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Cyber-physical systems (CPS) are the next generation of engineered systems into which computing, communication, and control technologies are now being closely integrated. They play an increasingly important role in critical infrastructures, governments and everyday life. Security is crucial in CPS, but they were not, unfortunately, initially conceived as a secure environment, and if these security issues are to be incorporated, then security must be considered from the very beginning of the system design. One way in which to solve this problem is by having a global perspective, which can be achieved by employing a Reference Architecture (RA), since it is a high-level abstraction of a system that could be useful in the implementation of complex systems. It is widely accepted that adding elements in order to address many security factors (integrity, confidentiality, availability, etc.) and facilitate the definition of the security requirements of a Security Reference Architecture (SRA) is a good starting point when attempting to solve these kinds of cybersecurity problems and protect the system from the beginning of the development. An SRA makes it possible to define the key elements of a specific environment, thus allowing a better understanding of the inherent elements of the environments, while promoting the integration of security aspects and mechanisms. The present paper, therefore, presents the definition of an SRA for CPS by using UML models in an attempt to facilitate secure CPS implementations.

Cyber-physical systems (CPS) are the next generation of engineered systems into which computing, communication, and control technologies are now being closely integrated. They play an increasingly important role in critical infrastructures, governments and everyday life. Security is crucial in CPS, but they were not, unfortunately, initially conceived as a secure environment, and if these security issues are to be incorporated, then security must be considered from the very beginning of the system design. One way in which to solve this problem is by having a global perspective, which can be achieved by employing a Reference Architecture (RA), since it is a high-level abstraction of a system that could be useful in the implementation of complex systems. It is widely accepted that adding elements in order to address many security factors (integrity, confidentiality, availability, etc.) and facilitate the definition of the security requirements of a Security Reference Architecture (SRA) is a good starting point when attempting to solve these kinds of cybersecurity problems and protect the system from the beginning of the development. An SRA makes it possible to define the key elements of a specific environment, thus allowing a better understanding of the inherent elements of the environments, while promoting the integration of security aspects and mechanisms. The present paper, therefore, presents the definition of an SRA for CPS by using UML models in an attempt to facilitate secure CPS implementations.

The work presented in this paper traces the history of active learning and further utilizes the available literature to define meaning and importance of active learning in higher education. The study highlights common practical problems faced by students and instructors in implementing active learning in higher education and further identifies a set of individual prac-tices being used worldwide to overcome the obstacles. Expectations and responsibilities of stu-dents and instructors are also specified to enhance the efficiency of active learning environment. The paper also traces the importance of student and instructor rapport for a successful learning environment.

"April 21, 1972." ; "72-100 SP." ; Cover title. ; Mode of access: Internet.

The concept of "reference conditions" describes the benchmark against which current conditions are compared when assessing the status of water bodies. In this paper we focus on the establishment of reference conditions for European lakes according to a phytoplankton biomass indicator—the concentration of chlorophyll-a. A mostly spatial approach (selection of existing lakes with no or minor human impact) was used to set the reference conditions for chlorophyll-a values, supplemented by historical data, paleolimnological investigations and modelling. The work resulted in definition of reference conditions and the boundary between "high" and "good" status for 15 main lake types and five ecoregions of Europe: Alpine, Atlantic, Central/Baltic, Mediterranean, and Northern. Additionally, empirical models were developed for estimating site-specific reference chlorophyll-a concentrations from a set of potential predictor variables. The results were recently formulated into the EU legislation, marking the first attempt in international water policy to move from chemical quality standards to ecological quality targets.