109 research outputs found

    Atomic-Number (Z)-Correlated Atomic Sizes for Deciphering Electron Microscopic Molecular Images

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    With the advent of atomic-resolution transmission electron microscopy (AR-TEM) achieving sub-{\AA}ngstrom image resolution and submillisecond time resolution, an era of visual molecular science where chemists can visually study the time evolution of molecular motions and reactions at atomistic precision has arrived. However, the appearance of experimental TEM images often differs greatly from that of conventional molecular models, and the images are difficult to decipher unless we know in advance the structure of the specimen molecules. The difference arises from the fundamental design of the molecular models that represent atomic connectivity and/or the electronic properties of molecules rather than the nuclear charge of atoms and electrostatic potentials that are felt by the e-beam in TEM imaging. We found a good correlation between the atomic number (Z) and the atomic size seen in TEM images when we consider shot noise in digital images. We propose here Z-correlated (ZC) atomic radii for modeling AR-TEM images of single molecules and ultrathin crystals, with which we can develop a good estimate of the molecular structure from the TEM image much more easily than with conventional molecular models. Two parameter sets were developed for TEM images recorded under high-noise (ZCHN) and low-noise (ZCLN) conditions. The new molecular models will stimulate the imaginations of chemists planning to use AR-TEM for their research.Comment: 27 pages, 6 figure

    Image Retrieval Method for Multiscale Objects from Optical Colonoscopy Images

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    Optical colonoscopy is the most common approach to diagnosing bowel diseases through direct colon and rectum inspections. Periodic optical colonoscopy examinations are particularly important for detecting cancers at early stages while still treatable. However, diagnostic accuracy is highly dependent on both the experience and knowledge of the medical doctor. Moreover, it is extremely difficult, even for specialist doctors, to detect the early stages of cancer when obscured by inflammations of the colonic mucosa due to intractable inflammatory bowel diseases, such as ulcerative colitis. Thus, to assist the UC diagnosis, it is necessary to develop a new technology that can retrieve similar cases of diagnostic target image from cases in the past that stored the diagnosed images with various symptoms of colonic mucosa. In order to assist diagnoses with optical colonoscopy, this paper proposes a retrieval method for colonoscopy images that can cope with multiscale objects. The proposed method can retrieve similar colonoscopy images despite varying visible sizes of the target objects. Through three experiments conducted with real clinical colonoscopy images, we demonstrate that the method is able to retrieve objects of any visible size and any location at a high level of accuracy

    スパイラル CT オ モチイタ ガクカンセツ ノ サンジゲン ヒョウカホウ

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    Three-dimensional (3-D) image reconstructed from Computed Tomography (CT) data is an ef>cient method to evaluate temporomandibular joint (TMJ) morphologically. Even the 3-D image reconstructed from spiral CT data has some distortion, typically along to the table feed direction, very few studies were reported about accuracy of reconstructed 3-D image size. The purpose of this research was to evaluate the distortion on 3-D image reconstructed with spiral CT (Somatom Plas4, Siemens Co, Germany) quantitatively. We used three imaging targets, eight ceramic balls placed at corners of cubic frame, a calibration cube that has the CT value nearly equal to cortex bone of human dried mandibular head. We evaluated relation between a threshold level of CT image processing and reconstructed 3-D image size with a custom-made computer program. CT data of ceramic balls clari>ed changes of the reconstructed image, -0.215mm for table feed direction and less than ±0.006mm for the other directions. The calibration cube was used for the arrangement of optimal scanning condition (reconstruction mode, collimation, reconstitution interval) and evaluation of reconstructed image size. The distortion of the image was +0.207mm for table feed direction and less than +0.029mm for the other directions. Changes of dried skull TMJ image reconstructed with the optimal scanning condition were -1.463mm for lateral direction of the condylar head, -0.956mm for back and forth direction and -0.580mm for table feed direction. Results of this research suggested that the level of the 3-D image distortion was mostly affected with the scanning condition. And the size of 3-D image was susceptible to the threshold level of CT image processing. Consequently, we think that the standardization of scanning condition should be concerned for the quantitative evaluation of 3-D TMJ image using CT data

    Common Variants in the COL4A4 Gene Confer Susceptibility to Lattice Degeneration of the Retina

