Trends in bulk electron-structural features of early transition-metal carbides

A detailed and systematic density-functional theory (DFT) study of a series of early transition-metal carbides (TMC's) in the NaCl structure is presented. The focus is on the trends in the electronic structure and nature of bonding, which are essential for the understanding of the reactivity of TMC's. The employed approach is based on a thorough complementary analysis of the electron density differences, the density of states (DOS), the band structure, and the real-space wave functions to gain insight into the bonding of this class of materials and get a more detailed picture of it than previously achieved, as the trend study allows for a systematic identification of the bond character along the different bands. Our approach confirms the presence of both the well-known TM--C and TM--TM bonds and, more importantly, it shows the existence and significance of direct C--C bonds in all investigated TMC's, which are frequently neglected but have been recently identified in some cases [Solid State Commun. 121, 411 (2002); Phys. Rev. B 75, 235438 (2007)]. New information on the spatial extent of the bonds, their \textit{k}-space location within the band structure, and their importance for the bulk cohesion is provided. Trends in covalency and ionicity are presented. The resulting electron-structural trends are analyzed and discussed within a two-level model

Evaluation of Statistical Features for Medical Image Retrieval

In this paper we present a complete system allowing the classification of medical images in order to detect possible diseases present in them. The proposed method is developed in two distinct stages: calculation of descriptors and their classification. In the first stage we compute a vector of thirty-three statistical features: seven are related to statistics of the first level order, fifteen to that of second level where thirteen are calculated by means of co-occurrence matrices and two with absolute gradient; the last thirteen finally are calculated using run-length matrices. In the second phase, using the descriptors already calculated, there is the actual image classification. Naive Bayes, RBF, Support VectorMa- chine, K-Nearest Neighbor, Random Forest and Random Tree classifiers are used. The results obtained from the proposed system show that the analysis carried out both on textured and on medical images lead to have a high accuracy

Statistical Features for Image Retrieval: A Quantitative Comparison

In this paper we present a comparison between various statistical descriptors and analyze their goodness in classifying textural images. The chosen statistical descriptors have been proposed by Tamura, Battiato and Haralick. In this work we also test a combination of the three descriptors for texture analysis. The databases used in our study are the well-known Brodatz’s album and DDSM(Heath et al., 1998). The computed features are classified using the Naive Bayes, the RBF, the KNN, the Random Forest and Random Tree models. The results obtained from this study show that we can achieve a high classification accuracy if the descriptors are used all together

Nature of Versatile Chemisorption on TiC(111) and TiN(111) Surfaces

Density-functional calculations on the polar TiX(111) (X = C, N) surfaces show (i) for clean surfaces, strong Ti3d-derived surface resonances (SR's) at the Fermi level and X2p-derived SR's deep in the upper valence band and (ii) for adatoms in periods 1-3, pyramidic trends in atomic adsorption energies, peaking at oxygen (9 eV). A concerted-coupling model, where adatom states couple to both kinds of SR's in a concerted way, describes the adsorption. The chemisorption versatility and the general nature of the model indicate ramifications and predictive abilities in, e.g., growth and catalysis.Comment: 5 pages, 4 figures, submitted to Physical Review Letters (2006

Shape matching by curve modelling and alignment

Automatic information retrieval in the eld of shape recognition has been widely covered by many research elds. Various techniques have been developed using different approaches such as intensity-based, modelbased and shape-based methods. Whichever is the way to represent the objects in images, a recognition method should be robust in the presence of scale change, translation and rotation. In this paper we present a new recognition method based on a curve alignment technique, for planar image contours. The method consists of various phases including extracting outlines of images, detecting signicant points and aligning curves. The dominant points can be manually or automatically detected. The matching phase uses the idea of calculating the overlapping indices between shapes as similarity measures. To evaluate the effectiveness of the algorithm, two databases of 216 and 99 images have been used. A performance analysis and comparison is provided by precision-recall curves

Raman spectroscopic investigation of chondroitinase ABC treatment after spinal cord injury in an organotypic model

This study investigated (1) the ability of an organotypic model of spinal cord injury (SCI) to recapitulate significant pathobiological events of in vivo SCI from a Raman spectroscopic perspective, and (2) the Raman spectroscopic effects of chondroitinase ABC (cABC) treatment on said model of SCI. Tissue from mouse spinal cords was excised, sectioned, and placed into culture, before being systematically injured to induce trauma. Cultures with and without cABC treatment were assessed using Raman spectroscopy at varying times post-injury. We demonstrate that Raman spectral phenomena characteristic of SCI can be observed using an organotypic model. By comparing these phenomena with well-known cellular mechanisms of SCI, we hypothesize their correlation with apoptosis, demyelination, and upregulation of endogenous biochemicals, such as chondroitin sulfate proteoglycans (CSPGs), among others. Furthermore, we demonstrate for the first time that Raman spectral phenomena are discernable during cABC treatment of SCI. Observed spectral variations correlate to the enzymatic degradation of CSPGs, protein compositional changes, and remyelination. Multivariate regression modeling confirms changes in lipid and chondroitin sulfate concentration during SCI and its cABC treatment, and provides a semi-quantitative measure of these changes. Overall, these data establish Raman spectroscopy as a viable resource for monitoring cABC treatment of SCI

Knowledge, attitudes and practices of malaria control among communities from the health district of Forécariah in the Republic of Guinea, West Africa.

BACKGROUND & OBJECTIVES: Malaria is the leading cause of death in children under 5-yr of age in the Republic of Guinea. This study aimed at investigating the knowledge, attitudes and practices of malaria control in urban and rural communities in Guinea in order to better target future health interventions. METHODS: A cross-sectional survey of 200 randomly selected households was conducted in an urban site and in three rural villages within the health district of Forιcariah using two semi-structured questionnaires. RESULTS: Only 18.5% of the respondents were aware of the role of mosquitoes in the transmission of malaria in both urban and rural households. Mosquito nets were identified as a malaria prevention method by 11.5% of the participants and only 8.5% of the respondents mentioned stagnant water as a potential mosquito breeding site. Households' heads were more aware of mosquito control methods, with 56 and 42% of the respondents recognizing that bednets or insecticidal coils can protect from mosquitoes, respectively. Despite the limited knowledge of malaria transmission and prevention, 55% of the households owned at least one long-lasting insecticide-treated net (LLIN) and 79% of the net-owning households slept under a net/LLIN the night before the survey. INTERPRETATION & CONCLUSION: In order to maximize the benefits of malaria control strategies, health education should be implemented, building on the higher awareness of mosquito control methods and stressing the role of vectors in transmitting the disease