研究者詳細 - 加茂　憲一

論文 - 加茂　憲一

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Statisitcal analysis of tree–forest damage by snow and wind: logistic regression model for tree damage and Cox regression for tree survival

K.Kamo, M.Konoshima, A.Yoshimoto

FORMATH ( FORMATH研究会 ) 15 44 - 55 2016年 [査読有り]

担当区分：筆頭著者 , 責任著者

Forest stands and individual trees are often devastated by natural disasters such as typhoons and heavy snowfall in Japan, resulting in significant economic losses to the forestry sector. Our objective is to identify key risk factors that affect the degree of damage. We apply two types of statistical approach: one is, a logistic regression model to snow damage data to investigate if there is any geographical element affecting the degree of damage at the stand level, and the other is, a survival analysis on tree failure data for factors affecting the degree of damage at the individual tree level. A logistic regression analysis revealed that the risk probability of snow damage is higher on older and thin stands. The analysis also indicates taking advantage of certain geographic conditions to reduce wind burden could decrease the degree of damage. A Cox regression analysis showed that tree age, diameter at breast height, and species were key factors that influenced the degree of tree failure. Specifying risk factors throughout statistical modeling helps to provide a comprehensive, systematic, and objective method to assess risk in forest management.

“A comparison of the dose distributions between the brachytherapy 125I source models, STM1251 and Oncoseed 6711, in a geometry lacking radiation equilibrium scatter conditions.”,

K. Tanaka, K. Kamo, K. Tateoka, O. Asanuma, K. Sato, H. Takeda, K. Sakata, J. Takada

Journal of Radiation Research, 55 (2015) 000-000. 55 1 - 6 2015年04月 [査読有り]

A comparison of the dose distributions between the brachytherapy I-125 source models, STM1251 and Oncoseed 6711, in a geometry lacking radiation equilibrium scatter conditions

Kenichi Tanaka, Ken-ichi Kamo, Kunihiko Tateoka, Osamu Asanuma, Kaori Sato, Hiromitsu Takeda, Koh-ichi Sakata, Jun Takada

JOURNAL OF RADIATION RESEARCH ( OXFORD UNIV PRESS ) 56 ( 2 ) 366 - 371 2015年03月 [査読有り]

The purpose of this study was to estimate the uncertainty in the dose distribution for the I-125 source STM1251, as measured with a radiophotoluminescent glass rod dosimeter and calculated using the Monte Carlo code EGS5 in geometry that included the source structure reported by Kirov et al. This was performed at a range of positions in and on a water phantom 18 cm in diameter and 16 cm in length. Some dosimetry positions were so close to the surface that the backscatter margin was insufficient for photons. Consequently, the combined standard uncertainty (CSU) at the coverage factor k of 1 was 11.0-11.2% for the measurement and 1.8-3.6% for the calculation. The calculation successfully reproduced the measured dose distribution within 13%, with CSU at k = 1.6 (P > 0.3). Dose distributions were then compared with those for the I-125 source Oncoseed 6711. Our results supported the American Association of Physicists in Medicine Task Group No. 43 Updated Protocol (TG43U1) formalism, in which STM1251 dose distributions were more penetrating than those of Oncoseed 6711. This trend was also observed in the region near the phantom surface lacking the equilibrium radiation scatter conditions. In this region, the difference between the TG43U1 formalism and the measurement and calculation performed in the present study was not significant (P > 0.3) for either of the source models. Selection of the source model based on the treatment plans according to the TG43U1 formalism will be practical.

Detecting a Local Cohort Effect for Cancer Mortality Data Using a Varying Coefficient Model

Tetsuji Tonda, Kenichi Satoh, Ken-ichi Kamo

JOURNAL OF EPIDEMIOLOGY ( JAPAN EPIDEMIOLOGICAL ASSOC ) 25 ( 10 ) 639 - 646 2015年 [査読有り]

Background: Cancer mortality is increasing with the aging of the population in Japan. Cancer information obtained through feasible methods is therefore becoming the basis for planning effective cancer control programs. There are three time-related factors affecting cancer mortality, of which the cohort effect is one. Past descriptive epidemiologic studies suggest that the cohort effect is not negligible in cancer mortality. Methods: In this paper, we develop a statistical method for automatically detecting a cohort effect and assessing its statistical significance for cancer mortality data using a varying coefficient model. Results: The proposed method was applied to liver and lung cancer mortality data on Japanese men for illustration. Our method detected significant positive or negative cohort effects. The relative risk was 1.54 for liver cancer mortality in the cohort born around 1934 and 0.83 for lung cancer in the cohort born around 1939. Conclusions: Cohort effects detected using the proposed method agree well with previous descriptive epidemiologic findings. In addition, the proposed method is expected to be sensitive enough to detect smaller, previously undetected birth cohort effects.

