Investors' perspective on portfolio insurance : expected utility vs prospect theories

This study supports the use of behavioural finance to explain the popularity of portfolio insurance. Portfolio insurance strategies are important financial solutions sold to institutional and individual investors, that protect against downside risk while maintaining some upside valuation potential. The way some of these strategies are engineered has been criticised, and portfolio insurance itself blamed for increasing market volatility in depressed markets. Despite this, investors keep on buying portfolio insurance that has a solid market share. This study contributes to understand the phenomenon. We compare investors' decision using two distinct frameworks: expected utility theory and behavioural theories. Based upon Monte Carlo simulation techniques we compare portfolio insurance strategies against uninsured basic benchmark strategies. We conclude that cumulative prospect theory may be a viable framework to explain the popularity of portfolio insurance. However, among portfolio insurance strategies, naïve strategies seem to be preferable to most commonly traded strategies.info:eu-repo/semantics/publishedVersio

Verbesserungsmöglichkelten von färberischen-und antimikrobiellen eigenschaften auf baumwolle

Comunicação apresentada no 20th IFATCC Congress, Weimer, Germany, 5 - 6 Maio 2005.In the present work, some specific amino compounds were linked to the cotton fabrics on a process that can impart at the same time dyeability and durable antimicrobial properties. The process was monitored on-line in a prototype dyeing system since the addition of cationic agents will influence dye uptake. Different dyeing conditions were tested with direct dyes, with and without salt, until the exhaustion curve was at least equivalent to the standard dyeing curve in the presence of salt

Comparing reverse complementary genomic words based on their distance distributions and frequencies

In this work we study reverse complementary genomic word pairs in the human DNA, by comparing both the distance distribution and the frequency of a word to those of its reverse complement. Several measures of dissimilarity between distance distributions are considered, and it is found that the peak dissimilarity works best in this setting. We report the existence of reverse complementary word pairs with very dissimilar distance distributions, as well as word pairs with very similar distance distributions even when both distributions are irregular and contain strong peaks. The association between distribution dissimilarity and frequency discrepancy is explored also, and it is speculated that symmetric pairs combining low and high values of each measure may uncover features of interest. Taken together, our results suggest that some asymmetries in the human genome go far beyond Chargaff's rules. This study uses both the complete human genome and its repeat-masked version.Comment: Post-print of a paper accepted to publication in "Interdisciplinary Sciences: Computational Life Sciences" (ISSN: 1913-2751, ESSN: 1867-1462

Dissimilar Symmetric Word Pairs in the Human Genome

In this work we explore the dissimilarity between symmetric word pairs, by comparing the inter-word distance distribution of a word to that of its reversed complement. We propose a new measure of dissimilarity between such distributions. Since symmetric pairs with different patterns could point to evolutionary features, we search for the pairs with the most dissimilar behaviour. We focus our study on the complete human genome and its repeat-masked version.Comment: Submitted 13-Feb-2017; accepted, after a minor revision, 17-Mar-2017; 11th International Conference on Practical Applications of Computational Biology & Bioinformatics, PACBB 2017, Porto, Portugal, 21-23 June, 201

Proteostasis networks in aging: novel insights from text-mining approaches

Aging is a topic of paramount importance in an increasingly elderly society and has been the focus of extensive research. Protein homeostasis (proteostasis) decline is a hallmark in aging and several age-related diseases, but which specific proteins and mechanisms are involved in proteostasis (de)regulation during the aging process remain largely unknown. Here, we used different text-mining tools complemented with protein–protein interaction data to address this complex topic. Analysis of the integrated protein interaction networks identified novel proteins and pathways associated to proteostasis mechanisms and aging or age-related disorders, indicating that this approach is useful to identify previously unknown links and for retrieving information of potential novel biomarkers or therapeutic targets.info:eu-repo/semantics/acceptedVersio

An endangered tree fern increases beta-diversity at a fine scale in the Atlantic Forest Ecosystem

