A logic for n-dimensional hierarchical refinement

Hierarchical transition systems provide a popular mathematical structure to represent state-based software applications in which different layers of abstraction are represented by inter-related state machines. The decomposition of high level states into inner sub-states, and of their transitions into inner sub-transitions is common refinement procedure adopted in a number of specification formalisms. This paper introduces a hybrid modal logic for k-layered transition systems, its first-order standard translation, a notion of bisimulation, and a modal invariance result. Layered and hierarchical notions of refinement are also discussed in this setting.Comment: In Proceedings Refine'15, arXiv:1606.0134

Behavioral institutions and refinements in generalized hidden logics

We investigate behavioral institutions and refinements in the context of the object oriented paradigm. The novelty of our approach is the application of generalized abstract algebraic logic theory of hidden heterogeneous deductive systems (called hidden k-logics) to the algebraic specification of object oriented programs. This is achieved through the Leibniz congruence relation and its combinatorial properties. We reformulate the notion of hidden k-logic as well as the behavioral logic of a hidden k-logic as institutions. We define refinements as hidden signature morphisms having the extra property of preserving logical consequence. A stricter class of refinements, the ones that preserve behavioral consequence, is studied. We establish sufficient conditions for an ordinary signature morphism to be a behavioral refinement. © J.UCS.FCT via UIM

Refinement by interpretation in {\pi}-institutions

The paper discusses the role of interpretations, understood as multifunctions that preserve and reflect logical consequence, as refinement witnesses in the general setting of pi-institutions. This leads to a smooth generalization of the refinement-by-interpretation approach, recently introduced by the authors in more specific contexts. As a second, yet related contribution a basis is provided to build up a refinement calculus of structured specifications in and across arbitrary pi-institutions.Comment: In Proceedings Refine 2011, arXiv:1106.348

Monomeric composition and linkage analysis of the polysaccharides present in the infusions of Fraxinus angustifolia leaves

In the Trás-os-Montes region, the use of infusions of Fraxinus angustifolia dried leaves as a protection against high levels of cholesterol, blood pressure and uric acid is widespread. Pectic polysaccharides isolated from the infusions of some medicinal plants have been reported as biologically active [1,2]. Pectic poly-saccharides have been described as structurally complex polymers, exhibiting different polymeric building blocks: homogalacturonans (HG), rhamnogalacturonans-I (RG-I), rhamnogalacturonans-II (RG-II) and xylogalacturonans (XG) [3]. The backbone of RG-I can be partly substituted with various side chains, such as arabinans, type-I and type-II arabinogalactans (AG-I and AG-II). The aim of this work is to provide a first insight of the nature of the pectic polysaccharides present in the infusions of F. angustifolia dried leaves

Polysaccharides from the infusions of P. tridentatum, F. angustifoliaand M. suaveolens

The use of plant infusions for medicinal purposes is present in secular traditions of all civilizations. In Portugal, in Trás-os-Montes region, the small shrub (Pterospartum tridentatum), the narrow-leafed ash (Fraxinus angustifolia), and the apple mint (Mentha suaveolens) are plants used for such purposes. According to the popular tradition, the infusions of P. Tridentatum, F. Angustifolia, and M. suaveolens protect against diabetes, high blood pressure, high levels of cholesterol, and uric acid [1].These health benefits are associated with the presence of phenolic compounds, essential oils, and polysaccharides, among others. Although phenolic compounds and essential oils have been studied in detail for more than two decades, the structures of the polysaccharides present in plant infusions and their involvement in the health benefits is still incipient. Infusions were prepared in two different ways: a traditional method, consisting in the infusion of the vegetal material with boiling water during five minutes (Method A), and a more intensive method, consisting in the infusion of the vegetal material with boiling water during four hours (Method B). The high molecular weight material was obtained by concentrating and dialyzing the extracts obtained by Methods A and B. The high molecular weight material obtained with the Method B contained more glycosidic material than the obtained with Method A. The high molecular weight material was fractionated using ethanol precipitation yielding fractions especially rich in uronic acids besides considerable amounts of arabinose, galactose, glucose and rhamnose, suggesting the presence of pectic polysaccharides. Detailed monomeric composition and glycosidic linkages of each fraction will be presented

