Associative memory design using overlapping decompositions

Cataloged from PDF version of article.This paper discusses the use of decomposition techniques in the design of associative memories via arti"cial neural networks. In particular, a disjoint decomposition which allows an independent design of lower-dimensional subnetworks and an overlapping decomposition which allows subnetworks to share common parts, are analyzed. It is shown by a simple example that overlapping decompositions may help in certain cases where design by disjoint decompositions fails. With this motivation, an algorithm is provided to synthesize neural networks using the concept of overlapping decompositions. Applications of the proposed design procedure to a benchmark example from the literature and to a pattern recognition problem indicate that it may improve the e!ectiveness of the existing methods. ( 2001 Published by Elsevier Science Ltd

State Aggregation-based Model of Asynchronous Multi-Fiber Optical Switching with Shared Wavelength Converters

Cataloged from PDF version of article.This paper proposes new analytical models to study optical packet switching architectures with multi-fiber interfaces and shared wavelength converters. The multi-fiber extension of the recently proposed Shared-Per-Input-Wavelength (SPIW) scheme is compared against the multi-fiber Shared-Per-Node (SPN) scheme in terms of cost and performance for asynchronous traffic. In addition to using Markov chains and fixed-point iterations for modeling the mono-fiber case, a novel state aggregation technique is proposed to evaluate the packet loss in asynchronous multi-fiber scenario. The accuracy of the performance models is validated by comparison with simulations in a wide variety of scenarios with both balanced and imbalanced input traffic. The proposed analytical models are shown to remarkably capture the actual system behavior in all scenarios we tested. The adoption of multi-fiber interfaces is shown to achieve remarkable savings in the number of wavelength converters employed and their range. In addition, the SPIW solution allows to save, in particular conditions, a significant number of optical gates compared to the SPN solution. Indeed, SPIW allows, if properly dimensioned, potential complexity and cost reduction compared to SPN, while providing similar performance. (C) 2013 Elsevier B.V. All rights reserved

MPLS Automatic Bandwidth Allocation via Adaptive Hysteresis

Cataloged from PDF version of article.MPLS automatic bandwidth allocation (or provisioning) refers to the process of dynamically updating the bandwidth allocation of a label switched path on the basis of actual aggregate traffic demand on this path. Since bandwidth updates require signaling, it is common to limit the rate of updates to reduce signaling costs. In this article, we propose a model-free asynchronous adaptive hysteresis algorithm for MPLS automatic bandwidth allocation under bandwidth update rate constraints. We validate the effectiveness of the proposed approach by comparing it against existing schemes in (i) voice and (ii) data traffic scenarios. The proposed method can also be used in more general GMPLS networks. (C) 2010 Elsevier B.V. All rights reserved

Shared-per-wavelength asynchronous optical packet switching: A comparative analysis

Cataloged from PDF version of article.This paper compares four different architectures for sharing wavelength converters in asynchronous optical packet switches with variable-length packets. The first two architectures are the well-known shared-per-node (SPN) and shared-per-link (SPL) architectures, while the other two are the shared-per-input-wavelength (SPIW) architecture, recently proposed as an optical switch architecture in synchronous context only, which is extended here to the asynchronous scenario, and an original scheme called shared-per-output-wavelength (SPOW) architecture that we propose in the current article. We introduce novel analytical models to evaluate packet loss probabilities for SPIW and SPOW architectures in asynchronous context based on Markov chains and fixed-point iterations for the particular scenario of Poisson input traffic and exponentially distributed packet lengths. The models also account for unbalanced traffic whose impact is thoroughly studied. These models are validated by comparison with simulations which demonstrate that they are remarkably accurate. In terms of performance, the SPOW scheme provides blocking performance very close to the SPN scheme while maintaining almost the same complexity of the space switch, and employing less expensive wavelength converters. On the other hand, the SPIW scheme allows less complexity in terms of number of optical gates required, while it substantially outperforms the widely accepted SPL scheme. The authors therefore believe that the SPIW and SPOW schemes are promising alternatives to the conventional SPN and SPL schemes for the implementation of next-generation optical packet switching systems. 2010 Elsevier B.V. All rights reserved

Mapping adaptation of barley to droughted environments

Identifying barley genomic regions influencing the response of yield and its components to water deficits will aid in our understanding of the genetics of drought tolerance and the development of more drought tolerant cultivars. We assembled a population of 192 genotypes that represented landraces, old, and contemporary cultivars sampling key regions around the Mediterranean basin and the rest of Europe. The population was genotyped with a stratified set of 50 genomic and EST derived molecular markers, 49 of which were Simple Sequence Repeats (SSRs), which revealed an underlying population sub-structure that corresponded closely to the geographic regions in which the genotypes were grown. A more dense whole genome scan was generated by using Diversity Array Technology (DArT®) to generate 1130 biallelic markers for the population. The population was grown at two contrasting sites in each of seven Mediterranean countries for harvest 2004 and 2005 and grain yield data collected. Mean yield levels ranged from 0.3 to 6.2 t/ha, with highly significant genetic variation in low-yielding environments. Associations of yield with barley genomic regions were then detected by combining the DArT marker data with the yield data in mixed model analyses for the individual trials, followed by multiple regression of yield on markers to identify a multi-locus subset of significant markers/QTLs. QTLs exhibiting a pre-defined consistency across environments were detected in bins 4, 6, 6 and 7 on barley chromosomes 3H, 4H, 5H and 7H respectivel

