394 research outputs found

    Population response of triploid grass carp to declining levels of hydrilla in the Santee Cooper Reservoirs, South Carolina

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    Approximately 768,500 triploid grass carp ( Ctenopharyngodon idella Valenciennes) were stocked into the Santee Cooper reservoirs, South Carolina between 1989 and 1996 to control hydrilla ( Hydrilla verticillata (L.f.) Royle). Hydrilla coverage was reduced from a high of 17,272 ha during 1994 to a few ha by 1998. During 1997, 1998 and 1999, at least 98 triploid grass carp were collected yearly for population monitoring. Estimates of age, growth, and mortality, as well as population models, were used in the study to monitor triploid grass carp and predict population trends. Condition declined from that measured during a previous study in 1994. The annual mortality rate was estimated at 28% in 1997, 32% in 1998 and 39% in 1999; however, only the 1999 mortality rate was significantly different. Few (2 out of 98) of the triploid grass carp collected during 1999 were older than age 9. We expect increased mortality due to an aging population and sparse hydrilla coverage. During 1999, we estimated about 63,000 triploid grass carp system wide and project less than 3,000 fish by 2004, assuming no future stocking. management, population size Ctenopharyngodon idella, Hydrill

    Childrens friendships in super-diverse localities: Encounters with social and ethnic difference

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    This article explores how children make, manage, or avoid friendships in super-diverse primary school settings. We draw on interviews and pictorial data from 78 children, aged 8–9 years across three local London primary schools to identify particular friendship groupings and the extent to which they followed existing patterns of social division. Children in the study did recognise social and cultural differences, but their friendship perceptions, affections, conflicts and practices meant that the way in which difference impacted relationships was partial and unstable. Friendship practices in the routine settings of school involved interactions across difference, but also entrenchments around similarity

    Ethical and methodological issues in engaging young people living in poverty with participatory research methods

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    This paper discusses the methodological and ethical issues arising from a project that focused on conducting a qualitative study using participatory techniques with children and young people living in disadvantage. The main aim of the study was to explore the impact of poverty on children and young people's access to public and private services. The paper is based on the author's perspective of the first stage of the fieldwork from the project. It discusses the ethical implications of involving children and young people in the research process, in particular issues relating to access and recruitment, the role of young people's advisory groups, use of visual data and collection of data in young people's homes. The paper also identifies some strategies for addressing the difficulties encountered in relation to each of these aspects and it considers the benefits of adopting participatory methods when conducting research with children and young people

    The association between family and community social capital and health risk behaviours in young people: an integrative review

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    Background: Health risk behaviours known to result in poorer outcomes in adulthood are generally established in late childhood and adolescence. These ‘risky’ behaviours include smoking, alcohol and illicit drug use and sexual risk taking. While the role of social capital in the establishment of health risk behaviours in young people has been explored, to date, no attempt has been made to consolidate the evidence in the form of a review. Thus, this integrative review was undertaken to identify and synthesise research findings on the role and impact of family and community social capital on health risk behaviours in young people and provide a consolidated evidence base to inform multi-sectorial policy and practice.<p></p> Methods: Key electronic databases were searched (i.e. ASSIA, CINAHL, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, Database of Abstracts of Reviews of Effects, Embase, Medline, PsycINFO, Sociological Abstracts) for relevant studies and this was complemented by hand searching. Inclusion/exclusion criteria were applied and data was extracted from the included studies. Heterogeneity in study design and the outcomes assessed precluded meta-analysis/meta-synthesis; the results are therefore presented in narrative form.<p></p> Results: Thirty-four papers satisfied the review inclusion criteria; most were cross-sectional surveys. The majority of the studies were conducted in North America (n=25), with three being conducted in the UK. Sample sizes ranged from 61 to 98,340. The synthesised evidence demonstrates that social capital is an important construct for understanding the establishment of health risk behaviours in young people. The different elements of family and community social capital varied in terms of their saliency within each behavioural domain, with positive parent–child relations, parental monitoring, religiosity and school quality being particularly important in reducing risk.<p></p> Conclusions: This review is the first to systematically synthesise research findings about the association between social capital and health risk behaviours in young people. While providing evidence that may inform the development of interventions framed around social capital, the review also highlights key areas where further research is required to provide a fuller account of the nature and role of social capital in influencing the uptake of health risk behaviours.<p></p&gt

