142 results on '"Naoki, Ishikawa"'
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52. Unified Differential Spatial Modulation.
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Naoki Ishikawa and Shinya Sugiura
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- 2014
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53. Quantum Algorithm for Higher-Order Unconstrained Binary Optimization and MIMO Maximum Likelihood Detection
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Masaya Norimoto, Ryuhei Mori, and Naoki Ishikawa
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Signal Processing (eess.SP) ,Quantum Physics ,FOS: Electrical engineering, electronic engineering, information engineering ,FOS: Physical sciences ,Electrical and Electronic Engineering ,Electrical Engineering and Systems Science - Signal Processing ,Quantum Physics (quant-ph) - Abstract
In this paper, we propose a quantum algorithm that supports a real-valued higher-order unconstrained binary optimization (HUBO) problem. This algorithm is based on the Grover adaptive search that originally supported HUBO with integer coefficients. Next, as an application example, we formulate multiple-input multiple-output maximum likelihood detection as a HUBO problem with real-valued coefficients, where we use the Gray-coded bit-to-symbol mapping specified in the 5G standard. The proposed approach allows us to construct an efficient quantum circuit for the detection problem and to analyze specific numbers of required qubits and quantum gates, whereas other conventional studies have assumed that such a circuit is feasible as a quantum oracle. To further accelerate the quantum algorithm, we also derive a probability distribution of the objective function value and determine a unique threshold to sample better states. Assuming a future fault-tolerant quantum computing, our proposed algorithm has the potential for significantly reducing query complexity in the classical domain and providing a quadratic speedup in the quantum domain., 14 pages, 14 figures, accepted for publication in IEEE Transactions on Communications more...
- Published
- 2022
54. Artificially Time-Varying Differential MIMO for Achieving Practical Physical Layer Security
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Eiji Okamoto, Jehad M. Hamamreh, Lixia Xiao, Naoki Ishikawa, and Chao Xu
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differential space-time block codes ,Computer science ,MIMO ,Chaotic ,Physical layer ,physical layer security ,TK5101-6720 ,differential modulation ,Encoding (memory) ,Key (cryptography) ,Telecommunication ,chaos theory ,Differential (infinitesimal) ,physical layer encryption ,Differential coding ,Algorithm ,Transportation and communications ,Communication channel ,HE1-9990 - Abstract
In this paper, we propose a differential multiple-input multiple-output (MIMO) scheme based on the novel concept of chaos-based time-varying unitary matrices to demonstrate—for the first time in the literature—the ability of differential encoding in achieving practical physical layer security even without the need for using channel estimation. In the proposed scheme, an erroneous secret key, which is extracted from the wireless nature, is used to initialize a chaos sequence that is responsible for generating artificially time-varying unitary matrices capable of obfuscating the transmitted data symbols from illegitimate eavesdroppers. Contrary to conventional studies, the key agreement ratio in this study is assumed to be imperfect, which is often true and very realistic in high-mobility scenarios. Following this, we conceive a new calibration algorithm for reconciling the chaotic sequence generated at the legitimate parties, thus making this calibration algorithm a unique, novel solution to the key sharing problem of conventional chaos-based communication techniques, which has been overlooked over the past few decades. It is found out that differential encoding obviates additional complexity and insecurity in dealing with channel estimation, whereas an eavesdropper must tackle the complicated differentially encoded patterns, which have an exponentially increasing complexity order. In addition, the obtained simulation results demonstrate that the proposed scheme can outperform conventional chaos-based MIMO schemes that assume perfect channel knowledge. more...
- Published
- 2021
55. Noncoherent Massive MIMO with Embedded One-Way Function Physical Layer Security
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Yuma Katsuki, Giuseppe Thadeu Freitas de Abreu, Koji Ishibashi, and Naoki Ishikawa
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Signal Processing (eess.SP) ,Computer Networks and Communications ,FOS: Electrical engineering, electronic engineering, information engineering ,Electrical Engineering and Systems Science - Signal Processing ,Safety, Risk, Reliability and Quality ,Computer Science::Information Theory - Abstract
We propose a novel physical layer security scheme that exploits an optimization method as a one-way function. The proposed scheme builds on nonsquare differential multiple-input multiple-output (MIMO), which is capable of noncoherent detection even in massive MIMO scenarios and thus resilient against risky pilot insertion and pilot contamination attacks. In contrast to conventional nonsquare differential MIMO schemes, which require space-time projection matrices designed via highly complex, discrete, and combinatorial optimization, the proposed scheme utilizes projection matrices constructed via low-complexity continuous optimization designed to maximize the coding gain of the system. Furthermore, using a secret key generated from the true randomness nature of the wireless channel as an initial value, the proposed continuous optimization-based projection matrix construction method becomes a one-way function, making the proposed scheme a physical layer secure differential MIMO system. An attack algorithm to challenge the proposed scheme is also devised, which demonstrates that the security level achieved improves as the number of transmit antennas increases, even in an environment where the eavesdropper can perfectly estimate channel coefficients and experience asymptotically large signal-to-noise ratios., Comment: 13 pages, 10 figures more...
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- 2022
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56. Detection of submitters suspected of pretending to be someone else in a community site.
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Naoki Ishikawa, Ryo Nishimura, Yasuhiko Watanabe, Yoshihiro Okada, and Masaki Murata
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- 2010
57. Differential-Detection Aided Large-Scale Generalized Spatial Modulation is Capable of Operating in High-Mobility Millimeter-Wave Channels
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Lie-Liang Yang, Mohammed El-Hajjar, Rakshith Rajashekar, Chao Xu, Shinya Sugiura, Naoki Ishikawa, and Lajos Hanzo
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Beamforming ,Computer science ,Detector ,020206 networking & telecommunications ,Scale (descriptive set theory) ,02 engineering and technology ,GSM ,Signal Processing ,Extremely high frequency ,0202 electrical engineering, electronic engineering, information engineering ,Electronic engineering ,Overhead (computing) ,Electrical and Electronic Engineering ,Differential (infinitesimal) ,Communication channel - Abstract
A large-scale differential-detection aided generalized spatial modulation (GSM) system is proposed, which relies on a novel Gram-Schmidt basis set and an adaptive low-complexity detector, and is evidently suitable for high-mobility millimeter-wave (mmWave) channels. We consider non-stationary time-varying mmWave channels and assume that the beam-angles remain relatively fixed, while the channel coefficients vary rapidly. In this scenario, it is a challenging task to find the accurate estimates of channel coefficients for digital beamforming, which becomes an even more severe problem, as the numbers of subarrays and subcarriers increase. Our analog-beamforming-aided nonsquare differentially-detected scheme achieves a higher transmission rate than the conventional coherent multiple-input multiple-output schemes because the pilot overhead and the complex-valued feedback are eliminated. Our simulation results following the IEEE 802.11ad specifications show that the performance of our proposed nonsquare differential GSM improved upon increasing the number of subarrays, where the maximum transmission rate of 16 [bps/Hz] was considered. more...
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- 2019
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58. Reply to the Letter to Editor regarding 'Autoimmune hepatitis with history of HCV treatment triggered by COVID‑19 vaccination: case report and literature review'
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Naoyuki Hasegawa, Ryota Matsuoka, Naoki Ishikawa, Masato Endo, Masahiko Terasaki, Emiko Seo, and Kiichiro Tsuchiya
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Gastroenterology ,General Medicine - Published
- 2022
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59. Differentially-encoded rectangular spatial modulation approaches the performance of its coherent counterpart
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Pei Xiao, Yue Xiao, Lajos Hanzo, Hang Ruan, Lei Lu, Lixia Xiao, and Naoki Ishikawa
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Computer science ,Detector ,MIMO ,020206 networking & telecommunications ,020302 automobile design & engineering ,02 engineering and technology ,Moment-generating function ,Spatial modulation ,0203 mechanical engineering ,Modulation ,Channel state information ,0202 electrical engineering, electronic engineering, information engineering ,Electrical and Electronic Engineering ,Differential coding ,Algorithm - Abstract
A simplified rectangular differential spatial modulation (S-RDSM) scheme is conceived for massive multiple-input multiple-output (MIMO) systems dispensing with the channel state information (CSI). In the proposed S-RDSM scheme, the information bits are first mapped to a conventional SM symbol and then rectangular differential encoding is invoked between a pair of SM symbols. Then a non-coherent detector relying on a forgetting factor is developed, which requires no CSI at the receiver. Explicitly, a low-complexity hard limited maximum likelihood (HL-ML) detector is conceived for our generalized S-RDSM scheme, which is characterized by our theoretical analysis. Furthermore, we derive the optimal forgetting factor in closed form, which is capable of significantly reducing the complexity of the associated optimization. Finally, the upper bounds of the average bit error probability (ABEP) are derived using the moment generating function (MGF), and are validated by our simulation results. Both the theoretical and simulation results have shown that the proposed S-RDSM system outperforms the existing non-coherent schemes, despite operating at 10% of the benchmarker’s complexity, whilst approaching the performance of its coherent SM counterpart at a comparable complexity. more...
- Published
- 2020
60. Multiple Input Multiple Output with Antenna Number Modulation and Adaptive Antenna Selection
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Mehmet O. Sagman, Jehad M. Hamamreh, Naoki Ishikawa, Muhammet Kirik, Hamamreh, Jehad M., and 291980 [Hamamreh, Jehad M.]
