Advanced Quantizer Designs for FDD-Based FD-MIMO Systems Using Uniform Planar Arrays

Massive multiple-input multiple-output (MIMO) systems, which utilize a large number of antennas at the base station, are expected to enhance network throughput by enabling improved multiuser MIMO techniques. To deploy many antennas in reasonable form factors, base stations are expected to employ antenna arrays in both horizontal and vertical dimensions, which is known as full-dimension (FD) MIMO. The most popular two-dimensional array is the uniform planar array (UPA), where antennas are placed in a grid pattern. To exploit the full benefit of massive MIMO in frequency division duplexing (FDD), the downlink channel state information (CSI) should be estimated, quantized, and fed back from the receiver to the transmitter. However, it is difficult to accurately quantize the channel in a computationally efficient manner due to the high dimensionality of the massive MIMO channel. In this paper, we develop both narrowband and wideband CSI quantizers for FD-MIMO taking the properties of realistic channels and the UPA into consideration. To improve quantization quality, we focus on not only quantizing dominant radio paths in the channel, but also combining the quantized beams. We also develop a hierarchical beam search approach, which scans both vertical and horizontal domains jointly with moderate computational complexity. Numerical simulations verify that the performance of the proposed quantizers is better than that of previous CSI quantization techniques.Comment: 15 pages, 6 figure

大規模ネットワーク管理のためのHTTP/SNMPリバースプロキシと管理トラヒックの公平性に関する研究

学位の種別: 課程博士審査委員会委員 : （主査）東京大学教授 瀬崎 薫, 東京大学教授 浅見 徹, 東京大学准教授 川原 圭博, 東京大学教授 森川 博之, 東京大学名誉教授 若原 恭University of Tokyo(東京大学

Evolution of the Stethoscope: Advances with the Adoption of Machine Learning and Development of Wearable Devices

The stethoscope has long been used for the examination of patients, but the importance of auscultation has declined due to its several limitations and the development of other diagnostic tools. However, auscultation is still recognized as a primary diagnostic device because it is non-invasive and provides valuable information in real-time. To supplement the limitations of existing stethoscopes, digital stethoscopes with machine learning (ML) algorithms have been developed. Thus, now we can record and share respiratory sounds and artificial intelligence (AI)-assisted auscultation using ML algorithms distinguishes the type of sounds. Recently, the demands for remote care and non-face-to-face treatment diseases requiring isolation such as coronavirus disease 2019 (COVID-19) infection increased. To address these problems, wireless and wearable stethoscopes are being developed with the advances in battery technology and integrated sensors. This review provides the history of the stethoscope and classification of respiratory sounds, describes ML algorithms, and introduces new auscultation methods based on AI-assisted analysis and wireless or wearable stethoscopes

In vivo genome editing with a small Cas9 orthologue derived from Campylobacter jejuni

Several CRISPR-Cas9 orthologues have been used for genome editing. Here, we present the smallest Cas9 orthologue characterized to date, derived from Campylobacter jejuni (CjCas9), for efficient genome editing in vivo. After determining protospacer-adjacent motif (PAM) sequences and optimizing single-guide RNA (sgRNA) length, we package the CjCas9 gene, its sgRNA sequence, and a marker gene in an all-in-one adeno-associated virus (AAV) vector and produce the resulting virus at a high titer. CjCas9 is highly specific, cleaving only a limited number of sites in the human or mouse genome. CjCas9, delivered via AAV, induces targeted mutations at high frequencies in mouse muscle cells or retinal pigment epithelium (RPE) cells. Furthermore, CjCas9 targeted to the Vegfa or Hif1a gene in RPE cells reduces the size of laser-induced choroidal neovascularization, suggesting that in vivo genome editing with CjCas9 is a new option for the treatment of age-related macular degeneration.