Strength estimation of a moving (125)Iodine source during implantation in brachytherapy: application to linked sources

Kenichi Tanaka, Satoru Endo, Kunihiko Tateoka, Osamu Asanuma, Masakazu Hori, Masaru Takagi, Gerard Bengua, Ken-ichi Kamo, Kaori Sato, Hiromitsu Takeda, Masato Hareyama, Koh-ichi Sakata, Jun Takada

JOURNAL OF RADIATION RESEARCH ( OXFORD UNIV PRESS ) 55 ( 6 ) 1146 - 1152 2014年11月 [査読有り]

This study sought to demonstrate the feasibility of estimating the source strength during implantation in brachytherapy. The requirement for measuring the strengths of the linked sources was investigated. The utilized sources were I-125 with air kerma strengths of 8.38-8.63 U (mu Gy m(2) h(-1)). Measurements were performed with a plastic scintillator (80 mm x 50 mm x 20 mm in thickness). For a source-to-source distance of 10.5 mm and at source speeds of up to 200 mm s(-1), a counting time of 10 ms and a detector-to-needle distance of 5 mm were found to be the appropriate measurement conditions. The combined standard uncertainty (CSU) with the coverage factor of 1 (k = 1) was similar to 15% when using a grid to decrease the interference by the neighboring sources. Without the grid, the CSU (k = 1) was similar to 5%, and an 8% overestimation due to the neighboring sources was found to potentially cause additional uncertainty. In order to improve the accuracy in estimating source strength, it is recommended that the measurment conditions should be optimized by considering the tradeoff between the overestimation due to the neighboring sources and the intensity of the measured value, which influences the random error.

Serological Surveillance Development for Tropical Infectious Diseases Using Simultaneous Microsphere-Based Multiplex Assays and Finite Mixture Models

Yoshito Fujii, Satoshi Kaneko, Samson Muuo Nzou, Matilu Mwau, Sammy M. Njenga, Chihiro Tanigawa, James Kimotho, Anne Wanjiru Mwangi, Ibrahim Kiche, Sohkichi Matsumoto, Mamiko Niki, Mayuko Osada-Oka, Yoshio Ichinose, Manabu Inoue, Makoto Itoh, Hiroshi Tachibana, Kazunari Ishii, Takafumi Tsuboi, Lay Myint Yoshida, Dinesh Mondal, Rashidul Haque, Shinjiro Hamano, Mwatasa Changoma, Tomonori Hoshi, Ken-ichi Kamo, Mohamed Karama, Masashi Miura, Kenji Hirayama

PLOS NEGLECTED TROPICAL DISEASES ( PUBLIC LIBRARY SCIENCE ) 8 ( 7 ) 1 - 15 2014年07月 [査読有り]

Background: A strategy to combat infectious diseases, including neglected tropical diseases (NTDs), will depend on the development of reliable epidemiological surveillance methods. To establish a simple and practical seroprevalence detection system, we developed a microsphere-based multiplex immunoassay system and evaluated utility using samples obtained in Kenya. Methods: We developed a microsphere-based immuno-assay system to simultaneously measure the individual levels of plasma antibody (IgG) against 8 antigens derived from 6 pathogens: Entamoeba histolytica (C-IgL), Leishmania donovani (KRP42), Toxoplasma gondii (SAG1), Wuchereria bancrofti (SXP1), HIV (gag, gp120 and gp41), and Vibrio cholerae (cholera toxin). The assay system was validated using appropriate control samples. The assay system was applied for 3411 blood samples collected from the general population randomly selected from two health and demographic surveillance system (HDSS) cohorts in the coastal and western regions of Kenya. The immunoassay values distribution for each antigen was mathematically defined by a finite mixture model, and cut-off values were optimized. Findings: Sensitivities and specificities for each antigen ranged between 71 and 100%. Seroprevalences for each pathogen from the Kwale and Mbita HDSS sites (respectively) were as follows: HIV, 3.0% and 20.1%; L. donovani, 12.6% and 17.3%; E. histolytica, 12.8% and 16.6%; and T. gondii, 30.9% and 28.2%. Seroprevalences of W. bancrofti and V. cholerae showed relatively high figures, especially among children. The results might be affected by immunological cross reactions between W. bancrofti-SXP1 and other parasitic infections; and cholera toxin and the enterotoxigenic E. coli (ETEC), respectively. Interpretation: A microsphere-based multi-serological assay system can provide an opportunity to comprehensively grasp epidemiological features for NTDs. By adding pathogens and antigens of interest, optimized made-to-order high-quality programs can be established to utilize limited resources to effectively control NTDs in Africa.

