabilities. While many traditional data processing threats remain, DBaaS introduces new challenges such as confidentiality violation and information leakage in the presence of privileged malicious insiders and adds new dimension to the data security. We address the problem of building a secure DBaaS for a public cloud infrastructure where, the Cloud Service Provider (CSP) is not completely trusted by the data owner. We present a high level description of several architectures combining modern cryptographic primitives for achieving this goal. A novel searchable security scheme is proposed to leverage secure query processing in presence of a malicious cloud insider without disclosing sensitive information. A holistic database security scheme comprised of data confidentiality and information leakage prevention is proposed in this dissertation. The main contributions of our work are: (i) A searchable security scheme for non-relational databases of the cloud DBaaS; (ii) Leakage minimization in the untrusted cloud. The analysis of experiments that employ a set of established cryptographic techniques to protect databases and minimize information leakage, proves that the performance of the proposed solution is bounded by communication cost rather than by the cryptographic computational effort

Compound Multiple Access Channel with Confidential Messages

In this paper, we study the problem of secret communication over a Compound Multiple Access Channel (MAC). In this channel, we assume that one of the transmitted messages is confidential that is only decoded by its corresponding receiver and kept secret from the other receiver. For this proposed setting (compound MAC with confidential messages), we derive general inner and outer bounds on the secrecy capacity region. Also, as examples, we investigate 'Less noisy' and 'Gaussian' versions of this channel, and extend the results of the discrete memoryless version to these cases. Moreover, providing numerical examples for the Gaussian case, we illustrate the comparison between achievable rate regions of compound MAC and compound MAC with confidential messages.Comment: Accepted at IEEE ICC 2014. arXiv admin note: substantial text overlap with arXiv:1402.479

Top Ten Journals Publishing on COVID-19: A Scientometric Analysis

Objectives: This study aimed at identifying and visualizing the scientometric indicators of top ten highly productive journals publishing documents on topics related to COVID-19. Methods: on April 4, 2021, using 36 COVID-19 keywords derived from MeSH retrieved all relevant global publications indexed in Scopus. Then, all studies were limited to top 10 highly productive journals in this field. An Exploratory and descriptive analysis of bibliographic data (number of publication/citations, journals, highly cited documents, highly cited/productive authors/countries, co-occurrence map of keywords, and co-citation map of sources) by using Microsoft Excel and VOSviewer software packages were performed. Results: The top ranked journals in publication numbers belonged to the International Journal of Environmental Research and Public Health (N=1304, 16.2%), Plos One (N=1158, 14.4%) and BMJ (997, 12.4%), respectively. The Lancet (N=69983), JAMA (N=42553) and the Journal of Medical Virology (19089) ranked first to third as to received citation numbers, respectively. Mahase, E (N=180, 2.23%), Lacobucci, G (N=126, 1.56%) and Rimmer, A (N=82, 1.01%) were ranked first to third as highly-productive authors, respectively. However, the highest-ranked authors in their citations/document indicator were Cheng, Z (3691), Gu, X (2736.25) and Xia, J (2269.66), respectively. First to third ranked countries in receiving citations were China (94776), United States (51621) and United Kingdom (32339), respectively.  Out of top 10 contributing countries in producing documents, United States (1976; 24.5%), United Kingdom (1372; 17%) and China (894; 11.1%) ranked first to third, respectively. Keywords co-occurrence and clustering showed that clinical manifestation and dissemination of the disease as well as its epidemiology have been heavily considered.  Discussion: This study offers important quantitative information on journals working on the disease. Identifying most productive journals can help potential researchers collaborate with researchers from pioneering journals and contribute to top journals for making influential works on COVID-19 and consequent knowledge on the control and treatment of the disease

Vergleich klinischer und radiologischer Ergebnisse roboterassistierter und koventionell implantierter Kniegelenksendoprothesen

In der Orthopädischen Klinik Kassel wurden von März 2000 bis Juli 2002 insgesamt 70 zementierte roboterassistierte Knieendoprothesen vom Typ Search Evolution mit einem fixed bearing Plateau bei 68 Patienten eingesetzt. Die Operationsindikation war die primäre Gonarthrose. Es wurden alle Patienten prospektiv erfasst und nach 3, 6, 12, 24 und 60 Monaten nachuntersucht unter Verwendung des Knee-Society-Scores. Dieses roboterassistierte Kollektiv wurde mit 232 Patienten verglichen, die 2001 eine manuell implantierte zementierte Knieprothese bekamen. Der Nachuntersuchungszeitraum betrug in dieser Gruppe ein Jahr. Bezüglich der klinischen Daten nach dem Knee-Society-Score konnten vergleichbare Ergebnisse durch den Operationsroboter CASPAR erzielt werden. Hinsichtlich der mechanischen Achsen sowie der Lage der Femurkomponente und Tibiakomponente konnten durch CASPAR signifikant bessere Ergebnisse erreicht werden. Zusammenfassend wurde in dieser Arbeit nachgewiesen, dass die Implantation einer Knieendoprothese durch den Einsatz des CASPAR-Systems passgenau möglich ist und signifikant bessere mechanische Beinachsen erzielt werden. Dabei liegen die klinischen Resultate der CASPAR Gruppe im Rahmen der in der Literatur beschriebenen herkömmlich operierten Nachuntersuchungsergebnisse. Nachteilig sind ein erhöhter Zeitaufwand und Kosten, ohne dass es eine erhöhte Komplikationsrate gibt

Efficient Solution Methods for Just-In-Time Machine and Shop Scheduling Problems

University of Technology Sydney. Faculty of Science.The classical machine (i.e., single and parallel machine) and shop scheduling (i.e., flow-shop, job-shop and open-shop) problems are concerned with performing a set of jobs on a given set of machines with or without precedence relations. This thesis explores variants of such problems, pertinent to the practice of Just-In-Time (JIT) manufacturing, where each job (operation) has a due date (or due window) and any deviation from it would incur either earliness or tardiness costs. Embracing JIT philosophy by companies and the need for developing realistic scheduling models have led to a growing body of research on earliness- tardiness minimization. Yet, most studies have been devoted to single machine scheduling problems and little research has been conducted to address the multiple-machine or shop scheduling settings. Moreover, the current solution methodologies often fail to deliver quality solutions particularly as the size of instances grows. Therefore, this PhD thesis will contribute to developing efficient algorithms being capable of obtaining high quality solutions for computationally challenging instances. In addition, we contribute to the existing approaches by integrating exact and heuristic algorithms to maximize the benefits associated with them