    Ética na pesquisa com crianças: ausências e desafios

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    Valendo-se da sociologia da infância, o texto discute as questões da infância, da pesquisa e da ética que devem enformar todos os procedimentos desencadeados no processo de pesquisa com crianças. Será inicialmente apresentado o estado da arte acerca das discussões que têm caraterizado esse debate, que, sendo recente, conta com uma significativa reflexão. Apresentamos, ainda, alguns desafios que são fundamentais serem enfrentados para que se consiga uma ética viável na investigação com crianças, que passam pela indispensabilidade de se pensar as questões de poder que se estabelecem entre adultos e crianças; que passam também pelo enfrentamento do desafio que decorre das hierarquias protocolares e a maneira como estas podem contribuir para a invisibilidade epistemológica das crianças na pesquisa; que passam, finalmente, por um questionamento crítico relativamente à forma como é salvaguardada a autoria, quer de crianças, quer de adultos, na análise, interpretação e produção dos dados.This paper discusses, from the sociology of childhood, the issues of childhood, research and ethics which must shape the methodological procedures undertaken in the research processes with children. We, firstly, will present the state-of-the-art theoretical discussions that have been characterizing this debate, which, although recent, are already very significant. We also present some challenges, which are essential to face, in order to achieve a feasible ethic in research with children, which are related to the need to think about the power issues between adults and children. We also have to consider that the challenge stems from the protocol hierarchies and how sometimes these can contribute to the epistemological invisibility of children in research. Finally, a third challenge that mobilizes a critical analysis related to the way issues of authorship of children and adult, in the analysis, interpretation and production of scientific texts, are respected.Valiéndose de la sociología en la infancia, el texto discute las cuestiones de la infancia, de la investigación y la ética que deben conformar todos los procedimientos desencadenados en el proceso de investigación con niños y niñas. En primer lugar se presenta el estado de la arte acerca de las discusiones que vienen caracterizando a tal debate, que aun siendo reciente, ya cuenta con una significativa reflexión. Presentamos también algunos de los desafíos que resulta fundamental afrontar para alcanzar una ética viable en la investigación con niños y niñas, que pasan por la obligada necesidad de pensar las cuestiones de poder que se establecen entre adultos y niños; que pasan también por el afrontamiento al desafío que resulta de las jerarquías protocolarias y la forma cómo estas pueden contribuir para la invisibilidad epistemológica de los niños y niñas en la investigación. Que pasan, por fin, por un cuestionamiento crítico en cuanto a la forma como se salvaguarda la autoría, ya sea de niños o de adultos, en el análisis, interpretación y producción de datos.CIEC - Centro de Investigação em Estudos da Criança, IE, UMinho (UI 317 da FCT), PortugalFundos Nacionais através da FCT (Fundação para a Ciência e a Tecnologia) e cofinanciado pelo Fundo Europeu de Desenvolvimento Regional (FEDER) através do COMPETE 2020 – Programa Operacional Competitividade e Internacionalização (POCI) no âmbito do CIEC (Centro de Investigação em Estudos da Criança, da Universidade do Minho) com a referência POCI-01-0145-FEDER-00756

    Beings in their own right? Exploring Children and young people's sibling and twin relationships in the Minority World

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    This paper examines the contributions that the sociological study of sibship and twinship in the Minority World can make to childhood studies. It argues that, in providing one forum within which to explore children and young people's social relationships, we can add to our understanding of children and young people's interdependence and develop a more nuanced understanding of agency. As emergent subjects, children, young people and adults are in a process of ‘becoming’. However, this does not mean that they can ‘become’ anything they choose to. The notion of negotiated interdependence (Punch 2002) is useful in helping us to grasp the contingent nature of children and young people's agency