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Computer science ,MIMO ,Rayleigh Channel ,Wireless communication ,Mekansal modülasyon ,Data_CODINGANDINFORMATIONTHEORY ,Anten numarası modülasyonu ,Uyarlanabilir anten seçimi ,Adaptive antenna selection ,Hardware_GENERAL ,Rayleigh Kanalı ,Electronic engineering ,MIMO-ANM ,Antenna number modulation ,6G ,Computer Science::Information Theory ,BER ,ComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKS ,Spatial modulation ,Transmission (telecommunications) ,Modulation ,Bit error rate ,Antenna (radio) ,Kablosuz iletişim ,Communication channel ,Phase-shift keying ,Data transmission - Abstract
Multiple input multiple output system with antenna number modulation (MIMO-ANM) is proposed in this paper as a novel transmission method that can be used instead of conventional MIMO with spatial modulation (MIMO-SM) for providing more advantageous and reliable data transmission in future wireless systems. In this scheme, the additional data bits are conveyed by changing the number of active transmit antennas instead of their indices while the number of receive antennas is kept singular. As such, MIMO-ANM is different from MIMO-SM as it can make the selection of the antennas in MIMO to be both channel and data dependent at the same time, resulting in what is called MIMO-ANM with adaptive antenna selection (MIMO-ANM-AAS), while MIMO-SM is unable to make the selection of the antennas channel-dependent because the indices of the selected antenna are purely data-dependent. By using such a transmission scheme, the overall reliability of the transmitted data stream can significantly be improved, which characterizes MIMO-ANM-AAS with much lower bit errors compared to MIMO-SM. In this paper, the concepts of MIMO-ANM and MIMO-ANM-AAS are established on the basis of conventional MIMO using binary phase shift keying (BPSK) symbol modulation over a Rayleigh fading channel. The validity of the system is investigated, where analytical and simulation results showing the bit error rate (BER) performance of the system are given. The numerical computer simulations furthermore compare the performances of MIMO-ANM-AAS with MIMO-SM to show its superiority, and the advantages of the concept are discussed. The acquired results show that MIMO-ANM-AAS offers highly reliable and resilient system thanks to its simultaneous bit transmission by different number of active antennas that can be made adaptive to the channel gains. This research was partly funded by TUBITAK under Grant/Award Number 119E392 more...
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- 2020
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61. Finite-Cardinality Single-RF Differential Space-Time Modulation for Improving the Diversity-Throughput Tradeoff
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Naoki Ishikawa, Rakshith Rajashekar, Shinya Sugiura, Peichang Zhang, Lajos Hanzo, Li Wang, and Chao Xu
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Block code ,Computer science ,MIMO ,020206 networking & telecommunications ,020302 automobile design & engineering ,Keying ,Throughput ,02 engineering and technology ,Topology ,Spatial modulation ,0203 mechanical engineering ,Transmission (telecommunications) ,Modulation ,Diversity gain ,Dispersion (optics) ,0202 electrical engineering, electronic engineering, information engineering ,Electrical and Electronic Engineering ,Differential coding ,Throughput (business) ,Phase-shift keying - Abstract
The matrix-based differential encoding invoked by Differential Space-Time Modulation (DSTM) typically results in an infinite-cardinality of arbitrary signals, despite the fact that the Transmit Antennas (TAs) can only radiate a limited number of patterns. As a remedy, the recently developed Differential Spatial Modulation (DSM) is capable of avoiding this problem by conceiving a beneficial sparse signal matrix design, which also facilitates low-complexity single-RF signal transmission. Inspired by this development, the Differential Space-Time Block Code using Index Shift Keying (DSTBC-ISK) further introduces a beneficial diverstiy gain without compromising the DSM's appealingly low transceiver complexity. However, the DSTBC-ISK's performance advantage tends to diminish as the throughput increases, especially when an increased number of Receive Antennas (RAs) is used. By contrast, the classic Differential Group Code (DGC) that actively maximizes its diversity gain for different Multiple-Input Multiple-Output (MIMO) system setups is capable of achieving a superior performance, but its detection complexity grows exponentially with the throughtput. Against this background, we propose the Differential Space-Time Shift Keying using Diagonal Algebraic Space-Time (DSTSK-DAST) scheme, which is the first DSTM that is capable of achieving the DGC's superior diversity gain at high throughputs without compromising the DSM's low transceiver complexity. As a further advance, we also conceive a new Differential Space-Time Shift Keying using Threaded Algebraic Space-Time (DSTSK-TAST) arrangement, which is capable of achieving an even further improved diversity gain at a substantially reduced signal detection complexity compared to the best DGCs. Furthermore, in order to strike a practical tradeoff, we develop a generic multi-element and multi-level-ring Amplitude Phase Shift Keying (APSK) design, and we also arrange for multiple reduced-size DSTM sub-blocks to be transmitted in a permuted manner, which exhibits an improved diversity-throughput tradeoff. more...
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- 2019
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62. Multicarrier Division Duplex Aided Millimeter Wave Communications
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Chao Xu, Lie-Liang Yang, Lajos Hanzo, Rakshith Rajashekar, and Naoki Ishikawa
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Beamforming ,General Computer Science ,Computer science ,General Engineering ,Guard band ,Duplex (telecommunications) ,020206 networking & telecommunications ,02 engineering and technology ,Spectral efficiency ,millimeter wave ,uniform linear array ,multicarrier division duplex ,analog-to-digital converter dynamic range ,020210 optoelectronics & photonics ,Transmission (telecommunications) ,Telecommunications link ,Extremely high frequency ,Full duplex ,0202 electrical engineering, electronic engineering, information engineering ,Electronic engineering ,General Materials Science ,lcsh:Electrical engineering. Electronics. Nuclear engineering ,orthogonal frequency division multiplexing ,lcsh:TK1-9971 ,Communication channel - Abstract
The existing time-division duplex (TDD) and frequency-division duplex (FDD) techniques rely on a guard time and/or a guard band to avoid self-interference (SI) between the uplink and downlink channels, which results in the wastage of precious spectral resources. The full-duplex (FD) schemes of in-band FD (IBFD), as well as multicarrier division duplex (MDD), may overcome this drawback while retaining the key benefits of both TDD and FDD. Moreover, the MDD exhibits the exclusive benefits of the reduced peak-to-average-power ratio (PAPR) for signal transmission as well as the SI-free signal detection. Against this background, in this paper, we propose a novel FD scheme conceived for frequency-selective millimeter-wave (mmWave) channels, which have not been investigated in the open literature. Furthermore, we propose a novel projection-aided iterative eigenvalue decomposition (P-IEVD) algorithm, which performs null-space SI cancellation in the inherent beamforming structure of mmWave communication. Our simulation results confirm that the MDD is capable of outperforming its half-duplex (HD) counterparts of the TDD/FDD, even the IBFD can only achieve a better bandwidth efficiency than the MDD when a sufficiently high SNR is provided. more...
- Published
- 2019
63. Dehydropropylpantothenamide isolated by a co-culture of Nocardia tenerifensis IFM 10554T in the presence of animal cells
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Yasumasa Hara, Kanae Sakai, Naoki Ishikawa, Takashi Yaguchi, Midori A. Arai, Tohru Gonoi, and Masami Ishibashi
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0301 basic medicine ,biology ,Chemistry ,Stereochemistry ,Nocardiosis ,Absolute configuration ,chemistry.chemical_element ,Nocardia ,Calcium ,biology.organism_classification ,medicine.disease ,03 medical and health sciences ,chemistry.chemical_compound ,030104 developmental biology ,Cell culture ,Amide ,medicine ,Molecular Medicine ,Co-Culture ,Nocardia Infections - Abstract
A new amide, named dehydropropylpantothenamide (1), was obtained by a co-culture of Nocardia tenerifensis IFM 10554T in the presence of the mouse macrophage-like cell line J774.1 in modified Czapek-Dox (mCD) medium. Compound 1 was synthesized from D-pantothenic acid calcium salt in 6 steps. The absolute configuration of natural compound 1 was determined by comparisons of the optical rotation and CD spectra of synthetic 1. In the present study, a new method for producing secondary metabolites was demonstrated using a "co-culture" in which the genus Nocardia was cultured in the presence of an animal cell line. more...
