953 research outputs found

    Metallicity at the explosion sites of interacting transients

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    Context. Some circumstellar-interacting (CSI) supernovae (SNe) are produced by the explosions of massive stars that have lost mass shortly before the SN explosion. There is evidence that the precursors of some SNe IIn were luminous blue variable (LBV) stars. For a small number of CSI SNe, outbursts have been observed before the SN explosion. Eruptive events of massive stars are named as SN impostors (SN IMs) and whether they herald a forthcoming SN or not is still unclear. The large variety of observational properties of CSI SNe suggests the existence of other progenitors, such as red supergiant (RSG) stars with superwinds. Furthermore, the role of metallicity in the mass loss of CSI SN progenitors is still largely unexplored. Aims. Our goal is to gain insight on the nature of the progenitor stars of CSI SNe by studying their environments, in particular the metallicity at their locations. Methods. We obtain metallicity measurements at the location of 60 transients (including SNe IIn, SNe Ibn, and SN IMs), via emission-line diagnostic on optical spectra obtained at the Nordic Optical Telescope and through public archives. Metallicity values from the literature complement our sample. We compare the metallicity distributions among the different CSI SN subtypes and to those of other core-collapse SN types. We also search for possible correlations between metallicity and CSI SN observational properties. Results. We find that SN IMs tend to occur in environments with lower metallicity than those of SNe IIn. Among SNe IIn, SN IIn-L(1998S-like) SNe show higher metallicities, similar to those of SNe IIL/P, whereas long-lasting SNe IIn (1988Z-like) show lower metallicities, similar to those of SN IMs. The metallicity distribution of SNe IIn can be reproduced by combining the metallicity distributions of SN IMs (that may be produced by major outbursts of massive stars like LBVs) and SNe IIP (produced by RSGs). The same applies to the distributions of the Normalized Cumulative Rank (NCR) values, which quantifies the SN association to H II regions. For SNe IIn, we find larger mass-loss rates and higher CSM velocities at higher metallicities. The luminosity increment in the optical bands during SN IM outbursts tend to be larger at higher metallicity, whereas the SN IM quiescent optical luminosities tend to be lower. Conclusions. The difference in metallicity between SNe IIn and SN IMs suggests that LBVs are only one of the progenitor channels for SNe IIn, with 1988Z-like and 1998S-like SNe possibly arising from LBVs and RSGs, respectively. Finally, even though linedriven winds likely do not primarily drive the late mass-loss of CSI SN progenitors, metallicity has some impact on the observational properties of these transients. Key words. supernovae: general - stars: evolution - galaxies: abundancesComment: Submitted to Astronomy and Astrophysics on 28/02/2015; submitted to arXiv after the 1st referee repor

    Sagnac interferometry for background subtraction in pump-probe spectroscopy

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    Metamorfosa Radikalisme pada Lembaga Pendidikan di Sulawesi Tenggara

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    Research on the metamorphosis of radicalism in educational institutions in Southeast Sulawesi has been conducted and focused on the segregation potential to be a radical individuals and groups to preach, especially in educational institutions in the Southeast Sulawesi. Data obtained through questionnaires, structured interviews, observation, document tracking and focus group discussion.The results showed that the metamorphosis of radicalism on the knot of educational institutions in Southeast Sulawesi spreading through the penetration movement in educational institutions such as on college campuses and in schools, especially in public campuses with the goal of lecturers and students and public schools targeted teachers and students. The spread on campus through student propaganda agency involving senior students and in the school and through extra-curricular involving senior students with methods of brainwashing. Lecturer plays an important role in the growth of radicalism as teachers and leaders of radical organizations with a method of indoctrination while teachers act through the hidden curriculum. The policy of the state budget subsidies to student organizations affiliated to the radical organization helped sustain the growth of radicalism on campus.The study recommends that efforts to break the chain of radicalism in educational institutions in Southeast Sulawesi can be done by educators either individually or as an educator together with governmen

    Mental well-being among the oldest old: revisiting the model of healthy ageing in a Finnish context