R.N. and T.S.S. were funded by the Brazilian Government research support agency Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES). A.E.M. acknowledges the ERC (BioTIME 250189 and BioCHANGE 727440) and the Royal Society. A.R.K. is funded by the Brazilian Science Without Borders scheme/CAPES (109113-1), D.M.S.M. acknowledges the CNPq (Fellowship of Research productivity 307839/2014-1).Some species make substantial contribution to habitat heterogeneity, supporting species coexistence. Dicksonia sellowiana Hook., an endangered tree fern, is a known phorophyte for epiphytes, has the potential to be such a taxon. We tested the hypothesis that D. sellowiana increases plant diversity in Brazilian Restinga forest, a biodiversity hotspot, by augmenting the habitat heterogeneity at a fine scale. To do this we quantified α-diversity and β-diversity in three habitat types: on the tree fern trunks, immediately beneath the trunks and away from the trunks. In total, 40 ferns were sampled. Overall we recorded 2602 individuals belonging to 61 phanerophyte species in 30 families. The number of individuals sampled varied among habitats but rarefaction showed that richness did not differ. In contrast, species composition varied markedly amongst habitats. Both statistical approaches detected high levels of β-diversity, particularly between the species found in the vicinity of the fern, and those in the samples away from the trunks. Indicator species analysis was used to identify the species characteristic of the different habitats. About 30% of the species were exclusively found in “away plots”, 17% were exclusively “below plots” and 15% were found only on the trunks, 13% were found on the trunks and below them, 12% on “bellow” and “away plots”, 10% of species occurred in all areas and 3% were found on trunks and “away plots”. Our results lead us to conclude that the endangered fern D. sellowiana plays an important role in promoting habitat heterogeneity within the Restinga forest. As this iconic species is threatened, its overexploitation may lead to impoverishment of plant communities. Conservation effort towards both the area and this species are crucial to maintaining Restinga plant diversity.PostprintPeer reviewe

Yeast as a model organism for studying the evolution of non-standard genetic codes

During the last 30 years, a number of alterations to the standard genetic code have been uncovered both in prokaryotes and eukaryotic nuclear and mitochondrial genomes. But, the study of the evolutionary pathways and molecular mechanisms of codon identity redefinition has been largely ignored due to the assumption that non-standard genetic codes can only evolve through neutral evolutionary mechanisms and that they have no functional significance. The recent discovery of a genetic code change in the genus Candida that evolved through an ambiguous messenger RNA decoding mechanism is bringing that naive assumption to an abrupt end by showing, in a rather dramatic way, that genetic code changes have profound physiological and evolutionary consequences for the species that redefine codon identity. In this paper, the recent data on the evolution of the Candida genetic code are reviewed and an experimental framework based on forced evolution, molecular genetics and comparative and functional genomics methodologies is put forward for the study of non-standard genetic codes and genetic code ambiguity in general. Additionally, the importance of using Saccharomyces cerevisiae as a model organism for elucidating the evolutionary pathway of the Candida and other genetic code changes is emphasised.publishe

Molecular mechanisms of ischemia and glutamate excitotoxicity

Excitotoxicity is classically defined as the neuronal damage caused by the excessive release of glutamate, and subsequent activation of excitatory plasma membrane receptors. In the mammalian brain, this phenomenon is mainly driven by excessive activation of glutamate receptors (GRs). Excitotoxicity is common to several chronic disorders of the Central Nervous System (CNS) and is considered the primary mechanism of neuronal loss of function and cell death in acute CNS diseases (e.g. ischemic stroke). Multiple mechanisms and pathways lead to excitotoxic cell damage including pro-death signaling cascade events downstream of glutamate receptors, calcium (Ca2+) overload, oxidative stress, mitochondrial impairment, excessive glutamate in the synaptic cleft as well as altered energy metabolism. Here, we review the current knowledge on the molecular mechanisms that underlie excitotoxicity, emphasizing the role of Nicotinamide Adenine Dinucleotide (NAD) metabolism. We also discuss novel and promising therapeutic strategies to treat excitotoxicity, highlighting recent clinical trials. Finally, we will shed light on the ongoing search for stroke biomarkers, an exciting and promising field of research, which may improve stroke diagnosis, prognosis and allow better treatment options.info:eu-repo/semantics/publishedVersio

Merging microarray studies to identify a common gene expression signature to several structural heart diseases

Background: Heart disease is the leading cause of death worldwide. Knowing a gene expression signature in heart disease can lead to the development of more efficient diagnosis and treatments that may prevent premature deaths. A large amount of microarray data is available in public repositories and can be used to identify differentially expressed genes. However, most of the microarray datasets are composed of a reduced number of samples and to obtain more reliable results, several datasets have to be merged, which is a challenging task. The identification of differentially expressed genes is commonly done using statistical methods. Nonetheless, these methods are based on the definition of an arbitrary threshold to select the differentially expressed genes and there is no consensus on the values that should be used. Results: Nine publicly available microarray datasets from studies of different heart diseases were merged to form a dataset composed of 689 samples and 8354 features. Subsequently, the adjusted p-value and fold change were determined and by combining a set of adjusted p-values cutoffs with a list of different fold change thresholds, 12 sets of differentially expressed genes were obtained. To select the set of differentially expressed genes that has the best accuracy in classifying samples from patients with heart diseases and samples from patients with no heart condition, the random forest algorithm was used. A set of 62 differentially expressed genes having a classification accuracy of approximately 95% was identified. Conclusions: We identified a gene expression signature common to different cardiac diseases and supported our findings by showing their involvement in the pathophysiology of the heart. The approach used in this study is suitable for the identification of gene expression signatures, and can be extended to different diseases.info:eu-repo/semantics/publishedVersio