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- 2017
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64. Identification of BMI1 Promoter Inhibitors from Beaumontia murtonii and Eugenia operculata
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Masami Ishibashi, Atsushi Iwama, Takashi Koyano, Kazufumi Toume, Midori A. Arai, Naoki Ishikawa, Thaworn Kowithayakorn, Tetsuhiro Chiba, and Yui Kaneta
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0301 basic medicine ,Carcinoma, Hepatocellular ,Blotting, Western ,Cell ,Pharmaceutical Science ,Antineoplastic Agents ,macromolecular substances ,Eugenia ,Analytical Chemistry ,Inhibitory Concentration 50 ,Mice ,03 medical and health sciences ,0302 clinical medicine ,Cancer stem cell ,Cell Line, Tumor ,Drug Discovery ,Murine leukemia virus ,medicine ,Animals ,Humans ,Luciferase ,Polycomb Repressive Complex 1 ,Pharmacology ,Reporter gene ,Molecular Structure ,biology ,Liver Neoplasms ,Organic Chemistry ,HEK 293 cells ,HCT116 Cells ,Thailand ,biology.organism_classification ,Molecular biology ,Triterpenes ,Apocynaceae ,Plant Leaves ,Cardenolides ,HEK293 Cells ,030104 developmental biology ,medicine.anatomical_structure ,Complementary and alternative medicine ,BMI1 ,Cell culture ,030220 oncology & carcinogenesis ,Neoplastic Stem Cells ,Molecular Medicine - Abstract
B-Cell-specific Moloney murine leukemia virus insertion region 1 (BMI1) is a core component of the polycomb repressive complex 1 (PRC1). Abnormal expression of BMI1 is associated with a number of human malignances and cancer stem cells (CSCs), which cause chemotherapy resistance. Therefore, small molecules that inhibit BMI1 expression are potential candidates for cancer therapy. In this study, a cell-based reporter gene assay was developed that allowed BMI1 promoter activity to be measured in 293T human embryonic kidney cells based on luciferase expression levels. Using this screening assay, the methanol-soluble extracts of Beaumontia murtonii and Eugenia operculata were selected as leads. Bioassay-guided fractionation of the extracts led to the isolation of three known cardenolides (1–3) and one new compound (4) from B. murtonii and two known triterpenoids (5 and 6) and one new compound (7) from E. operculata. These seven compounds inhibited BMI1 promoter activity (IC50 range 0.093–23.0 μM), and the most... more...
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- 2017
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65. Nabscessins A and B, Aminocyclitol Derivatives from Nocardia abscessus IFM 10029T
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Kanae Sakai, Tatsuo Nehira, Naoki Ishikawa, Shoko Hara, Yasumasa Hara, Masami Ishibashi, and Tohru Gonoi
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Antifungal ,Antifungal Agents ,medicine.drug_class ,Stereochemistry ,Nocardia abscessus ,Pharmaceutical Science ,Microbial Sensitivity Tests ,010402 general chemistry ,01 natural sciences ,Nocardia ,Analytical Chemistry ,Microbiology ,chemistry.chemical_compound ,RNA, Ribosomal, 16S ,Amide ,Drug Discovery ,medicine ,Ic50 values ,Phylogeny ,Pharmacology ,Cryptococcus neoformans ,Molecular Structure ,biology ,010405 organic chemistry ,Organic Chemistry ,bacterial infections and mycoses ,biology.organism_classification ,0104 chemical sciences ,Actinobacteria ,Aminocyclitol ,Complementary and alternative medicine ,chemistry ,Molecular Medicine ,Cyclitols - Abstract
Two new aminocyclitol amide derivatives, nabscessins A (1) and B (2), were isolated from the culture broth of a pathogenic actinomycete species, Nocardia abscessus IFM 10029T. The structures of nabscessins A and B were elucidated by spectral studies, and the compounds showed antifungal activity against Cryptococcus neoformans, with IC50 values of 32 and 16 μg/mL, respectively. more...
- Published
- 2017
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66. Full-Diversity Dispersion Matrices From Algebraic Field Extensions for Differential Spatial Modulation
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Lajos Hanzo, Shinya Sugiura, Rakshith Rajashekar, Naoki Ishikawa, and K. V. S. Hari
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Computer Networks and Communications ,MIMO ,Aerospace Engineering ,020302 automobile design & engineering ,020206 networking & telecommunications ,02 engineering and technology ,Topology ,Electrical Communication Engineering ,Transmit diversity ,Signal-to-noise ratio ,0203 mechanical engineering ,Control theory ,Modulation ,Automotive Engineering ,0202 electrical engineering, electronic engineering, information engineering ,Fading ,Electrical and Electronic Engineering ,Decoding methods ,Block (data storage) ,Channel use ,Mathematics - Abstract
We consider differential spatial modulation (DSM) operating in a block fading environment and propose sparse unitary dispersion matrices (DMs) using algebraic field extensions. The proposed DM sets are capable of exploiting full transmit diversity and, in contrast to the existing schemes, can be constructed for systems having an arbitrary number of transmit antennas. More specifically, two schemes are proposed: 1) field-extension-based DSM (FE-DSM), where only a single conventional symbol is transmitted per space–time block; and 2) FE-DSM striking a diversity–rate tradeoff (FE-DSM-DR), where multiple symbols are transmitted in each space–time block at the cost of a reduced transmit diversity gain. Furthermore, the FE-DSM scheme is analytically shown to achieve full transmit diversity, and both proposed schemes are shown to impose decoding complexity, which is independent of the size of the signal set. It is observed from our simulation results that the proposed FE-DSM scheme suffers no performance loss compared with the existing DM-based DSM (DM-DSM) scheme, whereas FE-DSM-DR is observed to give a better bit-error-ratio performance at higher data rates than its DM-DSM counterpart. Specifically, at data rates of 2.25 and 2.75 bits per channel use, FE-DSM-DR is observed to achieve about 1- and 2-dB signal-to-noise ratio (SNR) gain with respect to its DM-DSM counterpart. more...
- Published
- 2017
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67. Simplified Evaluation Method for Effect of High-Pressure Hydrogen On Ductility of Low Alloy Steel
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Naoki ISHIKAWA, Mizuki KONNO, Hiroyuki SAITO, and Hirokazu TSUJI
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- 2021
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68. Effects of dasatinib on airway inflammation induced by lipopolysaccharide and/or ovalbumin
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Naoki Ishikawa, Yasuo Kizawa, Kazuhiro Ito, Nanaka Ito, Genki Kimura, Yuki Nishimoto, Minami Saito, Yuka Koizumi, and Yukiko Eguchi
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biology ,Lipopolysaccharide ,business.industry ,Applied Mathematics ,General Mathematics ,Airway inflammation ,Dasatinib ,Ovalbumin ,chemistry.chemical_compound ,chemistry ,Immunology ,medicine ,biology.protein ,business ,medicine.drug - Published
- 2021
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69. Subcarrier Subset Selection-Aided Transmit Precoding Achieves Full-Diversity in Index Modulation
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Chao Xu, Lie-Liang Yang, Lajos Hanzo, Rakshith Rajashekar, and Naoki Ishikawa
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Computer Networks and Communications ,Computer science ,Aerospace Engineering ,020302 automobile design & engineering ,02 engineering and technology ,Topology ,Precoding ,Subcarrier ,Transmit diversity ,0203 mechanical engineering ,Transmission (telecommunications) ,Modulation ,Automotive Engineering ,Modulation (music) ,Electrical and Electronic Engineering ,Block (data storage) - Abstract
Index modulation (IM) is a recently proposed multi-carrier transmission scheme, which conveys information both by conventional symbols as well as by the specific subcarrier activation patterns conveying them. However, an impediment of IM is that it lacks transmit diversity gain. In this paper, we circumvent this limitation by proposing a limited-feedback assisted IM transmission scheme. Specifically, Euclidean distance based subcarrier subset selection (ED-SSS) is proposed and its attainable transmit diversity order is shown to be $N_c-N_{IM}+1$ , where $N_c$ is the total number of subcarriers in an IM block and $N_{IM}$ is the number of subcarriers used for IM. Furthermore, the ED-SSS is shown to be amenable to low-complexity implementation owing to the orthogonality of its subcarriers. In order to attain the maximum transmit diversity order of $N_c$ , ED-SSS is further extended with the aid of transmit precoding and its transmit diversity order is quantified. The proposed precoding assisted ED-SSS is shown to subsume several of the existing precoding aided IM transmission schemes. Simulation studies are conducted for validating our theoretical claims and also for quantifying the attainable performance gains of the proposed schemes. Specifically, at a BER of $10^{-3}$ an SNR gain as high as 8 dB is observed in case of precoding when compared to its counterpart operating without precoding. more...
- Published
- 2019
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70. Constituents from Entada scandens with TRAIL-resistance Overcoming Activity
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Firoj, Ahmed, Kazufumi, Toume, Naoki, Ishikawa, Midori A, Arai, Samir K, Sadhu, and Masami, Ishibashi
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Biological Products ,Receptors, TNF-Related Apoptosis-Inducing Ligand ,Molecular Structure ,Drug Resistance, Neoplasm ,Cell Line, Tumor ,Drug Discovery ,Humans ,Fabaceae ,Antineoplastic Agents, Phytogenic - Abstract
Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) has emerged as a promising anticancer agent because of its ability to selectively kill tumor cells. But TRAIL-resistance is a major problem of its therapy. A search for compounds for abrogating TRAIL-resistance has, thus, become an important strategy for anticancer drug discovery. In search of bioactive natural products for overcoming TRAIL-resistance, we previously reported some compounds with TRAIL-resistance overcoming activity. Bioassay guided fractionation of Entada scandens led to the isolation of four compounds (1-4). Of the isolates, compounds 1 and 3 showed moderate TRAIL-resistance overcoming activity in TRAIL-resistant human gastric adenocarcinoma (AGS) cells. more...
