A disaster-resilient multi-content optical datacenter network architecture

Cloud services based on datacenter networks are becoming very important. Optical networks are well suited to meet the demands set by the high volume of traffic between datacenters, given their high bandwidth and low-latency characteristics. In such networks, path protection against network failures is generally ensured by providing a backup path to the same destination, which is link-disjoint to the primary path. This protection fails to protect against disasters covering an area which disrupts both primary and backup resources. Also, content/service protection is a fundamental problem in datacenter networks, as the failure of a single datacenter should not cause the disappearance of a specific content/service from the network. Content placement, routing and protection of paths and content are closely related to one another, so the interaction among these should be studied together. In this work, we propose an integrated ILP formulation to design an optical datacenter network, which solves all the above-mentioned problems simultaneously. We show that our disaster protection scheme exploiting anycasting provides more protection, but uses less capacity, than dedicated single-link protection. We also show that a reasonable number of datacenters and selective content replicas with intelligent network design can provide survivability to disasters while supporting user demands

Enrichment of Organic Carbon in Sediment Transport by Interrill and Rill Erosion Processes

Erosion and loss of organic carbon (OC) result in degradation of the soil surface. Rill and interrill erosion processes on a silt loam soil were examined in laboratory rainfall and flume experiments. These experiments showed that rill and interrill erosion processes have contrasting impacts on enrichment of OC in transported sediment. Rill erosion was found to be nonselective, while for interrill erosion the enrichment ratio of OC, EROC, varied between 0.9 and 2.6 and was inversely related to the unit sediment discharge. At unit sediment discharge values >0.0017 kg s(-1) m(-1), the EROC remained equal to 1. The enrichment process was not influenced by raindrop impact. Enrichment of OC by "aggregate stripping" was found to be unimportant in our study. This was attributed to the low aggregate stability of the soil and the equal distribution of OC within the different soil aggregate classes

Energy efficiency considerations in integrated IT and optical network resilient infrastructures

The European Integrated Project GEYSERS - Generalised Architecture for Dynamic Infrastructure Services - is concentrating on infrastructures incorporating integrated optical network and IT resources in support of the Future Internet with special emphasis on cloud computing. More specifically GEYSERS proposes the concept of Virtual Infrastructures over one or more interconnected Physical Infrastructures comprising both network and IT resources. Taking into consideration the energy consumption levels associated with the ICT today and the expansion of the Internet in size and complexity, that incurring increased energy consumption of both IT and network resources, energy efficient infrastructure design becomes critical. To address this need, in the framework of GEYSERS, we propose energy efficient design of infrastructures incorporating integrated optical network and IT resources, supporting resilient end-to-end services. Our modeling results quantify significant energy savings of the proposed solution by jointly optimizing the allocation of both network and IT resources

Scalable Impairment-Aware Anycast Routing in Multi-Domain Optical Grid Networks

ABSTRACT In optical Grid networks, the main challenge is to account for not only network parameters, but also for resource availability. Anycast routing has previously been proposed as an effective solution to provide job scheduling services in optical Grids, offering a generic interface to access Grid resources and services. The main weakness of this approach is its limited scalability, especially in a multi-domain scenario. This paper proposes a novel anycast proxy architecture, which extends the anycast principle to a multi-domain scenario. The main purpose of the architecture is to perform aggregation of resource and network states, and as such improve computational scalability and reduce control plane traffic. Furthermore, the architecture has the desirable properties of allowing Grid domains to maintain their autonomy and hide internal configuration details from other domains. Finally, we propose an impairment-aware anycast routing algorithm that incorporates the main physical layer characteristics of large-scale optical networks into its path computation process. By integrating the proposed routing scheme into the introduced architecture we demonstrate significant network performance improvements. Keywords: Grid computing, routing algorithms, optical networks, physical impairments, anycast routing. INTRODUCTION Today, the need for network systems to support storage and computing services for science and business, is often satisfied by relatively isolated computing infrastructure (clusters). Migration to truly distributed and integrated applications requires optimization and (re)design of the underlying network technology to create a Grid platform for the cost and resource efficient delivery of network services with substantial data transfer, processing power and/or data storage requirements. Optical networks offer an undeniable potential for the Grid, given their proven track-record in the context of high-speed, long-haul, networking. Not only eScience applications dealing with large experimental data sets (e.g. particle physics) but also business/consumer oriented applications can benefit from optical Grid infrastructure [1]: both the high data rates typical of eScience applications and the low latency requirements of consumer/business applications (cf. interactivity) can effectively be addressed. When using transparent WDM as such network technology, signals are transported end-to-end optically without being converted to the electrical domain in between. Connection provisioning of all-optical connections (lightpaths) between source and destination nodes is based on specific routing and wavelength assignment algorithms (RWA). Traditional RWA schemes only account for network conditions such as connectivity and available capacity, without considering physical layer details. However, in transparent optical networks covering large geographical areas, the optical signal experiences the accumulation of physical impairments through transmission and switching, possibly resulting in unacceptable signal quality Another emerging and challenging task in distributed and heterogeneous computing environments, is job scheduling: when and where to execute a given Grid job, based on the requirements of the job (for instance a deadline and minimal computational power) and the current state of the network and resources. Traditionally, a local scheduler optimizes utilization and performance of a single Grid site, while a meta-scheduler is distributes workload across different sites. Current implementations of these (meta-)schedulers only account for Grid resource availability In this paper we propose a novel architecture to support impairment-aware anycast routing for large-scale optical Grid networks. Section 2 discusses general approaches to support multi-domain networks. We then proceed to introduce a novel architecture, which can provide anycast Grid services in a multi-domain scenario (Section 3). Simulation analysis is used to demonstrate the improved scalability without incurring significant performance loss. Furthermore, Section 4 shows how to incorporate physical layer impairments, to further improve the performance of optical Grid networks. Conclusions are presented in Section 5

