23,960 research outputs found

    The size--density relation of extragalactic HII regions

    Full text link
    We investigate the size--density relation in extragalactic HII regions, with the aim of understanding the role of dust and different physical conditions in the ionized medium. First, we compiled several observational data sets for Galactic and extragalactic HII regions and confirm that extragalactic HII regions follow the same size (D)--density (n) relation as Galactic ones. Motivated by the inability of static models to explain this, we then modelled the evolution of the size--density relation of HII regions by considering their star formation history, the effects of dust, and pressure-driven expansion. The results are compared with our sample data whose size and density span roughly six orders of magnitude. We find that the extragalactic size--density relation does not result from an evolutionary sequence of HII regions but rather reflects a sequence with different initial gas densities (``density hierarchy''). Moreover, the size of many HII regions is limited by dust absorption of ionizing photons, rather than consumption by ionizing neutral hydrogen. Dust extinction of ionizing photons is particularly severe over the entire lifetime of compact HII regions with typical gas densities of greater than 10^3 cm^{-3}. Hence, as long as the number of ionizing photons is used to trace massive star formation, much star-formation activity could be missed. Such compact dense environments, the ones most profoundly obscured by dust, have properties similar to ``maximum--intensity starbursts''. This implies that submillimeter and infrared wavelengths may be necessary to accurately assess star formation in these extreme conditions both locally and at high redshift.Comment: 18 pages, 11 figures, accepted for publication in Astronomy and Astrophysic

    Positive associations between consumerism and tobacco and alcohol use in early adolescence: cross-sectional study

    Get PDF
    <p>Background: There is concern about the negative impact of modern consumer culture on young people's mental health, but very few studies have investigated associations with substance use. In those which have, positive associations have been attributed to attempts to satisfy the unmet needs of more materialistic individuals.</p> <p>Objectives: This study examines associations between different dimensions of consumerism and tobacco and alcohol use among Scottish early adolescents.</p> <p>Design: Cross-sectional study.</p> <p>Setting and participants: 2937 (92% of those eligible) secondary school pupils (ages 12–14) completed questionnaires in examination conditions. Analyses were restricted to those with complete data on all relevant variables (N=2736 smoking; N=2737 drinking).</p> <p>Measures: Dependent variables comprised ever smoking and current drinking. Measures of consumerism comprised number of ‘premium’ (range 0–7) and ‘standard’ (range 0–5) material possessions and three Consumer Involvement subscales, ‘dissatisfaction’, ‘consumer orientation’ and ‘brand awareness’ (each range 3–12). Analyses also included school-year group and family affluence.</p> <p>Results: Ever smoking and current drinking were both more prevalent among adolescents with more ‘premium’ and ‘standard’ material possessions, greater consumer ‘dissatisfaction’ and ‘brand awareness’ (mutually adjusted analyses including school-year group and family affluence). The strongest relationships occurred for ‘brand awareness’: for each unit increase in ‘brand awareness’ the ORs (95% CI) of ever smoking were 1.17 (1.08 to 1.26) and 1.23 (1.14 to 1.33) in males and females, respectively; and those for drinking were 1.15 (1.08 to 1.23) and 1.21 (1.13 to 1.30). ‘Brand awareness’ had an equal or stronger relationship with both smoking and drinking than did family affluence.</p> <p>Conclusions: These results suggest aassociations between consumerism and both smoking and drinking might arise because adolescent identities incorporate both consumerism and substance use, or be the result of promotion (indirectly in the case of tobacco) linking consumerist or aspirational lifestyles with these behaviours.</p&gt

    Orientation of \u3ci\u3eHylobius Pales\u3c/i\u3e and \u3ci\u3ePachylobius Picivorus\u3c/i\u3e (Coleoptera: Curculionidae) to Visual Cues