    The bipolar outflow and disk of the brown dwarf ISO217

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    We show that the very young brown dwarf candidate ISO217 (M6.25) is driving an intrinsically asymmetric bipolar outflow with a stronger and slightly faster red-shifted component based on spectro-astrometry of forbidden [SII] emission lines observed in UVES/VLT spectra taken in 2009. ISO217 is only one of a handful of brown dwarfs and VLMS (M5-M8) for which an outflow has been detected and that show that the T Tauri phase continues at the substellar limit. We measure a spatial extension of the outflow of +/-190mas (+/-30AU) and velocities of +/-40-50kms/s. We show that the velocity asymmetry between both lobes is variable on timescales of a few years and that the strong asymmetry of a factor of 2 found in 2007 might be smaller than originally anticipated when using a more realistic stellar rest-velocity. We also detect forbidden [FeII]7155 emission, for which we propose as potential origin the hot inner regions of the outflow. To understand the ISO217 system, we determine the disk properties based on radiative transfer modeling of the SED. This disk model agrees very well with Herschel/PACS data at 70mu. We find that the disk is flared and intermediately inclined (~45deg). The total disk mass (4e-6 Msun) is small compared to the accretion and outflow rate of ISO217 (~1e-10 Msun/yr). We propose that this discrepancy can be explained by either a higher disk mass than inferred from the model (strong undetected grain growth) and/or by an on average lower accretion and outflow rate than the determined values. We show that a disk inclination significantly exceeding 45deg, as suggested from Halpha modeling and from both lobes of the outflow being visible, is inconsistent with the SED data. Thus, despite its intermediate inclination angle, the disk of this brown dwarf does not appear to obscure the red outflow component, which is very rarely seen for T Tauri objects (only one other case).Comment: Accepted for publication at A&A; minor changes (language editing

    Interface electronic states and boundary conditions for envelope functions

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    The envelope-function method with generalized boundary conditions is applied to the description of localized and resonant interface states. A complete set of phenomenological conditions which restrict the form of connection rules for envelope functions is derived using the Hermiticity and symmetry requirements. Empirical coefficients in the connection rules play role of material parameters which characterize an internal structure of every particular heterointerface. As an illustration we present the derivation of the most general connection rules for the one-band effective mass and 4-band Kane models. The conditions for the existence of Tamm-like localized interface states are established. It is shown that a nontrivial form of the connection rules can also result in the formation of resonant states. The most transparent manifestation of such states is the resonant tunneling through a single-barrier heterostructure.Comment: RevTeX4, 11 pages, 5 eps figures, submitted to Phys.Rev.

    Genetic studies of the Macushi and Wapishana Indians

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    Blood samples from 509 Macushi and 623 Wapishana Amerindians of Northern Brazil and Southern Guyana have been analyzed with reference to the occurrence of rare variants and genetic polymorphisms of the following 25 systems: (i) Erythrocyte enzymes : acid phosphatase-1, adenosine deaminase, adenylate kinase-k, carbonic anhydrase-1, carbonic anhydrase-2, esterase A 1,2,3, esterase D, galactose-1-phosphate uridyltransferase, isocitrate dehydrogenase, lactate dehydrogenase, malate dehydrogenase, nucleoside phosphorylase, peptidase A, peptidase B, phosphoglucomutase 1, phosphoglucomutase 2, phosphogluconate dehydrogenase, phosphohexoseisomerase, triosephosphate isomerase and (ii) Serum proteins : albumin, ceruloplasmin, haptoglobin, hemoglobin A, hemoglobin A 2 and transferrin. Fifteen different rare variants were detected, involving 11 of these systems. In addition, a previously undescribed variant of ESA 1,2,3 which achieves polymorphic proportions in both these tribes is described. Excluding this variant, the frequency of rare variants is 1.1/1000 in 12510 determinations in the Macushi and 4.7/1000 in 15 396 determinations in the Wapishana. The ESA 1,2,3 , polymorphism was not observed in 382 Makiritare, 232 Yanomama, 146 Piaroa, 404 Cayapo, 190 Kraho and 112 Moro. Irregularities in the intratribal distribution of this polymorphism in the Macushi and Wapishana render a decision as to the tribe of origin impossible at present. Gene frequencies are also given for previosly described polymorphisms of 5 systems: haptoglobin, phosphoglucomutase 1, erythrocyte acid phosphatase, esterase D, and galactose-1-phosphate-uridyl-transferase.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47605/1/439_2004_Article_BF00390440.pd
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