5,248 research outputs found

    Drawing Planar Graphs with a Prescribed Inner Face

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    Given a plane graph GG (i.e., a planar graph with a fixed planar embedding) and a simple cycle CC in GG whose vertices are mapped to a convex polygon, we consider the question whether this drawing can be extended to a planar straight-line drawing of GG. We characterize when this is possible in terms of simple necessary conditions, which we prove to be sufficient. This also leads to a linear-time testing algorithm. If a drawing extension exists, it can be computed in the same running time

    Universal Composability is Secure Compilation

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    Universal composability is a framework for the specification and analysis of cryptographic protocols with a strong compositionality guarantee: UC protocols are secure even when composed with other protocols. Secure compilation tells whether compiled programs are as secure as their source-level counterparts, no matter what target-level code they interact with. These two disciplines are studied in isolation, but we believe there is a deeper connection between them with benefits from both worlds to reap. This paper outlines the connection between universal composability and robust compilation, the latest of secure compilation theories. We show how to read the universal composability theorem in terms of a robust compilation theorem and vice-versa. This, in turn, shows which elements of one theory corresponds to which element in the other theory. We believe this is the first step towards understanding how can secure compilation theories be used in universal composability settings and vice-versa

    Human Breast Milk: A Source of Potential Probiotic Candidates

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    This study focuses on the isolation of lactobacilli/bifidobacteria from human breast milk and their first characterization, in the perspective to find new probiotic candidates to be included in food products. More specifically, breast-milk-isolated strains demonstrated a very good aptitude to adhere to intestinal cells, in comparison with L. rhamnosus GG strain, taken as reference. The same behavior has been found for hydrophobicity/auto-aggregation properties. A remarkable antagonistic activity was detected for these isolates not only against spoilage and pathogenic species of food interest, but also against the principal etiological agents of intestinal infections. Indeed, isolated strains impaired spoilage and pathogenic species growth, as well as biofilm formation by gut pathogens. In addition, breast milk strains were characterized for their antibiotic susceptibility, displaying species-specific and strain-specific susceptibility patterns. Finally, to assess their technological potential, the fermentation kinetics and viability of breast milk strains in pasteurized milk were investigated, also including the study of the volatile molecule profiles. In this regard, all the strains pointed out the release of aroma compounds frequently associated with the sensory quality of several dairy products such as acetic acid, diacetyl, acetoin, acetaldehyde. Data here reported point up the high potential of breast-milk-isolated strains as probiotics

    Lactobacillus paracasei A13 and high-pressure homogenization stress response

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    Sub-lethal high-pressure homogenization treatments applied to Lactobacillus paracasei A13 demonstrated to be a useful strategy to enhance technological and functional properties without detrimental effects on the viability of this strain. Modification of membrane fatty acid composition is reported to be the main regulatory mechanisms adopted by probiotic lactobacilli to counteract high-pressure stress. This work is aimed to clarify and understand the relationship between the modification of membrane fatty acid composition and the expression of genes involved in fatty acid biosynthesis in Lactobacillus paracasei A13, before and after the application of different sub-lethal hyperbaric treatments. Our results showed that Lactobacillus paracasei A13 activated a series of reactions aimed to control and stabilize membrane fluidity in response to high-pressure homogenization treatments. In fact, the production of cyclic fatty acids was counterbalanced by the unsaturation and elongation of fatty acids. The gene expression data indicate an up-regulation of the genes accA, accC, fabD, fabH and fabZ after high-pressure homogenization treatment at 150 and 200 MPa, and of fabK and fabZ after a treatment at 200 MPa suggesting this regulation of the genes involved in fatty acids biosynthesis as an immediate response mechanism adopted by Lactobacillus paracasei A13 to high-pressure homogenization treatments to balance the membrane fluidity. Although further studies should be performed to clarify the modulation of phospholipids and glycoproteins biosynthesis since they play a crucial role in the functional properties of the probiotic strains, this study represents an important step towards understanding the response mechanisms of Lactobacillus paracasei A13 to sub-lethal high-pressure homogenization treatments

    Suitability of the nisin Z-producer lactococcus lactis subsp. lactis CBM 21 to be used as an adjunct culture for squacquerone cheese production

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    This research investigated the technological and safety effects of the nisin Z producer Lactococcus lactis subsp. lactis CBM 21, tested as an adjunct culture for the making of Squacquerone cheese in a pilot-scale plant. The biocontrol agent remained at a high level throughout the cheese refrigerated storage, without having a negative influence on the viability of the conventional Streptococcus thermophilus starter. The inclusion of CBM 21 in Squacquerone cheesemaking proved to be more effective compared to the traditional one, to reduce total coliforms and Pseudomonas spp. Moreover, the novel/innovative adjunct culture tested did not negatively modify the proteolytic patterns of Squacquerone cheese, but it gave rise to products with specific volatile and texture profiles. The cheese produced with CBM 21 was more appreciated by the panelists with respect to the traditional one

