
Tokyo Denki University
UniversityTokyo, Japan
Research output, citation impact, and the most-cited recent papers from Tokyo Denki University (Japan). Aggregated across the NobleBlocks index of 300M+ scholarly works.
Top-cited papers from Tokyo Denki University
In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. For example, a key point that needs to be emphasized is thatthere is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process versus those that measure flux through the autophagy pathway (i.e., the completeprocess including the amount and rate of cargo sequestered and degraded). In particular, a block in macroautophagy that results in autophagosome accumulation must be differentiated from stimuli that increase autophagic activity, defined as increasedautophagy induction coupled with increased delivery to, and degradation within, lysosomes (inmost higher eukaryotes and some protists such as Dictyostelium) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the field understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in manycases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. It is worth emphasizing here that lysosomal digestion is a stage of autophagy and evaluating its competence is a crucial part of the evaluation of autophagic flux, or complete autophagy. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as forreviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multipleassays to monitor autophagy. Along these lines, because of the potential for pleiotropic effects due to blocking autophagy through genetic manipulation, it is imperative to target by gene knockout or RNA interference more than one autophagyrelated protein. In addition, some individual Atg proteins, or groups of proteins, are involved in other cellular pathways implying that not all Atg proteins can be used as a specific marker for an autophagic process. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular assays, we hope to encourage technical innovation in the field.
This study presents a new global baseline of mangrove extent for 2010 and has been released as the first output of the Global Mangrove Watch (GMW) initiative. This is the first study to apply a globally consistent and automated method for mapping mangroves, identifying a global extent of 137,600 km 2 . The overall accuracy for mangrove extent was 94.0% with a 99% likelihood that the true value is between 93.6–94.5%, using 53,878 accuracy points across 20 sites distributed globally. Using the geographic regions of the Ramsar Convention on Wetlands, Asia has the highest proportion of mangroves with 38.7% of the global total, while Latin America and the Caribbean have 20.3%, Africa has 20.0%, Oceania has 11.9%, North America has 8.4% and the European Overseas Territories have 0.7%. The methodology developed is primarily based on the classification of ALOS PALSAR and Landsat sensor data, where a habitat mask was first generated, within which the classification of mangrove was undertaken using the Extremely Randomized Trees classifier. This new globally consistent baseline will also form the basis of a mangrove monitoring system using JAXA JERS-1 SAR, ALOS PALSAR and ALOS-2 PALSAR-2 radar data to assess mangrove change from 1996 to the present. However, when using the product, users should note that a minimum mapping unit of 1 ha is recommended and that the error increases in regions of disturbance and where narrow strips or smaller fragmented areas of mangroves are present. Artefacts due to cloud cover and the Landsat-7 SLC-off error are also present in some areas, particularly regions of West Africa due to the lack of Landsat-5 data and persistence cloud cover. In the future, consideration will be given to the production of a new global baseline based on 10 m Sentinel-2 composites.
A family of numerical quadrature formulas is introduced by application of the trapezoidal rule to infinite integrals which result from the given integrals \int^b_a f(x)dx by suitable variable transformations x = \phi(u) . These formulas are characterized by having double exponential asymptotic behavior of the integrands in the resulting infinite integrals as u →± ∞ , and it is shown both analytically and numerically that such formulas are generally optimal with respect to the ecomony of the number of sampling points.
This article presents an elaborate coordination technique among multiple cell sites called coordinated multipoint transmission and reception in the Third Generation Partnership Project for LTE-Advanced. After addressing major radio access techniques in the LTE Release 8 specifications, system requirements and applied radio access techniques that satisfy the requirements for LTE-Advanced are described including CoMP transmission and reception. Then CoMP transmission and reception schemes and the related radio interface, which were agreed upon or are currently being discussed in the 3GPP, are presented. Finally, system-level simulation evaluations show that the CoMP transmission and reception schemes have a significant effect in terms of improving the cell edge user throughput based on LTE-Advanced simulation conditions.
