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Search Results: 1 - 10 of 1544 matches for " Masao Nakagawa "
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Asset Pricing with Stochastic Habit Formation  [PDF]
Masao Nakagawa
Journal of Mathematical Finance (JMF) , 2012, DOI: 10.4236/jmf.2012.22018
Abstract: This paper examines optimal consumption/portfolio choices under stochastic habit formation in which it is uncertain how deep consumers would become in the habit of consuming in future. By extending Shroder and Skiadas [1] to stochastic habit formation, the optimization problem with stochastic habit forming preferences is transformed into that with simple time-additive preferences. Optimal portfolios are composed of the tangency portfolio and habit hedging portfolio. Resulting risk premia are characterized by consumption beta, which is proportionate to the covariance with consumption changes, and habit beta, defined by using the covariance with habit.
Notes on Economic Growth with Scale Effects: Is Depopulation Compatible with Growth?  [PDF]
Masao Nakagawa, Asuka Oura, Yoshiaki Sugimoto
Theoretical Economics Letters (TEL) , 2015, DOI: 10.4236/tel.2015.52021
Abstract: This research develops a simple theory to analyze the compatibility of depopulation and sustainable growth. By introducing the scale effect of aggregate rather than average human capital, it shows that the economy may enter a sustainable growth path with fertility recovery, keeping away from a non-Malthusian poverty trap.
Thoracic Duct Cyst of the Anterior Mediastinum  [PDF]
Masao Saito, Tatsuo Nakagawa, Naohisa Chiba, Yasuto Sakaguchi, Shinya Ishikawa
Open Journal of Thoracic Surgery (OJTS) , 2014, DOI: 10.4236/ojts.2014.44017
Abstract: Mediastinal thoracic duct cyst is a rare benign cystic disease. The lesion is generally in the post-erior or superior mediastinum, where the thoracic duct passes. We herein report an extremely rare case of surgically resected anterior mediastinal thoracic duct cyst. A thoracic duct cyst should be considered as an uncommon differential diagnosis of an anterior mediastinal lesion.
Surgical Treatment for Mediastinal Lymph Node Carcinoma of Unknown Primary  [PDF]
Masao Saito, Tatsuo Nakagawa, Naohisa Chiba, Yasuto Sakaguchi, Shinya Ishikawa
Open Journal of Thoracic Surgery (OJTS) , 2014, DOI: 10.4236/ojts.2014.44018
Abstract: Carcinoma of unknown primary (CUP) is occasionally encountered in clinical oncology. Wide variation exists in CUP. We herein report a rare case of CUP of a mediastinal lymph node. A 61-year-old man with dermatomyositis was referred to our hospital for treatment of mediastinal adenopathy and gastric cancer. Biopsy of both lesions showed that they were histologically different from each other. Mediastinal lymphadenectomy and total gastrectomy were performed for a definitive diagnosis and radical cure. Pathological examination revealed two distinctly different disease processes. The patient underwent postoperative chemotherapy for residual gastric cancer. Twenty months postoperatively, he is alive with cancer. Although CUP usually has a poor prognosis, surgical treatment of metastatic mediastinal lymph node CUP is a feasible therapeutic option.
An Autonomous Selective Cooperative ARQ Protocol for Hybrid Mobile Wireless Sensor Networks
Nandar Lynn,Takyu Osamu,Adachi Koichi,Nakagawa Masao
Journal of Communications , 2011, DOI: 10.4304/jcm.6.2.157-167
Abstract: This paper presents a new cooperative ARQ protocol for a hybrid mobile wireless sensor network. The mobile relay nodes decode the signal from the source sensor using cyclic redundancy check (CRC) and forward it to the destination sink. A distributed relay selection that exploits overhearing of inter-relay node transmission is employed to achieve higher selection diversity gain during retransmissions. Upon reception from the source sensor, the number of relay nodes available to contend for transmission depends on the conditions of source-relay channels. When source-relay channels are instantaneously poor, achievable selection diversity gain decreases. Such relay availability dependency over source-relay channels can be reduced if erroneous relays exploit inter-relay channels to opportunistically listen (OL) to the transmission of the error-free selected relay. By combining the initially received erroneous signals with the signal overheard from the selected relay and decoding again, erroneous relays may be able to decode the signals successfully thanks to the spatial diversity. This results in an increase in relay availability for distributed selection in subsequent retransmissions. It is also shown that the selection protocol based on end to end channel quality approach cannot make full use of the increased relay availability. The proposed cooperative ARQ protocol ensures to make full use of the increased relay availability. The numerical results show that the proposed cooperative ARQ significantly improves the successful packet arrival rate.
