Kyushu University

About: Kyushu University is a education organization based out in Fukuoka, Japan. It is known for research contribution in the topics: Population & Catalysis. The organization has 68284 authors who have published 135190 publications receiving 3055928 citations. The organization is also known as: Kyūshū Daigaku.

The rate-distortion function for the quadratic Gaussian CEO problem

Abstract: A new multiterminal source coding problem called the CEO problem was presented and investigated by Berger, Zhang, and Viswanathan. Recently, Viswanathan and Berger have investigated an extension of the CEO problem to Gaussian sources and call it the quadratic Gaussian CEO problem. They considered this problem from a statistical viewpoint, deriving some interesting results. In this paper, we consider the quadratic Gaussian CEO problem from a standpoint of multiterminal rate-distortion theory. We regard the CEO problem as a certain multiterminal remote source coding problem with infinitely many separate encoders whose observations are conditionally independent if the remote source is given. This viewpoint leads us to a complete solution to the problem. We determine the tradeoff between the total amount of rate and squared distortion, deriving an explicit formula of the rate-distortion function. The derived function has the form of a sum of two nonnegative functions. One is a classical rate-distortion function for single Gaussian source and the other is a new rate-distortion function which dominates the performance of the system for a relatively small distortion. It follows immediately from our result that the conjecture of Viswanathan and Berger on the asymptotic behavior of minimum squared distortion for large rates is true.

Highly efficient organic light-emitting diode based on a hidden thermally activated delayed fluorescence channel in a heptazine derivative

Abstract: Considerable progress in organic light-emitting diodes (OLEDs) has triggered intensive effort to develop efficient solid-state electroluminescent (EL) materials over the past two decades. Among the many classes of materials being investigated, transition metal complexes are highly attractive because phosphorescent OLEDs containing Ir (III), Pt (II) and Os (II) complexes exhibit very high external quantum efficiencies (ηext). This is because such complexes effectively harvest triplet excitons, so their efficiencies are four times higher than that of conventional fluorescent OLEDs. However, phosphorescent OLEDs containing transition metal-based compounds are rather expensive and unsustainable because they contain rare metals. While OLEDs containing Cu (I) complexes that exhibit high ηext comparable to those with transition metal complexes have been examined as an alternative, the relatively low reliability and high driving voltage of such OLED are fundamental problems. Therefore, a novel way to realize high EL efficiency is required. Although fluorescent OLEDs have been assumed to show limited efficiency because of the branching ratio of singlet and triplet excitons of 1:3, the most recent fluorescence-based OLEDs have overcome this limitation using triplet-triplet annihilation and thermally activated delayed fluorescence (TADF) [1-2]. In particular, we have developed promising blue and green TADF materials [3-4]. However, the design of efficient orange or red emitters is inherently difficult because the photoluminescence (PL) quantum efficiency tends to decrease as the emission wavelength increases according to the energy gap law.

Exosomal microRNA in serum is a novel biomarker of recurrence in human colorectal cancer

Abstract: Background Functional microRNAs (miRNAs) in exosomes have been recognised as potential stable biomarkers in cancers. The aim of this study is to identify specific miRNAs in exosome as serum biomarkers for the early detection of recurrence in human colorectal cancer (CRC). Methods Serum samples were sequentially obtained from six patients with and without recurrent CRC. The miRNAs were purified from exosomes, and miRNA microarray analysis was performed. The miRNA expression profiles and copy number aberrations were explored using microarray and array CGH analyses in 124 CRC tissues. Then, we validated exosomal miRNAs in 2 serum sample sets (90 and 209 CRC patients) by quantitative real-time RT-PCR. Results Exosomal miR-17-92a cluster expression level in serum was correlated with the recurrence of CRC. Exosomal miR-19a expression levels in serum were significantly increased in patients with CRC as compared with healthy individuals with gene amplification. The CRC patients with high exosomal miR-19a expression showed poorer prognoses than the low expression group (P Conclusions Abundant expression of exosomal miR-19a in serum was identified as a prognostic biomarker for recurrence in CRC patients.