- Published
- 2018
71. Differential space-time coding dispensing with channel-estimation approaches the performance of its coherent counterpart in the open-loop massive MIMO-OFDM downlink
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Rakshith Rajashekar, Lajos Hanzo, Chao Xu, Shinya Sugiura, and Naoki Ishikawa
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Orthogonal frequency-division multiplexing ,Computer science ,Open-loop controller ,Code word ,020206 networking & telecommunications ,020302 automobile design & engineering ,02 engineering and technology ,MIMO-OFDM ,Topology ,Spatial modulation ,Unitary state ,symbols.namesake ,Fourier transform ,0203 mechanical engineering ,Modulation ,Telecommunications link ,0202 electrical engineering, electronic engineering, information engineering ,symbols ,Electrical and Electronic Engineering ,Coding (social sciences) ,Communication channel ,Computer Science::Information Theory - Abstract
In this paper, we propose a simple yet powerful mapping scheme that converts any conventional square-matrix-based differential space-time coding (DSTC) into a nonsquare-matrix-based DSTC. This allows DSTC schemes to be used practically in open-loop large-scale multiple-input multiple-output scenarios. Our proposed scheme may be viewed as the differential counterpart of coherent spatial modulation (SM), of the generalized SM, of Bell laboratories layered space-time architecture, and of subcarrier-index modulation. The fundamental impediment of the existing DSTC schemes is the excessive complexity imposed by the unitary constraint. Specifically, the transmission rate of conventional DSTC schemes decays as the number of transmit antennas increases. Our proposed scheme eliminates this impediment and thus achieves a significantly higher transmission rate. We introduce four novel construction methods for the nonsquare codewords, some of which include an arbitrary number of nonzero elements in each codeword column. Our analysis showsthat the proposed encoding technique reduces the complexity of both the inverse Fourier transform and of the detection processes. Our proposed scheme is shown to approach the performance of its coherent counterpart for low-mobility scenarios, where the number of transmit antennas is increased up to 256. more...
- Published
- 2018
72. 50 years of permutation, spatial and index modulation: From classic RF to visible light communications and data storage
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Shinya Sugiura, Lajos Hanzo, and Naoki Ishikawa
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Signal Processing (eess.SP) ,Orthogonal frequency-division multiplexing ,Computer science ,business.industry ,Visible light communication ,020206 networking & telecommunications ,020302 automobile design & engineering ,02 engineering and technology ,Multiplexing ,Time–frequency analysis ,Permutation ,0203 mechanical engineering ,Modulation ,Computer data storage ,FOS: Electrical engineering, electronic engineering, information engineering ,0202 electrical engineering, electronic engineering, information engineering ,Electronic engineering ,Wireless ,Electrical Engineering and Systems Science - Signal Processing ,Electrical and Electronic Engineering ,business - Abstract
In this treatise, we provide an interdisciplinary survey on spatial modulation (SM), where multiple-input multiple-output microwave and visible light, as well as single and multicarrier communications are considered. Specifically, we first review the permutation modulation (PM) concept, which was originally proposed by Slepian in 1965. The PM concept has been applied to a wide range of applications, including wired and wireless communications and data storage. By introducing a three-dimensional signal representation, which consists of spatial, temporal and frequency axes, the hybrid PM concept is shown to be equivalent to the recently proposed SM family. In contrast to other survey papers, this treatise aims for celebrating the hitherto overlooked studies, including papers and patents that date back to the 1960s, before the invention of SM. We also provide simulation results that demonstrate the pros and cons of PM-aided low-complexity schemes over conventional multiplexing schemes., 34 pages, 28 figures, 10 tables, accepted for publication in IEEE Communications Surveys & Tutorials more...
- Published
- 2018
73. Single-RF index shift keying aided differential space-time block coding
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Naoki Ishikawa, Chao Xu, Rakshith Rajashekar, Shinya Sugiura, and Lajos Hanzo
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Block code ,Minimum mean square error ,Computer science ,Detector ,020302 automobile design & engineering ,020206 networking & telecommunications ,Keying ,02 engineering and technology ,Amplitude-shift keying ,QAM ,Transmit diversity ,0203 mechanical engineering ,Modulation ,Signal Processing ,0202 electrical engineering, electronic engineering, information engineering ,Electrical and Electronic Engineering ,Algorithm ,Amplitude and phase-shift keying ,Quadrature amplitude modulation - Abstract
We propose a new single-RF Differential Space-Time Block Coding using Index Shift Keying (DSTBC-ISK), which is the first in the family of Differential Space-Time Modulation (DSTM) schemes that can simultaneously achieve the following three imperative objectives of (1) forming a finite-cardinality transmit-signals set under the matrix multiplications of differential encoding; (2) retaining a single-stream ML detection complexity that does not grow with the constellation size; (3) offering a beneficial transmit diversity gain over the recently developed Differential Spatial Modulation (DSM). In order to make a fair comparison, we also conceive a low-complexity single-stream detector for DSM, which does not impose any performance loss in comparison to the existing solutions in open literature. Furthermore, in order to improve the performance of finite-cardinality DSTM schemes at higher throughputs, we propose to generalize both Differential Amplitude Shift Keying (DASK) and Amplitude Shift Keying (ASK), which form the generic multi-level-ring star QAM constellation that subsumes the existing two/four-level-ring DASK solutions as special cases. Although the DASK approach has been popularly used in DSTM schemes, we demonstrate that our generalized ASK technique achieves a higher capacity and a better performance in channel coding assisted systems. Moreover, since the employment of star QAM constellations imposes the ring-amplitude dependent signal power problem for detection, we further develop bespoke Maximum-Likelihood (ML), Minimum Mean Squared Error (MMSE) and Least Square (LS) detectors for DSTM using DASK/ASK, which exhibit different performance versus complexity tradeoffs. Our simulation results demonstrate that the proposed DSTBC-ISK is capable of achieving substantial diversity gains over DSM without eroding its low transceiver complexity. more...
- Published
- 2018
74. Subcarrier-Index Modulation Aided OFDM - Will It Work?
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Lajos Hanzo, Shinya Sugiura, and Naoki Ishikawa
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General Computer Science ,Orthogonal frequency-division multiplexing ,Gaussian ,index modulation ,02 engineering and technology ,Multiplexing ,Subcarrier ,symbols.namesake ,Capacity planning ,0203 mechanical engineering ,Control theory ,0202 electrical engineering, electronic engineering, information engineering ,General Materials Science ,mutual information ,parallel combinatory ,Mathematics ,Computer Science::Information Theory ,OFDM ,Capacity ,General Engineering ,EXIT chart ,020206 networking & telecommunications ,020302 automobile design & engineering ,Mutual information ,Euclidean distance ,Modulation ,symbols ,lcsh:Electrical engineering. Electronics. Nuclear engineering ,Algorithm ,lcsh:TK1-9971 - Abstract
The achievable performance of subcarrier-index modulation (SIM) is analyzed in terms of its minimum Euclidean distance, constrained and unconstrained average mutual information, as well as its peak-to-average power ratio (PAPR). Our performance investigations identify the beneficial operating region of the SIM scheme over its conventional orthogonal frequency-division multiplexing (OFDM) counterpart, hence providing general design guidelines for the SIM parameters. More specifically, an SIM scheme is shown to be beneficial for the scenario of a relatively low transmission rate below 2 b/s/Hz. In addition, we demonstrate that the PAPR of the SIM scheme is comparable with that of its OFDM counterpart under the idealized simplifying assumption of having Gaussian input symbols. more...
- Published
- 2016
75. Hes1 inhibitor isolated by target protein oriented natural products isolation (TPO-NAPI) of differentiation activators of neural stem cells
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Masami Ishibashi, Midori A. Arai, Naoki Ishikawa, Akiko Suganami, Kenji Uemura, Mitsuha Tanaka, Thaworn Kowithayakorn, Noriko Sugimitsu, Takashi Koyano, and Yutaka Tamura
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0301 basic medicine ,congenital, hereditary, and neonatal diseases and abnormalities ,endocrine system ,Natural product ,Neurite ,Retinoic acid ,Proneural genes ,General Chemistry ,Biology ,Molecular biology ,Neural stem cell ,03 medical and health sciences ,chemistry.chemical_compound ,030104 developmental biology ,chemistry ,Neurosphere ,embryonic structures ,Target protein ,HES1 - Abstract
The Hes1 dimer inhibitor, agalloside (2), which can accelerate the differentiation of neural stem cells is described. Six natural products, including one new natural product, which bind to Hes1 were rapidly isolated by a developed "target protein oriented natural products isolation" (TPO-NAPI) method using Hes1-immobilized beads. Of the six compounds, 2 inhibited Hes1 dimer formation at both the protein- and cellular level. Neural stem cells treated with 2 differentiated to neurons with longer neurites than cells treated with varproic acid or retinoic acid. Moreover, 2 exhibited specificity for neurons. This promotion of differentiation was supported by an increase in the mRNA expression of the proneural genes, Mash1 and Ngn2, which were inhibited by Hes1. more...
