2,965 research outputs found

    Unveiling the nature of the "Green Pea" galaxies

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    We review recent results on the oxygen and nitrogen chemical abundances in extremely compact, low-mass starburst galaxies at redshifts between 0.1-0.3 recently named to as "Green Pea" galaxies. These galaxies are genuine metal-poor galaxies (∌\sim one fifth solar) with N/O ratios unusually high for galaxies of the same metallicity. In combination with their known general properties, i.e., size, stellar mass and star-formation rate, these findings suggest that these objects could be experiencing a short and extreme phase in their evolution. The possible action of both recent and massive inflow of gas, as well as stellar feedback mechanisms are discussed here as main drivers of the starburst activity and their oxygen and nitrogen abundances.Comment: To appear in JENAM Symposium "Dwarf Galaxies: Keys to Galaxy Formation and Evolution", P. Papaderos, G. Hensler, S. Recchi (eds.). Lisbon, September 2010, Springer Verlag, in pres

    The "Solar Model Problem" Solved by the Abundance of Neon in Stars of the Local Cosmos

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    The interior structure of the Sun can be studied with great accuracy using observations of its oscillations, similar to seismology of the Earth. Precise agreement between helioseismological measurements and predictions of theoretical solar models has been a triumph of modern astrophysics (Bahcall et al. 2005). However, a recent downward revision by 25-35% of the solar abundances of light elements such as C, N, O and Ne (Asplund et al. 2004) has broken this accordance: models adopting the new abundances incorrectly predict the depth of the convection zone, the depth profiles of sound speed and density, and the helium abundance (Basu Antia 2004, Bahcall et al. 2005). The discrepancies are far beyond the uncertainties in either the data or the model predictions (Bahcall et al. 2005b). Here we report on neon abundances relative to oxygen measured in a sample of nearby solar-like stars from their X-ray spectra. They are all very similar and substantially larger than the recently revised solar value. The neon abundance in the Sun is quite poorly determined. If the Ne/O abundance in these stars is adopted for the Sun the models are brought back into agreement with helioseismology measurements (Antia Basu 2005, Bahcall et al. 2005c).Comment: 13 pages, 3 Figure

    Outbreak of Fatal Childhood Lead Poisoning Related to Artisanal Gold Mining in Northwestern Nigeria, 2010.

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    Background: In May 2010, a team of national and international organizations was assembled to investigate children's deaths due to lead poisoning in villages in northwestern Nigeria. Objectives: To determine the cause of the childhood lead poisoning outbreak, investigate risk factors for child mortality, and identify children aged <5 years in need of emergency chelation therapy for lead poisoning. Methods: We administered a cross-sectional, door-to-door questionnaire in two affected villages, collected blood from children aged 2-59 months, and soil samples from family compounds. Descriptive and bivariate analyses were performed with survey, blood-lead, and environmental data. Multivariate logistic regression techniques were used to determine risk factors for childhood mortality. Results: We surveyed 119 family compounds. One hundred eighteen of 463 (25%) children aged <5 years had died in the last year. We tested 59% (204/345) of children, aged <5 years, and all were lead poisoned (≄10 ”g/dL); 97% (198/204) of children had blood-lead levels ≄45 ”g/dL, the threshold for initiating chelation therapy. Gold ore was processed inside two-thirds of the family compounds surveyed. In multivariate modeling significant risk factors for death in the previous year from suspected lead poisoning included: the child's age, the mother performing ore-processing activities, community well as primary water source, and the soil-lead concentration in the compound. Conclusion: The high levels of environmental contamination, percentage of children aged <5 years with elevated blood-lead levels (97%, >45 ”g/dL), and incidence of convulsions among children prior to death (82%) suggest that most of the recent childhood deaths in the two surveyed villages were caused by acute lead poisoning from gold ore-processing activities. Control measures included environmental remediation, chelation therapy, public health education, and control of mining activities

    Folate and Vitamin B-12 Status Is Associated With Bone Mineral Density and Hip Strength of Postmenopausal Chinese-Singaporean Women

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    The role of micronutrients such as folate and vitamin B-12 in bone quality has been widely studied with conflicting results. Ethnicity seems to play a large role on nutrient intake, as diet varies across cultures. In this study, we examined the relationships of BMD, proximal femur strength, and bone resorption with plasma folate and vitamin B-12 in a cohort of 93 healthy postmenopausal women of Chinese-Singaporean descent. The parameters examined were areal (aBMD) and volumetric BMD (vBMD) of the proximal femur and the third lumbar vertebra (L3), total body aBMD, proximal femur bending, compressive and impact strength indices (composite strength indices) and circulating levels of C-telopeptide of type I collagen. Eighteen participants (19.4%) had aBMD in the osteoporotic range (osteoporosis group), 59 (63.4%) in the osteopenic range (osteopenia group), and the remaining 16 (17.2%) in the normal range (normal BMD group). Circulating folate levels were significantly higher in the normal BMD group compared with the osteoporosis group. Using linear regression analysis, we found that overall, aBMD and vBMD are positively associated with folate concentrations, whereas composite strength indices were positively associated with vitamin B-12 concentrations. These findings support the existing literature and suggest a link between levels of circulating folate/vitamin B-12 and BMD/bone strength in the cohort examined. Further investigation is needed to examine if individuals with inadequate circulating levels of these nutrients could decrease their risk for fragility fractures through better nutrition or vitamin supplementation. © 2020 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research © 2020 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research

