The Bacillus cereus GerN and GerT protein homologs have distinct roles in spore germination and outgrowth, respectively

The GerT protein of Bacillus cereus shares 74% amino acid identity with its homolog GerN. The latter is a Na+/H+-K+ 19 antiporter that is required for normal spore germination in inosine. The germination properties of single and double mutants of B. cereus ATCC10876 reveal that unlike GerN, which is required for all germination responses that involve the GerI germinant receptor, the GerT protein does not have a significant role in germination, although it is required for the residual GerI-mediated inosine germination response of a gerN mutant. In contrast, GerT has a significant role in outgrowth; gerT mutant spores do not outgrow efficiently under alkaline conditions, and outgrow more slowly than wild type in the presence of high NaCl concentrations. The GerT protein in B. cereus therefore contributes to the success of spore outgrowth from the germinated state during alkaline or Na+ stress

Effects of culivation conditions for apples on growth rates of fruit fly larvae and contents of phenolics

The different cultivation treatments significantly and systematically affected both rate of development of fruit fly larvae and contents of phenolic compounds, but not the total number of flies produced. This is in accordance with the hypothesis that cultivation methods can give large enough changes in composition of plant foods to affect physiological aspects important for health of consumers. It indicates that further stusies should be made of the links between plant cultivation, plant composition and health, for example regarding the question of the nutritional value of organic versus conventional food

Advanced PON topologies with wireless connectivity

“This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder." “Copyright IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.”The interoperability of wireless and PON networking solutions is investigated to reduce deployment expenditure by means of centralised network management while providing ubiquitous access connections and mobility. Network modelling in the physical layer of WiMAX channel transmission based on FDM over legacy PONs has demonstrated EVMs below -30 dB and error-free multipath transmission. In addition, the development of a dynamic MAC protocol suite has been presented to assign bandwidth between the OLT and ONU BaseStations over a multi-wavelength, splitter-PON topology to demonstrate converged network scalability. This has been achieved by managing data-centric traffic with quality of service in view of diverse multi-user access technologies

Sum-Rate Maximization in Two-Way AF MIMO Relaying: Polynomial Time Solutions to a Class of DC Programming Problems

Sum-rate maximization in two-way amplify-and-forward (AF) multiple-input multiple-output (MIMO) relaying belongs to the class of difference-of-convex functions (DC) programming problems. DC programming problems occur as well in other signal processing applications and are typically solved using different modifications of the branch-and-bound method. This method, however, does not have any polynomial time complexity guarantees. In this paper, we show that a class of DC programming problems, to which the sum-rate maximization in two-way MIMO relaying belongs, can be solved very efficiently in polynomial time, and develop two algorithms. The objective function of the problem is represented as a product of quadratic ratios and parameterized so that its convex part (versus the concave part) contains only one (or two) optimization variables. One of the algorithms is called POlynomial-Time DC (POTDC) and is based on semi-definite programming (SDP) relaxation, linearization, and an iterative search over a single parameter. The other algorithm is called RAte-maximization via Generalized EigenvectorS (RAGES) and is based on the generalized eigenvectors method and an iterative search over two (or one, in its approximate version) optimization variables. We also derive an upper-bound for the optimal values of the corresponding optimization problem and show by simulations that this upper-bound can be achieved by both algorithms. The proposed methods for maximizing the sum-rate in the two-way AF MIMO relaying system are shown to be superior to other state-of-the-art algorithms.Comment: 35 pages, 10 figures, Submitted to the IEEE Trans. Signal Processing in Nov. 201

Power Allocation Based on SEP Minimization in Two-Hop Decode-and-Forward Relay Networks

The problem of optimal power allocation among the relays in a two-hop decode-and-forward cooperative relay network with independent Rayleigh fading channels is considered. It is assumed that only the relays that decode the source message correctly contribute in data transmission. Moreover, only the knowledge of statistical channel state information is available. A new simple closed-form expression for the average symbol error probability is derived. Based on this expression, a new power allocation method that minimizes the average symbol error probability and takes into account the constraints on the total average power of all the relay nodes and maximum instant power of each relay node is developed. The corresponding optimization problem is shown to be a convex problem that can be solved using interior point methods. However, an approximate closed-form solution is obtained and shown to be practically more appealing due to significant complexity reduction. The accuracy of the approximation is discussed. Moreover, the so obtained closed-form solution gives additional insights into the optimal power allocation problem. Simulation results confirm the improved performance of the proposed power allocation scheme as compared to other schemes.Comment: 27 pages, 5 figures, submitted to the IEEE Trans. Signal Processing in Feb. 201

An optimal fixed-priority assignment algorithm for supporting fault-tolerant hard real-time systems

The main contribution of this paper is twofold. First, we present an appropriate schedulability analysis, based on response time analysis, for supporting fault-tolerant hard real-time systems. We consider systems that make use of error-recovery techniques to carry out fault tolerance. Second, we propose a new priority assignment algorithm which can be used, together with the schedulability analysis, to improve system fault resilience. These achievements come from the observation that traditional priority assignment policies may no longer be appropriate when faults are being considered. The proposed schedulability analysis takes into account the fact that the recoveries of tasks may be executed at higher priority levels. This characteristic is very important since, after an error, a task certainly has a shorter period of time to meet its deadline. The proposed priority assignment algorithm, which uses some properties of the analysis, is very efficient. We show that the method used to find out an appropriate priority assignment reduces the search space from O(n!) to O(n/sup 2/), where n is the number of task recovery procedures. Also, we show that the priority assignment algorithm is optimal in the sense that the fault resilience of task sets is maximized as for the proposed analysis. The effectiveness of the proposed approach is evaluated by simulation