Routes for efficiency enhancement in fluorescent TADF exciplex host OLEDs gained from an electro‐optical device model

Fluorescence-based organic light-emitting diodes (OLEDs) using thermally activated delayed fluorescence (TADF) have increasingly attracted attention in research and industry. One method to implement TADF is based on an emitter layer composed of an exciplex host and a fluorescent dopant. Even though the experimental realization of this concept has demonstrated promising external quantum efficiencies, the full potential of this approach has not yet been assessed. To this end, a comprehensive electro-optical device model accounting for the full exciton dynamics including triplet harvesting and exciton quenching is presented. The model parameters are fitted to multiple output characteristics of an OLED comprising a TADF exciplex host with a fluorescent emitter, showing an external quantum efficiency of >10%. With the model at hand, an emission zone analysis and a parameter study are performed, and possible routes for further efficiency enhancement are presented

An Empirical Examination of Consumer Behavior for Search and Experience Goods in Sentiment Analysis

With the explosive increase of user-generated content such as product reviews and social media, sentiment analysis has emerged as an area of interest. Sentiment analysis is a useful method to analyze product reviews, and product feature extraction is an important task in sentiment analysis, during which one identifies features of products from reviews. Product features are categorized by product type, such as search goods or experience goods, and their characteristics are totally different. Thus, we examine whether the classification performance differs by product type. The findings show that the optimal threshold varies by product type, and simply decreasing the threshold to cover many features does not guarantee improvement of the classification performance

Development of a hybrid magnetic resonance/computed tomography-compatible phantom for magnetic resonance guided radiotherapy

The purpose of the present study was to develop a hybrid magnetic resonance/computed tomography (MR/CT)-compatible phantom and tissue-equivalent materials for each MR and CT image. Therefore, the essential requirements necessary for the development of a hybrid MR/CT-compatible phantom were determined and the development process is described. A total of 12 different tissue-equivalent materials for each MR and CT image were developed from chemical components. The uniformity of each sample was calculated. The developed phantom was designed to use 14 plugs that contained various tissue-equivalent materials. Measurement using the developed phantom was performed using a 3.0-T scanner with 32 channels and a Somatom Sensation 64. The maximum percentage difference of the signal intensity (SI) value on MR images after adding K2CO3 was 3.31%. Additionally, the uniformity of each tissue was evaluated by calculating the percent image uniformity (%PIU) of the MR image, which was 82.18 ±1.87% with 83% acceptance, and the average circular-shaped regions of interest (ROIs) on CT images for all samples were within ±5 Hounsfield units (HU). Also, dosimetric evaluation was performed. The percentage differences of each tissue-equivalent sample for average dose ranged from -0.76 to 0.21%. A hybrid MR/CT-compatible phantom for MR and CT was investigated as the first trial in this field of radiation oncology and medical physics

Readout-segmented echo-planar imaging in diffusion-weighted mr imaging in breast cancer: comparison with single-shot echo-planar imaging in image quality

Objective: The purpose of this study was to compare the image quality of standard single-shot echo-planar imaging (ss-EPI) and that of readout-segmented EPI (rs-EPI) in patients with breast cancer. Materials and Methods: Seventy-one patients with 74 breast cancers underwent both ss-EPI and rs-EPI. For qualitative comparison of image quality, three readers independently assessed the two sets of diffusion-weighted (DW) images. To evaluate geometric distortion, a comparison was made between lesion lengths derived from contrast enhanced MR (CE-MR) images and those obtained from the corresponding DW images. For assessment of image parameters, signal-to-noise ratio (SNR), lesion contrast, and contrast-to-noise ratio (CNR) were calculated. Results: The rs-EPI was superior to ss-EPI in most criteria regarding the qualitative image quality. Anatomical structure distinction, delineation of the lesion, ghosting artifact, and overall image quality were significantly better in rs-EPI. Regarding the geometric distortion, lesion length on ss-EPI was significantly different from that of CE-MR, whereas there were no significant differences between CE-MR and rs-EPI. The rs-EPI was superior to ss-EPI in SNR and CNR. Conclusion: Readout-segmented EPI is superior to ss-EPI in the aspect of image quality in DW MR imaging of the breast

COMPARISON OF ANGULAR KINEMATIC PATTERNS BETWEEN CARVING TURN AND SKIDDING TURN DURING ALPINE SKIING

The purpose of this study was to investigate the movement patterns between segments (lower spine, pelvis, thigh, shank) and ski using the relative angular displacement on anteroposterior and vertical axis. Fourteen alpine ski instructors were participated in this study. Eight inertial measurement units were used to measure kinematic variables. Each skier was asked to perform ten carving turns and ten skidding turns on the groomed 15°slope, respectively. On the vertical axis, relative angular displacement of lower spine-ski was significantly increased during carving turn, whereas relative angular displacement of shank-ski was significantly increased during skidding turn. On the anteroposterior axis, relative angular displacement of lower spine-ski, pelvis-ski and thigh-ski were significantly increased during carving turn