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Search Results: 1 - 10 of 613 matches for " Hisanobu Koyama "
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Classification of Emphysema Subtypes: Comparative Assessment of Local Binary Patterns and Related Texture Features  [PDF]
Mizuho Nishio, Hisanobu Koyama, Yoshiharu Ohno, Kazuro Sugimura
Advances in Computed Tomography (ACT) , 2015, DOI: 10.4236/act.2015.43007
Abstract: The purpose of this study was to assess usefulness of local binary patterns (LBP) and related texture features, namely completed local binary patterns (CLBP) and local ternary patterns (LTP), for the classification of emphysema subtypes on low-dose CT images. Fifty patients (34 men and 16 women; age, 67.5 ± 10.1 years) who underwent low-dose CT (60 mAs) were included. They were comprised of 17 never smokers, 13 smokers without COPD, and 20 smokers with COPD. By consensus reading of low-dose CT images from these patients, two radiologists selected 3681 nonoverlapping regions of interest (ROIs) and annotated them as one of the following three classes: normal tissue, centrilobular emphysema, and paraseptal emphysema. From these ROIs, histogram of CT densities, LBP, CLBP, and LTP were calculated, and the 3 types of texture histograms were concatenated with the CT density histogram. These 3 types of histograms (referred to as combined LBP, combined CLBP, and combined LTP) were used to classify ROI using linear support vector machine. For each type of the combined histogram, the accuracy of classification was determined by patient-based 10-fold cross validation. The best accuracy of combined LBP, combined CLBP, and combined LTP were 81.36%, 82.99%, and 83.29%, respectively. Compared to the classification accuracies obtained with combined LBP, those with combined LTP or combined CLBP were consistently improved. In conclusion, the results of this study suggest that, on low-dose CT, LTP and CLBP were more useful for the classification of emphysema subtypes than LBP.
Tumor Segmentation on 18F FDG-PET Images Using Graph Cut and Local Spatial Information  [PDF]
Mizuho Nishio, Atsushi K. Kono, Kazuhiro Kubo, Hisanobu Koyama, Tatsuya Nishii, Kazuro Sugimura
Open Journal of Medical Imaging (OJMI) , 2015, DOI: 10.4236/ojmi.2015.53022
Abstract: The purpose of this study was to develop methodology to segment tumors on 18F-fluorodeoxyg- lucose (FDG) positron emission tomography (PET) images. Sixty-four metastatic bone tumors were included. Graph cut was used for tumor segmentation, with segmentation energy divided into unary and pairwise terms. Locally connected conditional random fields (LCRF) were proposed for the pairwise term. In LCRF, three-dimensional cubic window with length L was set for each voxel, and voxels within the window were considered for the pairwise term. Three other types of segmentation were applied: region-growing based on 35%, 40%, and 45% of the tumor maximum standardized uptake value (RG35, RG40, and RG45, respectively), SLIC superpixels (SS), and region-based active contour models (AC). To validate the tumor segmentation accuracy, dice similarity coefficients (DSC) were calculated between the result of each technique and manual segmentation. Differences in DSC were tested using the Wilcoxon signed-rank test. Mean DSCs for LCRF at L = 3, 5, 7, and 9 were 0.784, 0.801, 0.809, and 0.812, respectively. Mean DSCs for the other techniques were: RG35, 0.633; RG40, 0.675; RG45, 0.689; SS, 0.709; and AC, 0.758. The DSC differences between LCRF and other techniques were statistically significant (p < 0.05). Tumor segmentation was reliably performed with LCRF.
On a Formula of Mellin and Its Application to the Study of the Riemann Zeta-function (with an erratum added 03/11/13)
Hisanobu Shinya
Journal of Mathematics Research , 2012, DOI: 10.5539/jmr.v4n6p12
Abstract: In this paper, we reconsider a formula of Mellin. We present a formula which relates the sum of two positive real numbers $m, n$ to their product $mn$. We apply this formula to derivation of a relationship involving the Hurwitz zeta-function. Then we define a series function (stemming from the proved relationship) and discuss an analogy in regard to the Lindel"{o}f hypothesis. Finally, a proof of the Lindel"{o}f hypothesis of the Riemann zeta-function is deduced from this analogy.
On a method for obtaining a planar region with two equichordal points
Hisanobu Shinya
Mathematics , 2004,
Abstract: This paper has been withdrawn by the author. It has been shown by G.A. Edgar that curves created by the presented method are not continuous at \theta = 0. See http://www.math.ohio-state.edu/~edgar/equichord/ .
Investigating some integrals involving the Lerch zeta-function
Hisanobu Shinya
Mathematics , 2007,
Abstract: Let $\varphi(x, u, s)$ denote the Lerch zeta-function defined for $\text{Re}(s) > 1$ and $x, u \in (0, 1)$ by the series $\varphi(x, u, s) := \sum_{n \geq 0}\exp[2 \pi i n x](n + u)^{-s}$, and let $\varphi^{*}(x, u, s) := \varphi(x, u, s) - u^{-s}$. Furthermore, let $[a, b]$ denote the straight line in the complex plane from the point $a$ to $b$ and $\gamma$ be any real number in $(0, \pi)$. In this paper, we investigate integrals of the form $\int_{[e^{i \gamma}, 0] + [0, 1]} \varphi^{*}(x, u, 1/2 + \beta - it) u^{-1 + \epsilon} du$, where $\beta \in (0, 1/2)$, $\epsilon > 0$, and $a_{1}, x \in (0, 1)$.
On an arithmetical approach to the Riemann hypothesis
Hisanobu Shinya
Mathematics , 2009,
Abstract: In the paper, we first prove a sufficient condition for the Riemann hypothesis which involves the order of magnitude of the partial sum of the Liouville function. Then we show a formula which is curiously related to the proved sufficient condition.
On a certain asymptotic relationship involving $\vartheta(t) - \lfloor t \rfloor$ and $t^{1/2}$
Hisanobu Shinya
Mathematics , 2008,
Abstract: Let $\lfloor t \rfloor$ denote the greatest positive integer less than or equal to a given positive real number $t$ and $\vartheta(t)$ the Chebyshev $\vartheta$-function. In this paper, we prove a certain asymptotic relationship involving $\vartheta(t) - \lfloor t \rfloor $ and $t^{1/2}$.
A note on gaps
Hisanobu Shinya
Mathematics , 2008,
Abstract: Let $p_{k}$ denote the $k$-th prime and $d(p_{k}) = p_{k} - p_{k - 1}$, the difference between consecutive primes. We denote by $N_{\epsilon}(x)$ the number of primes $\leq x$ which satisfy the inequality $d(p_{k}) \leq (\log p_{k})^{2 + \epsilon}$, where $\epsilon > 0$ is arbitrary and fixed, and by $\pi(x)$ the number of primes less than or equal to $x$. In this paper, we first prove a theorem that $\lim_{x \to \infty} N_{\epsilon}(x)/\pi(x) = 1$. A corollary to the proof of the theorem concerning gaps between consecutive squarefree numbers is stated.
A Qualitative Property of the Riemann zeta function
Hisanobu Shinya
Mathematics , 2005,
Abstract: The paper was withdrawn by the author. It contained various errors.
On the Gaps between Two Consecutive Prime Numbers
Hisanobu Shinya
Mathematics , 2005,
Abstract: In this article, a relation between a gap $d_{k}$ and divisors of composite numbers between $p_{k}$ and $p_{k+1}$ is established.
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