A dosimetry method for low dose rate brachytherapy by EGS5 combined with regression to reflect source strength shortage

Kenichi Tanaka, Kunihiko Tateoka, Osamu Asanuma, Ken-ichi Kamo, Kaori Sato, Hiromitsu Takeda, Masaru Takagi, Masato Hareyama, Jun Takada

JOURNAL OF RADIATION RESEARCH ( OXFORD UNIV PRESS ) 55 ( 3 ) 608 - 612 2014年05月 [査読有り]

The post-implantation dosimetry for brachytherapy using Monte Carlo calculation by EGS5 code combined with the source strength regression was investigated with respect to its validity. In this method, the source strength for the EGS5 calculation was adjusted with the regression, so that the calculation would reproduce the dose monitored with the glass rod dosimeters (GRDs) on a water phantom. The experiments were performed, simulating the case where one of two I-125 sources of Oncoseed 6711 was lacking strength by 4-48%. As a result, the calculation without regression was in agreement with the GRD measurement within 26-62%. In this case, the shortage in strength of a source was neglected. By the regression, in order to reflect the strength shortage, the agreement was improved up to 17-24%. This agreement was also comparable with accuracy of the dose calculation for single source geometry reported previously. These results suggest the validity of the dosimetry method proposed in this study.

Short-Term Projection of Cancer Incidence in Japan Using an AgePeriod Interaction Model with Spline Smoothing

Kota Katanoda, Ken-Ichi Kamo, Kumiko Saika, Tomohiro Matsuda, Akiko Shibata, Ayako Matsuda, Yoshikazu Nishino, Masakazu Hattori, Midori Soda, Akiko Ioka, Tomotaka Sobue, Hiroshi Nishimoto

JAPANESE JOURNAL OF CLINICAL ONCOLOGY ( OXFORD UNIV PRESS ) 44 ( 1 ) 36 - 41 2014年01月 [査読有り]

In Japan, population-based cancer incidence data are reported several years behind the latest year of cancer mortality data. To bridge this gap, we aimed to determine a short-term projection method for cancer incidence. Data between 1985 and 2007 were obtained from the population-based cancer registries in four prefectures (Miyagi, Yamagata, Fukui and Nagasaki). Three projection models were examined: generalized linear model with age and period (A P linear); generalized linear model with age, period and their interactions (AP linear); and generalized additive model with age, period and their interactions smoothed by spline (AP spline). We performed a 5-year projection for the years 2000 and 2005, based on the data of 198595 and 19852000, respectively. Seven cancer sites (stomach, liver, colorectal, lung, female breast, cervix uteri and prostate) and all cancers combined were analyzed. The accuracy of projection was evaluated by whether each observed number fell within the 95 confidence interval of the projected number. The AP spline model accurately projected 8 of 13 cancer sitesex combinations, whereas the number of sitesex combinations of accurate projection was 2 and 6 for A P linear and AP linear models, respectively. For liver and colorectal cancers, the AP spline model alone performed accurate projections; the relative differences between projected and observed numbers of cancer incidence ranged between 0.4 and 10.9 for the AP spline, and between 7.4 and 37.6 for the other two models. All three models failed to project sudden increases in prostate cancer between 2000 and 2005. The AP spline model is a candidate method for the projection of cancer incidence in Japan. However, we need a continuous validation for prostate cancer.

Measurement of the strength of iodine-125 seed moving at unknown speed during implantation in brachytherapy

Kenichi Tanaka, Satoru Endo, Kunihiko Tateoka, Osamu Asanuma, Ken-ichi Kamo, Kaori Sato, Hiromitsu Takeda, Masaru Takagi, Masato Hareyama, Jun Takada

JOURNAL OF RADIATION RESEARCH ( OXFORD UNIV PRESS ) 55 ( 1 ) 162 - 167 2014年01月 [査読有り]

The aim of this study is to demonstrate the feasibility of estimating the strength of the moving radiation source during patient implantation. The requirement for the counting time was investigated by comparing the results of the measurements for the static source with those for the source moving at 2, 5, 10 and 20 cm s(-1). The utilized source was I-125 with an air-kerma strength of 0.432 U (mu Gym(2)h(-1)). The detector utilized was a plastic scintillation detector (8 cm x 5 cm x 2 cm in thickness) set at 8 cm away from the needle to guide the source. Experiments were conducted in order to determine the most desirable counting time. Analysis using the maximum of the measured values while the source passed through the needle indicated that the results for the moving source increased more than those for the static source as the counting time decreased. The combined standard uncertainty, with the coverage factor of 1, was within 4% at the counting time of 100 ms. This investigation supported the feasibility of the method proposed for estimating the source strength during the implantation procedure, regardless of the source speed. The method proposed is a potential option for reducing the risk of accidental replacements of sources with those of incorrect strengths.

