1,408 research outputs found

    The extent of mixing in stellar interiors: the open clusters Collinder 261 and Melotte 66

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    Context: Determining carbon and nitrogen abundances in red giants provides useful diagnostics to test mixing processes in stellar atmospheres. Aims: Our main aim is to determine carbon-to-nitrogen and carbon isotope ratios for evolved giants in the open clusters Collinder 261 and Melotte 66 and to compare the results with predictions of theoretical models. Methods: High-resolution spectra were analysed using a differential model atmosphere method. Abundances of carbon were derived using the C_2 Swan (0,1) band head at 5635.5 A. The wavelength interval 7940-8130 A, which contains CN features, was analysed to determine nitrogen abundances and carbon isotope ratios. The oxygen abundances were determined from the [O_I] line at 6300 A. Results: The mean values of the elemental abundances in Collinder 261, as determined from seven stars, are: [C/Fe]=-0.23 +- 0.02 (s.d.), [N/Fe]=0.18 +- 0.09, [O/Fe]=-0.03 +- 0.07. The mean 12^C/13^C ratio is 11 +- 2, considering four red clump stars and 18 for one star above the clump. The mean C/N ratios are 1.60 +- 0.30 and 1.74, respectively. For the five stars in Melotte 66 we obtained: [C/Fe]=-0.21 +- 0.07 (s.d.), [N/Fe]=0.17 +- 0.07, [O/Fe]=0.16 +- 0.04. The 12^C/13^C and C/N ratios are 8 +- 2 and 1.67 +- 0.21, respectively. Conclusions: The 12^C/13^C and C/N ratios of stars in the investigated open clusters were compared with the ratios predicted by stellar evolution models. The mean values of 12^C/13^C ratios in Collinder 261 and Melotte 66 agree well with models of thermohaline-induced extra-mixing for the corresponding stellar turn-off masses of about 1.1 - 1.2 Msun. The mean C/N ratios are not decreased as much as predicted by the model in which the thermohaline- and rotation-induced extra-mixing act together.Comment: 6 pages, 8 figure

    Understanding addiction stigma: Examining desired social distance toward addicted individuals

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    Growing evidence documents pervasive and powerful stigmatization, discrimination, and prejudice directed towards individuals with mental illness. However, little is known about stigma towards individuals with substance disorders. This study examined the relationship between familiarity, perceived dangerousness, fear, and desired social distance towards individuals with substance dependence to alcohol, marijuana, and heroin. This study found that for marijuana and heroin, familiarity had an indirect effect, through perceived dangerousness and fear, on desired social distance. Furthermore, perceived dangerousness had a direct and indirect effect, through fear, on desired social distance. Finally fear had a direct effect on desired social distance. Greater familiarity predicted lower levels of perceived dangerousness, fear, and desired social distance for these two drugs. Similar results were found for alcohol; however, familiarity had an indirect effect on desired social distance only through fear. Furthermore, familiarity did not predict fear or perceived dangerousness. Future empirical work should examine the nature of this unique relationship between familiarity with alcohol addiction, perceived dangerousness, and fear. Overall, this study showed that mental health stigma models could be adapted to understand substance dependence stigma. However, the precise nature of the model varied among substances. This suggests that addiction to each substance is stigmatized in differing ways. Still, this study showed that familiarity tended to negatively predict desired social distance toward addicted individuals. Future research should explore this relationship and examine the effect of increasing familiarity on addiction stigma

    Living with HIV after Release from Prison: An Evaluation of the Long-term Health of Formerly Incarcerated Individuals who used Michigan’s Community Reentry Service

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    In 2003, Michigan implemented a reentry service to assist HIV-infected people incarcerated in state prisons in linking to HIV medical care immediately upon their release. We examined whether formerly incarcerated people were linked to care successfully, remained in care, and were in good health 3 years after their date of release. In all, 190 people used the service over the 5 years following its inception. Only a minority of those who were alive and not reincarcerated at the time of the evaluation engaged consistently with medical care. Unsurprisingly given low rates of engagement in care, 3 years after their release only 27% had achieved viral suppression. Concerted efforts to support formerly incarcerated HIV-infected individuals’ engagement in care over the long term are urgently needed

    Purposeful tool use in early lithic technologies

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    Abell 43: Longest period Planetary Nebula Nucleus variable

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    Based on 24h high speed photometry of the hybrid PG 1159 star Abell 43, we have detected 6 sighificant pulsations with periods between 2380 s and 6075 s. A short (4h) run on the almost spectroscopic twin NGC 7094 central star resulted in detection of 3 low amplitude pulsations with periods between 2000 s and 5000 s. The results are close to predictions for g-mode pulsations driven by the kappa-mechanism induced by the partial ionization of carbon and oxygen.Comment: 5 pages, 5 figures, to be published in Astronomy and Astrophysic

    Effects of growth control on yield and fruit quality of the apple cultivar ‘Rubin’

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    The effect of tree growth-control technologies on apple tree vegetative development, productivity and fruit quality was investigated with apple cultivar ‘Rubin’ on dwarf rootstock P 60 at the Institute of Horticulture, Lithuanian Research Centre for Agriculture and Forestry in 2015–2018. Eight treatments were established combining tree trunk incision by chainsaw before flowering, application of prohexadione-calcium in different dose and time, summer pruning in August and root pruning before flowering. Root pruning from both sides of the tree significantly reduced tree trunk diameter, shoot length and pruning weights but at the same time reduced fruit weight. It increased tree productivity and enhanced fruit colouring. Two applications of prohexadione-calcium significantly reduced mean shoot length and increased average fruit weight. Summer pruning had a positive impact on fruit colouring. Trunk incisions enhanced leaf P, K and Fe content. Pro-Ca increased leaf Ca content. Trees root pruned from both sides had one of the lowest contents of all tested minerals. All tree growth-control technologies had a positive impact on tree productivity , fruit quality and bearing stability comparing with control treatment

    Spectral Classification of Optical Counterparts to ROSAT All-Sky Survey X-ray Sources

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    Previous work statistically identified 5492 optical counterparts, with approximately 90% confidence, from among the approximately 18,000 X-ray sources appearing in the ROSAT All-Sky Survey Bright Source Catalog (RASS/BSC). Using low resolution spectra in the wavelength range 3700-7900 angstroms, we present spectroscopic classifications for 195 of these counterparts which have not previously been classified. Of these 195, we find 168 individual stars of F, G, K or M type, 6 individual stars of unknown type, 6 double stars, 6 AGN or galaxies and 7 unclassifiable objects; the spectra of the 2 remaining objects were saturated.Comment: 25 pages, 7 figure
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