Blood vessel enhancement via multi-dictionary and sparse coding: Application to retinal vessel enhancing

International audienceBlood vessel images can provide considerable information of many diseases, which are widely used by ophthalmologists for disease diagnosis and surgical planning. In this paper, we propose a novel method for the blood Vessel Enhancement via Multi-dictionary and Sparse Coding (VE-MSC). In the proposed method, two dictionaries are utilized to gain the vascular structures and details, including the Representation Dictionary (RD) generated from the original vascular images and the Enhancement Dictionary (ED) extracted from the corresponding label images. The sparse coding technology is utilized to represent the original target vessel image with RD. After that, the enhanced target vessel image can be reconstructed using the obtained sparse coefficients and ED. The proposed method has been evaluated for the retinal vessel enhancement on the DRIVE and STARE databases. Experimental results indicate that the proposed method can not only effectively improve the image contrast but also enhance the retinal vascular structures and details

Ion-exchange synthesis and superconductivity at 8.6 K of Na2Cr3As3 with quasi-one-dimensional crystal structure

A new Cr-based quasi-one-dimensional superconductor Na2Cr3As3 was synthesized by an ion-exchange method in sodium naphthalenide solution. The crystals are thread-like and the structure was analyzed by X-ray diffraction with a noncentrosymmetric hexagonal space group P-6m2 (No. 187), in which the (Cr3As3)2- linear chains are separated by Na+ ions, and the refined lattice parameters are a = 9.239(2) {\AA} and c = 4.209(6) {\AA}. The measurements for electrical resistivity, magnetic susceptibility, and heat capacity reveal a superconducting transition with unconventional characteristic at the Tc of 8.6 K, which exceeds that of all previously reported Cr-based superconductors

The Structure of O-antigen from Lipopolysaccharide of Rhizobium leguminosarum 128C53 and Its Nod-Fix-Mutant

The LPS of R. leguminosarum 128C53 smr rifr (a streptomycin and rifampicin resistant strain of wild type 128C53) and its mutant ANU54 (nod-, fix-) were isolated from the bacterial pellet by hot phenol/water extraction followed by gel filtration chromatography. The O-antigen was isolated by mild-acid hydrolysis of the LPS and purified by gel filtration chromatography using a Sephadex G-50 or G-25. The following results were the same for both the parent and mutant. The composition and linkage of the O-antigen were determined by gas chromatography (GC), GC-mass spectrometry, 1H and 13C nuclear magnetic resonance spectroscopy (NMR) techniques. The data indicate that the O-antigen of the LPS from parent R. leguminosarum 128C53 and its mutant ANU54 are identical. The O-antigen contains a tetrasaccharide repeating unit. The backbone consists of one 1,3-linked-rhamnose and two 1,3-linked-fucose residues. A terminal mannose is linked to the 2-position of one of the two fucose residues. The 1H-NMR analysis indicates that all the glycosyl residues are alpha linked. The exact position of the mannose residue is under further investigation

On Optimal Neighbor Discovery

Mobile devices apply neighbor discovery (ND) protocols to wirelessly initiate a first contact within the shortest possible amount of time and with minimal energy consumption. For this purpose, over the last decade, a vast number of ND protocols have been proposed, which have progressively reduced the relation between the time within which discovery is guaranteed and the energy consumption. In spite of the simplicity of the problem statement, even after more than 10 years of research on this specific topic, new solutions are still proposed even today. Despite the large number of known ND protocols, given an energy budget, what is the best achievable latency still remains unclear. This paper addresses this question and for the first time presents safe and tight, duty-cycle-dependent bounds on the worst-case discovery latency that no ND protocol can beat. Surprisingly, several existing protocols are indeed optimal, which has not been known until now. We conclude that there is no further potential to improve the relation between latency and duty-cycle, but future ND protocols can improve their robustness against beacon collisions.Comment: Conference of the ACM Special Interest Group on Data Communication (ACM SIGCOMM), 201

Dry transfer of graphene to dielectrics and flexible substrates using polyimide as a transparent and stable intermediate layer

We demonstrate the direct transfer of graphene from Cu foil to glass and flexible substrates such as PET, using polyimide (PI) mixed with an aminosilane (3-aminopropyltrimethoxysilane) or only PI, respectively, as intermediate layer. We probe the scalability and roll-to-roll processing of this technique by using two different equipment: hot press and a laminator. High quality, clean and continuous areas of graphene monolayer can be transferred with the advantage of Cu recycling for future growth catalyst as it is peeled-off mechanically from the substrate/PI/graphene structure. More important are the high transparency of the samples together with the electron doping achieved (n<sub>S</sub>= 0.21 to 4 x 10<sup>13</sup> cm<sup>-2</sup>), as the performing graphene face is not in direct contact with PMMA, PI or other materials, and the high mobility (µ<sub>H</sub> up to 1250 cm<sup>2</sup>/Vcenterdots). Stability of the structure in terms of sheet resistance (R<sub>S</sub>) at high temperatures, bending cycles and water immersion make this technique promising for future applications and implementation at the large scale.Postprint (author's final draft