278 research outputs found

    The Conductance of Some Non-Rigid Bolaform Electrolytes

    Get PDF
    Bolaform electrolytes are those which contain two or more charges separated by an inert framework. These are intermediate in structure between simple electrolytes and polyelectrolytes. Since these are similar to both synthetic and biological electrolytes, this investigation has been undertaken to determine some of their properties in solution. The sodium and magnesium salts of ethane, propane, butane, pentane, hexane and decane α,ω-disulfonates were prepared. Each acid was prepared by refluxing the α,ω-dibromide of the desired salt with sodium sulfite. The sodium and magnesium salts were prepared by ion-exchange techniques. The conductance of each salt was determined in methanol utilizing the weight dilution method. A data treatment method for unsymmetrical 1-2 electrolytes was tested. The Murphy-Cohen equation: ∧ = ∧° - S√C + E′ClnC + J′C was found to be invalid in the concentration range studied, 1.0 - 5.0 x 10-4moles/liter. The Onsager limiting law when applied to the sodium salt data gave ∧° values from approximately 108 (ohm-1cm2equiv-1) for the ethane salt to 100 (ohm-1cm2equiv-1) for the decane. Phoreograms showed these salts to be unassociated in methanol. The magnesium salts deviated substantially below the limiting law plot and consequently were considered highly associated. The ∧° values for the magnesium salts were calculated from Kohlrausch\u27s law, ∧° = λ+Mg + λ-anion. By fixing this value, association constants were found to be in a range of 108,950 for the ethane salt to 25,260 for the decane salt. These values show a monotonic decrease as the chain length of the salt increases. This is explained by charge separation considerations. As the chain length increases the charge density on the molecule decreases, illustrating a decrease in ion-ion interactions. The frictional coefficients of the sodium salts were determined from λ- data. These showed values of .0496 X 10-7 g/sec for the ethane salt to .0563 X 10-7 g/sec for decane salts. The Peterlin rod and bead model for the determination of frictional forces was successfully applied to the data. The Perrin rigid ellipsoid model did not show any agreement when experimental and theoretical frictional coefficient values were compared

    Ozone loss derived from balloon-borne tracer measurements and the SLIMCAT CTM

    Get PDF
    Balloon-borne measurements of CFC-11 (on flights of the DIRAC in situ gas chromatograph and the DESCARTES grab sampler), ClO and O3 were made during the 1999/2000 winter as part of the SOLVE-THESEO 2000 campaign. Here we present the CFC-11 data from nine flights and compare them first with data from other instruments which flew during the campaign and then with the vertical distributions calculated by the SLIMCAT 3-D CTM. We calculate ozone loss inside the Arctic vortex between late January and early March using the relation between CFC-11 and O3 measured on the flights, the peak ozone loss (1200 ppbv) occurs in the 440–470 K region in early March in reasonable agreement with other published empirical estimates. There is also a good agreement between ozone losses derived from three independent balloon tracer data sets used here. The magnitude and vertical distribution of the loss derived from the measurements is in good agreement with the loss calculated from SLIMCAT over Kiruna for the same days

    Gramene: a bird's eye view of cereal genomes

    Get PDF
    Rice, maize, sorghum, wheat, barley and the other major crop grasses from the family Poaceae (Gramineae) are mankind's most important source of calories and contribute tens of billions of dollars annually to the world economy (FAO 1999, ; USDA 1997, ). Continued improvement of Poaceae crops is necessary in order to continue to feed an ever-growing world population. However, of the major crop grasses, only rice (Oryza sativa), with a compact genome of ∼400 Mbp, has been sequenced and annotated. The Gramene database () takes advantage of the known genetic colinearity (synteny) between rice and the major crop plant genomes to provide maize, sorghum, millet, wheat, oat and barley researchers with the benefits of an annotated genome years before their own species are sequenced. Gramene is a one stop portal for finding curated literature, genetic and genomic datasets related to maps, markers, genes, genomes and quantitative trait loci. The addition of several new tools to Gramene has greatly facilitated the potential for comparative analysis among the grasses and contributes to our understanding of the anatomy, development, environmental responses and the factors influencing agronomic performance of cereal crops. Since the last publication on Gramene database by D. H. Ware, P. Jaiswal, J. Ni, I. V. Yap, X. Pan, K. Y. Clark, L. Teytelman, S. C. Schmidt, W. Zhao, K. Chang et al. [(2002), Plant Physiol., 130, 1606–1613], the database has undergone extensive changes that are described in this publication

