Behaviour of precast reinforced concrete slabs in steel-concrete composite bridge decks with bolted shear connectors

University of Technology, Sydney. Faculty of Engineering and Information Technology.Due to ease of fabrication and maintenance and speed of construction, precast prefabricated composite deck slabs have gained huge popularity all around the globe. The precast prefabricated structural systems do not require the costly in-situ formworks. Accordingly, the precast prefabricated structural systems can reduce the cost of labour and improve the safety and speed of construction. In addition, the prefabricated composite structures can significantly facilitate application of external reinforcement in lieu of conventional internal steel bars. The reinforced concrete (RC) structures, in general, suffer maintenance and repair difficulties, as internal reinforcements in reinforced concrete (RC) structures are susceptible to corrosion that can be typically accelerated by chloride and other corrosive material ingress. Once the corrosion occurs, reinforcement starts to expand inside the concrete and that in turn causes concrete cracking and spalling. Accordingly, the reinforced concrete member cannot perform its structural role properly. Second generation bridge deck slabs, namely steel-free deck slabs, in which conventional embedded reinforcements are replaced by external reinforcements have proved to be efficient in mitigating the problems associated with corrosion of reinforcing steel bars. The steel-free deck slabs rely on development of arching action to withstand the load. The inherent arching action in longitudinally restrained reinforced concrete members was realised about fifty years ago, however, the beneficial effects of arching action has not been recognised by most of the existing reinforced concrete design standards yet. So far only Northern Island Standard, DRD, NI (1990), and Canadian code, OHBD (1992) takes account of the enhancing effect of arching action in design practice. This intrinsic capacity of laterally restrained RC structures helps the flexural reinforced concrete members to show loading capacity far in excess of flexural resistance predicted by the conventional formulas. Apart from corrosion of reinforcing steel bars, the existing steel-concrete composite deck slabs cannot be repaired and rehabilitated conveniently and without the interruption to the traffic. Although many studies have been conducted examining a wide range of composite deck systems, lack of a practical precast prefabricated steel-concrete deck slab that allow for easy replacement of concrete slabs in case of deterioration is apparent. The restrained steel-free concrete deck provides a practical solution to the corrosion of reinforcement by removing the internal steel bars and replacing them with external steel straps. However, in the meshless slabs proposed by them, the future repair and replacement of concrete slab cannot be conducted easily without a major interruption to the traffic. To take advantage of the intrinsic characteristic of precast prefabricated deck slabs and to overcome the issues associated with corrosion of internal steel bars in RC bridge decks subject to corrosive environment, a novel steel-concrete deck with precast prefabricated concrete slabs is proposed and examined in this study. The results of experimental tests on precast prefabricated slabs with high strength bolts are presented and FE numerical simulation are carried out using ATENA 2D. The novelty of this research project lies in the application of high strength steel bolts for connecting the concrete slabs to steel girders. The high strength bolts are pre-tensioned with a special amount of tensile force induced in them by a torque meter wrench. This new steel-concrete composite deck has two main advantages; firstly, there is no requirement as to design and assemble formworks for constructing cast-in-situ concrete slabs and hence the construction of deck is much faster. Secondly, the high strength bolts can be opened and the precast slab can be easily released and replaced if required. This advantage allows for easy repair and maintenance of the concrete deck slab without causing significant interruption to the traffic during repair and rehabilitation