Rechargeable lithium batteries have rapidly risen to prominence as fundamental devices for green and sustainable energy development. Lithium batteries are now used as power sources for electric vehicles. However, materials innovations are still needed to satisfy the growing demand for increasing energy density of lithium batteries. In the past decade, lithium-excess compounds, Li2MeO3 (Me = Mn(4+), Ru(4+), etc.), have been extensively studied as high-capacity positive electrode materials. Although the origin as the high reversible capacity has been a debatable subject for a long time, recently it has been confirmed that charge compensation is partly achieved by solid-state redox of nonmetal anions (i.e., oxide ions), coupled with solid-state redox of transition metals, which is the basic theory used for classic lithium insertion materials, such as LiMeO2 (Me = Co(3+), Ni(3+), etc.). Herein, as a compound with further excess lithium contents, a cation-ordered rocksalt phase with lithium and pentavalent niobium ions, Li3NbO4, is first examined as the host structure of a new series of high-capacity positive electrode materials for rechargeable lithium batteries. Approximately 300 mAh ⋅ g(-1) of high-reversible capacity at 50 °C is experimentally observed, which partly originates from charge compensation by solid-state redox of oxide ions. It is proposed that such a charge compensation process by oxide ions is effectively stabilized by the presence of electrochemically inactive niobium ions. These results will contribute to the development of a new class of high-capacity electrode materials, potentially with further lithium enrichment (and fewer transition metals) in the close-packed framework structure with oxide ions.
Abstract Further increase in energy density of lithium batteries is needed for zero emission vehicles. However, energy density is restricted by unavoidable theoretical limits for positive electrodes used in commercial applications. One possibility towards energy densities exceeding these limits is to utilize anion (oxide ion) redox, instead of classical transition metal redox. Nevertheless, origin of activation of the oxide ion and its stabilization mechanism are not fully understood. Here we demonstrate that the suppression of formation of superoxide-like species on lithium extraction results in reversible redox for oxide ions, which is stabilized by the presence of relatively less covalent character of Mn 4+ with oxide ions without the sacrifice of electronic conductivity. On the basis of these findings, we report an electrode material, whose metallic constituents consist only of 3 d transition metal elements. The material delivers a reversible capacity of 300 mAh g −1 based on solid-state redox reaction of oxide ions.
A new concept in chromatography is proposed that utilizes a temperature-responsive surface with a constant aqueous mobile phase. The surface of the silica stationary phase in high-performance liquid chromatography (HPLC) has been modified with temperature-responsive polymers to exhibit temperature-controlled hydrophilic/hydrophobic changes. Poly(N-isopropylacrylamide) (PIPAAm) was grafted onto (aminopropyl)silica using an activated ester-amine coupling method. These grafted silica surfaces show hydrophilic properties at lower temperatures which, as temperature increases, transform to hydrophobic surface properties. The elution profile of five mixed steroids on an HPLC column packed with this material depends largely on the temperature of the aqueous mobile phase. Retention times increase with increasing temperature without any change in the eluent. Changes in the retention times of hydrophobic steroids were larger than those for hydrophilic steroids. The temperature-responsive interaction between PIPAAm-modified silica and these steroids is proposed to result from changes in the surface properties of the HPLC stationary phase by the transition of hydrophilic/hydrophobic surface-grafted IPAAm polymers. We demonstrate a novel and useful new chromatography system in which surface properties and the resulting function of the HPLC stationary phase are controlled by external temperature changes. This method should be effective in biological and biomedical separations of peptides and proteins using only aqueous mobile phases.
Abstract. The terrestrial forest carbon pool is poorly quantified, in particular in regions with low forest inventory capacity. By combining multiple satellite observations of synthetic aperture radar (SAR) backscatter around the year 2010, we generated a global, spatially explicit dataset of above-ground live biomass (AGB; dry mass) stored in forests with a spatial resolution of 1 ha. Using an extensive database of 110 897 AGB measurements from field inventory plots, we show that the spatial patterns and magnitude of AGB are well captured in our map with the exception of regional uncertainties in high-carbon-stock forests with AGB >250 Mg ha−1, where the retrieval was effectively based on a single radar observation. With a total global AGB of 522 Pg, our estimate of the terrestrial biomass pool in forests is lower than most estimates published in the literature (426–571 Pg). Nonetheless, our dataset increases knowledge on the spatial distribution of AGB compared to the Global Forest Resources Assessment (FRA) by the Food and Agriculture Organization (FAO) and highlights the impact of a country's national inventory capacity on the accuracy of the biomass statistics reported to the FRA. We also reassessed previous remote sensing AGB maps and identified major biases compared to inventory data, up to 120 % of the inventory value in dry tropical forests, in the subtropics and temperate zone. Because of the high level of detail and the overall reliability of the AGB spatial patterns, our global dataset of AGB is likely to have significant impacts on climate, carbon, and socio-economic modelling schemes and provides a crucial baseline in future carbon stock change estimates. The dataset is available at https://doi.org/10.1594/PANGAEA.894711 (Santoro, 2018).