Benchmark of EGS5 for 125I brachytherapy

K.Tanaka, K.Tateoka, O.Asanuma, K.Kamo, K.Sato, H.Takeda, M.Takagi, M.Hareyama, J.Takada

Progress in Nuclear Science and Technology 4 888 - 890 2014年 [査読有り]

Bias-corrected AIC for selecting variables in poisson regression models

Ken-Ichi Kamo, Hirokazu Yanagihara, Kenichi Satoh

Communications in Statistics - Theory and Methods 42 ( 11 ) 1911 - 1921 2013年06月 [査読有り]

担当区分：筆頭著者 , 責任著者

In the present article, we consider the variable selection problem in Poisson regression models. Akaike's information criterion (AIC) is the most commonly applied criterion for selecting variables. However, the bias of the AIC cannot be ignored, especially in small samples. We herein propose a new bias-corrected version of the AIC that is constructed by stochastic expansion of the maximum likelihood estimator. The proposed information criterion can reduce the bias of the AIC from O(n-1) to O(n-2). The results of numerical investigations indicate that the proposed criterion is better than the AIC. © 2013 Taylor & Francis Group, LLC.

Comparative analysis on selecting growth function based on three different information criteria for the purpose of carbon estimation

Ken-Ichi Kamo, Atsushi Yoshimoto

Forest Science and Technology 9 ( 2 ) 65 - 71 2013年06月 [査読有り]

担当区分：筆頭著者 , 責任著者

Growth models are in general constructed by some kind of mathematical function, so-called "growth function". Since there are several possible growth functions, the first task for the growth analysis is to select the most suitable growth function for the target data among candidates. In this paper, three statistical procedures are presented and compared on the basis of the information criterion for the purpose of selecting a growth function. A demonstrative example is provided to show how the three statistical procedures differ and select different growth functions for the same growth data, and how differently the amount of carbon sequestrated in a forest stand is affected by the selected growth function. © 2013 Copyright Taylor and Francis Group, LLC.

Comparative analysis of growth functions based on Mallows’ Cp type criterion

K.Kamo, A.Yoshimoto

Forest Resource Management and Mathematical Modeling 12 133 - 147 2013年 [査読有り]

担当区分：筆頭著者 , 責任著者

離散データに対する回帰モデルによる冠雪害の解析

加茂憲一, 嘉戸昭夫, 吉本敦

統計数理 ( 統計数理研究所 ) 61 ( 2 ) 189 - 200 2013年 [査読有り]

担当区分：筆頭著者 , 責任著者

Clinical and genetic analysis of microtia in Japan

Makoto Yamauchi, Takatoshi Yotsuyanagi, Kanae Ikeda, Mayu Yoshikawa, Satoshi Urushidate, Makoto Mikami, Kenichi Kamo

JOURNAL OF PLASTIC SURGERY AND HAND SURGERY ( INFORMA HEALTHCARE ) 46 ( 5 ) 330 - 334 2012年10月 [査読有り]

担当区分：最終著者

Microtia is thought to have a multifactorial inheritance, but several investigators disagree. Here we report our survey of the hereditary factors and possible causes. We conducted a questionnaire survey of 428 patients with microtia who were being treated at two hospitals from September 2006 to September 2008. We recorded their age, sex, affected side, duration of gestation, birth weight, age of parents at patients' birth, accompanying malformations, number of siblings, familial occurrence, smoking habit of parents, and medication/disorders of mother during pregnancy, and analysed the results. There were preponderances of male (61%), unilateral (90%) and right-sided disease (59%). Other than the first and second branchial arch syndrome, microtia is often accompanied by other congenital deformities, in particular congenital heart disease; cleft lip, or palate, or both; vertebral defects; and anomalies of extremities. The occurrence in first-degree relatives was 2%. Most maternal disorders and medication taken during pregnancy were common and there was no clear link. Statistically, there was a tendency to low birth weight and high maternal age, but it is not possible to identify these as a specific cause of microtia. Multifactorial inheritance is unlikely to be the cause of microtia as there was only one finding in agreement with its widely accepted characteristics. However, we cannot completely discount it as there were too few cases in some groups to make a judgement.