    Gramene: a bird's eye view of cereal genomes

    Get PDF
    Rice, maize, sorghum, wheat, barley and the other major crop grasses from the family Poaceae (Gramineae) are mankind's most important source of calories and contribute tens of billions of dollars annually to the world economy (FAO 1999, ; USDA 1997, ). Continued improvement of Poaceae crops is necessary in order to continue to feed an ever-growing world population. However, of the major crop grasses, only rice (Oryza sativa), with a compact genome of ∼400 Mbp, has been sequenced and annotated. The Gramene database () takes advantage of the known genetic colinearity (synteny) between rice and the major crop plant genomes to provide maize, sorghum, millet, wheat, oat and barley researchers with the benefits of an annotated genome years before their own species are sequenced. Gramene is a one stop portal for finding curated literature, genetic and genomic datasets related to maps, markers, genes, genomes and quantitative trait loci. The addition of several new tools to Gramene has greatly facilitated the potential for comparative analysis among the grasses and contributes to our understanding of the anatomy, development, environmental responses and the factors influencing agronomic performance of cereal crops. Since the last publication on Gramene database by D. H. Ware, P. Jaiswal, J. Ni, I. V. Yap, X. Pan, K. Y. Clark, L. Teytelman, S. C. Schmidt, W. Zhao, K. Chang et al. [(2002), Plant Physiol., 130, 1606–1613], the database has undergone extensive changes that are described in this publication

    Gramene: a bird's eye view of cereal genomes

    Get PDF
    Rice, maize, sorghum, wheat, barley and the other major crop grasses from the family Poaceae (Gramineae) are mankind's most important source of calories and contribute tens of billions of dollars annually to the world economy (FAO 1999, ; USDA 1997, ). Continued improvement of Poaceae crops is necessary in order to continue to feed an ever-growing world population. However, of the major crop grasses, only rice (Oryza sativa), with a compact genome of ∼400 Mbp, has been sequenced and annotated. The Gramene database () takes advantage of the known genetic colinearity (synteny) between rice and the major crop plant genomes to provide maize, sorghum, millet, wheat, oat and barley researchers with the benefits of an annotated genome years before their own species are sequenced. Gramene is a one stop portal for finding curated literature, genetic and genomic datasets related to maps, markers, genes, genomes and quantitative trait loci. The addition of several new tools to Gramene has greatly facilitated the potential for comparative analysis among the grasses and contributes to our understanding of the anatomy, development, environmental responses and the factors influencing agronomic performance of cereal crops. Since the last publication on Gramene database by D. H. Ware, P. Jaiswal, J. Ni, I. V. Yap, X. Pan, K. Y. Clark, L. Teytelman, S. C. Schmidt, W. Zhao, K. Chang et al. [(2002), Plant Physiol., 130, 1606–1613], the database has undergone extensive changes that are described in this publication

    Poverty, Neighbourhood Antisocial Behaviour, and Children’s Mental Health Problems: Findings from the 2014 Ontario Child Health Study

    Get PDF
    Objectives: To determine if levels of neighbourhood poverty and neighbourhood antisocial behaviour modify associations between household poverty and child and youth mental health problems. Methods: Data come from the 2014 Ontario Child Health Study—a provincially representative survey of 6537 families with 10,802 four- to 17-year-olds. Multivariate multilevel modelling was used to test if neighbourhood poverty and antisocial behaviour interact with household poverty to modify associations with children’s externalizing and internalizing problems based on parent assessments of children (4- to 17-year-olds) and self-assessments of youth (12- to 17-year-olds). Results: Based on parent assessments, neighbourhood poverty, and antisocial behaviour modified associations between household poverty and children’s mental health problems. Among children living in households below the poverty line, levels of mental health problems were 1) lower when living in neighbourhoods with higher concentrations of poverty and 2) higher when living in neighbourhoods with more antisocial behaviour. These associations were stronger for externalizing versus internalizing problems when conditional on antisocial behaviour and generalized only to youth-assessed externalizing problems. Conclusion: The lower levels of externalizing problems reported among children living in poor households in low-income neighbourhoods identify potential challenges with integrating poorer households into more affluent neighbourhoods. More important, children living in poor households located in neighbourhoods exhibiting more antisocial behaviour are at dramatically higher risk for mental health problems. Reducing levels of neighbourhood antisocial behaviour could have large mental health benefits, particularly among poor children

