557 research outputs found
Effect of nickel in solid solution on hydrogen transport kinetics in low alloy steels
The use of low alloy steels (LAS) in H2S-containing environments in the oil and gas industry is governed by the ISO standard 15156-2 (NACE MR0175-2). One requirement, which has been disputed over the years, is that the nickel (Ni) content shall not exceed 1 wt%. This work investigated the effect of Ni in solid solution on hydrogen diffusion, solubility, and trapping in ferritic/pearlitic research-grade LAS with nominal Ni contents from 0 to 3 wt%. Hydrogen permeability experiments were carried out in a Devanathan-Stachurski setup at 15, 45 and 70 °C. The effective diffusion coefficients, calculated by the tlag method, decreased with increasing Ni content. The sub-surface hydrogen concentration in lattice and trap sites increased with increasing Ni content. There was no difference between the first and subsequent hydrogen permeation transients, suggesting that Ni in solid solution forms reversible traps. The effect of Ni in refining the microstructure may be superimposed on the effect of Ni in solid solution, and should be investigated in future work
Comparative support for the expensive tissue hypothesis: Big brains are correlated with smaller gut and greater parental investment in Lake Tanganyika cichlids
This is the final version of the article. Available from the publisher via the DOI in this record.The brain is one of the most energetically expensive organs in the vertebrate body. Consequently, the energetic requirements of encephalization are suggested to impose considerable constraints on brain size evolution. Three main hypotheses concerning how energetic constraints might affect brain evolution predict covariation between brain investment and (1) investment into other costly tissues, (2) overall metabolic rate, and (3) reproductive investment. To date, these hypotheses have mainly been tested in homeothermic animals and the existing data are inconclusive. However, there are good reasons to believe that energetic limitations might play a role in large-scale patterns of brain size evolution also in ectothermic vertebrates. Here, we test these hypotheses in a group of ectothermic vertebrates, the Lake Tanganyika cichlid fishes. After controlling for the effect of shared ancestry and confounding ecological variables, we find a negative association between brain size and gut size. Furthermore, we find that the evolution of a larger brain is accompanied by increased reproductive investment into egg size and parental care. Our results indicate that the energetic costs of encephalization may be an important general factor involved in the evolution of brain size also in ectothermic vertebrates.The authors thank the staff of the Department of Fisheries of the Ministry
of Agriculture and Cooperatives at Mpulungu, Zambia, for their
cooperation during fieldwork, especially for collecting fishes from the
deeper levels. They also thank H. Tanaka for collecting fish samples for
us. This study was funded through the student exchange support program
(scholarship for long-term study abroad) from the Japanese Student Services
Organization (JASSO) to MT, the Zoologiska foundation to MT and
AK, a Davis Expedition Fund grant, Helge Axelsson Johnson grant, and a
Stiftelsen Hierta-Retzius stipendiefond grant to AH, the Austrian Science
Fund (J 3304-B24) to AK, and a Swedish Research Council grant to NK.
The authors have no conflict of interest to declare
Horizontal Equity and Taxpayer Characteristics: Who Is Advantaged and Disadvantaged by the Federal Income Tax?
In this paper, household utility levels are estimated indirectly from household labor-supply data to derive before- and after-tax utility indexes. A household is considered advantaged (disadvantaged) by the income tax if its utility index ranking increases (decreases) as a result of the tax. The study finds that tax-advantaged households have, on average, more children and are more likely to own their own homes while tax-disadvantaged households are more likely to be two-earner families. The implications of the findings for the horizontal equity of the income tax are discussed.
Therapeutic affordances of online support group use in women with endometriosis
Background: The Internet has provided women living with endometriosis new opportunities to seek support online. Online support groups may provide a range of therapeutic affordances which may benefit these women.
Objective: To examine the presence of therapeutic affordances as perceived by women who use endometriosis online support groups.
Methods: Sixty-nine women (aged 19 to 50 years; Mean = 34.2; 65.2% UK; 21.7% USA) participated in an online interview exploring online support group use. Participants had been using online support groups on average 2 years and 4 months (Range = 1 month to 14 years, 9 months). Responses were analysed using inductive thematic analysis.
Results: The analysis revealed 4 therapeutic affordances related to online support group use; i) “connection” i.e. the ability to connect in order to support each other, exchange advice, and to try to overcome feelings of loneliness; ii) “exploration” i.e. the ability to look for information, learn and bolster their knowledge; iii) “narration” i.e. the ability to share their experiences, as well as read about the experiences of others; and iv) “self-presentation” i.e. the ability to manage how they present themselves online. The associated outcomes of use were predominantly positive, such as reassurance and improved coping. However, a number of negative aspects were revealed including: concerns about the accuracy of information, arguments between members, over-reliance on the group, becoming upset by negative experiences or good news items and confidentiality of personal information.
Conclusions: Our findings support the SCENA model (Self-presentation, Connection, Exploration, Narration and Adaptation) proposed by Merolli et al., (2014) and reveal a range of positive aspects that may benefit members, particularly in relation to reassurance and coping. However, negative aspects need to be addressed in order to maximise the potential benefit of support groups. Some of these can be addressed relatively easily through making privacy policies clearer, including health professionals to moderate content and structuring forums to encourage the sharing of positive stories
Isolation and partial characterization of heparan sulphate proteoglycans from human hepatic amyloid
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