Enhanced bias stress stability of a-InGaZnO thin film transistors by inserting an ultra-thin interfacial InGaZnO:N layer

Amorphous indium-gallium-zinc oxide (a-IGZO) thin film transistors (TFTs) having an ultra-thin nitrogenated a-IGZO (a-IGZO:N) layer sandwiched at the channel/gate dielectric interface are fabricated. It is found that the device shows enhanced bias stress stability with significantly reduced threshold voltage drift under positive gate bias stress. Based on x-ray photoelectron spectroscopy measurement, the concentration of oxygen vacancies within the a-IGZO:N layer is suppressed due to the formation of N-Ga bonds. Meanwhile, low frequency noise analysis indicates that the average trap density near the channel/dielectric interface continuously drops as the nitrogen content within the a-IGZO:N layer increases. The improved interface quality upon nitrogen doping agrees with the enhanced bias stress stability of the a-IGZO TFTs.This work was supported in part by the State Key Program for Basic Research of China under Grant Nos. 2010CB327504, 2011CB922100, and 2011CB301900; in part by the National Natural Science Foundation of China under Grant Nos. 60936004 and 11104130; in part by the Natural Science Foundation of Jiangsu Province under Grant Nos. BK2011556 and BK2011050; and in part by the Priority Academic Program Development of Jiangsu Higher Education Institutions

Associations between Leisure Activities and HIV Risk Behaviors among Rural Migrants in Urban China

Although much has been documented on factors affecting HIV risk behavior among rural-to-urban migrants in China, data are lacking on the impact of leisure activities. In this study, we examined the association between leisure activities and HIV risk behavior among a sample of rural-to-urban migrants from two large cities (Beijing and Nanjing) in China. Cross-sectional data were analyzed for a sample of 4,085 participants aged 18 to 30 years (40.5% females). Findings from the analysis indicated that although the migrants worked long hours, they engaged in a number of activities when they did not work, including watching television (60.2%), reading (59.1%), sleeping (55.6%), and chatting with friends and co-workers (45.0%). Multiple regression analysis indicated that reading, doing chores (females only), listening to radio programs/audio CDs (male only) were associated with reduced likelihood of HIV risk behavior while playing cards in groups, visiting entertaining installments, watching videos (including Xrated, males only), and wondering around (females only) were associated with increased likelihood of HIV risk behavior. Findings of this study suggest that constructive and individualized activities (e.g., reading, listening to radios, and doing chores) may prevent migrants from engage in HIV risk behaviors while group and entertaining activities related to drugs and sex may increase the odds for migrants to engage in HIV risk behaviors. Prevention research should consider leisure activities as both an influential factor (including time trends and gender differences) for program development and an important venue for program delivery

Mining product adopter information from online reviews for improving product recommendation

We present in this article an automated framework that extracts product adopter information from online reviews and incorporates the extracted information into feature-based matrix factorization formore effective product recommendation. In specific, we propose a bootstrapping approach for the extraction of product adopters from review text and categorize them into a number of different demographic categories. The aggregated demographic information of many product adopters can be used to characterize both products and users in the form of distributions over different demographic categories. We further propose a graphbased method to iteratively update user- and product-related distributions more reliably in a heterogeneous user-product graph and incorporate them as features into the matrix factorization approach for product recommendation. Our experimental results on a large dataset crawled from JINGDONG, the largest B2C e-commerce website in China, show that our proposed framework outperforms a number of competitive baselines for product recommendation

Incorporating social role theory into topic models for social media content analysis

In this paper, we explore the idea of social role theory (SRT) and propose a novel regularized topic model which incorporates SRT into the generative process of social media content. We assume that a user can play multiple social roles, and each social role serves to fulfil different duties and is associated with a role-driven distribution over latent topics. In particular, we focus on social roles corresponding to the most common social activities on social networks. Our model is instantiated on microblogs, i.e., Twitter and community question-answering (cQA), i.e., Yahoo! Answers, where social roles on Twitter include "originators" and "propagators", and roles on cQA are "askers" and "answerers". Both explicit and implicit interactions between users are taken into account and modeled as regularization factors. To evaluate the performance of our proposed method, we have conducted extensive experiments on two Twitter datasets and two cQA datasets. Furthermore, we also consider multi-role modeling for scientific papers where an author's research expertise area is considered as a social role. A novel application of detecting users' research interests through topical keyword labeling based on the results of our multi-role model has been presented. The evaluation results have shown the feasibility and effectiveness of our model

Electrical instability of amorphous indium-gallium-zinc oxide thin film transistors under monochromatic light illumination

The electrical instability behaviors of a positive-gate-bias-stressed amorphous indium-gallium-zinc oxide (a-IGZO) thin film transistor(TFT) are studied under monochromatic light illumination. It is found that as the wavelength of incident light reduces from 750 nm to 450 nm, the threshold voltage of the illuminated TFT shows a continuous negative shift, which is caused by photo-excitation of trapped electrons at the channel/dielectric interface. Meanwhile, an increase of the sub-threshold swing (SS) is observed when the illumination wavelength is below 625 nm (∼2.0 eV). The SS degradation is accompanied by a simultaneous increase of the field effect mobility (μFE) of the TFT, which then decreases at even shorter wavelength beyond 540 nm (∼2.3 eV). The variation of SS and μFE is explained by a physical model based on generation of singly ionized oxygen vacancies (Vo⁺) and double ionized oxygen vacancies (Vo²⁺) within the a-IGZO active layer by high energy photons, which would form trap states near the mid-gap and the conduction band edge, respectively.This work was supported by the State Key Program for Basic Research of China under Grant Nos. 2010CB327504, 2011CB922100, 2011CB301900; the National Natural Science Foundation of China under Grant Nos. 60825401, 60936004, 11104130, BK2011556, and BK2011050