    Minimal Obstructions for Partial Representations of Interval Graphs

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    Interval graphs are intersection graphs of closed intervals. A generalization of recognition called partial representation extension was introduced recently. The input gives an interval graph with a partial representation specifying some pre-drawn intervals. We ask whether the remaining intervals can be added to create an extending representation. Two linear-time algorithms are known for solving this problem. In this paper, we characterize the minimal obstructions which make partial representations non-extendible. This generalizes Lekkerkerker and Boland's characterization of the minimal forbidden induced subgraphs of interval graphs. Each minimal obstruction consists of a forbidden induced subgraph together with at most four pre-drawn intervals. A Helly-type result follows: A partial representation is extendible if and only if every quadruple of pre-drawn intervals is extendible by itself. Our characterization leads to a linear-time certifying algorithm for partial representation extension

    Cyclooxygenase-2 inhibitors. 1,5-diarylpyrrol-3-acetic esters with enhanced inhibitory activity toward cyclooxygenase-2 and improved cyclooxygenase-2/cyclooxygenase-1 selectivity.

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    he important role of cyclooxygenase-2 (COX-2) in the pathogenesis of inflammation and side effect limitations of current COX-2 inhibitor drugs illustrates a need for the design of new compounds based on alternative structural templates. We previously reported a set of substituted 1,5-diarylpyrrole derivatives, along with their inhibitory activity toward COX enzymes. Several compounds proved to be highly selective COX-2 inhibitors and their affinity data were rationalized through docking simulations. In this paper, we describe the synthesis of new 1,5-diarylpyrrole derivatives that were assayed for their in vitro inhibitory effects toward COX isozymes. Among them, the ethyl-2-methyl-5-[4-(methylsulfonyl)phenyl]-1-[3-fluorophenyl]-1H-pyrrol-3- acetate (1d), which was the most potent and COX-2 selective compound, also showed a very interesting in vivo anti-inflammatory and analgesic activity, laying the foundations for developing new lead compounds that could be effective agents in the armamentarium for the management of inflammation and pain

    The Partial Visibility Representation Extension Problem

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    For a graph GG, a function ψ\psi is called a \emph{bar visibility representation} of GG when for each vertex vV(G)v \in V(G), ψ(v)\psi(v) is a horizontal line segment (\emph{bar}) and uvE(G)uv \in E(G) iff there is an unobstructed, vertical, ε\varepsilon-wide line of sight between ψ(u)\psi(u) and ψ(v)\psi(v). Graphs admitting such representations are well understood (via simple characterizations) and recognizable in linear time. For a directed graph GG, a bar visibility representation ψ\psi of GG, additionally, puts the bar ψ(u)\psi(u) strictly below the bar ψ(v)\psi(v) for each directed edge (u,v)(u,v) of GG. We study a generalization of the recognition problem where a function ψ\psi' defined on a subset VV' of V(G)V(G) is given and the question is whether there is a bar visibility representation ψ\psi of GG with ψ(v)=ψ(v)\psi(v) = \psi'(v) for every vVv \in V'. We show that for undirected graphs this problem together with closely related problems are \NP-complete, but for certain cases involving directed graphs it is solvable in polynomial time.Comment: Appears in the Proceedings of the 24th International Symposium on Graph Drawing and Network Visualization (GD 2016

    Quality and stability of different seafood products treated with high hydrostatic pressure (HPP) intended for raw consumption

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    The consumption of raw fish has rapidly increased in recent years, but being a highly perishable product, it is characterised by a very short microbiological shelf life. High hydrostatic pressure (HPP) processing is a non -thermal technology has emerged recently as a promising alternative to thermal processing for food pasteurization capable of maintaining fresh-like characteristics and nutritional value. However, the induced changes in product quality should be assessed carefully. The present research aimed to investigate the effect of HPP on different seafood products, namely grey mullet, tiger prawn and rose shrimp, intended for raw consumption. Three pres-sure levels (400, 500 and 600 MPa) were applied for 10 min. During refrigerated storage, microbiological quality, chemical parameters, colour and texture and fat oxidation were analysed. Results showed that the application of lower pressure was able to inactivate E. coli, pseudomonas and/or positive coagulase staphylococci; however, they were able to recover during storage. In addition, the application of 600-MPa pressure extended the microbio-logical shelf life by up to 30 days. For all samples, general whitening occurred while the texture was affected in a different way for the three considered species. Fat oxidation was only minimally affected and remained quite low during storage
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