- Published
- 2016
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76. New phenazine analogues from Streptomyces sp. IFM 11694 with TRAIL resistance-overcoming activities
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Kazuki Yamaku, Masami Ishibashi, Utpal Kumar Karmakar, Mohamed S. Abdelfattah, and Naoki Ishikawa
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Magnetic Resonance Spectroscopy ,Antiparasitic ,medicine.drug_class ,Phenazine ,Ethyl acetate ,Antineoplastic Agents ,Apoptosis ,Adenocarcinoma ,01 natural sciences ,Streptomyces ,Mass Spectrometry ,TNF-Related Apoptosis-Inducing Ligand ,chemistry.chemical_compound ,Biosynthesis ,Stomach Neoplasms ,Cell Line, Tumor ,Drug Discovery ,medicine ,Humans ,Pharmacology ,Dose-Response Relationship, Drug ,biology ,010405 organic chemistry ,Nuclear magnetic resonance spectroscopy ,biology.organism_classification ,0104 chemical sciences ,010404 medicinal & biomolecular chemistry ,Proto-Oncogene Proteins c-bcl-2 ,chemistry ,Biochemistry ,Drug Resistance, Neoplasm ,Cell culture ,Phenazines - Abstract
Two new phenazine derivatives, aotaphenazine (1) and 5,10-dihydrophencomycin (2), were isolated from the ethyl acetate extract of Streptomyces sp. IFM 11694. In addition, the known 1-phenazinecarboxylic acid (3), phencomycin (4) and 1,6-phenazinedicarboxylic acid (5) were identified. The structures of the isolated compounds (1-5) were characterized by spectroscopic methods including NMR and mass spectrometry data. Compound 1 showed the ability to overcome tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) resistance at concentration of 12.5 μM. Aotaphenazine (1) enhanced the levels of apoptosis inducing proteins DR4, DR5, p53 and also decreased the levels of cell survival protein Bcl-2 in TRAIL-resistant human gastric adenocarcinoma (AGS) cells in a dose-dependent manner. more...
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- 2015
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77. Sesquiterpenes with TRAIL-resistance overcoming activity from Xanthium strumarium
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Samir Kumar Sadhu, Utpal Kumar Karmakar, Naoki Ishikawa, Masami Ishibashi, Midori A. Arai, Firoj Ahmed, and Kazufumi Toume
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Magnetic Resonance Spectroscopy ,Cell Survival ,Stereochemistry ,Clinical Biochemistry ,Molecular Conformation ,Pharmaceutical Science ,CHOP ,Sesquiterpene ,Biochemistry ,Xanthium strumarium ,TNF-Related Apoptosis-Inducing Ligand ,HeLa ,chemistry.chemical_compound ,DU145 ,Cell Line, Tumor ,Drug Discovery ,Humans ,Molecular Biology ,biology ,Organic Chemistry ,HEK 293 cells ,Xanthium ,biology.organism_classification ,Antineoplastic Agents, Phytogenic ,Plant Leaves ,HEK293 Cells ,chemistry ,Drug Resistance, Neoplasm ,Apoptosis ,Caspases ,Cancer cell ,MCF-7 Cells ,Molecular Medicine ,Drug Screening Assays, Antitumor ,Tumor Suppressor Protein p53 ,Apoptosis Regulatory Proteins ,Sesquiterpenes ,HeLa Cells - Abstract
The ability of TRAIL to selectively induce apoptosis in cancer cells while sparing normal cells makes it an attractive target for the development of new cancer therapy. In search of bioactive natural products for overcoming TRAIL-resistance from natural resources, we previously reported a number of active compounds. In our screening program on natural resources targeting overcoming TRAIL-resistance, activity-guided fractionations of the extract of Xanthium strumarium led to the isolation of five sesquiterpene compounds (1-5). 11α,13-dihydroxanthinin (2) and 11α,13-dihydroxanthuminol (3) were first isolated from natural resources and xanthinosin (1), desacetylxanthanol (4), and lasidiol p-methoxybenzoate (5) were known compounds. All compounds (1-5) showed potent TRAIL-resistance overcoming activity at 8, 20, 20, 16, and 16 μM, respectively, in TRAIL-resistant AGS cells. Compounds 1 and 5 enhanced the levels of apoptosis inducing proteins DR4, DR5, p53, CHOP, Bax, cleaved caspase-3, cleaved caspase-8, and cleaved caspase-9 and also decreased the levels of cell survival protein Bcl-2 in TRAIL-resistant AGS cells in a dose-dependent manner. Compound 1 also enhanced the levels of DR4 and DR5 proteins in a time-dependent manner. Thus, compounds 1 and 5 were found to induce both extrinsic and intrinsic apoptotic cell death. Compound 1 also exhibit TRAIL-resistance overcoming activity in DLD1, DU145, HeLa, and MCF7 cells but did not decrease viability in non-cancer HEK293 cells up to 8 μM. more...
- Published
- 2015
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78. Boehmenan, a lignan from Hibiscus ficulneus, showed Wnt signal inhibitory activity
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Samir Kumar Sadhu, Masami Ishibashi, Firoj Ahmed, Naoki Ishikawa, Midori A. Arai, Kazufumi Toume, and Takumi Shono
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Cell Survival ,Clinical Biochemistry ,Cell ,Pharmaceutical Science ,Biochemistry ,Lignans ,Cell Line ,Proto-Oncogene Proteins c-myc ,chemistry.chemical_compound ,Western blot ,Drug Discovery ,medicine ,Humans ,Luciferase ,Cytotoxicity ,Wnt Signaling Pathway ,Molecular Biology ,beta Catenin ,Lignan ,medicine.diagnostic_test ,Plant Extracts ,Organic Chemistry ,HEK 293 cells ,Wnt signaling pathway ,HCT116 Cells ,Molecular biology ,Wnt Proteins ,Cytosol ,HEK293 Cells ,medicine.anatomical_structure ,Hibiscus ,chemistry ,Molecular Medicine - Abstract
The Wnt signal pathway modulates numerous biological processes, and its aberrant activation is related to various diseases. Therefore, inhibition of the Wnt signal may provide an effective (or efficient) strategy for these diseases. Cell-based luciferase assay targeting the Wnt signal (TOP assay) revealed that Hibiscus ficulneus extract inhibited the Wnt signal. The activity-guided isolation of the MeOH extract of H. ficulneus stems yielded four known (1-4) lignans along with myriceric acid (5). Compounds 1-4 potently inhibited the Wnt signal with TOPflash IC50 values of 1.0, 4.5, 6.3, and 1.9 μM, respectively. Compound 1 exhibited cytotoxicity against both Wnt-dependent (HCT116) and Wnt-independent (RKO) cells. Western blot analysis showed that 1 decreased the expression of full, cytosolic and nuclear β-catenin along with c-myc in STF/293 cells. Our results suggested that 1 may have inhibited the Wnt signal by decreasing β-catenin levels. more...
- Published
- 2015
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79. Maximizing Constrained Capacity of Power-Imbalanced Optical Wireless MIMO Communications Using Spatial Modulation
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Naoki Ishikawa and Shinya Sugiura
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Engineering ,business.industry ,MIMO ,Spectral density ,Context (language use) ,Atomic and Molecular Physics, and Optics ,Power (physics) ,Signal-to-noise ratio ,Modulation ,Optical wireless ,Electronic engineering ,business ,Intensity modulation ,Computer Science::Information Theory - Abstract
In this paper, we present a constellation optimization technique that can be invoked for optical spatial modulation (OSM) multiple-input multiple-output (MIMO) systems within the context of optical wireless (OW) systems that is designed to negate the high channel correlation imposed on conventional OSM schemes. More specifically, the proposed unified OSM architecture relies on power-imbalanced (PI) multiple transmit light sources. Furthermore, we formulate the constrained capacity of the proposed PI-OSM scheme, and then provide the design guidelines of our OSM scheme's PI constellation, in which the parameters have been optimized to ensure the associated constrained capacity is maximized. Our simulation results demonstrate that our proposed scheme is capable of outperforming conventional OSM and OW-MIMO schemes over a wide range of signal-to-noise ratios. more...
- Published
- 2015
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80. Naturally occurring FANCF–Hes1 complex inhibitors from Wrightia religiosa
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Nozomi Hamahiga, Tagrid Kaddar, Takashi Koyano, Midori A. Arai, Kenji Uemura, Thaworn Kowithayakorn, Madeleine Carreau, Masami Ishibashi, and Naoki Ishikawa
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Pharmacology ,endocrine system ,congenital, hereditary, and neonatal diseases and abnormalities ,Flavonoid glycosides ,Stereochemistry ,Dimer ,Organic Chemistry ,Complex formation ,Pharmaceutical Science ,Biology ,Biochemistry ,Wrightia religiosa ,chemistry.chemical_compound ,chemistry ,FANCF ,embryonic structures ,Drug Discovery ,Molecular Medicine ,F protein ,HES1 ,Enhancer - Abstract
The isolation and evaluation of inhibitors of Fanconi F protein (FANCF) – hairy and enhancer of split 1 (Hes1) complex are described. A high-throughput screening assay for small-molecule inhibitors of the FANCF–Hes1 complex was realized. Successful complex formation between fluorophore (Cy3)-labeled human FANCF and immobilized rat or human HES1 on a microplate was established. Screening of our plant extract library using this system resulted in the isolation of eight natural products, including two new flavonoid glycosides (3 and 4), from Wrightia religiosa. Of these compounds, 3, 5, and 7 showed potent inhibition of the FANCF–Hes1 complex formation. Compound 7 disrupted the FANCF–Hes1 complex more efficiently than the Hes1 dimer. more...
