An efficient virtual topology design and traffic engineering scheme for IP/WDM networks

We propose an online traffic engineering (TE) scheme for efficient routing of bandwidth guaranteed connections on a Multiprotocol label switching (MPLS)/wavelength division multiplexing (WDM) network with a traffic pattern varying with the time of day. We first consider the problem of designing the WDM virtual topology utilizing multi-hour statistical traffic pattern. After presenting an effective solution to this offline problem, we introduce a Dynamic tRaffic Engineering AlgorithM (DREAM) that makes use of the bandwidth update and rerouting of the label switched paths (LSPs). The performance of DREAM is compared with commonly used online TE schemes and it is shown to be superior in terms of blocked traffic ratio. © IFlP International Federation for Information Processing 2007

Multi-layer virtual topology design in optical networks under physical layer impairments and multi-hour traffic demand

In this paper, we consider the virtual topology design (VTD) problem in multi-protocol label switching (MPLS)/wavelength division multiplexing (WDM) networks with an hourly changing traffic pattern, in the presence of physical layer impairments. We propose a multi-layer VTD scheme that satisfies the constraints in both layers with guaranteed bit error rates assuming no wavelength conversion. The proposed scheme involves interaction of the control planes of MPLS and WDM layers and can be applied without the necessity of a unified control plane. When the virtual topology is designed by considering only MPLS layer constraints, some lightpaths in the designed topology cannot be established, and this may result in a large amount of blocked traffic. We show that, by applying interaction between MPLS and WDM layers during topology design, the blocking ratio is reduced by an amount between 53% and 89% in the investigated cases. We also propose different information sharing strategies between the layers and show that, if physical layer information is available to the MPLS layer, a better blocking performance can be achieved and physical layer resource usage can be reduced by an amount up to 21%. © 2012 Optical Society of America

TSCP: A tabu search algorithm for wavelength converting node placement in WDM optical networks

Sparse wavelength conversion can increase the performance of all-optical wavelength division multiplexing (WDM) networks signi cantly by relaxing the wavelength continuity constraint. In this paper, we study the wavelength converter placement problem in multi- ber networks with static traf c demands. We present a tabu search based heuristic algorithm. The objective of the algorithm is to satisfy all the traf c demands with the minimum total cost of bers achieved in the full conversion case, by placing minimum number of wavelength converting nodes. We also implement a greedy algorithm and compare the performances of these converter placement algorithms with the optimum solutions on a sample network. The Tabu search based algorithm achieves the optimum solution in 72% of the test cases and it increases the average number of wavelength converting nodes by less than 10% with respect to the optimum solution. The effect of the utilized routing scheme on the generated solutions and the correlation between the converter node locations and the amount of traf c passing through the nodes are also investigated. © 2005 IEEE

Static lightpath establishment in multilayer traffic engineering under physical layer impairments

This paper investigates the lightpath establishment problem in the optical layer, which arises in multilayer traffic engineering. The static version of the problem is considered, in which the set of requested lightpaths is known initially, and the objective is to set up as many of these lightpaths as possible by assigning the physical layer resources efficiently. In establishing the lightpaths, physical layer impairments are also considered, such that the bit error rates of all established lightpaths should remain within acceptable limits. A heuristic algorithm, called ROLE, is proposed for the solution of this problem. An integer linear programming (ILP) formulation for the static lightpath establishment with physical layer impairments is also developed, which considers the aggregated effect of physical layer impairments. This formulation is used as a performance benchmark for ROLE on smaller-size networks. It also provides upper bounds even when the ILP model cannot be solved to optimality. The performance of ROLE is close to the optimum solutions for all studied problem sets, for which the optimum solution can be obtained. ROLE significantly outperforms previously proposed algorithms in terms of the number of lightpaths established. The effect of switch cross-talk ratio on the problem solution is also investigated. © 2009 OSA

A comparative study of single-layer and multi-layer traffic engineering approaches on transparent optical networks

This paper comparatively studies single-layer and multi-layer traffic engineering strategies on an IP/MPLS/WDM network. These strategies are evaluated and compared in two different scenarios. In the first scenario, the strategies make use of statistical information on the traffic patterns. In the second scenario, the traffic engineering decisions are based on the instantaneous traffic information only. The performance and benefits of both approaches are discussed based on simulations considering both throughput and network resource usage. © 2007 IEEE

Optical core networks research in the e-Photon-ONe+ project

This paper reports a summary of the joint research activities on Optical Core Networks within the e-Photon-ONe+ project. It provides a reasonable overview of the topics considered of interest by the European research community and supports the idea of building joint research activities that can leverage on the expertise of different research groups. © 2009 IEEE

Research on optical core networks in the e-Photon/ONe network of excellence

This papers reports the advances in Optical Core networks research coordinated in the framework of the e-Photon/ONe and e-Photon/ONe+ networks of excellence

The cell based dressing with living allogenic keratinocytes in the treatment of foot ulcers: a case study

In this study, we aimed to investigate the efficacy of cell based dressing with living allogenic keratinocytes in diabetic foot patients. To address this issue, the cultured keratinocytes were attached to the microcarriers produced from polyethylene and silica. The microcarriers were then applied to the wounds at 3-day intervals. Forty patients with grade II and III diabetic foot ulcers were included into the study. The patients were randomised into two groups (n = 20). The treatment and control groups received cell based dressing and microcarriers kept in culture medium overnight, respectively. The wound size was recorded at 3 days intervals. The wounds were also categorised by a specific scoring system considering the wound contraction, granulation tissue formation, epithetisation and discharge from the wounds. The high score indicates better condition

In Vitro Effects Of Rosmarinic Acid On Glutathione Reductase And Glucose 6-Phosphate Dehydrogenase

Context: Glutathione reductase (GR, NADPH:oxidized glutathione oxidoreductase, E. C 1.6.4.2) is a flavoprotein that catalyzes the NADPH-dependent reduction of oxidized glutathione (GSSG). GR is a crucial enzyme in the antioxidant system by maintaining reduced glutathione (GSH). Glucose 6-phosphate dehydrogenase (G6PD, glucose 6-phosphate (G6P):NADP(+) oxidoreductase, EC 1.1.1.49) is the key regulatory enzyme of the pentose phosphate pathway and maintains NADPH for reductive reactions. Objective: Rosmarinic acid (RA; alpha alpha-O-caffeoyl-3,4-dihydroxyphenyl lactic acid) is an ester of caffeic acid (CA) and 3,4-dihydroxyphenyllactic acid. It has a number of interesting biological activities. The inhibiting activities of the RA on GR and G6PD are investigated here for the first time. Materials and methods: GR and G6PD were purified from tissues, then the effects of RA are investigated. Results: This study reports that RA, which was isolated from Echium vulgare L. (Boraginaceae), inhibits purified GR and G6PD in a concentration-dependent manner. Kinetic characterizations and inhibition constants are investigated. Discussion and conclusion: Because of their importance in the antioxidative defense system, investigation of the inhibitors of these enzymes is important for drug development.WoSScopu

Optical Core Networks Research in thee-Photon-ONe+ Project

This paper reports a summary of the joint research activities on Optical Core Networks within the e-Photon-ONe+ project. It provides a reasonable overview of the topics considered of interest by the European research community and supports the idea of building joint research activities that can leverage on the expertise of different research groups