Carbonaceous meteorites are thought to be fragments of C-type (carbonaceous) asteroids. Samples of the C-type asteroid (162173) Ryugu were retrieved by the Hayabusa2 spacecraft. We measured the mineralogy and bulk chemical and isotopic compositions of Ryugu samples. The samples are mainly composed of materials similar to those of carbonaceous chondrite meteorites, particularly the CI (Ivuna-type) group. The samples consist predominantly of minerals formed in aqueous fluid on a parent planetesimal. The primary minerals were altered by fluids at a temperature of 37° ± 10°C, about [Formula: see text] million (statistical) or [Formula: see text] million (systematic) years after the formation of the first solids in the Solar System. After aqueous alteration, the Ryugu samples were likely never heated above ~100°C. The samples have a chemical composition that more closely resembles that of the Sun's photosphere than other natural samples do.
This paper presents simple and convenient generalized Minkowski metrics on the multidimensional feature space in which coordinate axes are associated with not only quantitative features but also qualitative and structural features. The metrics are defined on a new mathematical model (U/sup (d/),[+], [X]) which is called simply the Cartesian space model, where U/sup (d/) is the feature space which permits mixed feature types, [+] is the Cartesian join operator which yields a generalized description for given descriptions on U/sup (d/), and [X] is the Cartesian meet operator which extracts a common description from given descriptions on U/sup (d/). To illustrate the effectiveness of our generalized Minkowski metrics, we present an approach to the hierarchical conceptual clustering, and a generalization of the principal component analysis for mixed feature data.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
TAMA300, an interferometric gravitational-wave detector with 300-m baseline length, has been developed and operated with sufficient sensitivity to detect gravitational-wave events within our galaxy and sufficient stability for observations; the interferometer was operated for over 10 hours stably and continuously. With a strain-equivalent noise level of h approximately 5x10(-21)/sqrt[Hz], a signal-to-noise ratio of 30 is expected for gravitational waves generated by a coalescence of 1.4M-1.4M binary neutron stars at 10 kpc distance. We evaluated the stability of the detector sensitivity with a 2-week data-taking run, collecting 160 hours of data to be analyzed in the search for gravitational waves.
The recently emerging three-dimensional (3D) displays in the electronic shops imitate depth illusion by overlapping two parallax 2D images through either polarized glasses that viewers are required to wear or lenticular lenses fixed directly on the display. Holography, on the other hand, provides real 3D imaging, although usually limiting colors to monochrome. The so-called rainbow holograms--mounted, for example, on credit cards--are also produced from parallax images that change color with viewing angle. We report on a holographic technique based on surface plasmons that can reconstruct true 3D color images, where the colors are reconstructed by satisfying resonance conditions of surface plasmon polaritons for individual wavelengths. Such real 3D color images can be viewed from any angle, just like the original object.
A technique based on deadbeat control theory is proposed to obtain a nearly sinusoidal PWM (pulsewidth-modulated) inverter output voltage using only a voltage sensor. The closed loop sampled-data feedback scheme inherently results in very fast response to load disturbance and nonlinear load, producing low total harmonic distortion. Parameter estimation of the plant provides a type of self-tuning of the proposed controller. A theoretical analysis, simulation, and experimental results are presented for a single-phase PWM inverter controlled by an Intel 8086 microprocessor.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
In this paper, a new simple control strategy for AC input current of voltage-type pulsewidth modulation (PWM) rectifiers which can eliminate the steady-state control error completely is proposed. This control method requires neither the instantaneous value of the supply voltage nor any accurate circuit parameters on the AC side of the rectifier. Thus, a robust operation against the variation of the circuit parameters can be achieved. In the proposed control system, a digital resonant element implemented by a digital signal processor (DSP) is introduced as a feedback controller. The digital resonant element exhibits a function similar to an integrator for the fundamental frequency components. Thus, it can eliminate the steady-state control error of the input current completely, The principle of the proposed control method is discussed, and its effectiveness is shown theoretically. The detailed method of the implementation of the lossless digital resonant element is explained. The effects of the harmonics in the supply voltage on the AC input current waveform are clarified. To confirm the effectiveness of the proposed control method, some experimental results from two laboratory test systems are shown.