- Published
- 2015
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81. Anti-proliferative effect of Moringa oleifera Lam (Moringaceae) leaf extract on human colon cancer HCT116 cell line
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Masami Ishibashi, Naoki Ishikawa, Penpun Wetwitayaklung, Jintana Tragulpakseerojn, Perayot Pamonsinlapatham, Auayporn Apirakaramwong, Tatsuro Yoneyama, Naoto Yamaguchi, and Moringa oleifera, Anti-proliferation, Colon cancer, AKT, ERK1/2 phosphorylation, Chemoprevention more...
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0301 basic medicine ,Traditional medicine ,Cell growth ,Pharmaceutical Science ,Thin-layer chromatography ,Moringa ,03 medical and health sciences ,chemistry.chemical_compound ,030104 developmental biology ,0302 clinical medicine ,Column chromatography ,chemistry ,Mechanism of action ,Biochemistry ,030220 oncology & carcinogenesis ,Isoquercetin ,medicine ,Pharmacology (medical) ,MTT assay ,Astragalin ,medicine.symptom - Abstract
Purpose : To investigate the in vitro anti-proliferative effect and mechanism of action of Moringa oleifera Lam. leaf extract on human colon carcinoma HCT116 cell line. Methods : M. oleifera leaves were extracted with methanol. It was fractionated by Sephadex LH-20 column chromatography. Several fractions were identified by thin layer chromatography (TLC), proton nuclear magnetic resonance (1H NMR) and mass spectrometry (MS). The growth inhibitory activity and mechanism of action of the extracts in HCT116 colon cancer cells were investigated by 3-(4, 5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT) assay and Western blotting. Results : Successive fractions from M. oleifera leaf crude extracts by column chromatography were combined into four pooled batches (MOL1 - MOL4) according to their absorbance at 260 nm and TLC pattern. MOL2 and MOL3 contain astragalin and isoquercetin, respectively. The results from MTT assay indicated that cell proliferation was significantly (p < 0.05) inhibited in a concentration-dependent fashion, especially by MOL2, MOL3 and MOL4. MOL2 and MOL3 exhibited a stronger cell growth inhibition than their major ingredients. The anti-proliferative activity of MOL2 - MOL4 in HCT116 colon cancer cells was mediated by downregulation of ERK1/2 phosphorylation. Conclusion : M. oleifera leaf extract has a strong anti-proliferative activity which is exerted by decreasing ERK1/2 phosphorylation. Thus, the extract has a potential for use in cancer chemoprevention. Keywords : Moringa oleifera , Anti-proliferation, Colon cancer, AKT, ERK1/2 phosphorylation, Chemoprevention more...
- Published
- 2017
82. Unified Differential Spatial Modulation
- Author
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Shinya Sugiura and Naoki Ishikawa
- Subjects
Computer science ,business.industry ,Transmitter ,Keying ,Interval (mathematics) ,Control and Systems Engineering ,Diversity gain ,Electrical and Electronic Engineering ,Telecommunications ,business ,Algorithm ,Quadrature amplitude modulation ,Amplitude and phase-shift keying ,Computer Science::Information Theory ,Communication channel ,Block (data storage) - Abstract
This letter proposes a unified differential spatial modulation (DSM) architecture, where a flexible rate-diversity tradeoff is achieved, while enabling a simple single-RF transmitter structure along with non-coherent detection that dispenses with channel estimation at the receiver. In our proposed scheme, by assigning a set of sparse complex-valued antenna-index matrices, only one transmit antenna element is activated during each symbol interval and then a phase-shift keying (PSK) symbol is transmitted from the activated antenna element. The explicit benefit of the proposed scheme's universal DSM framework is ability to strike a balance between previous DSM schemes, such as the symbol-based and the block-based DSM schemes. Moreover, to attain a useful attainable diversity gain, we further extend the proposed DSM scheme in a manner that permits flexible planning of the number of symbols employed per antenna-index block. more...
- Published
- 2014
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83. Evaluation of Performance in Bifacial Solar Cell
- Author
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Takuo Notohara, Shinji Goda, Yasuyuki Ota, Koichi Sugibuchi, Naoki Ishikawa, and Kensuke Nishioka
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Engineering ,Optics ,Tilt (optics) ,business.industry ,law ,Solar cell ,General Engineering ,Common method ,business ,Solar mirror ,Light scattering ,law.invention - Abstract
The most common method for solar cell installation is the inclining mounting method, this method can also be used with the bifacial solar cell. For the installation, its important to understand the properties of light which is entering the back surface of the bifacial solar cell. In this study, we measured the incidence light of the back surface of bifacial solar cell and compared its output power to the common single-surface solar cell to investigate the optimal condition for its installation in terms of (1) tilt angle, (2) height, (3) optimal region and (4) ground surface condition where the panel should be installed. more...
- Published
- 2014
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84. Novel cytotoxic isobenzofuran derivatives from Streptomyces sp. IFM 11490
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Yixizhuoma, Masami Ishibashi, Kentaro Tsukahara, Kazufumi Toume, Naoki Ishikawa, and Mohamed S. Abdelfattah
- Subjects
biology ,Isobenzofuran ,Chemistry ,Stereochemistry ,Organic Chemistry ,Ethyl acetate ,biology.organism_classification ,Biochemistry ,Streptomyces ,chemistry.chemical_compound ,Gastric adenocarcinoma ,Cell culture ,Drug Discovery ,Cytotoxic T cell ,Cytotoxicity ,Two-dimensional nuclear magnetic resonance spectroscopy - Abstract
Three new isobenzofuran derivatives, named elmonin (1), elmenols A (2) and B (3), have been isolated from the ethyl acetate extract of the Streptomyces sp. IFM 11490. The structures of compounds 1–3 were established using extensive spectroscopic data analyses, including 1D and 2D NMR spectroscopy. The relative configuration of 2 was confirmed by single-crystal X-ray diffraction. Compounds 1 and 3 showed moderate cytotoxicity against the human gastric adenocarcinoma (AGS) cell line. more...
- Published
- 2015
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85. Algebraic Differential Spatial Modulation Is Capable of Approaching the Performance of Its Coherent Counterpart
- Author
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Shinya Sugiura, K. V. S. Hari, Naoki Ishikawa, Rakshith Rajashekar, Lajos Hanzo, and Chao Xu
- Subjects
MIMO ,Detector ,Electrical Communication Engineering - Technical Reports ,020206 networking & telecommunications ,020302 automobile design & engineering ,02 engineering and technology ,Topology ,Electrical Communication Engineering ,Transmit diversity ,0203 mechanical engineering ,Channel state information ,Control theory ,0202 electrical engineering, electronic engineering, information engineering ,Bit error rate ,Electrical and Electronic Engineering ,Differential coding ,Amplitude and phase-shift keying ,Phase-shift keying ,Mathematics - Abstract
We show that certain signal constellations invoked for classic differential encoding result in a phenomenon we term as the {\em unbounded differential constellation size} (UDCS). Various existing differential transmission schemes that suffer from this issue are identified. Then, we propose an enhanced algebraic field extension based differential spatial modulation scheme (AFE-DSM) and its enhanced counterpart that strikes a diversity-rate trade-off (AFE-DSM-DR), both of which overcome the UDCS issue without compromising its full transmit diversity advantage. Furthermore, the proposed schemes are extended to incorporate amplitude and phase shift keying (APSK) in order to exploit all the available degrees of freedom. Additionally, we propose a pair of detection schemes specially designed for APSK aided differential transmission schemes. Explicitly, we conceive the buffered minimum mean squared error (B-MMSE) detector and buffered maximum likelihood (B-ML) detector, which exploit the knowledge of previously detected symbols in order to further improve the detection performance. Our simulation results have shown that the proposed detectors are capable of bridging the performance gap between the conventional differential detector (CDD) and the coherent detector that has full channel state information. Specifically, when employing the proposed APSK aided AFE-DSM scheme operating at a rate of 2 bits per channel use (bpcu), the B-MMSE and B-ML detectors are observed to give about 3 dB and 3.5 dB signal-to-noise ratio gain with respect to their CDD counterpart at a bit error ratio of $10^{-5}$. more...
- Published
- 2017
86. Elmenols C-H, new angucycline derivatives isolated from a culture of Streptomyces sp. IFM 11490
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Mohamed S. Abdelfattah, Yixizhuoma, Masami Ishibashi, and Naoki Ishikawa
- Subjects
Stereochemistry ,Ethyl acetate ,Ether ,Moderate activity ,Anthraquinones ,Antineoplastic Agents ,Adenocarcinoma ,010402 general chemistry ,01 natural sciences ,Streptomyces ,Angucyclinone ,TNF-Related Apoptosis-Inducing Ligand ,chemistry.chemical_compound ,Gastric adenocarcinoma ,Tetrangulol ,Stomach Neoplasms ,Cell Line, Tumor ,Drug Discovery ,Humans ,Pharmacology ,biology ,010405 organic chemistry ,Spectrum Analysis ,biology.organism_classification ,0104 chemical sciences ,chemistry ,Drug Resistance, Neoplasm ,Two-dimensional nuclear magnetic resonance spectroscopy - Abstract
Chemical investigations of the ethyl acetate extract of Streptomyces sp. IFM 11490 have led to the isolation of six new angucycline metabolites, named elmenols C–H (1–6), along with the previously reported elmonin (7) and elmenols A (8) and B (9). The known LS1924A (10), 6-deoxy-8-methylrabelomycin (11), tetrangulol methyl ether (12) and angucyclinone (13) were additionally identified. The structures of the isolated compounds were elucidated by means of spectroscopic methods including UV, IR, HRESIMS, and 1D and 2D NMR. Compounds 1–6 were evaluated for their abilities to overcome tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) resistance in human gastric adenocarcinoma (AGS) cells. Compounds 5 (10 μm) and 6 (50 μm) in combination with TRAIL showed moderate activity in sensitizing TRAIL-resistant AGS cells. more...
