Alternative 2D Shape Representations using the Symmetry Set

Among the many attempts made to represent families of 2D shapes in a simpler way, the Medial Axis takes a prominent place. Its graphical representation is intuitively appealing and can be computed efficiently. Small perturbations of the shape can have large impact on the and are regarded as instabilities, although these changes are mathematically known from the investigations on a super set, the Symmetry Set . This set has mainly been in a mathematical research stage, partially due to computational aspects, and partially due to its unattractive representation in the plane. In this paper novel methods are introduced to overcome both aspects. As a result, it is possible to represent the as a string is presented. The advantage of such a structure is that it allows fast and simple query algorithms for comparisons. Second, alternative ways to visualize the are presented. They use the distances from the shape to the set as extra dimension as well as the so-called pre-Symmetry Set and anti-Symmetry Set. Information revealed by these representations can be used to calculate the linear string representation structure. Example shapes from a data base are shown and their data structures derived. Arjan Kuijper is Senior Researcher at the Johann Radon Institute (RICAM) of the Austrian Academy of Sciences in Linz, Austria. He received his M.Sc. degree in applied mathematics in 1995 from the University of Twente, The Netherlands. During the period 1996–1997 he worked at ELTRA Parkeergroep, Ede, The Netherlands. He has been a Ph.D. student (1997–2001), associate researcher (2001–2002), and postdoc (202) at the Institute of Information and Computing Sciences of Utrecht University. In 2003-2005 he served as assistant research professor at the IT University of Copenhagen in Denmark. His interest subtends all mathematical aspects of image and shape analysis, notably multi-scale representations (scale spaces), catastrophe and singularity theory, medial axes and symmetry sets, partial differential equations, singular theories, and their applications. Ole Fogh Olsen is associate professor in the image group at the IT University of Copenhagen. He received the PhD degree in 2000 in computer science from University of Copenhagen, Denmark. Main research interest areas are image analysis, medical image analysis and computer vision with focus on scale space theory, differential geometry, singularity theory, statistics, segmentation, optic flow and shape modelling. Peter Giblin is Professor of Mathematics at the University of Liverpool and a former Head of the Mathematical Sciences Department. He joined the staff there in 1967 and has been visiting professor at the University of North Carolina at Chapel Hill, Five Colleges in Amherst, Massachusetts, and Brown University. His research interests are in singularity theory and its applications to differential geometry and computer vision. Mads Nielsen received a MSc in 1992 and a PhD in 1995 both in computer science from DIKU, Department of Computer Science, University of Copenhagen, Denmark. During his PhD studies he spent one year 93–94 at the Robotvis lab at INRIA, Sophia-Antipolis, France. In the second half of 1995 he was post-doc at the Image Sciences Institute of Utrecht University, The Netherlands. In 1996 he was joint post-doc at DIKU and 3D-Lab, School of Dentistry, University of Copenhagen, where he served as assistant professor 1997–99. In 1998–99 he served as external associate professor at Institute of Mathematical Modelling, Technical University of Denmark. April 1999 he became the first associate professor at the new IT University of Copenhagen. Since June 2002 he has been professor the same place heading the Image Analysis Group. He is head of the PhD-studies at ITU, member of the Academical Council of ITU, General chair of MICCAI 2006, member of the editorial board of IJCV and JMIV. His research interests are in the mathematical foundation of image analysis, the computational aspects, and the applications, especially in the medical area.     

Adaptive backbone protocol for heterogeneous wireless networks

We propose Adaptive Backbone Protocol ABP, a lightweight protocol for distributed formation of a backbone over Heterogeneous Wireless Networks. ABP does not require any neighborhood information and consequently scales well with the number of nodes and network size. We present an analytical framework to study the performance of ABP. By making the nodes rotate the role of backbone nodes, we extend the life of the network.     

Sm@rtConfig: A context-aware runtime and tuning system using an aspect-oriented approach for data intensive engineering applications

Distributing the workload upon all available Processing Units (PUs) of a high-performance heterogeneous platform (e.g., PCs composed by CPU–GPUs) is a challenging task, since the execution cost of a task on distinct PUs is non-deterministic and affected by parameters not known a priori. This paper presents Sm@rtConfig, a context-aware runtime and tuning system based on a compromise between reducing the execution time of engineering applications and the cost of tasks' scheduling on CPU–GPUs' platforms. Using Model-Driven Engineering and Aspect Oriented Software Development, a high-level specification and implementation for Sm@rtConfig has been created, aiming at improving modularization and reuse in different applications. As case study, the simulation subsystem of a CFD application has been developed using the proposed approach. These system's tasks were designed considering only their functional concerns, whereas scheduling and other non-functional concerns are handled by Sm@rtConfig aspects, improving tasks modularity. Although Sm@rtConfig supports multiple PUs, in this case study, these tasks have been scheduled to execute on an platform composed by one CPU and one GPU. Experimental results show an overall performance gain of 21.77% in comparison to the static assignment of all tasks only to the GPU.     