Study on the Weaving Behavior of High Density Bidirectional Pedestrian Flow

Weaving area may be the critical risk place in the subway transfer station. When improving service level of the weaving area, the characteristic of pedestrian weaving behavior should be systemically discussed. This paper described the mechanism of weaving behavior on high density pedestrian which was analyzed by the collection data of controlled experiment. Different weaving behaviors were contrasted due to different volumes in the bidirectional passageway. Video analysis was conducted to extract pedestrian moving behavior and calibrate the movement data with SIMI Motion. Influence of the high density weaving pedestrian was studied based on the statistical results (e.g., velocity, walking distance, and journey time). Furthermore, the quantitative method by speed analysis was announced to discriminate the conflict point. The scopes of weaving area and impact area at different pedestrian volumes were revealed to analyze the pedestrian turning angle. The paper concluded that walking pedestrians are significantly influenced by the weaving conflict and trend to turn the moving direction to avoid the conflict in weaving area; the ratio of stable weaving area and impact area is 2 to 3. The conclusions do provide a method to evaluate the transfer station safety and a facility layout guidance to improve the capacity

Cognitive Performance Concomitant With Vision Acuity Predicts 13-Year Risk for Mortality

Objective: To assess the joint impact of cognitive performance and visual acuity on mortality over 13-year follow-up in a representative US sample.Methods: Data from National Health and Nutrition Examination Survey (NHANES) participants (≥18 years old) were linked with the death record data of the National Death Index (NDI) with mortality follow-up through December 31, 2011. Cognitive performance was evaluated by the Digit Symbol Substitution Test (DSST) and cognitive performance impairment was defined as the DSST score equal to or less than the median value in the study population. Visual impairment (VI) was defined as presenting visual acuity worse than 20/40 in the better-seeing eye. Risks of all-cause and specific-cause mortality were estimated with Cox proportional hazards models after adjusting for confounders.Results: A total of 2,550 participants 60 years and older from two waves of (NHANES, 1999–2000, 2001–2002) were included in the current analysis. Over a median follow-up period of 9.92 years, 952 (35.2%) died of all causes, of whom 239 (23.1%), 224 (24.0%), and 489 (52.9%) died from cardiovascular disease (CVD), cancer, and non-CVD/non-cancer mortality, respectively. Cognitive performance impairment and VI increased the odds for mortality. Co-presence of VI among cognitive impaired elderly persons predicted nearly a threefold increased risk of all-cause mortality [hazard ratios (HRs), 2.74; 95% confidence interval (CI), 2.02–3.70; P < 0.001) and almost a fourfold higher risk of non-CVD/non-cancer mortality (HR, 3.72; 95% CI, 2.30–6.00; P < 0.001) compared to having neither impairment.Conclusion: People aged 60 years and over with poorer cognitive performance were at higher risk of long-term mortality, and were especially vulnerable to further mortality when concomitant with VI. It is informative for clinical implication in terms of early preventive interventions

Depth related variation of isoprenoid and hydroxylated tetraether lipids in Lake Lugu, Southwest China:Implications for palaeoenvironmental reconstructions

Archaeal glycerol dibiphytanyl glycerol tetraethers (isoGDGTs) and their hydroxylated derivatives (OH-GDGTs) have been increasingly applied to reconstruct past changes in lake temperature and lake-level using down-core sediments. However, a detailed examination of the distribution pattern of iso- and OH-GDGTs in lacustrine sediments is so far limited. To investigate the controls on the sedimentary GDGT distribution in lakes, we examined the archaeal GDGT distribution in surface sediments at different water depths from Lake Lugu, a deep alpine lake in southwest China. Our aim is to determine their distribution, sources and controlling factors. Based on the significant correlations between iso- and OH-GDGTs in deep-water sediments (> 20 m), we suggest that the main biological source of archaeal GDGTs in surface sediments is aquatic Group I.1a Thaumarchaeota (Nitrosoarchaeum). The depth-related variation of iso- and OH-GDGTs indicates that water depth is the main factor affecting the distribution of archaeal GDGTs in Lake Lugu, reflecting that Thaumarchaeota prefer to live in the deeper layer above the oxycline. This relationship leads to a positive correlation between %Cren, %OH-GDGTs, and Cren/Cren’ with water depth, confirming their potential application for paleo-lake level reconstruction. Our study improves the understanding of the factors that control the archaeal GDGTs in a deep alpine lake and suggest that they might be used as lake-level indicators

Reducing Bidirectional Pedestrian Conflict Based on Lane Formation Phenomenon in Subway Corridors

With the rapid increase of the subway passenger volume, the conflict among passengers emerges as a significant issue which affects subway serviceability, especially in the bidirectional flow. The aim of this study is to explore the characteristics of the bidirectional flow of pedestrians in a subway corridor. Pedestrian experiments were conducted to investigate microscopic characteristics of the pedestrian flow. It was found that the microscopic characteristics, including the walking speed and turning angle, were time-dependent and had a generalized trend with time. It was also found that different pedestrian volumes affected the microscopic characteristics. Based on the trend of the microscopic characteristics, the lane formation phenomenon was observed and quantitatively studied, identifying three phases: conflict phase, lane formation phase, and steady lane phase. To alleviate the bidirectional pedestrian conflict, additional pedestrian experiments for the countermeasure of adding separating strap in the corridor, which was based on the lane formation analysis, was conducted. The effectiveness of the countermeasure was demonstrated through a before-and-after comparison. The results showed that adding the separation between the adjacent lanes had the best performance in reducing the conflicts. The results would provide a rationale for subway managers in optimizing the corridor bidirectional pedestrian flow.</p