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    Lattice degeneration of the retina is a vitreoretinal disorder characterized by a visible fundus lesion predisposing the patient to retinal tears and detachment. The etiology of this degeneration is still uncertain, but it is likely that both genetic and environmental factors play important roles in its development. To identify genetic susceptibility regions for lattice degeneration of the retina, we performed a genome-wide association study (GWAS) using a dense panel of 23,465 microsatellite markers covering the entire human genome. This GWAS in a Japanese cohort (294 patients with lattice degeneration and 294 controls) led to the identification of one microsatellite locus, D2S0276i, in the collagen type IV alpha 4 (COL4A4) gene on chromosome 2q36.3. To validate the significance of this observation, we evaluated the D2S0276i region in the GWAS cohort and in an independent Japanese cohort (280 patients and 314 controls) using D2S0276i and 47 single nucleotide polymorphisms covering the region. The strong associations were observed in D2S0276i and rs7558081 in the COL4A4 gene (Pc = 5.8×10−6, OR = 0.63 and Pc = 1.0×10−5, OR = 0.69 in a total of 574 patients and 608 controls, respectively). Our findings suggest that variants in the COL4A4 gene may contribute to the development of lattice degeneration of the retina

    The habu genome reveals accelerated evolution of venom protein genes

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    Evolution of novel traits is a challenging subject in biological research. Several snake lineages developed elaborate venom systems to deliver complex protein mixtures for prey capture. To understand mechanisms involved in snake venom evolution, we decoded here the ~1.4-Gb genome of a habu, Protobothrops flavoviridis. We identified 60 snake venom protein genes (SV) and 224 non-venom paralogs (NV), belonging to 18 gene families. Molecular phylogeny reveals early divergence of SV and NV genes, suggesting that one of the four copies generated through two rounds of whole-genome duplication was modified for use as a toxin. Among them, both SV and NV genes in four major components were extensively duplicated after their diversification, but accelerated evolution is evident exclusively in the SV genes. Both venom-related SV and NV genes are significantly enriched in microchromosomes. The present study thus provides a genetic background for evolution of snake venom composition

    Initial solidification phenomena in the continuous casting slab mould

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    In a study of initial solidification during the continuous casting of steel slabs, the formation of oscillation marks and their effect on the surface quality of the slabs have been examined by metallographical investigation of slab samples and by performing a set of mathematical analyses. The metallographic study of the oscillation marks has revealed that the adjacent subsurface structure may exhibit "hooks". The depth of oscillation marks exhibiting subsurface hooks is affected by the carbon content of the steel, while oscillation marks without adjacent hooks do not show the carbon dependence. Another important factor which affects the depth of oscillation marks is variation of the meniscus level. Quick upward movement of the meniscus level increases the depth of oscillation marks. The theoretical analysis of heat flow at the meniscus indicates that the meniscus may partially freeze within the period of a typical mould oscillation cycle. Lubrication theory has shown that a significant pressure can be generated in the flux channel by the reciprocating motion of the mould relative to the shell. The shape of the meniscus has been computed as a function of the pressure developed in the mould flux. This has demonstrated that the "contact" point of the meniscus with the mould wall moves out of phase with the mould displacement by π/2, and has a greater amplitude than the stroke of mould oscillation. Thus near the beginning of the positive strip period molten steel can overflow at the meniscus when a rigid hook-like shell exists, whilst the meniscus in the absence of a rigid shell, caused by high superheat and/or steel convection at the solidification front, is drawn toward the mould wall to form the oscillation marks without a subsurface hook. Consequently the effect of various casting variables on the depth of oscillation marks can be explained on theoretical grounds. Positive segregation of phosphorus has been observed at the bottom of the oscillation marks and has been classified mainly into two types. One type is observed at the end of the overflow region on the subsurface hook. A heat-flow model which takes into account the shape of the oscillation marks has revealed that this type of positive segregation is caused by local delay of solidification at the bottom of the oscillation marks. Another type of positive segregation has been found in a layer on the bottom of oscillation marks without subsurface hooks. This form of segregation cannot be explained by the heat flow model, but is likely due to a penetration mechanism in which the negative pressure in the flux channel generated during the upward motion of the mould draws out interdendritic liquid from the semi-solidified shell. Transverse cracks are found along the bottom of oscillation marks. The surface of the transverse cracks exhibits an interdendretic appearance in the vicinity of the slab surface, which implies that the cracks are hot tears initiated in the mould region. A heat-flow analysis predicts that deep oscillation marks cause nonuniformity of the shell in the mould, which was also observed in the metallographic investigation. According to the heat-flow analysis not only the depth but also the pitch of oscillation marks affects the shell profile. Therefore increasing the frequency of mould oscillation effectively reduces transverse cracks, by decreasing both the depth and the pitch of oscillation marks.Applied Science, Faculty ofMaterials Engineering, Department ofGraduat
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