15,178 research outputs found

    A Twin Study of Early-Childhood Asthma in Puerto Ricans

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    Background:The relative contributions of genetics and environment to asthma in Hispanics or to asthma in children younger than 3 years are not well understood.Objective:To examine the relative contributions of genetics and environment to early-childhood asthma by performing a longitudinal twin study of asthma in Puerto Rican children ≀3 years old.Methods:678 twin infants from the Puerto Rico Neo-Natal Twin Registry were assessed for asthma at age 1 year, with follow-up data obtained for 624 twins at age 3 years. Zygosity was determined by DNA microsatellite profiling. Structural equation modeling was performed for three phenotypes at ages 1 and 3 years: physician-diagnosed asthma, asthma medication use in the past year, and β‰₯1 hospitalization for asthma in the past year. Models were additionally adjusted for early-life environmental tobacco smoke exposure, sex, and age.Results:The prevalences of physician-diagnosed asthma, asthma medication use, and hospitalization for asthma were 11.6%, 10.8%, 4.9% at age 1 year, and 34.1%, 40.1%, and 8.5% at 3 years, respectively. Shared environmental effects contributed to the majority of variance in susceptibility to physician-diagnosed asthma and asthma medication use in the first year of life (84%-86%), while genetic effects drove variance in all phenotypes (45%-65%) at age 3 years. Early-life environmental tobacco smoke, sex, and age contributed to variance in susceptibility.Conclusion:Our longitudinal study in Puerto Rican twins demonstrates a changing contribution of shared environmental effects to liability for physician-diagnosed asthma and asthma medication use between ages 1 and 3 years. Early-life environmental tobacco smoke reduction could markedly reduce asthma morbidity in young Puerto Rican children. Β© 2013 Bunyavanich et al

    Quality and acceptability of patient-reported outcome measures used to assess fatigue in axial spondyloarthritis (axSpA): a systematic review (protocol)

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    BACKGROUND: The prevalence of axial spondyloarthritis (axSpA) is estimated between 0.15 and 1.2%, with many of those patients experiencing severe fatigue. Current axSpA assessment guidance recommends use of a single-item visual analogue scale for fatigue severity. However, concerns have been raised about the ability of such a limited assessment to identify patients with major fatigue, to detect important change in fatigue or to reflect the multi-dimensional nature of fatigue. The proposed systematic review will identify and evaluate the quality and acceptability of single- and multi-item patient-reported outcome measures (PROMs) used to assess fatigue in axSpA, seeking to make recommendations for the β€˜best’ measures for research and/or clinical practice. METHODS/DESIGN: The review will seek to include published studies which report evidence of the development and/or measurement and/or practical properties of clearly defined and reproducible measures of fatigue following completion by patients with axSpA. Five major databases will be searched from 1980 to August 2017: MEDLINE (OVID), EMBASE (OVID), PsycINFO (OVID), World of Science and CINAHL. Study methodological quality will be assessed against the COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) checklist. The measurement and/or practical properties of reviewed measures will be assessed against current international standards. A short list of the β€˜best’-quality PROMs will be produced. The review will be reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. DISCUSSION: This study will provide the first robust and transparent evaluation of patient-reported measures of fatigue used in the axSpA population, synthesising evidence of quality, relevance and acceptability. The review will benefit patients, clinicians, health professionals and researchers wishing to enhance axSpA-fatigue assessment in routine practice, service evaluation and research. The findings will impact future research which seeks to better understand the nature of axSpA fatigue and evaluate the relative benefit of fatigue-management strategies. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42016042271 ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s13643-018-0777-7) contains supplementary material, which is available to authorized users

    Effect plant density and poultry manure on rapid multiplication of a cassava propagule

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    This study appraised the effect of plant density and poultry manure rates on rapid multiplication of a cassava propagule during the late cropping season of 2007. Nine (9) treatments consisting of three cassava densities (1.0 x 1.0, 1.0 x 0.5, 1.0m x 0.25m) amended with three rates of poultry manure (0, 2 and 4 tons/ha) were laid out in 3 x 3 factorial arrangement in a randomized complete design with three replications. The research work was carried out at the Teaching and Research Farm, Federal University of Technology, Owerri in the humid rainforest of Southeastern Nigeria. Growth and yield data were collected and statistically analyzed. The soil fertility at planting was low. Poultry manure rates significantly improved the growth and yield of cassava. Cassavas spaced 1.0m x 0.25m and amended with 4 tons/ha of poultry manure were significantly tall with moderate girth and highest stem bundles and root tuber yield. Regenerative stem cuttings had good field establishment vigour. Post-harvest soil chemical analysis showed improvement in nutrient status of the soil. Cassava spaced 1.0m x 0.25m and amended with 4 tons/ha of poultry manure had highest benefit cost ratio

    Evoking the Knowledge of Tree Tenure in the Humid Tropics: A Review of Dimensions in Agro-Plantation System in Nigeria

