Assay of the antioxidant capacity of foods using an iron(II)-catalysed lipid peroxidation model for greater nutritional relevance

The formation of free radicals by the iron-catalysed Fenton reaction is a major cause of oxidative damage in the body. Here a common assay of antioxidant capacity, inhibition of the β-carotene-linoleic acid model of lipid peroxidation, has been modified by the addition of ferrous iron (final concentration 36 μmol/l), which makes the rate of oxidation of the lipids occur twenty-five times faster. Such an assay can simulate the oxidative damage to membrane lipids and low density lipoproteins occurring in the body in the presence of free iron. It thus may be nutritionally more relevant than traditional chemical assays of antioxidant capacity, as it measures pre-emptive antioxidant activity, i.e. activity which prevents free radicals being formed in the first place. Pre-empting their formation is likely to be more protective than scavenging of free radicals. The relative antioxidant activity of some food products found using this new assay was very different from that found using a radical-scavenging assay. Vitamin C, at 280 mg/l, was found to be sixty times better than blackcurrant puree in scavenging free radicals, but only one eighth as good as the blackcurrant puree in preventing iron-catalysed lipid peroxidation

The Significance of Birds in the Works of Augusto Roa Bastos

Birds have occupied a central role in the works of the Paraguayan writer, Augusto Roa Bastos (1917-2005), from the beginning of his literary career. In texts ranging from his early poetry to his complete short stories, compiled in 2003, the bird motif repeatedly resurfaces, raising the question of the relevance of birds in Roa Bastos’s oeuvre. This article argues that birds are used symbolically throughout Roa Bastos’s poetry and prose works, by drawing upon their significance within Guarani myths and literature. The article focuses on several symbolic associations for birds in Guarani culture, including their relationship to oral language, their prophetic value, their association with thunderstorms, and their view of the owl as an ambiguous creature that signifies both death and rebirth. This article studies Roa Bastos’s poetry, the short stories “El pájaro-mosca” ‘The Hummingbird,’ “Cuando un pájaro entierra sus plumas” ‘When a Bird Buries its Feathers,’ “El país donde los niños no querían nacer” ‘The Country Where Children Didn’t Want to be Born,’ and the novels Yo el Supremo ‘I The Supreme,’ Vigilia del almirante ‘The Admiral’s Vigil,’ and Madama Sui ‘Madame Sui.

Augusto Roa Bastos\u27s Trilogy as Postmodern Practice

Augusto Roa Bastos\u27s most recent novel, El fiscal (1993), completes the author\u27s trilogy on the monotheism of power, which the novel constitutes in conjunction with the prior works Hijo de hombre (1960) and Yo el Supremo (1974). These novels form a larger whole by virtue of the way in which they attempt to define Paraguay\u27s identity through the nation\u27s history. Hijo de hombre focuses on both the Chaco War and a series of Paraguayan civil wars; Yo el Supremo concentrates on the nineteenth-century dictatorship of Dr. José Gaspar Rodríguez de Francia; and El fiscal presents both Alfredo Stroessner\u27s dictatorship (1954-1989) and the nineteenth-century War of the Triple Alliance (during the dictatorship of Francisco Solano López). Moreover, each novel approaches history in a way which is postmodern. This study both discusses the controversy surrounding the term postmodernism and analyzes the way in which these novels carry out some of the characteristics attributed to postmodernism by various critics. These postmodern traits help to unify the three novels and justify their status as a trilogy

The White Male as Narrative Axis in Mayra Santos-Febres’s Nuestra señora de la noche

Mayra Santos-Febres’s 2006 novel, Nuestra señora de la noche, is based on the life of the Puerto Rican madam, Isabel la Negra, a legendary figure in Puerto Rican culture. Using both Mervin Alleyne’s theory of racial discrimination and Aída Hurtado’s theory of racially-based gender discrimination, which shows how the reactions of white and black females are governed by their relation of dependency on or rejection by the white male, this study illustrates how the character Isabel la Negra evolves as a postmodern, feminist character who opposes racism and gender subordination in Puerto Rico through her role as a prostitute. Conversely, the study also illustrates how madness, associated with both white (Cristina Rangel) and black (Montse) females in the novel, is a powerless rather than feminist strategy, into which women descend due to their mistreatment by patriarchal society. The study illustrates how Fernando Fornarís, the white male protagonist, serves as the narrative axis for the development of women’s polarized reactions to patriarchal domination in the novel