- Published
- 2016
87. Cerasoidine, a Bis-aporphine Alkaloid Isolated from Polyalthia cerasoides during Screening for Wnt Signal Inhibitors
- Author
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Naoki Ishikawa, Thaworn Kowithayakorn, Midori A. Arai, Takumi Shono, Kazufumi Toume, Takashi Koyano, Masami Ishibashi, and Hyuma Masu
- Subjects
Circular dichroism ,Aporphines ,Stereochemistry ,Pharmaceutical Science ,Cerasoidine ,Biology ,01 natural sciences ,Plant Roots ,Analytical Chemistry ,chemistry.chemical_compound ,Alkaloids ,Drug Discovery ,T Cell Transcription Factor 1 ,Humans ,Aporphine ,IC50 ,Nuclear Magnetic Resonance, Biomolecular ,beta Catenin ,Pharmacology ,Molecular Structure ,010405 organic chemistry ,Alkaloid ,Organic Chemistry ,Wnt signaling pathway ,Thailand ,0104 chemical sciences ,Chiral column chromatography ,Wnt Proteins ,010404 medicinal & biomolecular chemistry ,Complementary and alternative medicine ,Biochemistry ,chemistry ,Polyalthia ,Molecular Medicine ,Polyalthia cerasoides - Abstract
A new bis-aporphine alkaloid, cerasoidine (1), was isolated from the root extract of Polyalthia cerasoides together with the known bis-aporphine bidebiline E (2) during screening for compounds with Wnt signal inhibitory activities. The structure of cerasoidine (1) was established by X-ray analysis and shown by chiral HPLC analyses and electronic circular dichroism to be a 57:43 mixture of R(-)- and S(+)-atropisomers. Bidebiline E (2) exhibited inhibition of transcriptional activity of TCF/β-catenin with an IC50 value of 20.2 μM and was also found to inhibit Wnt signaling by decreasing nuclear β-catenin. more...
- Published
- 2016
88. Stereochemical Assignment and Biological Evaluation of BE-14106 Unveils the Importance of One Acetate Unit for the Antifungal Activity of Polyene Macrolactams
- Author
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Shinichi Nishimura, Kohei Fujita, Masami Ishibashi, Ryosuke Sugiyama, Hideaki Kakeya, Naoki Ishikawa, and Midori A. Arai
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Antifungal Agents ,Lactams ,Stereochemistry ,Lactams, Macrocyclic ,Pharmaceutical Science ,Marine Biology ,010402 general chemistry ,01 natural sciences ,Analytical Chemistry ,Actinobacteria ,chemistry.chemical_compound ,Structure-Activity Relationship ,Drug Discovery ,Schizosaccharomyces ,Structure–activity relationship ,Molecule ,Pharmacology ,chemistry.chemical_classification ,biology ,Molecular Structure ,010405 organic chemistry ,Organic Chemistry ,Biological activity ,biology.organism_classification ,Polyene ,Yeast ,0104 chemical sciences ,Anti-Bacterial Agents ,Hydrocarbon ,Complementary and alternative medicine ,chemistry ,Molecular Medicine ,Growth inhibition - Abstract
Heronamides are a class of potent antifungal metabolites produced by marine-derived actinomycetes. The number of hydroxy groups and the stereochemistry of the two hydroxylated methine carbons are important for the activity of heronamide C, whereas the effect of the hydrocarbon chains is not known. In this study, the stereochemistry and the biological activity of BE-14106, another member of the heronamide class of antibiotics, isolated from an actinomycete Actinoalloteichus cyanogriseus IFM 11549 was investigated. Spectroscopic analysis coupled with photo- and O2-induced conversion revealed that BE-14106 and the heronamides had the same stereochemistry. BE-14106 showed potent growth inhibition against fission yeast cells with an MIC value of 0.50 μM (0.21 μg/mL), being 4 times less potent than heronamide C, which revealed the importance of the structure of the hydrocarbon tail for the activity. more...
- Published
- 2016
89. Generalized-spatial-modulation-based reduced-RF-chain millimeter-wave communications
- Author
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Lajos Hanzo, Shinya Sugiura, Rakshith Rajashekar, and Naoki Ishikawa
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Beamforming ,Engineering ,Computer Networks and Communications ,business.industry ,Transmitter ,ComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKS ,Electrical engineering ,Aerospace Engineering ,020302 automobile design & engineering ,020206 networking & telecommunications ,02 engineering and technology ,Data_CODINGANDINFORMATIONTHEORY ,Communications system ,Spatial multiplexing ,Antenna array ,0203 mechanical engineering ,GSM ,Automotive Engineering ,Extremely high frequency ,0202 electrical engineering, electronic engineering, information engineering ,Electronic engineering ,ComputerSystemsOrganization_SPECIAL-PURPOSEANDAPPLICATION-BASEDSYSTEMS ,Radio frequency ,Electrical and Electronic Engineering ,business - Abstract
Generalized spatial modulation (GSM)-based millimeter-wave (mmWave) communications system is proposed. The GSM transmitter is characterized by a lower number of radio frequency (RF) chains than the number of transmit antennas, hence it is capable of reducing both the transmitter cost as well as the energy consumption. The antenna array alignment is optimized so as to maximize the rank of the channel matrix encountered. Furthermore, we employ an array of analog beamformers, which allows us to benefit both from the beamforming gain as well as from the GSM scheme’s high rate. It is demonstrated that the constrained capacity of the GSM transmitter equipped with as few as two RF chains is capable of approaching the performance of the full-RF spatial multiplexing having eight RF chains. more...
- Published
- 2016
90. Bioassay-Guided Isolation of Compounds from Datura stramonium with TRAIL-Resistance Overcoming Activity
- Author
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Utpal K, Karmakar, Kazufumi, Toume, Naoki, Ishikawa, Midori A, Arai, Samir K, Sadhu, Firoj, Ahmed, and Masami, Ishibashi
- Subjects
TNF-Related Apoptosis-Inducing Ligand ,Datura stramonium ,Alkaloids ,Gene Expression Regulation ,Cell Survival ,Drug Resistance, Neoplasm ,Plant Extracts ,Humans ,Biological Assay ,Antineoplastic Agents, Phytogenic ,Cell Line - Abstract
TRAIL is a potent inducer of apoptosis in most cancer cells, but not in normal cells, and therefore has deserved intense interest as a promising agent for cancer therapy. In the search for bioactive natural products for overcoming TRAIL-resistance, we previously reported a number of active compounds. In our screening program on natural resources targeting overcoming TRAIL-resistance, activity-guided fractionation of the MeOH extract of Datura stramonium leaves led to the isolation of three alkaloids--scopolamine (1), trigonelline (2), and tyramine (3). Compounds 1, 2, and 3 exhibited TRAIL-resistance overcoming activity at 50, 150, and 100 µM, respectively in TRAIL-resistant AGS cells. more...
- Published
- 2016
91. ChemInform Abstract: Novel Cytotoxic Isobenzofuran Derivatives from Streptomyces sp. IFM 11490
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Mohamed S. Abdelfattah, Kazufumi Toume, Yixizhuoma Yixizhuoma, Naoki Ishikawa, Kentaro Tsukahara, and Masami Ishibashi
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chemistry.chemical_compound ,Isobenzofuran ,chemistry ,biology ,Stereochemistry ,Cytotoxic T cell ,General Medicine ,biology.organism_classification ,Streptomyces - Published
- 2016
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92. ORAL CANCER X INHERITANCE: FAMILIAR HISTORY OF MALIGNANCIES IN FIRST GRADE RELATIVES OF ORAL CANCER PATIENTS
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Caludia Yumi Maeda, Gessica De Jesus Souza, Paula Sena Da Mata, Desiree Rosa Cavalcanti, Priscila Hawana Alves Da Silva, Fernandina Alves Moreira, and Caio Naoki Ishikawa
- Subjects
Oncology ,medicine.medical_specialty ,business.industry ,Cancer ,medicine.disease ,Pathology and Forensic Medicine ,Inheritance (object-oriented programming) ,Internal medicine ,medicine ,Radiology, Nuclear Medicine and imaging ,Dentistry (miscellaneous) ,Surgery ,Oral Surgery ,business - Published
- 2017
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93. Classification of extracellularly recorded neurons by their discharge patterns and their correlates with intracellularly identified neuronal types in the frontal cortex of behaving monkeys
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Keichiro Kato, Youngnam Kang, Masanori Saruwatari, Naoki Ishikawa, Shunpei Unno, Akichika Mikami, Masato Inoue, and Satoshi Katai
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Frontal cortex ,Eye Movements ,Statistics as Topic ,Action Potentials ,Biology ,Statistics, Nonparametric ,Discharge rate ,Bursting ,Rhythm ,Reward ,medicine ,Extracellular ,Animals ,Wakefulness ,Neurons ,Behavior, Animal ,General Neuroscience ,In vitro slice ,Macaca mulatta ,Frontal Lobe ,medicine.anatomical_structure ,nervous system ,Cerebral cortex ,Homogeneous ,Neuroscience ,Photic Stimulation - Abstract
Neurons in the cerebral cortex are not homogeneous. However, neuronal types have been ignored in most previous work studying neuronal processes in behaving monkeys. We propose a new method to identify neuronal types in extracellular recording studies of behaving monkeys. We classified neurons as either bursting or non-bursting, and then classified the bursting neurons into three types: (i) neurons displaying a burst of many spikes (maximum number of spikes within a burst; NSB maxor = 8) at a high discharge rate (maximum interspike interval; ISI max5 ms); (ii) neurons displaying a burst of fewer spikes (NSB maxor = 5) at a high discharge rate (ISI max5 ms); and (iii) neurons displaying a burst of a few spikes (NSB maxor = 7) at relatively long ISIs (ISI max5 ms). We found that the discharge patterns of the four groups corresponded to those of regular spiking (RS), fast spiking (FS), fast rhythmic bursting (FRB) and intrinsic bursting (IB) neurons demonstrated in intracellular recording studies using in vitro slice preparations, respectively. In addition, we examined correlations with the task events for neurons recorded in the frontal eye field and neuronal interactions for pairs of neurons recorded simultaneously from a single electrode. We found that they were substantially different between RS and FS types. These results suggest that neurons in the frontal cortex of behaving monkeys can be classified into four types based on their discharge patterns, and that these four types contribute differentially to cortical operations. more...