PTPN22 gene polymorphism in Takayasu's arteritis

Objective. Takayasu's arteritis (TA) is a chronic, rare granulomatous panarteritis of unknown aetiology involving mainly the aorta and its major branches. In this study, genetic susceptibility to TA has been investigated by screening the functional single nucleotide polymorphism (SNP) of PTPN22 gene encoding the lymphoid-specific protein tyrosine phosphatase. Methods. Totally, 181 patients with TA and 177 healthy controls are genotyped by PCR-RFLP method for the SNP rs2476601 (A/G) of PTPN22 gene. Polymorphic region was amplified by PCR and digested with Xcm I enzyme. Results. Detected frequencies of heterozygous genotype (AG) were 5.1% (9/177) in control group and 3.8% (7/181) in TA group (P = 0.61, odds ratio: 0.75, 95% CI: 0.3, 2.0). No association with angiographic type, vascular involvement or prognosis of TA was observed either. Conclusion. The distribution of PTPN22 polymorphism did not reveal any association with TA in Turkey. © The Author 2008. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved

Factor V G1691A (Leiden) is a major etiological factor in Egyptian Budd-Chiari syndrome patients

Objective: Budd-Chiari syndrome is a multifactorial disease in which several prothrombotic disorders may predispose patients to the development of thrombosis at this uncommon location (hepatic veins). The aim of this study was to determine the prevalence and characteristics of inherited thrombophilia in Egyptian Budd-Chiari syndrome patients.Materials and Methods: The study included 47 Budd-Chiari syndrome patients (20 children and 27 adults). Genotyping of Factor V G1691A (Leiden), prothrombin G20210A (PT), and methylenetetrahydrofolate reductase C677T were performed using real-time PCR and fluorescence melting curve detection analysis.Results: Factor V Leiden was observed in 29 patients (61.7%). It is the only factor that caused Budd-Chiari syndrome in 18 of the patients and in 5 of the patients with inferior vena cava involvement. Myeloproliferative disease was noted in 12 (25.5%) patients, antiphospholipid syndrome in 5 (10.6%), and Behcet’s disease in 3 (6.4%). Interestingly, 3 of the children with Budd-Chiari syndrome had lipid storage disease.Conclusion: Factor V Leiden was a major etiological factor in Egyptian Budd-Chiari syndrome patients, which may have been related to the high frequency of this mutation in the study region. Factor V Leiden was also a strong thrombophilic factor and the leading cause of inferior vena cava thrombosis in these patients. Lipid storage disease should be included as a risk factor for Budd-Chiari syndrome

Clinical characteristics and molecular genetic analysis of 22 patients with neonatal diabetes from the South-Eastern region of Turkey: predominance of non-KATP channel mutations.

PublishedJournal ArticleResearch Support, Non-U.S. Gov'tThis is an open access article available at http://www.eje-online.org/content/172/6/697.BACKGROUND: Neonatal diabetes mellitus (NDM) is a rare form of monogenic diabetes and usually presents in the first 6 months of life. We aimed to describe the clinical characteristics and molecular genetics of a large Turkish cohort of NDM patients from a single centre and estimate an annual incidence rate of NDM in South-Eastern Anatolian region of Turkey. DESIGN AND METHODS: NDM patients presenting to Diyarbakir Children State Hospital between 2010 and 2013, and patients under follow-up with presumed type 1 diabetes mellitus, with onset before 6 months of age were recruited. Molecular genetic analysis was performed. RESULTS: Twenty-two patients (59% males) were diagnosed with NDM (TNDM-5; PNDM-17). Molecular genetic analysis identified a mutation in 20 (95%) patients who had undergone a mutation analysis. In transient neonatal diabetes (TNDM) patients, the genetic cause included chromosome 6q24 abnormalities (n=3), ABCC8 (n=1) and homozygous INS (n=1). In permanent neonatal diabetes (PNDM) patients, homozygous GCK (n=6), EIF2AK3 (n=3), PTF1A (n=3), and INS (n=1) and heterozygous KCNJ11 (n=2) mutations were identified. Pancreatic exocrine dysfunction was observed in patients with mutations in the distal PTF1A enhancer. Both patients with a KCNJ11 mutation responded to oral sulphonylurea. A variable phenotype was associated with the homozygous c.-331C>A INS mutation, which was identified in both a PNDM and TNDM patient. The annual incidence of PNDM in South-East Anatolian region of Turkey was one in 48 000 live births. CONCLUSIONS: Homozygous mutations in GCK, EIF2AK3 and the distal enhancer region of PTF1A were the commonest causes of NDM in our cohort. The high rate of detection of a mutation likely reflects the contribution of new genetic techniques (targeted next-generation sequencing) and increased consanguinity within our cohort.The genetic testing was funded by the Wellcome Trust (Senior Investigator Award to Profs S Ellard and A T Hattersley), and by Diabetes UK (Project funding to Dr D J Mackay). H Demirbilek was funded by European Society for Paediatric Endocrinology (ESPE) and The Scientific and Technological Research Council of Turkey (TUBITAK) for his 1 year clinical fellowship at University College London (UCL), Institute of Child Health, Great Ormond Street Hospital for Children, NHS Trust, Department of Paediatric Endocrinology