Complexity aspects of generalized Helly hypergraphs

In [V.I. Voloshin, On the upper chromatic number of a hypergraph, Australas. J. Combin. 11 (1995) 25-45], Voloshin proposed the following generalization of the Helly property. Let p?1, q?0 and s?0. A hypergraph H is (p,q)-intersecting when every partial hypergraph H^′⊆H formed by p or less hyperedges has intersection of cardinality at least q. A hypergraph H is (p,q,s)-Helly when every partial (p,q)-intersecting hypergraph H^′⊆H has intersection of cardinality at least s. In this work, we study the complexity of determining whether H is (p,q,s)-Helly.     

Physicochemical,functional and structural characterization of fibre from defatted Rosa rubiginosa and Gevuina avellana seeds

The composition, functional properties and structural features of the fiber from Rosa rubiginosa defatted seeds and from Gevuina avellana defatted and partially deproteinized seeds were evaluated. The effect of phosphate salts and temperature during the extraction of fibres and the influence of two drying technologies on the distribution of soluble and insoluble dietary fibre were assessed. The extraction of protein and monosaccharides was favoured by increasing temperature in the range studied. Water and oil absorption capacities higher than 10 g g^?1 were observed for soluble and insoluble fibres from Gevuina avellana and for the soluble ones from Rosa rubiginosa. The insoluble fibre product from Rosa and Gevuina contained 650–810 g kg^?1 and 390–440 g kg^?1 neutral detergent fibre respectively. The protein content in the insoluble fibre varied in the range 100–150 g kg^?1 and 120–260 g kg^?1 and in the soluble fibre between 200–550 g kg^?1 and 180–370 g kg^?1 for Rosa and Gevuina respectively. Copyright © 2004 Society of Chemical Industry     

The Helly property on subfamilies of limited size

In this work we consider the problem of determining whether a hypergraph has the p-Helly property, when the considered subfamilies are limited by a size k. That is, whether every partial hypergraph with at most k edges is p-Helly. Further, we study the related problem applied to the cliques of a graph. In all cases, depending on the values of p and k, either we show that the problem can be solved in polynomial time, or we describe a NP-hardness proof.     

The direct agglutination test: a non-specific test specific for the diagnosis of visceral leishmaniasis?

Serology has an important role to play in the diagnosis of the severe clinical syndrome of visceral leishmaniasis (VL). The direct agglutination test (DAT), a simple agglutination test which requires no laboratory facilities, has become the preferred test, particularly for field studies. The nature of the antigens responsible for the agglutination of leishmanial promastigotes by the serum of VL patients is not known. A series of experiments which provide some clues to the molecular basis for the test and which indicate that there might be more in DAT than meets the eye is reported.     

Mixed-mode (I + II) fracture characterization of wood bonded joints

In this work fracture characterization of wood bonded joints is performed. The main objective is to define a fracture criterion under mixed-mode loading (I + II), in order to provide a safer and reliable design of wood bonded joints. Experimental fracture characterization tests were carried out. For mode I and mode II loading, the double cantilever beam and the end notched flexure tests were selected. Under mixed-mode I + II loading the mixed-mode bending test was used considering different mixed-mode ratios. A data reduction scheme based on the specimen compliance, the beam theory and on a crack equivalent concept was used to overcome the difficulties inherent to the above referred tests. The fracture linear energetic criterion showed to be adequate to describe the fracture envelop with an exception, as discussed in the paper.     

Effect of vitamin K in bone metabolism and vascular calcification: A review of mechanisms of action and evidences

Osteoporosis is a public health concern associated with an increased risk of bone fractures and vascular calcification. Vitamin K presents unique benefits on these issues, although understudied. The two main forms of vitamin K are phylloquinone (vitamin K₁) and menaquinone (vitamin K₂). In this study, it was especially investigated the action of vitamin K₂ in bones and vessels. Vitamin K₂ has shown to stimulate bone formation by promoting osteoblast differentiation and carboxylation of osteocalcin, and increasing alkaline phosphatase, insulin-like growth factor-1, growth differentiation factor-15, and stanniocalcin 2 levels. Furthermore, vitamin K₂ reduces the pro-apoptotic proteins Fas and Bax in osteoblasts, and decreases osteoclast differentiation by increasing osteoprotegerin and reducing the receptor activator of nuclear factor kappa-B ligand. In blood vessels, vitamin K₂ reduces the formation of hydroxyapatite, through the carboxylation of matrix Gla protein and Gla rich protein, inhibits the apoptosis of vascular smooth muscle cells, by increasing growth arrest-specific gene 6, and reduces the transdifferentiation of vascular smooth muscle cells to osteoblasts. The commonly used dosage of vitamin K₂ in human studies is 45 mg/day and its application can be an interesting strategy in benefitting bone and vascular health, especially to osteoporotic post-menopausal women.     

Improved algorithms for recognizing p-Helly and hereditary p-Helly hypergraphs

A hypergraph H is set of vertices V together with a collection of nonempty subsets of it, called the hyperedges of H. A partial hypergraph of H is a hypergraph whose hyperedges are all hyperedges of H, whereas for V^′⊆V the subhypergraph (induced by V^′) is a hypergraph with vertices V^′ and having as hyperedges the subsets obtained as nonempty intersections of V^′ and each of the hyperedges of H. For p?1 say that H is p-intersecting when every subset formed by p hyperedges of H contain a common vertex. Say that H is p-Helly when every p-intersecting partial hypergraph H^′ of H contains a vertex belonging to all the hyperedges of H^′. A hypergraph is hereditary p-Helly when every (induced) subhypergraph of it is p-Helly. In this paper we describe new characterizations for hereditary p-Helly hypergraphs and discuss the recognition problems for both p-Helly and hereditary p-Helly hypergraphs. The proposed algorithms improve the complexity of the existing recognition algorithms.     

Molecular recognition effects in atomistic models of imprinted polymers

In this article we present a model for molecularly imprinted polymers, which considers both complexation processes in the pre-polymerization mixture and adsorption in the imprinted structures within a single consistent framework. As a case study we investigate MAA/EGDMA polymers imprinted with pyrazine and pyrimidine. A polymer imprinted with pyrazine shows substantial selectivity towards pyrazine over pyrimidine, thus exhibiting molecular recognition, whereas the pyrimidine imprinted structure shows no preferential adsorption of the template. Binding sites responsible for the molecular recognition of pyrazine involve one MAA molecule and one EGDMA molecule, forming associations with the two functional groups of the pyrazine molecule. Presence of these specific sites in the pyrazine imprinted system and lack of the analogous sites in the pyrimidine imprinted system is directly linked to the complexation processes in the pre-polymerization solution. These processes are quite different for pyrazine and pyrimidine as a result of both enthalpic and entropic effects.