- Published
- 2010
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94. Sulfotanone, a new alkyl sulfonic acid derivative from Streptomyces sp. IFM 11694 with TRAIL resistance-overcoming activity
- Author
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Utpal Kumar Karmakar, Masami Ishibashi, Naoki Ishikawa, and Mohamed S. Abdelfattah
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Magnetic Resonance Spectroscopy ,Stereochemistry ,Drug Resistance ,Antineoplastic Agents ,Sulfonic acid ,Adenocarcinoma ,01 natural sciences ,Streptomyces ,TNF-Related Apoptosis-Inducing Ligand ,chemistry.chemical_compound ,Stomach Neoplasms ,Cell Line, Tumor ,Benzene Derivatives ,Humans ,Mycelium ,Alkyl ,chemistry.chemical_classification ,Biological Products ,biology ,Molecular Structure ,010405 organic chemistry ,Drug Synergism ,Nuclear magnetic resonance spectroscopy ,biology.organism_classification ,0104 chemical sciences ,010404 medicinal & biomolecular chemistry ,chemistry ,Cell culture ,Molecular Medicine ,Sulfonic Acids ,Two-dimensional nuclear magnetic resonance spectroscopy ,Derivative (chemistry) - Abstract
One new alkyl sulfonic acid derivative, sulfotanone (1), and the known panosialin wA (2) were isolated from the methanolic extract of mycelium of Streptomyces sp. 11694. The structure of the new compound (1) was established by a combination of spectroscopic techniques, including HRESIMS, IR, 1D and 2D NMR measurements. Compound 1 (40 µM) in combination with TRAIL showed synergistic activity in sensitizing TRAIL-resistance in human gastric adenocarcinoma cell lines. more...
- Published
- 2015
95. Exit-Chart-Based Design of Irregular Precoded Power-Imbalanced Optical Spatial Modulation
- Author
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Shinya Sugiura and Naoki Ishikawa
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Signal-to-noise ratio ,Modulation ,Benchmark (computing) ,Electronic engineering ,Word error rate ,Adaptive optics ,EXIT chart ,Algorithm ,Decoding methods ,Mathematics ,Optical wireless communications - Abstract
In this paper, we propose a near-capacity irregular precoded power-imbalanced (PI) optical spatial modulation (OSM) scheme. The PI-OSM scheme was developed for negating the effects of high channel correlation, which is often observed in optical wireless communications. In our proposed scheme, multiple PI-OSM subcodes are used to create a novel irregular precoded PI-OSM architecture. This allows us to match the extrinsic information transfer curves of the inner and outer codes in a flexible manner, hence reducing the signal-to-noise ratio required for achieving an infinitesimally low bit error rate (BER). Our numerical simulation results demonstrate that the irregular precoded PI-OSM scheme achieves a high performance, particularly in noise-dominant channels, and it outperforms the repetition-coded benchmark scheme with pulse-amplitude modulation. more...
- Published
- 2015
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96. Isolation of β-indomycinone guided by cytotoxicity tests from Streptomyces sp. IFM11607 and revision of its double bond geometry
- Author
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Kentaro, Tsukahara, Kazufumi, Toume, Hanako, Ito, Naoki, Ishikawa, and Masami, Ishibashi
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Molecular Structure ,Cell Survival ,Cell Line, Tumor ,Humans ,Anthraquinones ,Antineoplastic Agents ,Streptomyces - Abstract
The antibiotic β-indomycinone was isolated from Streptomyces sp. IFM11607 by cytotoxicity-guided fractionation against human gastric adenocarcinoma AGS cells, and the geometry of its δ17,18-double bond was revised from E to Z based on the coupling constant. more...
- Published
- 2015
97. Germacranolides from Enhydra fluctuans with TRAIL-resistance Abrogating Activity
- Author
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Masami Ishibashi, Naoki Ishikawa, Midori A. Arai, Samir Kumar Sadhu, Firoj Ahmed, and Utpal Kumar Karmakar
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0301 basic medicine ,Pharmacology ,Plant Science ,General Medicine ,Biology ,Enhydra fluctuans ,03 medical and health sciences ,030104 developmental biology ,0302 clinical medicine ,Complementary and alternative medicine ,030220 oncology & carcinogenesis ,Drug Discovery ,Cancer cell ,Cancer research ,Trail resistance - Abstract
TRAIL selectively kills cancer cells without harming most normal cells. However, TRAIL resistance is a major problem for its therapeutic use. Developing a strategy to overcome resistance is crucial for the successful use of TRAIL as an antitumor agent. In our screening program of natural products that can abrogate TRAIL resistance, four germacranolides (1–4) were isolated from the aerial parts of Enhydra fluctuans. All compounds exhibited potent TRAIL-resistance overcoming activity against TRAIL-resistant human gastric adenocarcinoma (AGS) cells. more...
- Published
- 2017
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98. EVALUATION OF THE DIAGNOSIS PROCESS IN A GROUP OF ORAL CANCER PATIENTS OF SOUTHEAST BRAZIL
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Caio Naoki Ishikawa, Paula Sena Da Mata, Fernandina Alves Moreira, Claudia Yumi Maeda, Desiree Rosa Cavalcanti, Priscila Santana Da Silva, and Gessica De Jesus Souza
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medicine.medical_specialty ,business.industry ,General surgery ,Medicine ,Cancer ,Dentistry ,Radiology, Nuclear Medicine and imaging ,Dentistry (miscellaneous) ,Surgery ,Oral Surgery ,business ,medicine.disease ,Pathology and Forensic Medicine - Published
- 2017
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99. Development of database and comprehensive indexes for opening valuation of local activities in Japan - analysis of 125 cities of Ibaraki, Shiga, and Tokyo prefectures
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Naoki Ishikawa, Ryosuke Nakatani, Yusuke Monma, and Sumika Arima
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Geography ,Database ,computer.software_genre ,computer ,Visualization ,Valuation (finance) - Abstract
This study introduced the designs of a database and indexes for local vitalization. As the first step, Japanese 180 cities' information is stored in the database and analyzed. In the analysis, not only visualization of basic information but also newly structured index expressing local vitalization, degrees of local vitality, internal vitalization, and exchange vitalization, were used. This study tries to resolve four issues of the index design, interactive, comprehensive, quantitative, and structural. As the result of the study, a common design of the database and data-based visualization tool is useful for understanding a local status correctly. Indexes of vitalization are useful to compare well contrast. more...
- Published
- 2014
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100. Single- and Multiple-RF Aided Non-Coherent Generalized Spatial Modulation
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Shinya Sugiura and Naoki Ishikawa
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Channel state information ,Modulation ,GSM ,ComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKS ,MIMO ,Transmitter ,Bit error rate ,Electronic engineering ,Data_CODINGANDINFORMATIONTHEORY ,Differential coding ,Computer Science::Information Theory ,Communication channel ,Mathematics - Abstract
Motivated by the recent generalized spatial modulation (GSM)-multiple input multiple-output (MIMO) concept, in this paper we conceive a non- coherently detected GSM architecture, which is achieved with the aid of Cayley unitary differential encoding. More specifically, the proposed differentially-encoded transmitter structure enables us to eliminate any limitations imposed by pilot insertions and channel state information (CSI) estimation, while attaining the GSM scheme's increased transmission rate as well as reduced number of RF chains at the transmitter. Furthermore, we extend the proposed non-coherent GSM scheme to operate in a single-antenna transmitter structure. Our performance results reveal that a high transmission rate is achieved, while attaining reduced-RF branches and dispensing with the channel estimation at the receiver. more...
- Published
- 2014
- Full Text
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