Evolution of dispersal under a fecundity-dispersal trade-off

Resources invested in dispersal structures as well as time and energy spent during transfer may often decrease fecundity. Here we analyse an extended version of the Hamilton-May model of dispersal evolution, where we include a fecundity-dispersal trade-off and also mortality between competition and reproduction. With adaptive dynamics and critical function analysis we investigate the evolution of dispersal strategies and ask whether adaptive diversification is possible. We exclude evolutionary branching for concave trade-offs and show that for convex trade-offs diversification is promoted in a narrow parameter range. We provide theoretical evidence that dispersal strategies can monotonically decrease with increasing survival during dispersal. Moreover, we illustrate the existence of two alternative attracting dispersal strategies. The model exhibits fold bifurcation points where slight changes in survival can lead to evolutionary catastrophes. (C) 2015 Elsevier Ltd. All rights reserved.Peer reviewe

Schur\u27s Lemma For Coupled Reducibility And Coupled Normality

Let $\mathcal A = \{A_{ij} \}_{i, j \in \mathcal I}$, where $\mathcal I$ is an index set, be a doubly indexed family of matrices, where $A_{ij}$ is $n_i \times n_j$. For each $i \in \mathcal I$, let $\mathcal V_i$ be an $n_i$-dimensional vector space. We say $\mathcal A$ is reducible in the coupled sense if there exist subspaces, $\mathcal U_i \subseteq \mathcal V_i$, with $\mathcal U_i \neq \{0\}$ for at least one $i \in \mathcal I$, and $\mathcal U_i \neq \mathcal V_i$ for at least one $i$, such that $A_{ij} (\mathcal U_j) \subseteq \mathcal U_i$ for all $i, j$. Let $\mathcal B = \{B_{ij} \}_{i, j \in \mathcal I}$ also be a doubly indexed family of matrices, where $B_{ij}$ is $m_i \times m_j$. For each $i \in \mathcal I$, let $X_i$ be a matrix of size $n_i \times m_i$. Suppose $A_{ij} X_j = X_i B_{ij}$ for all $i, j$. We prove versions of Schur\u27s lemma for $\mathcal A, \mathcal B$ satisfying coupled irreducibility conditions. We also consider a refinement of Schur\u27s lemma for sets of normal matrices and prove corresponding versions for $\mathcal A, \mathcal B$ satisfying coupled normality and coupled irreducibility conditions

Linking fruit traits to variation in predispersal vertebrate seed predation, insect seed predation, and pathogen attack

The importance of vertebrates, invertebrates, and pathogens for plant communities has long been recognized, but their absolute and relative importance in early recruitment of multiple coexisting tropical plant species has not been quantified. Further, little is known about the relationship of fruit traits to seed mortality due to natural enemies in tropical plants. To investigate the influences of vertebrates, invertebrates, and pathogens on reproduction of seven canopy plant species varying in fruit traits, we quantified reductions in fruit development and seed germination due to vertebrates, invertebrates, and fungal pathogens through experimental removal of these enemies using canopy exclosures, insecticide, and fungicide, respectively. We also measured morphological fruit traits hypothesized to mediate interactions of plants with natural enemies of seeds. Vertebrates, invertebrates, and fungi differentially affected predispersal seed mortality depending on the plant species. Fruit morphology explained some variation among species; species with larger fruit and less physical protection surrounding seeds exhibited greater negative effects of fungi on fruit development and germination and experienced reduced seed survival integrated over fruit development and germination in response to vertebrates. Within species, variation in seed size also contributed to variation in natural enemy effects on seed viability. Further, seedling growth was higher for seeds that developed in vertebrate exclosures for Anacardium excelsum and under the fungicide treatment for Castilla elastica, suggesting that predispersal effects of natural enemies may carry through to the seedling stage. This is the first experimental test of the relative effects of vertebrates, invertebrates, and pathogens on seed survival in the canopy. This study motivates further investigation to determine the generality of our results for plant communities. If there is strong variation in natural enemy attack among species related to differences in fruit morphology, then quantification of fruit traits will aid in predicting the outcomes of interactions between plants and their natural enemies. This is particularly important in tropical forests, where high species diversity makes it logistically impossible to study every plant life history stage of every species

The evolution of immigration strategies facilitates niche expansion by divergent adaptation in a structured metapopulation model

Local adaptation and habitat choice are two key factors that control the distribution and diversification of species. Here we model habitat choice mechanistically as the outcome of dispersal with nonrandom immigration. We consider a structured metapopulation with a continuous distribution of patch types and determine the evolutionarily stable immigration strategy as the function linking patch type to the probability of settling in the patch on encounter. We uncover a novel mechanism whereby coexisting strains that only slightly differ in their local adaptation trait can evolve substantially different immigration strategies. In turn, different habitat use selects for divergent adaptations in the two strains. We propose that the joint evolution of immigration and local adaptation can facilitate diversification and discuss our results in the light of niche conservatism versus niche expansion.Peer reviewe