Gastric-and-Intestinal Mixed Intestinal Metaplasia Is Irreversible Point with Eradication of Helicobacter pylori  [PDF]
Yuka Kiriyama, Tomomitsu Tahara, Tomoyuki Shibata, Masaaki Okubo, Mitsuru Nakagawa, Asako Okabe, Naoki Ohmiya, Makoto Kuroda, Atsushi Sugioka, Masao Ichinose, Masae Tatematsu, Tetsuya Tsukamoto
Open Journal of Pathology (OJPathology) , 2016, DOI: 10.4236/ojpathology.2016.62012
Abstract: Helicobacter pylori (H. pylori) represents an important factor in the development of atrophic gastritis, intestinal metaplasia (IM), and gastric cancer. Eradication of H. pylori has been reported to prevent gastric cancer only in cases without atrophy or IM. However, histological changes with eradication have yet to be fully clarified. We evaluated 38 H. pylori-positive cases before and after eradication at the gland level; pyloric glands were classified as showing gastric proper (G) and IM gland types, with the latter including gastric-and-intestinal mixed IM (GI-IM) and solely intestinal IM (I-IM), depending on the remaining gastric phenotypes. On eradication, acute and chronic inflammation attenuated rapidly and gradually, respectively, whereas levels of MUC5AC and MUC6 expression were not markedly altered. Gland width, size of nuclei and cytoplasm and their ratio in surface foveolar epithelium, the number of Ki-67-positive cells and the length of the proliferating zone in each gland were significantly decreased in G glands after eradication compared with those in GI-IM and I-IM. The number of mitotic phase cells, positive for phosphorylated histone H3 at serine 28, was increased in both types of IM compared to that in G glands in the H. pylori-infected state, but unexpectedly remained unchanged with eradication. These results suggest that GI-IM, as the beginning of IM, could represent a histological irreversible point with eradication and be considered as a “histological point of no return”.
HTLV-1 modulates the frequency and phenotype of FoxP3+CD4+ T cells in virus-infected individuals
Yorifumi Satou, Atae Utsunomiya, Junko Tanabe, Masanori Nakagawa, Kisato Nosaka, Masao Matsuoka
Retrovirology , 2012, DOI: 10.1186/1742-4690-9-46
Abstract: To investigate the effect of HTLV-1 infection on CD4+ T-cell subsets, we used flow cytometry to analyze the T-cell phenotype and HTLV-1 infection in peripheral mononuclear cells (PBMCs) of four groups of subjects, including 23 HTLV-1-infected asymptomatic carriers (AC), 10 patients with HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP), 10 patients with adult T-cell leukemia (ATL), and 10 healthy donors. The frequency of FoxP3+ cells in CD4+ T cells in AC with high proviral load and patients with HAM/TSP or ATL was higher than that in uninfected individuals. The proviral load was positively correlated with the percentage of CD4+ T cells that were FoxP3+. The CD4+FoxP3+ T cells, themselves, were frequently infected with HTLV-1. We conclude that FoxP3+ T- cells are disproportionately infected with HTLV-1 during chronic infection. We next focused on PBMCs of HAM/TSP patients. The expression levels of the Treg associated molecules CTLA-4 and GITR were decreased in CD4+FoxP3+ T cells. Further we characterized FoxP3+CD4+ T-cell subsets by staining CD45RA and FoxP3, which revealed an increase in CD45RA?FoxP3low non-suppressive T-cells. These findings can reconcile the inflammatory phenotype of HAM/TSP with the observed increase in frequency of FoxP3+ cells. Finally, we analyzed ATL cells and observed not only a high frequency of FoxP3 expression but also wide variation in FoxP3 expression level among individual cases.HTLV-1 infection induces an abnormal frequency and phenotype of FoxP3+CD4+ T cells.
Novel Cathode Materials for Sodium Ion Batteries Derived from Layer Structured Titanate Cs2Ti5O11·(1 + x)H2O  [PDF]
Masao Ohashi
Materials Sciences and Applications (MSA) , 2018, DOI: 10.4236/msa.2018.96037
Abstract: A layer structured titanate Cs2Ti5O11·(1 + x)H2O (x = 0.70) has been prepared in a solid state reaction using Cs2CO3 and anatase type TiO2 at 900°C. Ion exchange reactions of Cs+ in the interlayer space were studied in aqueous solutions. The single phases of Li+, Na+ and H+ exchange products were obtained. The three kinds of resulting titanates were evaluated for use as the cathodes in rechargeable sodium batteries after dehydrations by heating at 200°C in a vacuum. The electrochemical measurements showed that they exhibited the reversible Na+ intercalation-deintercalation in a voltage range of 0.5 - 3.5 V or 0.7 - 4.0 V. The Li+ exchange product showed the best performance of the discharge-charge capacities in this study. The initial Na+ intercalation-deintercalation capacities of the Li2Ti5O11 were 120 mAh/g and 100 mAh/g; the amounts of Na+ correspond to 1.9 and 1.6 of the formula unit, respectively. The titanates are nontoxic, inexpensive and environmentally benign.