Modelling Environmental Problem-Solving Through STEAM Activities : 4Dframe's Warka Water Workshop

In this paper the Korean 4Dframe educational modelling kit’s rich capacities are presented within a STEAM (Science, Technology, Engineering, Arts and Mathematics) education workshop. The workshop is an adaptation of the Warka Water social design project, launched by the architect Arturo Vittori in response to Ethiopia’s diminished sources of drinking water. Participants of the workshop will study the geometry of the Warka Water tower and understand its water harvesting technique, which is based on collecting water from the air.nonPeerReviewe

Zinc molybdate/functionalized carbon nanofiber composites modified electrodes for high-performance amperometric detection of hazardous drug Sulfadiazine

Pharmaceuticals are generally designed to be nondegradable or slowly degradable to prevent chemical degradation as it is employed as therapeutics for human or animal. This results in a widespread risk when they enter, accumulate or persist in the environment. Pharmaceutical pollution is emerging as wide-reaching concern due to its ostensible consequences, by dissemination in the environment. This demands for inventing novel analytical routes to monitor and mitigate pharmaceutical pollutants. Therefore, this paper presents synthesis of Zinc molybdate nano particles embedded on functionalized carbon nanofibers to fabricate glassy carbon electrode towards sensitive detection of Sulfadiazine (SDZ). The synergistic effect produced in the composite had enabled it with improved charge transfer kinetics and benefited with more active surface area. The proposed ZnMoO4/f-CNF sensor shows significant static characteristics such as wide linear response ranges (0.125 to1575.2 μM), low detection limit (0.0006 μM) and selectivity, and increased stability. Also, its practicability was analyzed by SDZ detection in real samples

Biogeography of Korea’s top predator, the yellow-throated Marten: evolutionary history and population dynamics

Abstract Background Peninsulas often harvest high genetic diversity through repeated southward migrations of species during glacial maxima. Studies addressing within-species evolutionary responses to climate fluctuations in northeast Asia are limited compared to other regions of the world, and more so in the Korean Peninsula. In this study, we conducted the first population-level study of the yellow-throated marten, Martes flavigula, from the Korean Peninsula, Russian, Taiwanese and Chinese localities in a biogeographic framework using mitochondrial (cyt-b, nd2, cr) and nuclear gene sequencing (ghr). Results Bayesian analyses revealed a rather young population, with a split from the most recent common ancestor at around 125 kya. Martes flavigula likely colonized the Korean Peninsula from Mainland China through the Yellow Sea twice, ca. 60 kya and 20 kya. Korean martens diversified during the Late Pleistocene with at least two dispersal events out of Korea, towards the southwest to Taiwan (ca. 80 kya) and towards the North into Russia and eastern China; most likely after the Last Glacial Maxima (ca. 20 kya). We argue that the lack of population structure and mixed populations is possibly a consequence of the high dispersal capability of the species. The Bayesian skyline plot revealed a population decline within the last 5000 years, suggesting potential negative biotic and anthropogenic effects in the area. We find that local populations are not genetically differentiated, therefore no perceptible population structure within Korea was found. Conclusions The topography and geography of the Korean Peninsula has played a pivotal role in its colonization. Connections between the Korean Peninsula and the Mainland through sea-level drops of the Yellow Sea at times of glacial maxima and the high dispersal capability of M. flavigula adds to the lack of geographical structure in this species and the paraphyly of Korean lineages

Ag2S-CoS hetero-nanowires terminated with stepped surfaces for improved oxygen evolution reaction

Water electrolysis has received great attention for producing hydrogen, but sluggish kinetics of oxygen evolution reaction (OER) has remained a big challenge. Recently, cobalt sulfide materials have been widely explored as great choice in highly efficient electrocatalysts due to their good electrical conductivity and bi-functionality toward OER and hydrogen evolution reaction (HER). However, cobalt sulfide shows outstanding HER activity, but its OER activity should be improved. Herein, hexagonal-phase cobalt sulfide (CoS) nanowires with abundant stepped surfaces and defect sites were prepared via a seed-growth approach with silver sulfide (Ag2S) nanoparticles. The Ag2S-CoS hetero-nanowires (HNWs) exhibited excellent electrochemical performances for oxygen evolution reaction (overpotential = 275 mV, Tafel slope = 77.1 mVdec???1, charge transfer resistance = 1.3 ??) in 1.0 M KOH solution. The origin of superior activity was investigated using a combined experimental and theoretical approach. This work highlights the importance of surface defects for improving oxygen evolution reaction performance of water electrolysis