    Transcriptome analysis of Brachypodium during fungal pathogen infection reveals both shared and distinct defense responses with wheat

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    © 2017 The Author(s). Fusarium crown rot (FCR) of wheat and barley, predominantly caused by the fungal pathogen Fusarium pseudograminearum, is a disease of economic significance. The quantitative nature of FCR resistance within cultivated wheat germplasm has significantly limited breeding efforts to enhanced FCR resistance in wheat. In this study, we characterized the molecular responses of Brachypodium distachyon (Brachypodium hereafter) to F. pseudograminearum infection using RNA-seq to determine whether Brachypodium can be exploited as a model system towards better understanding of F. pseudograminearum-wheat interaction. The transcriptional response to infection in Brachypodium was strikingly similar to that previously reported in wheat, both in shared expression patterns of wheat homologs of Brachypodium genes and functional overlap revealed through comparative gene ontology analysis in both species. Metabolites produced by various biosynthetic pathways induced in both wheat and Brachypodium were quantified, revealing a high degree of overlap between these two species in metabolic response to infection but also showed Brachypodium does not produce certain defence-related metabolites found in wheat. Functional analyses of candidate genes identified in this study will improve our understanding of resistance mechanisms and may lead to the development of new strategies to protect cereal crops from pathogen infection

    Emerging pharmacotherapy of tinnitus

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    Tinnitus, the perception of sound in the absence of an auditory stimulus, is perceived by about 1 in 10 adults, and for at least 1 in 100, tinnitus severely affects their quality of life. Because tinnitus is frequently associated with irritability, agitation, stress, insomnia, anxiety and depression, the social and economic burdens of tinnitus can be enormous. No curative treatments are available. However, tinnitus symptoms can be alleviated to some extent. The most widespread management therapies consist of auditory stimulation and cognitive behavioral treatment, aiming at improving habituation and coping strategies. Available clinical trials vary in methodological rigor and have been performed for a considerable number of different drugs. None of the investigated drugs have demonstrated providing replicable long-term reduction of tinnitus impact in the majority of patients in excess of placebo effects. Accordingly, there are no FDA or European Medicines Agency approved drugs for the treatment of tinnitus. However, in spite of the lack of evidence, a large variety of different compounds are prescribed off-label. Therefore, more effective pharmacotherapies for this huge and still growing market are desperately needed and even a drug that produces only a small but significant effect would have an enormous therapeutic impact. This review describes current and emerging pharmacotherapies with current difficulties and limitations. In addition, it provides an estimate of the tinnitus market. Finally, it describes recent advances in the tinnitus field which may help overcome obstacles faced in the pharmacological treatment of tinnitus. These include incomplete knowledge of tinnitus pathophysiology, lack of well-established animal models, heterogeneity of different forms of tinnitus, difficulties in tinnitus assessment and outcome measurement and variability in clinical trial methodology. © 2009 Informa UK Ltd.Fil: Langguth, Berthold. Universitat Regensburg; AlemaniaFil: Salvi, Richard. State University of New York; Estados UnidosFil: Elgoyhen, Ana Belen. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; Argentin

    The politicisation of evaluation: constructing and contesting EU policy performance

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    Although systematic policy evaluation has been conducted for decades and has been growing strongly within the European Union (EU) institutions and in the member states, it remains largely underexplored in political science literatures. Extant work in political science and public policy typically focuses on elements such as agenda setting, policy shaping, decision making, or implementation rather than evaluation. Although individual pieces of research on evaluation in the EU have started to emerge, most often regarding policy “effectiveness” (one criterion among many in evaluation), a more structured approach is currently missing. This special issue aims to address this gap in political science by focusing on four key focal points: evaluation institutions (including rules and cultures), evaluation actors and interests (including competencies, power, roles and tasks), evaluation design (including research methods and theories, and their impact on policy design and legislation), and finally, evaluation purpose and use (including the relationships between discourse and scientific evidence, political attitudes and strategic use). The special issue considers how each of these elements contributes to an evolving governance system in the EU, where evaluation is playing an increasingly important role in decision making
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