Bias-corrected AIC for selecting variables in multinomial logistic regression models

Hirokazu Yanagihara, Ken-ichi Kamo, Shinpei Imori, Kenichi Satoh

LINEAR ALGEBRA AND ITS APPLICATIONS ( ELSEVIER SCIENCE INC ) 436 ( 11 ) 4329 - 4341 2012年06月 [査読有り]

In this paper, we consider the bias correction of Akaike's information criterion (AIC) for selecting variables in multinomial logistic regression models. For simplifying a formula of the bias-corrected AIC, we calculate the bias of the AIC to a risk function through the expectations of partial derivatives of the negative log-likelihood function. As a result, we can express the bias correction term of the bias-corrected AIC with only three matrices consisting of the second, third, and fourth derivatives of the negative log-likelihood function. By conducting numerical studies, we verify that the proposed bias-corrected AIC performs better than the crude AIC. (C) 2012 Elsevier Inc. All rights reserved.

MEM spectral analysis for predicting influenza epidemics in Japan

Ayako Sumi, Ken-Ichi Kamo

Environmental Health and Preventive Medicine 17 ( 2 ) 98 - 108 2012年03月 [査読有り]

担当区分：最終著者

Objectives The prediction of influenza epidemics has long been the focus of attention in epidemiology and mathematical biology. In this study, we tested whether time series analysis was useful for predicting the incidence of influenza in Japan. Methods The method of time series analysis we used consists of spectral analysis based on the maximum entropy method (MEM) in the frequency domain and the nonlinear least squares method in the time domain. Using this time series analysis, we analyzed the incidence data of influenza in Japan from January 1948 to December 1998 these data are unique in that they covered the periods of pandemics in Japan in 1957, 1968, and 1977. Results On the basis of the MEM spectral analysis, we identified the periodic modes explaining the underlying variations of the incidence data. The optimum least squares fitting (LSF) curve calculated with the periodic modes reproduced the underlying variation of the incidence data. An extension of the LSF curve could be used to predict the incidence of influenza quantitatively. Conclusions Our study suggested that MEM spectral analysis would allow us to model temporal variations of influenza epidemics with multiple periodic modes much more effectively than by using the method of conventional time series analysis, which has been used previously to investigate the behavior of temporal variations in influenza data. © The Japanese Society for Hygiene 2011.

Cancer Incidence and Incidence Rates in Japan in 2006: Based on Data from 15 Population-based Cancer Registries in the Monitoring of Cancer Incidence in Japan (MCIJ) Project

Tomohiro Matsuda, Tomomi Marugame, Ken-ichi Kamo, Kota Katanoda, Wakiko Ajiki, Tomotaka Sobue

JAPANESE JOURNAL OF CLINICAL ONCOLOGY ( OXFORD UNIV PRESS ) 42 ( 2 ) 139 - 147 2012年02月 [査読有り]

The Japan Cancer Surveillance Research Group estimated the cancer incidence in 2006 as part of the Monitoring of Cancer Incidence in Japan (MCIJ) project, on the basis of data collected from 15 of 32 population-based cancer registries. The total number of incidences in Japan for 2006 was estimated as 664 398 (C00-C96). The leading cancer site was stomach for men and breast for women. Age-standardized incidence rates remained at almost the same level as for the previous 3 years.

Verification of dose calculation for brachytherapy using EGS5

K. Tanaka, K. Tateoka, O. Asanuma, K. Kamo, K. Sato, H. Takeda, M. Takagi, M. Hareyama, J. Takada

Proceedings of the 19th EGS Users' Meeting in Japan 94 - 97 2012年

The dose obtained from measurement with a radiophotoluminescent glass rod dosimeter (GRD) was compared to the dose calculated with the Monte Carlo (MC) code 'EGS5,' using 125I source structures for model STM1251 and Oncoceed 6711. Some of the GRD positions were so close to the phantom surface that the backscatter margin was less than 5 cm, insufficient for photons. Consequently, the agreement between the MC calculation and GRD measurement support the validity of both methods.

Survival analysis and tree failure: Results from a tree-pulling experiment

Kamo Kenichi

Forest Resource Management and Mathematical Modeling 11 195 - 209 2012年 [査読有り]

担当区分：筆頭著者 , 責任著者

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