2,859 research outputs found

    Balanced metrics on Hartogs domains

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    An n-dimensional strictly pseudoconvex Hartogs domain D_F can be equipped with a natural Kaehler metric g_F. In this paper we prove that if m_0g_F is balanced for a given positive integer m_0 then m_0>n and (D_F, g_F) is holomorphically isometric to an open subset of the n-dimensional complex hyperbolic space.Comment: 9 page

    A modification of the Chen-Nester quasilocal expressions

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    Chen and Nester proposed four boundary expressions for the quasilocal quantities using the covariant Hamiltonian formalism. Based on these four expressions, there is a simple generalization that one can consider, so that a two parameter set of boundary expressions can be constructed. Using these modified expressions, a nice result for gravitational energy-momentum can be obtained in holonomic frames.Comment: 11 page

    Plant antioxidants for food safety and quality: Exploring new trends of research

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    Antioxidants are an heterogeneous group of compounds able to counteract cell oxidation by acting as reducing agents, as free radical scavengers, and quenchers of radical species and other pro-oxidants, such as metals [...]

    Balanced metrics on Cartan and Cartan-Hartogs domains

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    This paper consists of two results dealing with balanced metrics (in S. Donaldson terminology) on nonconpact complex manifolds. In the first one we describe all balanced metrics on Cartan domains. In the second one we show that the only Cartan-Hartogs domain which admits a balanced metric is the complex hyperbolic space. By combining these results with those obtained in [13] (Kaehler-Einstein submanifolds of the infinite dimensional projective space, to appear in Mathematische Annalen) we also provide the first example of complete, Kaehler-Einstein and projectively induced metric g such that αg\alpha g is not balanced for all α>0\alpha >0.Comment: 11 page

    Gravitational energy from a combination of a tetrad expression and Einstein's pseudotensor

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    The energy-momentum for a gravitating system can be considered by the tetard teleparalle gauge current in orthonormal frames. Whereas the Einstein pseudotensor used holonomic frames. Tetrad expression itself gives a better result for gravitational energy than Einstein's. Inspired by an idea of Deser, we found a gravitational energy expression which enjoys the positive energy property by combining the tetrad expression and the Einstein pseudotensor, i.e., the connection coefficient has a form appropriate to a suitable intermediate between orthonormal and holonomic frames.Comment: 5 page

    Measuring gender norms about relationships in early adolescence : results from the global early adolescent study

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    Introduction: Gender norms are increasingly recognized as drivers of health and wellbeing. While early adolescence constitutes a critical window of development, there is limited understanding about how adolescents perceive gender relations across different cultural settings. This study used a mixed-method approach, grounded in the voices of young people around the world, to construct and test a cross-cultural scale assessing the perceptions of gender norms regulating romantic relationships between boys and girls in early adolescence. Methods: The study draws on the Global Early Adolescent study (GEAS), a study focusing on gender norms and health related outcomes over the course of adolescence in urban poor settings worldwide. In-depth interviews were first conducted among approximately 200 adolescents between 10-14 years in seven sites across 4 continents to identify common scripts guiding romantic relations in early adolescence. These scripts were then transformed into a multidimensional scale. The scale was tested among 120 adolescents in each of 14 GEAS sites, followed by a second pilot among 75 adolescents in six sites. We evaluated the psychometric criteria of each subscale using principal component analysis, and parallel analysis, followed by exploratory factor analysis to guide the selection of a more parsimonious set of items. Results: Results suggested a two-factor structure, consisting of an "adolescent romantic expectations" subscale and a "Sexual Double Standard" subscale. Both subscales yielded high internal validity in each site, with polychoric Cronbach alpha values above 0.70 with the exception of Kinshasa for the adolescent romantic expectations scale (0.64) and Hanoi for the sexual double standard scale (0.61). Conclusion: This study reveals common perceptions of gendered norms about romantic engagement in early adolescence, normative for both sexes, but socially valued for boys while devaluated for girls. The findings illustrate that social hierarchies of power in romantic relationships form early in adolescence, regardless of cultural setting

    New positive small vacuum region gravitational energy expressions

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    We construct an infinite number of new holonomic quasi-local gravitational energy-momentum density pseudotensors with good limits asymptotically and in small regions, both materially and in vacuum. For small vacuum regions they are all a positive multiple of the Bel-Robinson tensor and consequently have positive energy.Comment: 4 page

    Challenges and opportunities of light-emitting diode (Led) as key to modulate antioxidant compounds in plants. a review

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    Plant antioxidants are important compounds involved in plant defense, signaling, growth, and development. The quantity and quality of such compounds is genetically driven; nonetheless, light is one of the factors that strongly influence their synthesis and accumulation in plant tissues. Indeed, light quality affects the fitness of the plant, modulating its antioxidative profile, a key element to counteract the biotic and abiotic stresses. With this regard, light-emitting diodes (LEDs) are emerging as a powerful technology which allows the selection of specific wavelengths and intensities, and therefore the targeted accumulation of plant antioxidant compounds. Despite the unique advantages of such technology, LED application in the horticultural field is still at its early days and several aspects still need to be investigated. This review focused on the most recent outcomes of LED application to modulate the antioxidant compounds of plants, with particular regard to vitamin C, phenols, chlorophyll, carotenoids, and glucosinolates. Additionally, future challenges and opportunities in the use of LED technology in the growth and postharvest storage of fruits and vegetables were also addressed to give a comprehensive overview of the future applications and trends of research

    Entrepreneurial intention studies: A hybrid bibliometric method to identify new directions for theory and research

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    Fragmentation is the main obstacle to scientific progress on entrepreneurial intention. To address this issue, we systematise the current literature with a hybrid bibliometric method that combines co-citation and bibliographic coupling analysis for the first time in entrepreneurial intention studies to show the field's knowledge base and research fronts and to examine how divergent perspectives have challenged the core knowledge of the field. We highlight three recurring dimensions of entrepreneurial intention studies: (1) personal factors, (2) social factors and (3) investigational settings. In addition to introducing new constructs, divergent perspectives have emphasised the interplay between these components and challenged the mechanisms connecting them. Based on these findings, we extend previous classifications in the literature by providing a framework that integrates divergent perspectives with the field's knowledge base, helping establish future research avenues and improving the theorising process of entrepreneurial intention
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