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    Purpose: This study aimed to examine how participants aged 80 years old or over describe their mental well-being-exploring the suitability of the model of healthy ageing when outlining the mental well-being concept.Methods: Six structured focus group interviews with 28 participants were conducted in Western Finland in 2017. Qualitative content analysis was performed, where both manifest and latent content was considered in a process involving meaning condensation and coding, followed by categorization.Results: The healthy ageing model constituted a useful framework for the conceptualization of mental well-being, illustrating the links between these two constructs. The analysis resulted in a four-dimensional model of mental well-being in oldest old age, the key components being: Activities-enjoyment and fulfilment; Capability-functioning and independence; Orientation-awareness, shifted perspectives and values; and Connectedness-sense of belonging.Conclusions: Although functional status plays an important role for well-being in general, it is not the principal component of self-reported mental well-being within the heterogeneous group of the oldest old. Further, many persons in this age group do not view themselves as passive or dependent, on the contrary, they underline the importance of empowering attitudes, a positive mindset and actively creating circumstances which support their mental well-being

    Effects of Temperature on the Threshold of Phosphorus for Algal Blooms

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    Artturi Assists Finnish Advisers and Farmers to Succeed in Grass-Based Dairy Production

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    Artturi is a collective name for a wide range of services. It is a common tool for different bodies who share an interest in strengthening grass-based dairy production in Finland: research, advisory service and industries. The Service is named after A. I. (Artturi Ilmari) Virtanen, the Finnish scientist who was awarded the Nobel prize in 1945, partly based on his work in developing the ensiling process of grass. The Artturi web site is available in Internet at: http://www.agronet.fi/artturi. Access to Artturi Services is free and no registration is required. The language used is Finnish. During summer 2003, 15,000 visits were recorded at the web site

    Liver secretin receptor predicts portoenterostomy outcomes and liver injury in biliary atresia

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    Biliary atresia (BA) is a chronic neonatal cholangiopathy characterized by fibroinflammatory bile duct damage. Reliable biomarkers for predicting native liver survival (NLS) following portoenterostomy (PE) surgery are lacking. Herein we explore the utility of 22 preidentified profibrotic molecules closely connected to ductular reaction (DR) and prevailing after successful PE (SPE), in predicting PE outcomes and liver injury. We used qPCR and immunohistochemistry in a BA cohort including liver samples obtained at PE (n = 53) and during postoperative follow-up after SPE (n = 25). Of the 13 genes over-expressed in relation to cholestatic age-matched controls at PE, only secretin receptor (SCTR) expression predicted cumulative 5-year NLS and clearance of jaundice. Patients in the highest SCTR expression tertile showed 34–55% lower NLS than other groups at 1–5 years after PE (P = 0.006–0.04 for each year). SCTR expression was also significantly lower [42 (24–63) vs 75 (39–107) fold, P = 0.015] among those who normalized their serum bilirubin after PE. Liver SCTR expression localized in cholangiocytes and correlated positively with liver fibrosis, DR, and transcriptional markers of fibrosis (ACTA2) and cholangiocytes (KRT7, KRT19) both at PE and after SPE. SCTR is a promising prognostic marker for PE outcomes and associates with liver injury in BA

    Seasonal change in the daily timing of behaviour of the common vole, Microtus arvalis

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    1. Seasonal effects on daily activity patterns in the common vole were established by periodic trapping in the field and continuous year round recording of running wheel and freeding activity in cages exposed to natural meteorological conditions. 2. Trapping revealed decreased nocturnality in winter as compared to summer. This was paralelled by a winter reduction in both nocturnal wheel running and feeding time in cages. 3. Frequent trap checks revealed a 2 h rhythm in daytime catches in winter, not in summer. Cage feeding activity in daytime was always organized in c. 2 h intervals, but day-to-day variations in phase blurred the rhythm in summer in a summation of individual daily records. Thus both seasonal and short-term temporal patterns are consistent between field trappings and cage feeding records. 4. Variables associated with the seasonal change in daily pattern were: reproductive state (sexually active voles more nocturnal), age (juveniles more nocturnal), temperature (cold days: less nocturnal), food (indicated by feeding experiments), habitat structure (more nocturnal in habitat with underground tunnels). 5. Minor discrepancies between field trappings and cage feeding activity can be explained by assuming increased trappability of voles in winter. Cage wheel running is not predictive of field trapping patterns and is thought to reflect behavioral motivations not associated with feeding but with other activities (e.g., exploratory, escape, interactive behaviour) undetected by current methods, including radiotelemetry and passage-counting. 6. Winter decrease in nocturnality appears to involve a reduction in nocturnal non-feeding and feeding behaviour and is interpreted primarily as an adaptation to reduce energy expenditure in adverse but socially stable winter conditions.
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