Targeting the eIF4A RNA helicase blocks translation of the MUC1-C oncoprotein

The oncogenic MUC1-C subunit is aberrantly overexpressed in most human breast cancers by mechanisms that are not well understood. The present studies demonstrate that stimulation of non- malignant MCF-10A cells with epidermal growth factor (EGF) or heregulin (HRG) results in marked upregulation of MUC1-C translation. Growth factor-induced MUC1-C translation was found to be mediated by PI3K->AKT, and not MEK->ERK1/2, signaling. We also show that activation of the mTORC1->S6K1 pathway decreases PDCD4, an inhibitor of the eIF4A RNA helicase, and contributes to the induction of MUC1-C translation. In concert with these results, treatment of growth factor-stimulated MCF-10A cells with the eIF4A RNA helicase inhibitors, silvestrol and CR-1-31-B, blocked increases in MUC1-C abundance. The functional significance of the increase in MUC1-C translation is supported by the demonstration that MUC1-C, in turn, forms complexes with EGFR and promotes EGFR-mediated activation of the PI3K->AKT pathway and the induction of growth. Compared to MCF-10A cells, constitutive overexpression of MUC1-C in breast cancer cells was unaffected by EGF stimulation, but was blocked by inhibiting PI3K->AKT signaling. The overexpression of MUC1-C in breast cancer cells was also inhibited by blocking eIF4A RNA helicase activity with silvestrol and CR-1-31-B. These findings indicate that EGF-induced MUC1-C expression is mediated by the PI3K->AKT pathway and the eIF4A RNA helicase, and that this response promotes EGFR signaling in an autoinductive loop. The findings also indicate that targeting the eIF4A RNA helicase is a novel approach for blocking MUC1-C overexpression in breast cancer cells.P50 CA100707 - NCI NIH HHS; R01 CA042802 - NCI NIH HHS; R01 CA097098 - NCI NIH HHS; R01 GM073855 - NIGMS NIH HH

Review on Graph Feature Learning and Feature Extraction Techniques for Link Prediction

The problem of link prediction has recently attracted considerable attention by research community. Given a graph, which is an abstraction of the relationships among entities, the task of link prediction is to anticipate future connections among entities in the graph, concerning its current state. Extensive studies have examined this problem from different aspects and proposed various methods, some of which might work very well for a specific application but not as a global solution. This work presents an extensive review of state-of-art methods and algorithms proposed on this subject and categorizes them into four main categories: similarity-based methods, probabilistic methods, relational models, and learning-based methods. Additionally, a collection of network data sets has been presented in this paper, which can be used to study link prediction. To the best of our knowledge, this survey is the first comprehensive study that considers all of the mentioned challenges and solutions for link prediction in graphs with the improvements in the recent years, including the unsupervised and supervised techniques and their evolution over the recent years.Comment: 31 pages, 7 figure

Assessment of human errors in driving accidents; Analysis of the causes based on aberrant behaviors

Introduction: Today, mortalities and injuries due to traffic accidents have been confirmed as a global phenomenon. Meanwhile, mistakes and high risk behaviors by drivers, is the most important intervening factor in traffic accidents. This study is to analyze the causes of traffic accidents according to drivers' aberrant behaviors. Methods: This cross-sectional study was conducted on 540 taxi drivers using Manchester Driving Behaviour Questinnaire in 0-5 Likert scale. After being gathered, the data were analyzed by SPSS 11.5 using Pearson Correlation and Logistic Regression. Findings: The mean score of aberrant driving behaviors was obtained 2.06 (± 0.47) and lapse obtained the highest score and driving mistakes did the lowest. As age advanced, the rate of aberrant behaviours declined (P = 0.006). Commitment of mistakes and offences was more prevalent in ages under 30 years compared to other age ranges and lapse in the individuals over 50 years was more prevalent compared to other items. The results of logistic regression indicated that all variables of DBQ are important in predicting Iranian drivers' aberrant behaviors (P < 0.001), but intentional offences had the highest correlation. There was an inverse correlation between driving history and intentional offences and mistakes (P < 0.001). Conclusion: According to the results, it could be said that intentional offences and lapse in driving behaviors are more predictive of self-reported accidents compared to other variables. The drivers in low ages are more willing to practice aberrant behaviors due to lack of adequate skill and experience and having intrinsic excitements. By contrast, as age advances, intentional offenses declines and the rate of lapses ascends. It seems that through provision of regular, periodic training for the drivers by occupation and creating awareness, aberrant behaviors and, by extension, traffic accidents could be effectively decreased