    Get PDF
    Pitfall traps with above-ground silhouettes of various colors and diameters were used in field tests to evaluate the role of vision in host orientation by adult pales weevils, Hylobius pales, and pitch-eating weevils, Pachylobius picivorus. White traps (11 em outer diameter) baited with ethanol and turpentine caught significantly more weevils than similarly baited black or green traps (11 cm outer diameter). Trap diameter (range of 6-22 cm outer diameter) did not affect trap catch. Pitfall traps can be used to monitor root weevil populations in young pine plantations and Christmas tree farms, where they are major pests. These results demonstrate that visual and chemical cues can be integrated to improve trap efficiency

    Managing multiple morbidity in mid-life: a qualitative study of attitudes to drug use

    Get PDF
    OBJECTIVE: To examine attitudes towards drug use among middle aged respondents with high levels of chronic morbidity. DESIGN: Qualitative study with detailed interviews. SETTING: West of Scotland. PARTICIPANTS: 23 men and women aged about 50 years with four or more chronic illnesses. MAIN OUTCOME MEASURE: Participants' feelings about long term use of drugs to manage chronic multiple morbidity. RESULTS: Drugs occupied a central place in the way people managed their comorbidities. Respondents expressed an aversion to taking drugs, despite acknowledging that they depended on drugs to live as "normal" a life as possible. Respondents expressed ambivalence to their drugs in various ways. Firstly, they adopted both regular and more flexible regimens and might adhere to a regular regimen in treating one condition (such as hypertension) while adopting a flexible regimen in relation to others, in response to their experience of symptoms or varying demands of their daily life. Secondly, they expressed reluctance to take drugs, but an inability to be free of them. Thirdly, drugs both facilitated performance of social roles and served as evidence of an inability to perform such roles. CONCLUSIONS: Insight into the considerable tension experienced by people managing complex drug regimens to manage multiple chronic illness may help medical carers to support self care practices among patients and to optimise concordance in their use of prescribed drugs

    Preservation Verus Private Rights: Mining in the National Parks and Forests

    Get PDF

    Consumerism and well-being in early adolescence

    Get PDF
    It has been suggested that consumerism is negatively related to well-being in children and adolescents, as well as adults. Few studies have explored whether certain aspects of consumerism have stronger associations with well-being than others, or between-group differences in associations. This article uses data from a sample of early adolescents to examine: levels of consumerism; relationships between different aspects of consumerism and well-being; and differences according to gender, school year group and family affluence. Data were obtained in 2010 via secondary school pupil surveys (N=2934). Consumerism measures comprised number of ‘standard’ and ‘premium’ possessions and four dimensions of consumer involvement; well-being measures comprised self-esteem, psychological distress and anger. There was evidence of high penetration of consumerist values. There were positive associations between number of possessions and anger, and between ‘dissatisfaction’ and poorer well-being, regardless of how measured. ‘Brand awareness’ was associated with positive male well-being, but negative female well-being. Many relationships between consumerism and well-being were stronger than those between family affluence and well-being. These results suggest only certain aspects of consumerism are associated with poorer adolescent well-being. Although, for some sub-groups, other aspects might be associated with better well-being, there was no evidence that modern consumer goods promote happiness

    Theories of Technological Progress and the British Textile Industry from Kay to Cartwright

    Get PDF
    Editada en la FundaciĂłn Empresa PĂșblicaLa industria textil britĂĄnica continĂșa en el centro del debate sobre la revoluciĂłn industrial. Las innovaciones tĂ©cnicas en el perĂ­odo produjeron una aceleraciĂłn extraordinaria del crecimiento del output y una considerable reducciĂłn de los precios de los tejidos. En este trabajo presentamos un estudio de la comunidad de los inventores responsables de la transformaciĂłn tecnolĂłgica, lo que nos permite alcanzar una serie de conclusiones nuevas sobre el ritmo y direcciĂłn de la actividad innovadora durante la revoluciĂłn industrialThe cotton textile industry remains central to all accounts of the first industrial revolution. Innovations in this period precipitated an extraordinary acceleration in the growth of output and a steep decline in the cost of producing all varieties of cloth. In this paper we outline an explanation through an analysis of the community of inventors responsible for the technological transformation, which enables us to offer some generalizations of the pace and pattern of the inventive activity in this period.Publicad
    • 

    corecore