1,518 research outputs found

    Variation in the distribution of Antarctic krill Euphausia superba around South Georgia

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    There is considerable spatial structure within the South Georgia krill-based ecosystem in terms of predator demand, commercial fishery pressure and krill abundance. Here we investigate the hypothesis that there is also spatial structure in the krill population composition, finding differences in length-frequency histograms between the eastern and western ends of the island. Between 1981 and 1997 the British Antarctic Survey carried out 6 major cruises where krill were taken from both ends of South Georgia. Cluster analysis revealed that the length-frequency histograms could be grouped into 4 main types with relatively simple biological characteristics: Cluster 1 contained small krill (mean size 23.9 mm) up to 2 yr old (1+ yr class); Cluster 2 (mean size 31.1 mm) contained a mixture of 1+ with some 2+ and 3+ yr classes; Cluster 3 contained medium-sized krill (mean size 41.4 mm) probably 2+ and 3+ yr classes; Cluster 4 contained large krill (mean size 50.3 mm) likely to be 3+ or older. Principal components analysis (PCA) provided good separation of these clusters using the first 2 axes (80% of the total variance). There were no obvious differences in the length composition of krill sampled from different water depths, although there were some indications that differences did occur between different water masses. Detailed inspection of the individual cruises revealed that the length-frequency histograms at the western end of the island contained more large krill than those from the eastern end of the island and also that when Weddell Sea water was found within a cruise then this contained the smallest krill. We consider that such differences may arise not only because krill may experience different conditions at each end of the island but also may originate from 2 separate sources which may have different population structures

    Elucidating drivers of oral epithelial dysplasia formation and malignant transformation to cancer using RNAseq

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    Oral squamous cell carcinoma (OSCC) is a prevalent cancer with poor prognosis. Most OSCC progresses via a non-malignant stage called dysplasia. Effective treatment of dysplasia prior to potential malignant transformation is an unmet clinical need. To identify markers of early disease, we performed RNA sequencing of 19 matched HPV negative patient trios: normal oral mucosa, dysplasia and associated OSCC. We performed differential gene expression, principal component and correlated gene network analysis using these data. We found differences in the immune cell signatures present at different disease stages and were able to distinguish early events in pathogenesis, such as upregulation of many HOX genes, from later events, such as down-regulation of adherens junctions. We herein highlight novel coding and non-coding candidates for involvement in oral dysplasia development and malignant transformation, and speculate on how our findings may guide further translational research into the treatment of oral dysplasia

    Moderate-to-Vigorous Physical Activity in Primary School Children: Inactive Lessons Are Dominated by Maths and English.

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    BACKGROUND: A large majority of primary school pupils fail to achieve 30-min of daily, in-school moderate-to-vigorous physical activity (MVPA). The aim of this study was to investigate MVPA accumulation and subject frequency during academic lesson segments and the broader segmented school day. METHODS: 122 children (42.6% boys; 9.9 ± 0.3 years) from six primary schools in North East England, wore uniaxial accelerometers for eight consecutive days. Subject frequency was assessed by teacher diaries. Multilevel models (children nested within schools) examined significant predictors of MVPA across each school-day segment (lesson one, break, lesson two, lunch, lesson three). RESULTS: Pupils averaged 18.33 ± 8.34 min of in-school MVPA, and 90.2% failed to achieve the in-school 30-min MVPA threshold. Across all school-day segments, MVPA accumulation was typically influenced at the individual level. Lessons one and two-dominated by maths and English-were less active than lesson three. Break and lunch were the most active segments. CONCLUSION: This study breaks new ground, revealing that MVPA accumulation and subject frequency varies greatly during different academic lessons. Morning lessons were dominated by the inactive delivery of maths and English, whereas afternoon lessons involved a greater array of subject delivery that resulted in marginally higher levels of MVPA

    Association of surfactant protein A polymorphisms with otitis media in infants at risk for asthma

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    BACKGROUND: Otitis media is one of the most common infections of early childhood. Surfactant protein A functions as part of the innate immune response, which plays an important role in preventing infections early in life. This prospective study utilized a candidate gene approach to evaluate the association between polymorphisms in loci encoding SP-A and risk of otitis media during the first year of life among a cohort of infants at risk for developing asthma. METHODS: Between September 1996 and December 1998, women were invited to participate if they had at least one other child with physician-diagnosed asthma. Each mother was given a standardized questionnaire within 4 months of her infant's birth. Infant respiratory symptoms were collected during quarterly telephone interviews at 6, 9 and 12 months of age. Genotyping was done on 355 infants for whom whole blood and complete otitis media data were available. RESULTS: Polymorphisms at codons 19, 62, and 133 in SP-A1, and 223 in SP-A2 were associated with race/ethnicity. In logistic regression models incorporating estimates of uncertainty in haplotype assignment, the 6A(4)/1A(5)haplotype was protective for otitis media among white infants in our study population (OR 0.23; 95% CI 0.07,0.73). CONCLUSION: These results indicate that polymorphisms within SP-A loci may be associated with otitis media in white infants. Larger confirmatory studies in all ethnic groups are warranted

    Observational evidence for the accretion-disk origin for a radio jet in an active galaxy

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    Accretion of gas onto black holes is thought to power the relativistic jets of material ejected from active galactic nuclei (AGN) and the 'microquasars' located in our Galaxy(1-3). In microquasars, superluminal radio-emitting features appear and propagate along the jet shortly after sudden decreases in the Xray fluxes(1). This establishes a direct observational link between the black hole and the jet: the X-ray dip is probably caused by the disappearance of a section of the inner accretion disk(4) as it falls past the event horizon, while the remainder of the disk section is ejected into the jet, creating the appearance of a superluminal bright spot(5). No such connection has hitherto been established for AGN, because of insufficient multi-frequency data. Here we report the results of three years of monitoring the X-ray and radio emission of the galaxy 3C120. As has been observed for microquasars, we find that dips in the X-ray emission are followed by ejections of bright superluminal knots in the radio jet. The mean time between X-ray dips appears to scale roughly with the mass of the black hole, although there are at present only a few data points.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/62888/1/nature00772.pd

    Association of tamoxifen use and reduced risk of contralateral breast cancer for BRCA1 and BRCA2 mutation carriers

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