Abstract
Digitized radio-over-fiber (D-RoF) transport schemes are being pointed as viable alternative solutions to their analog counterparts, in order to avoid distortion/dynamic range problems. Here we propose a novel D-RoF architecture that takes advantage of a bandpass sigma-delta modulator at the transmitter which subsequently permits the usage of a simpler/cheaper base station that avoids the employment of a digital to analog converter. The proposed architecture exploits the properties of the digital signal to enable the extraction of an higher carrier frequency through the employment of a bandpass filter. Furthermore, we present a comprehensive analysis regarding the impact of a low-cost electro-optic modulation on the quality of received demodulated signal. Finally, a comparison performance analysis between the conventional D-RoF and the proposed architecture is presented. We conclude that although the proposed architecture performs similarly to conventional D-RoF schemes, it is more competitive for either upgrading installed systems as well as for new deployments. (C) 2014 Optical Society of America

Abstract
Object Oriented Mat lab Adaptive Optics (OOMAO) is a Mat lab toolbox dedicated to Adaptive Optics (AO) systems. OOMAO is based on a small set of classes representing the source, atmosphere, telescope, wavefront sensor, Deformable Mirror (DM) and an imager of an AO system. This simple set of classes allows simulating Natural Guide Star (NGS) and Laser Guide Star (LGS) Single Conjugate AO (SCAO) and tomography AO systems on telescopes up to the size of the Extremely Large Telescopes (ELT). The discrete phase screens that make the atmosphere model can be of infinite size, useful for modeling system performance on large time scales. OOMAO comes with its own parametric influence function model to emulate different types of DMs. The cone effect, altitude thickness and intensity profile of LGSs are also reproduced. Both modal and zonal modeling approach are implemented. OOMAO has also an extensive library of theoretical expressions to evaluate the statistical properties of turbulence wavefronts. The main design characteristics of the OOMAO toolbox are object oriented modularity, vectorized code and transparent parallel computing. OOMAO has been used to simulate and to design the Multi Object AO prototype Raven at the Subaru telescope and the Laser Tomography AO system of the Giant Magellan Telescope. In this paper, a Laser Tomography AO system on an ELT is simulated with OOMAO. In the first part, we set up the class parameters and we link the instantiated objects to create the source optical path. Then we build the tomographic reconstructor and write the script for the pseudo-open-loop controller.

Abstract
In safety-critical systems a global high-reliability is sought, including in the communication network when a distributed control system is used. The FlexRay protocol was developed within the automotive industry with the necessary characteristics to respond to the demands of safety-critical applications, e.g. X-by-wire. Nevertheless, the FlexRay protocol does not define a mechanism to guarantee message delivery, nor defines global error signaling, leaving the resolution of these problems to the application. This paper presents a preliminary proposal for a mechanism that uses temporal redundancy to recover transient errors in time-triggered messages. An extra node is used to trigger message retransmissions whenever errors or omissions do effectively occur. This mechanism uses the FlexRay dynamic segment to implement message retransmissions, leading to a minimum recovery time, typically one cycle, together with a very small bandwidth usage.

Abstract
Purpose - This study investigates the use of the internet by the largest companies based in Sweden and Spain to communicate their engagement in corporate social responsibility (CSR) activities. Its purpose is to analyse to what extent, if any, are there differences in the CSR communication on the web sites companies from these two countries. Design/methodology/approach - The paper examines CSR communication on the internet by companies based in Sweden and Spain. Non-parametric statistics are used to analyse some factors that influence disclosure, namely country, industry affiliation, profitability, and size. Findings - Findings suggest that in spite of the existence of a high degree of similarity between CSR communication practices, companies from Spain place social responsibility information in more prominent sections and devote more space to said information. Swedish companies are found to disclose more their codes of conduct/ethics and CSR-related press clips and published articles. Research limitations/implications - The sample is small. There may be content analysis issues associated with subjectivity in the coding process. Originality/value - It adds to the scarce research on CSR communication by companies in these countries by providing new empirical data and extends prior research comparing such practices in different international models of CSR.

Abstract
Computer-supported online 3-D virtual world environments have been waxed and waned in interest and representativeness for supporting collaborative- and simulation-based practices. In a post-modern societal framework that requires inexpensive solutions for high-risk situations, research efforts in virtual worlds have developed a basis for understanding the use of virtual reality for multidisciplinary scenarios such as distance learning, training, therapy treatments, and social interaction. Complex relationships can be established simultaneously between several students functioning as integrated learning units using different media, and interacting with their physical environment in the context of real-world settings. In this sense, a recurrently updated research agenda for virtual worlds can characterize the current needs at a systematic way. This paper presents a meta-analysis of 35 publications to identify gaps and opportunities for research in collaborative three-dimensional environments based on content analysis. At a general perspective, there is a lack of established approaches to measure the influence and research potential of sociocultural factors in virtual worlds’ usage, autism spectrum and other healthcare-related settings, learning outcomes, content characteristics, task support for groups and crowds, and online data collection.

Abstract
There is an increasing concern about transient errors in deep sub-micron processor architectures. Software-only error detection approaches that exploit program invariants for silent error detection incur large execution overheads and are unreliable as state can be corrupted after invariant check points. In this paper we explore the use of configurable hardware structures for the continuous evaluation of high-level program invariants at the assembly-level. We evaluate the resource requirements and performance of the proposed hardware structures on a contemporary reconfigurable hardware device. The results, for a small set of kernels codes, reveal that these hardware structures require a very small number of resources and are fairly insensitive to the complexity of the invariants thus making the proposed hardware approach an attractive alternative to software-only invariant checking by integrating them in traditional processor architectures. © 2014 Springer International Publishing Switzerland.