242 research outputs found

    Assessing the genetic and pathogenic variability of Pyrenophora teres f. maculata (spot form net blotch of barley) and its ability to overcome currently-used sources of resistance on the Canadian prairies

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    Non-Peer ReviewedEighty two isolates of the fungus Pyrenophora teres f. maculata, causal agent of spot form net blotch (SFNB) of barley, were collected across the Canadian prairies. Following genetic analysis using 13 microsatellite DNA markers, 27 isolates were selected to assess the degree of pathogenic variation in the fungus. Pathogenic variability was evaluated by inoculating isolates onto 11 barley genotypes as differential hosts at the seedling stage. One week following inoculation, the second and third leaves of each plant were rated on to a 1–9 disease severity scale, and plants with scores of 1–3 and >3 were scored as resistant and susceptible, respectively. The entire experiment was repeated. Cluster analysis revealed 13 distinct pathotype groups (virulence patterns) among the 27 representative isolates. Disease severity ratings ranged from 2.2 to 6.1 with a mean of 4.6. To assess the risk of resistance breakdown, the resistance of four barley cultivars (‘AAC Synergy’, ‘CDC Meredith’, ‘Cerveza’ and ‘Major’), which had been previously identified as resistant to SFNB on the Canadian prairies, was evaluated at the seedling stage against six isolates of P. teres f. maculata representing four different pathotypes. The resistance in ‘CDC Meredith’ was clearly overcome by all isolates tested, while ‘AAC Synergy’, ‘Cerveza’ and ‘Major’ still exhibited resistance against all of the pathotypes. The identification of fungal isolates virulent on ‘CDC Meredith’ suggests that producers should avoid growing the same resistant barley variety in short rotation, and avoid relying on resistance as the sole approach to disease management. Judicious use of fungicides, coupled with rotations of at least two years between barley crops and diversity in the barley varieties grown, will promote effective and sustainable management of spot form net blotch

    Diversidade de resultados no estudo do transtorno de déficit de atenção e hiperatividade

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    Com este artigo pretende-se abordar a problemática da diversidade de dados na investigação do Transtorno de Déficit de Atenção e Hiperatividade (TDAH). Apresenta-se uma revisão da literatura centrada na heterogeneidade de conclusões relativas à caracterização do transtorno, à distinção dos subtipos, aos contextos de informação, às diferenças de gênero e à comorbidade. Na tentativa de compreender a disparidade de conclusões, salientam-se potenciais fatores explicativos, nomeadamente a heterogeneidade das amostras, a diversidade de metodologias e de procedimentos de investigação, entre outros.With this paper we aimed at addressing the problem of data diversity in Attention-Deficit Hyperactivity Disorder (ADHD) research. We present a literature review based on the heterogeneity of findings about the characterization of the disorder, subtypes differentiation, sources of information, sex differences and comorbidities. In an effort to understand the variety of findings, we underline potential explanations, such as the sample’s heterogeneity or the multiplicity of methods and procedures, among others.(undefined

    The diagnostic accuracy of US, CT, MRI and 1H-MRS for the evaluation of hepatic steatosis compared with liver biopsy: a meta-analysis

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    OBJECTIVE: To meta-analyse the diagnostic accuracy of US, CT, MRI and (1)H-MRS for the evaluation of hepatic steatosis. METHODS: From a comprehensive literature search in MEDLINE, EMBASE, CINAHL and Cochrane (up to November 2009), articles were selected that investigated the diagnostic performance imaging techniques for evaluating hepatic steatosis with histopathology as the reference standard. Cut-off values for the presence of steatosis on liver biopsy were subdivided into four groups: (1) >0, >2 and >5% steatosis; (2) >10, >15 and >20%; (3) >25, >30 and >33%; (4) >50, >60 and >66%. Per group, summary estimates for sensitivity and specificity were calculated. The natural-logarithm of the diagnostic odds ratio (lnDOR) was used as a single indicator of test performance. RESULTS: 46 articles were included. Mean sensitivity estimates for subgroups were 73.3-90.5% (US), 46.1-72.0% (CT), 82.0-97.4% (MRI) and 72.7-88.5% ((1)H-MRS). Mean specificity ranges were 69.6-85.2% (US), 88.1-94.6% (CT), 76.1-95.3% (MRI) and 92.0-95.7% ((1)H-MRS). Overall performance (lnDOR) of MRI and (1)H-MRS was better than that for US and CT for all subgroups, with significant differences in groups 1 and 2. CONCLUSION: MRI and (1)H-MRS can be considered techniques of choice for accurate evaluation of hepatic steatosi
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