| 1. |
- Boersma, Jordan, et al.
(författare)
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Male White-shouldered Fairywrens (Malurus alboscapulatus) elevate androgens greater when courting females than during territorial challenges
- 2022
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Ingår i: Hormones and Behavior. - : Elsevier. - 0018-506X .- 1095-6867. ; 142
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Tidskriftsartikel (refereegranskat)abstract
- Androgens like testosterone mediate suites of physical and behavioral traits across vertebrates, and circulation varies considerably across and within taxa. However, an understanding of the causal factors of variation in circulating testosterone has proven difficult despite decades of research. According to the challenge hypothesis, agonistic interactions between males immediately prior to the breeding season produce the highest levels of testosterone measured during this period. While many studies have provided support for this hypothesis, most species do not respond to male-male competition by elevating testosterone. As a result, a recent revision of the hypothesis ('challenge hypothesis 2.0') places male-female interactions as the primary cause of rapid elevations in testosterone circulation in male vertebrates. Here, we offer a test of both iterations of the challenge hypothesis in a tropical bird species. We first illustrate that male White-shouldered Fairywrens (Malurus alboscapulatus) differ by subspecies in plasma androgen concentrations. Then we use a social network approach to find that males of the subspecies with higher androgens are characterized by greater social interaction scores, including more time aggregating to perform sexual displays. Next, we use a controlled experiment to test whether males respond to simulated territorial intrusion and/or courtship competition contexts by elevating androgens. We found that males elevated androgens during territorial intrusions relative to flushed controls, however, males sampled during courtship competitions had greater plasma androgens both relative to controls and males sampled while defending territories. Ultimately, our results are consistent with challenge hypothesis 2.0, as sexual interactions with extra-pair females were associated with greater elevation of androgens than territorial disputes.
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| 2. |
- Frey, E, et al.
(författare)
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Determination of the universality class of gadolinium
- 1997
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Ingår i: PHYSICAL REVIEW LETTERS. - : AMERICAN PHYSICAL SOC. - 0031-9007. ; 79:25, s. 5142-5145
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- We resolve a long-standing puzzle for the static and dynamic critical behavior of gadolinium by a combined theoretical and experimental investigation, It is shown that the spin dynamics of a ferromagnet with hcp lattice structure and a spin-spin interacti
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| 3. |
- Henneberger, S, et al.
(författare)
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mu SR investigations of gadolinium in the paramagnetic regime near the ferromagnetic transition
- 1997
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Ingår i: HYPERFINE INTERACTIONS. - : BALTZER SCI PUBL BV. - 0304-3843. ; 104:1-4, s. 301-306
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- We report on the measurements of the muon relaxation rate in gadolinium (Gd) in the critical regime down to T - T-C = 0.1 K. The results are compared to the predictions of mode-coupling calculations for a uniaxial and dipolar ferromagnet. One observes tha
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| 4. |
- Schwabl, M., et al.
(författare)
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Development of a biomass heating device for low energy and passive houses
- 2013
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Ingår i: Management of environmental quality. - 1477-7835 .- 1758-6119. ; 24:5, s. 652-666
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Decreasing energy demand due to improved building standards requires the development of new biomass combustion technologies to be able to provide individual biomass heating solutions. The purpose of this paper is, therefore, the development of a pellet water heating stove with minimal emission at high thermal efficiency. Design/methodology/approach: The single components of a 10 kW water heating pellet stove are analysed and partly redesigned considering the latest scientific findings and experimental know-how in combustion engineering. The outcome of this development is a 12 kW prototype which is subsequently down-scaled to a 6 kW prototype. Finally, the results of the development are evaluated by testing of an accredited institute. Findings: Based on an existing pellet water heating stove, the total excess air ratio was reduced, a strict air staging was implemented and the fuel supply was homogenized. All three measures improved the operating performance regarding emissions and thermal efficiency. The evaluation of the development process showed that the CO emissions are reduced by over 90 per cent during full load and by 30-60 per cent during minimum load conditions. Emissions of particulate matter are reduced by 70 per cent and the thermal efficiency increased to 95 per cent. Originality/value: The result represents a new state of technology in this sector for minimal emissions and maximal thermal efficiency, which surpasses the directives of the Eco label "UZ37" in Austria and "Blauer Engel" in Germany, which are amongst the most stringent performance requirements in the European Union. Hence this design possesses a high potential as heating solution for low and passive energy houses.
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| 5. |
- Schwabl, P, et al.
(författare)
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Meiotic sex in Chagas disease parasite Trypanosoma cruzi
- 2019
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Ingår i: Nature communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 10:1, s. 3972-
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Tidskriftsartikel (refereegranskat)abstract
- Genetic exchange enables parasites to rapidly transform disease phenotypes and exploit new host populations. Trypanosoma cruzi, the parasitic agent of Chagas disease and a public health concern throughout Latin America, has for decades been presumed to exchange genetic material rarely and without classic meiotic sex. We present compelling evidence from 45 genomes sequenced from southern Ecuador that T. cruzi in fact maintains truly sexual, panmictic groups that can occur alongside others that remain highly clonal after past hybridization events. These groups with divergent reproductive strategies appear genetically isolated despite possible co-occurrence in vectors and hosts. We propose biological explanations for the fine-scale disconnectivity we observe and discuss the epidemiological consequences of flexible reproductive modes. Our study reinvigorates the hunt for the site of genetic exchange in the T. cruzi life cycle, provides tools to define the genetic determinants of parasite virulence, and reforms longstanding theory on clonality in trypanosomatid parasites.
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