Dynamic Key-Value Memory Networks for Knowledge Tracing

Knowledge Tracing (KT) is a task of tracing evolving knowledge state of students with respect to one or more concepts as they engage in a sequence of learning activities. One important purpose of KT is to personalize the practice sequence to help students learn knowledge concepts efficiently. However, existing methods such as Bayesian Knowledge Tracing and Deep Knowledge Tracing either model knowledge state for each predefined concept separately or fail to pinpoint exactly which concepts a student is good at or unfamiliar with. To solve these problems, this work introduces a new model called Dynamic Key-Value Memory Networks (DKVMN) that can exploit the relationships between underlying concepts and directly output a student's mastery level of each concept. Unlike standard memory-augmented neural networks that facilitate a single memory matrix or two static memory matrices, our model has one static matrix called key, which stores the knowledge concepts and the other dynamic matrix called value, which stores and updates the mastery levels of corresponding concepts. Experiments show that our model consistently outperforms the state-of-the-art model in a range of KT datasets. Moreover, the DKVMN model can automatically discover underlying concepts of exercises typically performed by human annotations and depict the changing knowledge state of a student.Comment: To appear in 26th International Conference on World Wide Web (WWW), 201

The characteristics of adults with upper gastrointestinal bleeding admitted to Tripoli Medical Center: a retrospective case-series analysis

Background: Acute upper gastrointestinal bleeding (UGIB) is a common reason for hospital admissions worldwide. Aetiological causes of UGIB vary according to geographic region and socioeconomic status. However, despite the implementation of early endoscopy as the standard method for the diagnosis and treatment of UGIB, data on the characteristics of patients with UGIB in Libya are still minimal. In this study, we describe patient demographics, aetiological causes for UGIB, and possible risk factors for upper gastrointestinal bleeding in patients admitted to the Gastroenterology Department at Tripoli Medical Center from January 2001 through June 2006. Method: This is a retrospective case-series analysis of all adult patients with upper gastrointestinal bleeding admitted to the Gastroenterology Department at TMC. Patients’ medical records were individually reviewed and relevant data abstracted. Results: A total of 928 cases with diagnoses of UGIB were admitted to Tripoli Medical Center during the study period. Of these cases, 60.3% were males and 39.7% females (3:2) and males were significantly younger than females (49.6 years vs. 53.9 years, p=0.001). The most common cause of UGIB was peptic ulcer (37.1%) of which duodenal ulcer was the most common (30.7% of all UGIB), especially amongst male patients (36.4%). The second most common cause was bleeding due to varices (29.8%), especially amongst females (35.1%). Additionally, smoking and NSAIDs use were reported by 18.6% and 9.7% of cases and both were significantly associated with bleeding due to peptic ulcers. Conclusion: This study has investigated the characteristics of adults with UGIB at a tertiary referral center in Libya. The high frequency of bleeding due to varices amongst females mandates further investigations into the possible underlying hepatic causes and their management, and the potential impact on patient outcome and prognosis.Keywords: bleeding; UGIB; gastroenterology; Liby

Techno-Economic Analysis and Modelling of the Feasibility of Wind Energy in Kuwait

There continues to be significant attention and investment in wind power generation, which can supply a high percentage of the global demand for renewable energy if harvested efficiently. The research study is based on a techno-economic analysis of the feasibility of implementing wind power generation in Kuwait for 105 MW of electricity generation based on 50 wind turbines, which is a major requirement for clean energy. The study focused on three main areas of analysis and numerical modelling using the RETScreen software tool. The first area involved evaluating the performance and efficacy of generating wind power by collecting, analysing, and modelling data on observed wind levels, wind turbine operation, and wind power generation. The second area comprised an environmental impact report to assess the environmental benefits of implementing wind power. The third area involved economic analysis of installing wind power in Kuwait. The analysis was undertaken to determine the energy recovery time for wind energy and determine the mitigation of global warming and pollution levels, the decrease of toxic emissions, and any cost savings from implementing clean energy systems in Kuwait. Additionally, sensitivity analysis was undertaken to determine the impact of certain variables in the modelling process. The results were used to estimate that the energy price would be $0.053 per kWh for a power generation capacity of 105 MWh based on an initial cost of US$168 million and O&M of $5 million for 214,000 MWh of electricity exported to the grid. Moreover, the wind turbine farm will potentially avoid the emission of approximately 1.8 million t of carbon dioxide per year, thereby saving about$9 million over 20 years spent through installing carbon capture systems for conventional power plants. The wind farm is estimated to have a payback time of 9.1 years

Techno-Economic Analysis and Modelling of the Feasibility of Wind Energy in Kuwait

There continues to be significant attention and investment in wind power generation, which can supply a high percentage of the global demand for renewable energy if harvested efficiently. The research study is based on a techno-economic analysis of the feasibility of implementing wind power generation in Kuwait for 105 MW of electricity generation based on 50 wind turbines, which is a major requirement for clean energy. The study focused on three main areas of analysis and numerical modelling using the RETScreen software tool. The first area involved evaluating the performance and efficacy of generating wind power by collecting, analysing, and modelling data on observed wind levels, wind turbine operation, and wind power generation. The second area comprised an environmental impact report to assess the environmental benefits of implementing wind power. The third area involved economic analysis of installing wind power in Kuwait. The analysis was undertaken to determine the energy recovery time for wind energy and determine the mitigation of global warming and pollution levels, the decrease of toxic emissions, and any cost savings from implementing clean energy systems in Kuwait. Additionally, sensitivity analysis was undertaken to determine the impact of certain variables in the modelling process. The results were used to estimate that the energy price would be $0.053 per kWh for a power generation capacity of 105 MWh based on an initial cost of US$168 million and O&M of $5 million for 214,000 MWh of electricity exported to the grid. Moreover, the wind turbine farm will potentially avoid the emission of approximately 1.8 million t of carbon dioxide per year, thereby saving about$9 million over 20 years spent through installing carbon capture systems for conventional power plants. The wind farm is estimated to have a payback time of 9.1 years

Anti-Inflammatory Action of Angiotensin 1-7 in Experimental Colitis.

BACKGROUND:There is evidence to support a role for angiotensin (Ang) 1-7 in reducing the activity of inflammatory signaling molecules such as MAPK, PKC and SRC. Enhanced angiotensin converting enzyme 2 (ACE2) expression has been observed in patients with inflammatory bowel disease (IBD) suggesting a role in its pathogenesis, prompting this study. METHODS:The colonic expression/activity profile of ACE2, Ang 1-7, MAS1-receptor (MAS1-R), MAPK family and Akt were determined by western blot and immunofluorescence. The effect of either exogenous administration of Ang 1-7 or pharmacological inhibition of its function (by A779 treatment) was determined using the mouse dextran sulfate sodium model. RESULTS:Enhanced colonic expression of ACE2, Ang1-7 and MAS1-R was observed post-colitis induction. Daily Ang 1-7 treatment (0.01-0.06 mg/kg) resulted in significant amelioration of DSS-induced colitis. In contrast, daily administration of A779 significantly worsened features of colitis. Colitis-associated phosphorylation of p38, ERK1/2 and Akt was reduced by Ang 1-7 treatment. CONCLUSION:Our results indicate important anti-inflammatory actions of Ang 1-7 in the pathogenesis of IBD, which may provide a future therapeutic strategy to control the disease progression