    Children’s Mental Health Need and Expenditures in Ontario: Findings from the 2014 Ontario Child Health Study

    Get PDF
    Objective: To estimate the alignment between the Ontario Ministry of Children and Youth Services (MCYS) expenditures for children’s mental health services and population need, and to quantify the value of adjusting for need in addition to population size in formula-based expenditure allocations. Two need definitions are used: “assessed need,” as the presence of a mental disorder, and “perceived need,” as the subjective perception of a mental health problem. Methods: Children’s mental health need and service contact estimates (from the 2014 Ontario Child Health Study), expenditure data (from government administrative data), and population counts (from the 2011 Canadian Census) were combined to generate formula-based expenditure allocations based on 1) population size and 2) need (population size adjusted for levels of need). Allocations were compared at the service area and region level and for the 2 need definitions (assessed and perceived). Results: Comparisons were made for 13 of 33 MCYS service areas and all 5 regions. The percentage of MCYS expenditure reallocation needed to achieve an allocation based on assessed need was 25.5% at the service area level and 25.6% at the region level. Based on perceived need, these amounts were 19.4% and 27.2%, respectively. The value of needs-adjustment ranged from 8.0% to 22.7% of total expenditures, depending on the definition of need. Conclusion: Making needs adjustments to population counts using population estimates of children’s mental health need (assessed or perceived) provides additional value for informing and evaluating allocation decisions. This study provides much-needed and current information about the match between expenditures and children’s mental health need

    The 2014 Ontario Child Health Study—Methodology

    Get PDF
    Objective: To describe the methodology of the 2014 Ontario Child Health Study (OCHS): a province-wide, cross-sectional, epidemiologic study of child health and mental disorder among 4- to 17-year-olds living in household dwellings. Method: Implemented by Statistics Canada, the 2014 OCHS was led by academic researchers at the Offord Centre for Child Studies (McMaster University). Eligible households included families with children aged 4 to 17 years, who were listed on the 2014 Canadian Child Tax Benefit File. The survey design included area and household stratification by income and 3-stage cluster sampling of areas and households to yield a probability sample of families. Results: The 2014 OCHS included 6,537 responding households (50.8%) with 10,802 children aged 4 to 17 years. Lower income families living in low-income neighbourhoods were less likely to participate. In addition to measures of childhood mental disorder assessed by the Mini International Neuropsychiatric Interview for Children and Adolescents (MINI-KID) and OCHS Emotional Behavioural Scales (OCHS-EBS), the survey contains measures of neighbourhoods, schools, families and children, and includes administrative data held by the Ministries of Education and Health and Long-Term Care. Conclusions: The complex survey design and differential non-response of the 2014 OCHS required the use of sampling weights and adjustment for design effects. The study is available throughout Canada in the Statistics Canada Research Data Centres (RDCs). We urge external investigators to access the study through the RDCs or to contact us directly to collaborate on future secondary analysis studies based on the OCHS

    Changes in the Prevalence of Child and Youth Mental Disorders and Perceived Need for Professional Help between 1983 and 2014: Evidence from the Ontario Child Health Study

    Get PDF
    Objectives: To examine: 1) changes in the prevalence of mental disorders and perceived need for professional help among children (ages 4 to 11) and youth (ages 12 to 16) between 1983 and 2014 in Ontario and 2) whether these changes vary by age and sex, urban-rural residency, poverty, lone-parent status, and immigrant background. Methods: The 1983 (n = 2836) and 2014 (n = 5785) Ontario Child Health Studies are provincially representative cross-sectional surveys with identical self-report checklist measures of conduct disorder, hyperactivity, and emotional disorder, as well as perceived need for professional help, assessed by integrating parent and teacher responses (ages 4 to 11) and parent and youth responses (ages 12 to 16). Results: The overall prevalence of perceived need for professional help increased from 6.8% to 18.9% among 4- to 16-year-olds. An increase in any disorder among children (15.4% to 19.6%) was attributable to increases in hyperactivity among males (8.9% to 15.7%). Although the prevalence of any disorder did not change among youth, conduct disorder decreased (7.2% to 2.5%) while emotional disorder increased (9.2% to 13.2%). The prevalence of any disorder increased more in rural and small to medium urban areas versus large urban areas. The prevalence of any disorder decreased for children and youth in immigrant but not nonimmigrant families. Conclusions: Although there have been decreases in the prevalence of conduct disorder, increases in other mental disorders and perceived need for professional help underscore the continued need for effective prevention and intervention programs
    corecore