Molecular Mechanisms of the Whole DNA Repair System: A Comparison of Bacterial and Eukaryotic Systems
Rihito Morita,Shuhei Nakane,Atsuhiro Shimada,Masao Inoue,Hitoshi Iino,Taisuke Wakamatsu,Kenji Fukui,Noriko Nakagawa,Ryoji Masui,Seiki Kuramitsu
Journal of Nucleic Acids , 2010, DOI: 10.4061/2010/179594
Abstract: DNA is subjected to many endogenous and exogenous damages. All organisms have developed a complex network of DNA repair mechanisms. A variety of different DNA repair pathways have been reported: direct reversal, base excision repair, nucleotide excision repair, mismatch repair, and recombination repair pathways. Recent studies of the fundamental mechanisms for DNA repair processes have revealed a complexity beyond that initially expected, with inter- and intrapathway complementation as well as functional interactions between proteins involved in repair pathways. In this paper we give a broad overview of the whole DNA repair system and focus on the molecular basis of the repair machineries, particularly in Thermus thermophilus HB8. 1. Introduction It is essential for all living organisms to warrant accurate functioning and propagation of their genetic information. However, the genome is constantly exposed to various environmental and endogenous agents, which produce a large variety of DNA lesions (Figure 1) [1, 2]. Environmental damage can be induced by several chemical reactive species and physical agents. Endogenous damages occur spontaneously and continuously even under normal physiologic conditions through intrinsic instability of chemical bonds in DNA structure. The biological consequences of these damages usually depend on the chemical nature of the lesion. Most of these lesions affect the fidelity of DNA replication, which leads to mutations. Some of human genetic diseases are associated to defects in DNA repair (Table 1). Table 1: Distribution of DNA repair genes. Related human diseases are listed by referencing the following databases: KEGG disease ( http://www.genome.jp/kegg/disease/), GeneCards ( http://www.genecards.org/), and Online Mendelian Inheritance in Man ( http://www.ncbi.nlm.nih.gov/omim). Descriptions in the parentheses indicate the subunit organizations of holoenzymes. Figure 1: Different repair systems for the principal types of DNA lesion produced by a wide range of factors. UV-light induces cyclobutane pyrimidine dimers or (6-4) photoproducts that are repaired by nucleotide excision repair and direct reversal systems. Alkylating agents can modify all of the bases and the phosphates of the DNA, and some repair proteins remove these alkyl adducts in a direct manner. Oxygen radicals modify DNA, and the base excision repair system acts to reverse these changes. The main cause of spontaneous mutation is deamination, and base excision repair and alternative repair systems remove the lesions. Other bulky adducts or interstrand
Exceptionally high incidence of symptomatic grade 2–5 radiation pneumonitis after stereotactic radiation therapy for lung tumors
Hideomi Yamashita, Keiichi Nakagawa, Naoki Nakamura, Hiroki Koyanagi, Masao Tago, Hiroshi Igaki, Kenshiro Shiraishi, Nakashi Sasano, Kuni Ohtomo
Radiation Oncology , 2007, DOI: 10.1186/1748-717x-2-21
Abstract: From May 2004 to April 2006, 25 patients were treated with SRT at the University of Tokyo Hospital. Eighteen patients had primary lung cancer and seven had metastatic lung cancer. SRT was given in 6–7 fields with an isocenter dose of 48 Gy in four fractions over 5–8 days by linear accelerator.Seven of the 25 patients suffered from RP of symptomatic grade 2–5 according to the NCI-CTC version 3.0. The overall incidence rate of RP grade2 or more was 29% at 18 months after completing SRT and three patients died from RP. RP occurred at significantly increased frequencies in patients with higher conformity index (CI) (p = 0.0394). Mean lung dose (MLD) showed a significant correlation with V5–V20 (irradiated lung volume) (p < 0.001) but showed no correlation with CI. RP did not statistically correlate with MLD. MLD had the strongest correlation with V5.Even in SRT, when large volumes of lung parenchyma are irradiated to such high doses as the minimum dose within planning target volume, the incidence of lung toxicity can become high.Since 1990, stereotactic radiotherapy (SRT) has been widely available for the treatment of intracranial lesions. Recently, the use of SRT has gradually been expanded to include the treatment of extra-cranial lesions. In particular, SRT has been demonstrated as a safe and effective modality in the treatment of primary and metastatic lung tumors [1]. Initial clinical results were favorable, and local control rates around 90% have been reported [1-9]. Since May 2004, we have employed SRT for body trunk tumors using a simple body cast system at the University of Tokyo Hospital.Regarding normal tissue, the use of a single dose rather than a conventional fractionated dose may increase the risk of complications. However, few cases with severe toxicity have been reported [10].A few patients undergoing high-dose SRT suffered from RP, which was treated by administration of steroids. The percentage of total lung volume receiving greater than or equal to 20
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