3,338 research outputs found
Train Support Vector Machine Using Fuzzy C-means Without a Prior Knowledge for Hyperspectral Image Content Classification
In this paper, a new cooperative classification method called auto-train support vector machine (SVM) is proposed. This new method converts indirectly SVM to an unsupervised classification method. The main disadvantage of conventional SVM is that it needs a priori knowledge about the data to train it. To avoid using this knowledge that is strictly required to train SVM, in this cooperative method, the data, that is, hyperspectral images (HSIs), are first clustered using Fuzzy C-means (FCM); then, the created labels are used to train SVM. At this stage, the image content is classified using the auto-trained SVM. Using FCM, clustering reveals how strongly a pixel is assigned to a class thanks to the fuzzification process. This information leads to gaining two advantages, the first one is that no prior knowledge about the data (known labels) is needed and the second one is that the training data selection is not done randomly (the training data are selected according to their degree of membership to a class). The proposed method gives very promising results. The method is tested on two HSIs, which are Indian Pines and Pavia University. The results obtained have a very high accuracy of the classification and exceed the existing manually trained methods in the literature
Exact Analysis of Offset-based Service Differentiation in Single-channel Multi-class OBS
Cataloged from PDF version of article.We study a multi-class optical burst switching (OBS)
node using the horizon reservation scheme. Multiple traffic
classes are differentiated using different offset times per class.
Assuming Poisson burst arrivals and phase-type distributed burst
lengths, we exactly solve for per-class blocking probabilities using
the well-known theory of feedback Markov fluid queues
Hemoglobin alpha 2 gene +861 G>A polymorphism in Turkish population
Thalassemia is an inherited blood disorder which is divided into two groups: alpha and beta. HBA1 and HBA2 are the two genes associated with alpha thalassemia. The aim of this study is to investigate abnormal hemoglobin variants of alpha globin gene in healthy abnormal hemoglobincarrying individuals with intact beta globin gene. DNA was extracted from peripheral blood samples of seven healthy carrier individuals who have abnormal hemoglobin variants and 16 control individuals from Turkey. Complete coding and intronic sequences of HBA1 and HBA2 genes wereamplified by polymerase chain reaction (PCR) and PCR products of HBA1 and HBA2 were sequenced. We were unable to find any base change in our carrier group in the HBA1 gene. We have observed an A/G polymorphism in the downstream untranslated region (+861 G>A) of the HBA2gene. Our study showed that 14.29% (1/7 carriers) of the carrier group and 37.50% (6/16 controls) of the control group were heterozygous for the +861 G>A polymorphism. The distribution of allele frequencies and genotypes of HBA2 between carrier and control samples were analyzedand it is seen that the distribution of allele frequencies and that of genotypes were not statistically significant between carrier and control samples (P-value = 0.4131, P-value= 0.366, respectively). HBA2 +861 G>A nucleotide substitution is a neutral polymorphism previously reported in other populations. This is the first report in Turkish population
Differentiated ABR: A new architecture for flow control and service differentiation in optical burst switched networks
In this paper, we study a new control plane protocol, called Differentiated ABR (D-ABR), for flow control and service differentiation in optical burst switched networks. Using D-ABR, we show using simulations that the optical network can be designed to work at any desired burst blocking probability by the flow control service of the proposed architecture. This architecture requires certain modifications to the existing control plane mechanisms as well as incorporation of certain scheduling mechanisms at the ingress nodes; however we do not make any specific assumptions on the data plane for the optical core nodes. Moreover, with this protocol, it is possible to almost perfectly isolate high priority and low priority traffic throughout the optical network as in the strict priority-based service differentiation in electronically switched networks. © 2005 IEEE
Maternal risk factors in young Egyptian mothers of Down syndrome
Introduction: We investigated the possible maternal risk factors that mayincrease the incidence of Down syndrome (DS) in young Egyptian mothers(younger than 35 years) especially methylene tetrahydrofolate reductase(MTHFR) enzyme C677T polymorphism.Subjects and Methods: The study included 200 mothers of karyotypicallyascertained non-disjunction DS attending Genetics clinic, Children’s hospital, Ain Shams University (100 mothers were < 35 years and 100 mothers ≥ 35 years). 50 mothers of none-DS children served as a control group. For all cases, history was taken laying stress on: Parental ages at conception, maternal grandparent’s ages at conception of mother, DS birth order, history of oral contraceptive use 6 months before conception, genital infection, vitamin supplementation and smoking or exposure to irradiation.Results: MTHFR C677T mutational analysis was done to twenty DS motherswith ages ≤ 35 years revealed that 35% of young mothers had C677T mutation (10% had homozygous mutation and 25% had heterozygous mutation). MTHFR C677T polymorphism was found to be a possible maternal genetic risk factor for DS although statistically non-significant.Other maternal risk factors included the use of oral contraceptive pills (OCP) 6 months before pregnancy which was significantly higher only in DSmothers ≥ 35 years. on the other hand, parental consanguinity, maternal grandparents’ ages, the presence of genital infection and birth order did not show a significant difference between young and old mothers of DS.Conclusion: MTHFR C677T could not be considered as a maternal risk factor in young Egyptian mothers of DS. The risk effect may depend on gene-environment interaction between the genotype and dietary intake in particular folic acid consumption which should be further studied on a larger scale population including other MTHFR polymorphisms and environmental factors. Other risk factors may include the use of OCP in older mothers. Parents consanguinity, paternal age and maternal grandparents’ ages were not found to be risk factors in DS in this study.Keywords: Down syndrome, risk factors, mothers, MTHFR