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    This paper explored the natural situation of trees, concept, potentials and importance of tree tenure, tree and land tenure, types of tree tenure, problems of forest reservation in south eastern Nigeria and the way forward. The tropical rainforest of Nigeria occupies 9.7% of the total land mass of 98.3213km2, but is the most densely populated and source of Nigeria’s bulk timber. In the natural situation no nutrients is lost due to a balanced nutrient recycling and there are slight variations in temperature light, humidity, and characteristic meet groups. The concept and importance of tree tenure borders the fact that much of life on earth owes its’ existence to trees. Land and tree ownership rights are largely governed by customary tenure rules and these rights are rarely revoked. Land tenure does not necessarily mean tree tenure. Trees may be owned privately, communally or by government. Each of these forms of ownership have their advantages and disadvantages. In private/individual tree tenure, trees are owned by planting, inheritance, gender, purchase/lease and culture. Communal tree tenure involves full ownership, restricted ownership, village squares and evil forests/sacred bush. Government tree tenure is through acquisition and maintenance of forest resources at the local, state or federal levels. Some of the challenges of maintenance forest reserves include diseases and pests, wild fires, poaching, village/community participation, poor budgetary allocation among others. A proper knowledge of tree tenure is a must if trees are to be managed scientifically in such a way that their productivity is sustained

    An implementation of Deflate in Coq

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    The widely-used compression format "Deflate" is defined in RFC 1951 and is based on prefix-free codings and backreferences. There are unclear points about the way these codings are specified, and several sources for confusion in the standard. We tried to fix this problem by giving a rigorous mathematical specification, which we formalized in Coq. We produced a verified implementation in Coq which achieves competitive performance on inputs of several megabytes. In this paper we present the several parts of our implementation: a fully verified implementation of canonical prefix-free codings, which can be used in other compression formats as well, and an elegant formalism for specifying sophisticated formats, which we used to implement both a compression and decompression algorithm in Coq which we formally prove inverse to each other -- the first time this has been achieved to our knowledge. The compatibility to other Deflate implementations can be shown empirically. We furthermore discuss some of the difficulties, specifically regarding memory and runtime requirements, and our approaches to overcome them

    Probiotic administration in congenital heart disease: a pilot study.

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    ObjectiveTo investigate the impact of probiotic Bifidobacterium longum ssp. infantis on the fecal microbiota and plasma cytokines in neonates with congenital heart disease.Study designSixteen infants with congenital heart disease were randomly assigned to receive either B. infantis (4.2 Γ— 10(9) colony-forming units two times daily) or placebo for 8 weeks. Stool specimens from enrolled infants and from six term infants without heart disease were analyzed for microbial composition. Plasma cytokines were analyzed weekly in the infants with heart disease.ResultsHealthy control infants had increased total bacteria, total Bacteroidetes and total bifidobacteria compared to the infants with heart disease, but there were no significant differences between the placebo and probiotic groups. Plasma interleukin (IL)10, interferon (IFN)Ξ³ and IL1Ξ² levels were transiently higher in the probiotic group.ConclusionCongenital heart disease in infants is associated with dysbiosis. Probiotic B. infantis did not significantly alter the fecal microbiota. Alterations in plasma cytokines were found to be inconsistent

    The mechanical and electrical properties of direct-spun carbon nanotube mat-epoxy composites

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    Composites of direct-spun carbon nanotube (CNT) mats and epoxy are manufactured and tested in order to determine their mechanical and electrical properties. The mats are spun directly from a floating catalyst, chemical vapour deposition reactor. The volume fraction of epoxy is varied widely by suitable dilution of the epoxy resin with acetone. Subsequent evaporation of the acetone, followed by a cure cycle, leads to composites of varying volume fraction of CNT, epoxy and air. The modulus, strength, electrical conductivity and piezoresistivity of the composites are measured. The CNT mats and their composites exhibit an elastic-plastic stress-strain response under uniaxial tensile loading, and the degree of anisotropy is assessed by testing specimens in 0{\deg}, 45{\deg} and 90{\deg} directions with respect to the draw direction of mat manufacture. The electrical conductivity scales linearly with CNT volume fraction, irrespective of epoxy volume fraction. In contrast, the modulus and strength depend upon both CNT and epoxy volume fractions in a non-linear manner. The macroscopic moduli of the CNT mat-epoxy composites are far below the Voigt bound based on the modulus of CNT walls and epoxy. A micromechanical model is proposed to relate the macroscopic modulus and yield strength of a CNT mat-epoxy composite to the microstructure

    The mechanical and electrical properties of direct-spun carbon nanotube mats

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    The mechanical and electrical properties of a direct-spun carbon nanotube mat are measured. The mat comprises an interlinked random network of nanotube bundles, with approximately 40 nanotubes in a bundle. A small degree of in-plane anisotropy is observed. The bundles occasionally branch, and the mesh topology resembles a 2D lattice of nodal connectivity slightly below 4. The macroscopic in-plane tensile response is elasto-plastic in nature, with significant orientation hardening. In-situ microscopy reveals that the nanotube bundles do not slide past each other at their junctions under macroscopic stain. A micromechanical model is developed to relate the macroscopic modulus and flow strength to the longitudinal shear response of the nanotube bundles. The mechanical and electrical properties of the mat are compared with those of other nanotube arrangements over a wide range of density
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