Composição glicosídica e actividade antioxidante de extractos de infusões de folhas de freixo (Fraxinus angustifolia)

Neste trabalho foram preparadas infusões de folhas de freixo secas. Cada infusão foi dividida em duas fracções, tendo uma sido utilizada para a obtenção do material polimérico por diálise (Dial) e a outra submetida a uma extracção em fase sólida C18, sendo a fase aquosa recolhida composta pelo material não retido (C18 H2O) e a fracção de metanol composta pelo material retido e eluído neste solvente (C18 MeOH). A análise da composição glicosídica mostrou que a fracção C18 H2O era rica em glucose e manose; a fracção C18 MeOH era rica em glucose e a fracção Dial era rica em ácidos urónicos, arabinose, galactose e glucose. A fracção C18 H2O era a mais pobre em compostos fenólicos e a que apresentou menor actividade antirradicalar. As fracções C18 MeOH e Dial apresentaram actividades antirradicalares semelhantes entre si, apesar de possuírem quantidades de compostos fenólicos totais distintas. A fracção Dial, constituída por material de peso molecular superior a 12-14 kDa, foi ainda sujeita a uma análise de ligações glicosídicas, através da análise por GC-MS dos respectivos acetatos de alditol parcialmente metilados. O resultado obtido permitiu inferir a presença de resíduos glicosídicos característicos de arabinogalactanas do tipo II, xiloglucanas e xilanas

Polysaccharides from the infusions of P. tridentatum, F. angustifolia, and M. suaveolens

The use of plant infusions for medicinal purposes is present in secular traditions of all civilizations. In Portugal, in Trás-os-Montes region, the small shrub (Pterospartum tridentatum), the narrow-leafed ash (Fraxinus angustifolia), and the apple mint (Mentha suaveolens) are plants used for such purposes. According to the popular tradition, the infusions of P. Tridentatum, F. Angustifolia, and M. suaveolens protect against diabetes, high blood pressure, high levels of cholesterol, and uric acid [1].These health benefits are associated with the presence of phenolic compounds, essential oils, and polysaccharides, among others. Although phenolic compounds and essential oils have been studied in detail for more than two decades, the structures of the polysaccharides present in plant infusions and their involvement in the health benefits is still incipient. Infusions were prepared in two different ways: a traditional method, consisting in the infusion of the vegetal material with boiling water during five minutes (Method A), and a more intensive method, consisting in the infusion of the vegetal material with boiling water during four hours (Method B). The high molecular weight material was obtained by concentrating and dialyzing the extracts obtained by Methods A and B. The high molecular weight material obtained with the Method B contained more glycosidic material than the obtained with Method A. The high molecular weight material was fractionated using ethanol precipitation yielding fractions especially rich in uronic acids besides considerable amounts of arabinose, galactose, glucose and rhamnose, suggesting the presence of pectic polysaccharides. Detailed monomeric composition and glycosidic linkages of each fraction will be presented

Isolation and characterization of polysaccharides from Fraxinus angustifolia infusions

In folk medicine there is a great variety of plants that are used for as infusions, such as Camellia sinensis and Matricaria recutita. Despite the reported biological activities and health benefits of these infusions, most of the knowledge achieved so far is based on folk tradition passed over several generations, without a sound scientific basis. In Trás-os-Montes region, the dried leaves of the narrow-leafed ash “freixo” (Fraxinus angustifolia) are used for medicinal purposes, particularly against high levels of cholesterol, blood pressure and uric acid. These health benefits are associated with the presence of biologically active compounds such as phenolic compounds, essential oils, and polysaccharides, among others. Although phenolic compounds and essential oils have been studied in detail for more than two decades, the structures of the polysaccharides present in plant infusions and their involvement in the health benefits is still incipient. Therefore, in this work we present a study regarding the structure of the polysaccharides present in the infusions of “freixo” dried leaves. “Freixo” leaves were collected and dried according to the popular tradition and used for the preparation of the infusions. The polysaccharides were recovered by dialysis, fractionated by ethanol precipitation and anion exchange chromatography, yielding fractions with distinct ethanol solubility and uronic acid content. Sugar and linkage analysis evidenced the presence of pectic polysaccharides, frequently reported as immunostimulatory active. The assessment of the biological activity of these fractions is in progress