Super-resolution using multiple quantized images
In this paper, we study the effect of limited amplitude resolution (pixel depth) in super-resolution problem. The problem we address differs from the standard super-resolution problem in that amplitude resolution is considered as important as spatial resolution. We study the trade-off between the pixel depth and spatial resolution of low resolution (LR) images in order to obtain the best visual quality in the reconstructed high resolution (HR) image. The proposed framework reveals great flexibility in terms of pixel depth and number of LR images in super-resolution problem, and demonstrates that it is possible to obtain target visual qualities with different measurement scenarios including images with different amplitude and spatial resolutions. © 2010 IEEE
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
Thrombotic gene polymorphisms and postoperative outcome after coronary artery bypass graft surgery
<p>Abstract</p> <p>Background</p> <p>Emerging perioperative genomics may influence the direction of risk assessment and surgical strategies in cardiac surgery. The aim of this study was to investigate whether single nucleotide polymorphisms (SNP) affect the clinical presentation and predispose to increased risk for postoperative adverse events in patients undergoing coronary artery bypass grafting surgery (CABG).</p> <p>Methods</p> <p>A total of 220 patients undergoing first-time CABG between January 2005 and May 2008 were screened for factor V gene G1691A (FVL), prothrombin/factor II G20210A (PT G20210A), angiotensin I-converting enzyme insertion/deletion (ACE-ins/del) polymorphisms by PCR and Real Time PCR. End points were defined as death, myocardial infarction, stroke, postoperative bleeding, respiratory and renal insufficiency and event-free survival. Patients were compared to assess for any independent association between genotypes for thrombosis and postoperative phenotypes.</p> <p>Results</p> <p>Among 220 patients, the prevalence of the heterozygous FVL mutation was 10.9% (n = 24), and 3.6% (n = 8) were heterozygous carriers of the PT G20210A mutation. Genotype distribution of ACE-ins/del was 16.6%, 51.9%, and 31.5% in genotypes I/I, I/D, and D/D, respectively. FVL and PT G20210A mutations were associated with higher prevalence of totally occluded coronary arteries (p < 0.001). Furthermore the risk of left ventricular aneurysm formation was significantly higher in FVL heterozygote group compared to FVL G1691G (<it>p </it>= 0.002). ACE D/D genotype was associated with hypertension (<it>p </it>= 0.004), peripheral vascular disease (p = 0.006), and previous myocardial infarction (<it>p </it>= 0.007).</p> <p>Conclusions</p> <p>FVL and PT G20210A genotypes had a higher prevalence of totally occluded vessels potentially as a result of atherothrombotic events. However, none of the genotypes investigated were independently associated with mortality.</p
Patterns of genetic diversity and linkage disequilibrium in a highly structured Hordeum vulgare association-mapping population for the Mediterranean basin
Population structure and genome-wide linkage disequilibrium (LD) were investigated in 192 Hordeum vulgare accessions providing a comprehensive coverage of past and present barley breeding in the Mediterranean basin, using 50 nuclear microsatellite and 1,130 DArT® markers. Both clustering and principal coordinate analyses clearly sub-divided the sample into five distinct groups centred on key ancestors and regions of origin of the germplasm. For given genetic distances, large variation in LD values was observed, ranging from closely linked markers completely at equilibrium to marker pairs at 50 cM separation still showing significant LD. Mean LD values across the whole population sample decayed below r 2 of 0.15 after 3.2 cM. By assaying 1,130 genome-wide DArT® markers, we demonstrated that, after accounting for population substructure, current genome coverage of 1 marker per 1.5 cM except for chromosome 4H with 1 marker per 3.62 cM is sufficient for whole genome association scans. We show, by identifying associations with powdery mildew that map in genomic regions known to have resistance loci, that associations can be detected in strongly stratified samples provided population structure is effectively controlled in the analysis. The population we describe is, therefore, shown to be a valuable resource, which can be used in basic and applied research in barle
Effect of surface contamination on interfacial mass transfer rate
The influence of surface contamination upon the mass transfer rate of a low diffusivity gas across a flat surface is studied using direct numerical simulations. The interfacial mass transfer is driven by isotropic turbulence diffusing from below. Similar to Shen et al. (J. Fluid Mech. 506, 2004, pp. 79-115) the surface contamination is modelled by relating the normal gradient of the horizontal velocities at the top to the horizontal gradients of the surfactant concentrations. A broad range of contamination levels is considered, including clean to severely contaminated conditions. The time-averaged results show a strong correlation between the gas transfer velocity and the clean surface fraction of the surface area. In the presence of surface contamination the mass transfer velocity KL is found to scale as a power of the Schmidt number, i.e. Sc−q, where q smoothly transitions from q = 1/2 for clean surfaces to q = 2/3 for very dirty interfaces. A power law KL ∝ Sc−q is proposed in which both the exponent q and the constant of proportionality become functions of the clean surface fraction
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