A novel context ontology to facilitate interoperation of semantic services in environments with wearable devices

The LifeWear-Mobilized Lifestyle with Wearables (Lifewear) project attempts to create Ambient Intelligence (AmI) ecosystems by composing personalized services based on the user information, environmental conditions and reasoning outputs. Two of the most important benefits over traditional environments are 1) take advantage of wearable devices to get user information in a nonintrusive way and 2) integrate this information with other intelligent services and environmental sensors. This paper proposes a new ontology composed by the integration of users and services information, for semantically representing this information. Using an Enterprise Service Bus, this ontology is integrated in a semantic middleware to provide context-aware personalized and semantically annotated services, with discovery, composition and orchestration tasks. We show how these services support a real scenario proposed in the Lifewear project

The content of ascorbic acid and tocopherol in the tissues and eggs of wild <i>Macrobrachium rosenbergii</i> during maturation

Variations in the concentrations of ascorbic acid (AA) and tocopherols in association with the gonadal development of the freshwater prawn Macrobrachium rosenbergii were investigated in females captured in the Mae Klong River, Thailand. Mean ovarian AA levels ranged from 210 to 540 µg/g dry weight (dw) and were at least 11-fold higher than midgut gland (MG) levels. Variations in ovarian AA levels are believed to be related to the biosynthesis of steroid hormones, the formation of collagen, and the deposition of egg yolk compounds. alpha-Tocopherol (alpha-T) was the predominant form of vitamin E in prawn tissues and eggs. The level of alpha-T in the MG was constant, whereas in the ovaries, it ranged from 143 to 425 µg/g dw. The incorporation of a-T into the ovary was highly correlated (r² = 0.87) to ovarian lipid levels, which probably reflects the role of this vitamin as a major antioxidant agent. The present results provide further evidence of the essentiality of these vitamins in crustacean reproduction

Osteogenesis imperfecta: the audiological phenotype lacks correlation with the genotype

Contains fulltext : 97190.pdf (publisher's version ) (Open Access)ABSTRACT: BACKGROUND: Osteogenesis Imperfecta (OI) is a heritable connective tissue disorder mainly caused by mutations in the genes COL1A1 and COL1A2 and is associated with hearing loss in approximately half of the cases. The hearing impairment usually starts between the second and fourth decade of life as a conductive hearing loss, frequently evolving to mixed hearing loss thereafter. A minority of patients develop pure sensorineural hearing loss. The interindividual variability in the audiological characteristics of the hearing loss is unexplained. METHODS: With the purpose of evaluating inter- and intrafamilial variability, hearing was thorougly examined in 184 OI patients (type I: 154; type III: 4; type IV: 26), aged 3-89 years, with a mutation in either COL1A1 or COL1A2 and originating from 89 different families. Due to the adult onset of hearing loss in OI, correlations between the presence and/or characteristics of the hearing loss and the underlying mutation were investigated in a subsample of 114 OI patients from 64 different families who were older than 40 years of age or had developed hearing loss before the age of 40. RESULTS: Hearing loss was diagnosed in 48.4% of the total sample of OI ears with increasing prevalence in the older age groups. The predominant type was a mixed hearing loss (27.5%). A minority presented a pure conductive (8.4%) or pure sensorineural (12.5%) loss. In the subsample of 114 OI subjects, no association was found between the nature of the mutation in COL1A1 or COL1A2 genes and the occurrence, type or severity of hearing loss. Relatives originating from the same family differed in audiological features, which may partially be attributed to their dissimilar age. CONCLUSIONS: Our study confirms that hearing loss in OI shows a strong intrafamilial variability. Additional modifications in other genes are assumed to be responsible for the expression of hearing loss in OI

The effects of symmetry on the dynamics of antigenic variation

In the studies of dynamics of pathogens and their interactions with a host immune system, an important role is played by the structure of antigenic variants associated with a pathogen. Using the example of a model of antigenic variation in malaria, we show how many of the observed dynamical regimes can be explained in terms of the symmetry of interactions between different antigenic variants. The results of this analysis are quite generic, and have wider implications for understanding the dynamics of immune escape of other parasites, as well as for the dynamics of multi-strain diseases.Comment: 21 pages, 4 figures; J. Math. Biol. (2012), Online Firs