The 2011 Great East Japan Earthquake caused the severe liquefaction of reclaimed lands in the Tokyo Bay area, from Shinkiba in Tokyo through Urayasu, Ichikawa and Narashino Cities to Chiba City. However, the reclaimed lands that had been improved by the sand compaction pile method, the gravel drain method or other methods did not liquefy. The reclaimed lands that did liquefy had been constructed after around 1966 with soil dredged from the bottom of the bay. The dredged and filled soils were estimated to have been liquefied by the earthquake. Seismic intensities in the liquefied zones were not high, although the liquefied grounds were covered with boiled sand. Most likely it was the very long duration of the main shock, along with the large aftershock that hit 29 min later, which induced the severe liquefaction. Sidewalks and alleys buckled at several sites, probably due to a kind of sloshing around of the liquefied ground. Moreover, much sand boiled from the ground and the ground subsided significantly because the liquefied soil was very fine. Many houses settled notably and tilted. In Urayasu City, 3680 houses were more than partially destroyed. Sewage pipes meandered or were broken, their joints were extruded from the ground, and many manholes were horizontally sheared. This remarkable damage may also have occurred due to the sloshing around of the liquefied ground.
Large-scale high-energy batteries with electrode materials made from the Earth-abundant elements are needed to achieve sustainable energy development. On the basis of material abundance, rechargeable sodium batteries with iron- and manganese-based positive electrode materials are the ideal candidates for large-scale batteries. In this review, iron- and manganese-based electrode materials, oxides, phosphates, fluorides, etc, as positive electrodes for rechargeable sodium batteries are reviewed. Iron and manganese compounds with sodium ions provide high structural flexibility. Two layered polymorphs, O3- and P2-type layered structures, show different electrode performance in Na cells related to the different phase transition and sodium migration processes on sodium extraction/insertion. Similar to layered oxides, iron/manganese phosphates and pyrophosphates also provide the different framework structures, which are used as sodium insertion host materials. Electrode performance and reaction mechanisms of the iron- and manganese-based electrode materials in Na cells are described and the similarities and differences with lithium counterparts are also discussed. Together with these results, the possibility of the high-energy battery system with electrode materials made from only Earth-abundant elements is reviewed.
A very fast deconvolution method, which is based on the fast Fourier transform (FFT), can be used to control the outputs from a multichannel plant comprising any number of control sources and error sensors. The result is a matrix of causal finite impulse response filters whose performance is optimized at a large number of discrete frequencies. The paper is particularly aimed at multichannel sound reproduction and more specifically reproducing the sound field from a set of loudspeakers.
The first total synthesis of (+)-chaetocin has been accomplished in nine steps starting from known N-Cbz-N-Me-serine using radical alpha-bromination reaction of diketopiperazine 10 and Co(I)-mediated reductive dimerization reaction of 12 as key reactions. The enantiomers show comparable inhibitory activity toward histone methyltransferase (HMT) G9a, but analogues without the sulfur functionality are inactive.
A repetitive voltage compensation technique that generates a high-quality sinusoidal output voltage from a single-phase pulse width modulation (PWM) inverter used for uninterruptible power supplies is described. A repetitive control technique eliminates the steady-state error in the distorted output voltage caused by cyclic loads. The proposed PWM inverter system uses microprocessor-based closed-loop digital feedback with a sinusoidal reference. The PWM pattern is determined at every sampling instant by the proposed algorithm, implemented by a microprocessor using a set of detected output voltages and the reference signals through one cycle. The system has low distortion and very fast response for AC phase-controlled loads.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Diamond-like carbon (DLC) films have been extensively applied in industries owing to their excellent characteristics such as high hardness. In particular, there is a growing demand for their use as protective films for mechanical parts owing to their excellent wear resistance and low friction coefficient. DLC films have been deposited by various methods and many deviate from the DLC regions present in the ternary diagrams proposed for sp3 covalent carbon, sp2 covalent carbon, and hydrogen. Consequently, redefining the DLC region on ternary diagrams using DLC coatings for mechanical and electrical components is urgently required. Therefore, we investigate the sp3 ratio, hydrogen content, and other properties of 74 types of amorphous carbon films and present the classification of amorphous carbon films, including DLC. We measured the sp3 ratios and hydrogen content using near-edge X-ray absorption fine structure and Rutherford backscattering-elastic recoil detection analysis under unified conditions. Amorphous carbon films were widely found with nonuniform distribution. The number of carbon atoms in the sp3 covalent carbon without bonding with hydrogen and the logarithm of the hydrogen content were inversely proportional. Further, we elucidated the DLC regions on the ternary diagram, classified the amorphous carbon films, and summarized the characteristics and applications of each type of DLC.