| 1. |
- Axelsson, Eva, et al.
(författare)
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Recessiveness and Dominance in Barley Mutants Deficient in Mg-Chelatase Subunit D, an AAA Protein Involved in Chlorophyll Biosynthesis.
- 2006
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Ingår i: Plant Cell. - : Oxford University Press (OUP). - 1040-4651 .- 1532-298X. ; 18:12, s. 3606-3616
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Tidskriftsartikel (refereegranskat)abstract
- Mg-chelatase catalyzes the insertion of Mg2+ into protoporphyrin IX at the first committed step of the chlorophyll biosynthetic pathway. It consists of three subunits: I, D, and H. The I subunit belongs to the AAA protein superfamily ( ATPases associated with various cellular activities) that is known to form hexameric ring structures in an ATP-dependant fashion. Dominant mutations in the I subunit revealed that it functions in a cooperative manner. We demonstrated that the D subunit forms ATP-independent oligomeric structures and should also be classified as an AAA protein. Furthermore, we addressed the question of cooperativity of the D subunit with barley (Hordeum vulgare) mutant analyses. The recessive behavior in vivo was explained by the absence of mutant proteins in the barley cell. Analogous mutations in Rhodobacter capsulatus and the resulting D proteins were studied in vitro. Mixtures of wild-type and mutant R. capsulatus D subunits showed a lower activity compared with wild-type subunits alone. Thus, the mutant D subunits displayed dominant behavior in vitro, revealing cooperativity between the D subunits in the oligomeric state. We propose a model where the D oligomer forms a platform for the stepwise assembly of the I subunits. The cooperative behavior suggests that the D oligomer takes an active part in the conformational dynamics between the subunits of the enzyme.
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| 2. |
- Jonason, Peter K., et al.
(författare)
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Country-level correlates of the Dark Triad traits in 49 countries
- 2020
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Ingår i: Journal of personality. - : Wiley. - 0022-3506 .- 1467-6494. ; 88:6, s. 1252-1267
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: The Dark Triad traits (i.e., narcissism, psychopathy, Machiavellianism) capture individual differences in aversive personality to complement work on other taxonomies, such as the Big Five traits. However, the literature on the Dark Triad traits relies mostly on samples from English-speaking (i.e., Westernized) countries. We broadened the scope of this literature by sampling from a wider array of countries.Method: We drew on data from 49 countries (N = 11,723; 65.8% female;Age(Mean) = 21.53) to examine how an extensive net of country-level variables in economic status (e.g., Human Development Index), social relations (e.g., gender equality), political orientations (e.g., democracy), and cultural values (e.g., embeddedness) relate to country-level rates of the Dark Triad traits, as well as variance in the magnitude of sex differences in them.Results: Narcissism was especially sensitive to country-level variables. Countries with more embedded and hierarchical cultural systems weremorenarcissistic. Also, sex differences in narcissism werelargerinmoredeveloped societies: Women were less likely to be narcissistic in developed (vs. less developed) countries.Conclusions: We discuss the results based on evolutionary and social role models of personality and sex differences. That higher country-level narcissism was more common in less developed countries, whereas sex differences in narcissism were larger in more developed countries, is more consistent with evolutionary than social role models.
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| 3. |
- Marciniak, Magdalena, et al.
(författare)
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Impact of Stripe Shape on the Reflectivity of Monolithic High Contrast Gratings
- 2021
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Ingår i: ACS Photonics. - : American Chemical Society (ACS). - 2330-4022. ; 8:11, s. 3173-3184
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Tidskriftsartikel (refereegranskat)abstract
- Monolithic high contrast gratings (MHCGs) composed of a one-dimensional grating patterned in a monolithic layer provide up to 100% optical power reflectance and can be fabricated in almost any semiconductor and dielectric material used in modern optoelectronics. MHCGs enable monolithic integration, polarization selectivity, and versatile phase tuning. They can be from 10 to 20 times thinner than distributed Bragg reflectors. The subwavelength dimensions of MHCGs significantly reduce the possibility of ensuring the smoothness of the sidewalls of the MHCG stripes and make precise control of the shape of the MHCG stripe cross-section difficult during the etching process. The question is then whether it is more beneficial to improve the etching methods to obtain a perfect cross-section shape, as assumed by the design, or whether it is possible to find geometrical parameters that enable high optical power reflectance using the shape that a given etching method provides. Here, we present a numerical study supported by the experimental characterization of MHCGs fabricated in various materials using a variety of common surface nanometer-scale shaping methods. We demonstrate that MHCG stripes with an arbitrary cross-section shape can provide optical power reflectance of nearly 100%, which greatly relaxes their fabrication requirements. Moreover, we show that optical power reflectance exceeding 99% with a record spectral bandwidth of more than 20% can be achieved for quasi-Trapezoidal cross-sections of MHCGs. We also show that sidewall corrugations of the MHCG stripes have only a slight impact on MHCG optical power reflectance if the amplitude of the corrugation is less than 16% of the MHCG period. This level of stripe fabrication precision can be achieved using the most current surface etching methods. Our results are significant for the design and production of a variety of photonic devices employing MHCGs. The flexibility with regard to cross-section shape facilitates the reliable fabrication of highly reflective subwavelength grating mirrors. This in turn will enable the manufacture of monolithically integrated high-quality-factor optical micro-and nanocavity devices.
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