Effect of struture and form on the ability of plant sterols to inhibit cholesterol absorption in hamsters

We investigated the effect of three types of plant sterols (4-desmethylsterols, 4,4′-dimethylsterols, and pentacyclic triterpene alcohols) in three forms (free, esterified with FA, or with phenolic acids) on cholesterol absorption. Plant sterol fractions derived from soybean (99% 4-desmethylsterols), rice bran (70% 4,4′-dimethylsterols), or shea nut (89% pentacyclic triterpene alcohols) were fed to male hamsters (n=20/group) as free sterols or esterified with FA or phenolic acids (cinnamic or ferulic). Cholesterol absorption was measured after 5–8.5 (mean, 7) wk by a dual-isotope technique. Soybean sterol intake significantly reduced cholesterol absorption efficiency (23%) and plasma total cholesterol (11%). Rice bran sterols tended to lower cholesterol absorption efficiency by 7% and plasma total cholesterol by 5%, whereas shea nut sterols had no effect. In hamsters, dietary 4-desmethylsterols were more effective than 4,4′-dimethylsterols in lowering cholesterol absorption and levels of cholesterol in blood. Pentacyclic triterpene alcohols had no effect on the absorption of cholesterol or on its level in blood. Esterification with FA did not impair the ability of 4-desmethylsterols and 4,4′-dimethylsterols to inhibit cholesterol absorption, whereas esterification with phenolic acids reduced this ability. This study supports the use of 4-desmethylsterols, esterified with FA to increase solubility, as the most effective cholesterol-lowering plant sterols in the diet.     

Similar but Not the Same: First Kinetic and Structural Analyses of a Methanol Dehydrogenase Containing a Europium Ion in the Active Site

Since the discovery of the biological relevance of rare earth elements (REEs) for numerous different bacteria, questions concerning the advantages of REEs in the active sites of methanol dehydrogenases (MDHs) over calcium(II) and of why bacteria prefer light REEs have been a subject of debate. Here we report the cultivation and purification of the strictly REE‐dependent methanotrophic bacterium Methylacidiphilum fumariolicum SolV with europium(III), as well as structural and kinetic analyses of the first methanol dehydrogenase incorporating Eu in the active site. Crystal structure determination of the Eu‐MDH demonstrated that overall no major structural changes were induced by conversion to this REE. Circular dichroism (CD) measurements were used to determine optimal conditions for kinetic assays, whereas inductively coupled plasma mass spectrometry (ICP‐MS) showed 70 % incorporation of Eu in the enzyme. Our studies explain why bacterial growth of SolV in the presence of Eu³⁺ is significantly slower than in the presence of La³⁺/Ce³⁺/Pr³⁺: Eu‐MDH possesses a decreased catalytic efficiency. Although REEs have similar properties, the differences in ionic radii and coordination numbers across the series significantly impact MDH efficiency.     

Liquid and vapor phase adsorption of chlorinated volatile organic compounds on hydrophobic molecular sieves

This work focused on the potential application of various hydrophobic molecular sieves for the sorption of four model chlorinated volatile organic compounds (CVOCs, i.e., chloroform, trichloroethylene, tetrachloroethylene, and carbon tetrachloride) from dilute liquid water streams.

Results obtained thus far have shown that silicalite-1 has a high affinity for these CVOCs, higher in fact than Centaur^® activated carbon, used as a benchmark in this study. Loading results for trichloroethylene from both liquid and vapor phase indicated that the liquid phase did not penetrate the pores of silicalite-1, while the solution did penetrate the pores of Centaur^® and a dealuminated NaY used for comparison.

Finally, three definitions from the literature for the “hydrophobicity” of molecular sieves were considered. An alternative definition for hydrophobicity is introduced here, which is easy to determine and is based on water retention.     

Probiotic assessment of Enterococcus faecalis CP58 isolated from human gut

A total of seventy lactic acid bacteria (LAB) were isolated from the faeces of healthy humans and their identities were confirmed by sequencing of their 16S rDNA genes. Of these only 5 isolates were found to resist bile salts and indicated survival in the simulated in vitro digestion assay which reproduces the stomach and intestinal digestion indicating their tolerance to gastric enzymes and the low pH conditions. Species that showed the best resistance to these conditions were: Lactobacillus casei, Lactobacillus sp., uncultured bifidobacteria, Enterococcus faecalis and Streptococcus anginosus. These strains were investigated further to study their capacity to adhere to human intestinal Caco-2 cells. E. faecalis was the most adherent strain. Examination of the virulence determinants for this strain indicated that it was positive for efaAfs, gelE, agg, cpd, cob, ccf and cad, a profile that is similar to that of many E. faecalis isolates from food sources. The cytolysin biosynthetic genes cylA, cylB and cylM that are more associated with the clinical isolates of E. faecium were not detected in this strain. The antibiotic susceptibility tests indicated that the strain was sensitive to vancomycin, tetracycline, rifampicin and erythromycin but resistant only to kanamycin and chloramphenicol. These data suggest that the strain E. faecalis CP58 may be tested further for beneficial properties and developed as a new probiotic.