302 research outputs found
Structural study using <sup>29</sup> Si and <sup>27</sup> Al Solid State MAS NMR and compressive strength analysis of metakaolin-based geopolymer paste
No full textGeopolymers are hardened aluminosilicate gel that develop strength via the crosslinking of tetrahedral silicate and aluminate. Past Research has highlighted a wide range of mechanical properties of geopolymer synthesised from various aluminosilicate materials. This research focuses on studying the effect of variation in the percentages of metakaolin, sodium silicate and sodium hydroxide at a fixed water to solids ratio on the development of geopolymer structure and compressive strength. Kaolin was thermally treated and XRD and FTIR traced the changes in crystalline Kaolin and its transformation into a more disordered structure of metakaolin. Characterisation techniques were used for the study of geopolymer produced. FTIR analysis illustrated the changes in the characteristic bands of metakaolin after being activated with sodium silicate and sodium hydroxide to form geopolymer. The 27Al and 29Si Solid State MAS NMR spectra confirmed the formation of polymerised tetrahedral silicate interconnected to tetrahedral aluminate in the form of Q4(4Al) and Q4(3Al) which are responsible for the attained compressive strength of geopolymer. The produced geopolymers exhibited high early compressive strength and high 28-day compressive strength in the range of 30–81 MPa. This promotes the use of geopolymers as a replacement to Ordinary Portland cement especially in targeted construction applications.This study is part of Ph.D of author Heba Fouad and the PhD was a fellowship granted by Yousef Jameel Foundation. Also, Heba Fouad also would like to show her gratitude to Dr. Abdel Hamid Emwas and Dr. Mariusz Jaremko for conducting Solid State MAS NMR samples in KAUST Core lab
Metabolic Phenotype of Stage 1 and Stage 2 Type 1 Diabetes Using Modeling of β Cell Function
No full textBackground: Staging preclinical type 1 diabetes (T1D) and monitoring the response to disease-modifying treatments rely on the oral glucose tolerance test (OGTT). However, it is unknown whether OGTT-derived measures of beta cell function can detect subtle changes in metabolic phenotype, thus limiting their usability as endpoints in prevention trials. Objective : To describe the metabolic phenotype of people with Stage 1 and Stage 2 T1D using metabolic modelling of beta cell function. Methods: We characterized the metabolic phenotype of individuals with islet autoimmunity in the absence (Stage 1) or presence (Stage 2) of dysglycemia. Participants were screened at a TrialNet site and underwent a 5-point, 2-hour OGTT. Standard measures of insulin secretion (area under the curve, C-peptide, Homeostatic Model Assessment [HOMA] 2-B) and sensitivity (HOMA Insulin Resistance, HOMA2-S, Matsuda Index) and oral minimal model-derived insulin secretion (phi total), sensitivity (sensitivity index), and clearance were adopted to characterize the cohort. Results: Thirty participants with Stage 1 and 27 with Stage 2T1D were selected. Standard metrics of insulin secretion and sensitivity did not differ between Stage 1 and Stage 2 T1D, while the oral minimal model revealed lower insulin secretion (P < .001) and sensitivity (P = .034) in those with Stage 2 T1D, as well as increased insulin clearance (P = .006). A higher baseline phi total was associated with reduced odds of disease progression, independent of stage (OR 0.92 [0.86, 0.98], P = .016). Conclusion: The oral minimal model describes the differential metabolic phenotype of Stage 1 and Stage 2 T1D and identifies the phi total as a progression predictor. This supports its use as a sensitive tool and endpoint for T1D prevention trials
Differential inflammatory gene expression patterns in JNK2 knockout mice in response to IL1, cartilage injury and surgically induced osteoarthritis
No full textRecently, we identified an important role for the mitogen activated protein kinase, JNK2 in regulating IL1-induced aggrecan degradation in human articular chondrocytes (Ismail et al, AandR 2015). Furthermore, we found that deletion of JNK2 in mice retarded the development of surgically induced OA, highlighting the importance of this kinase in cartilage degradation in vivo (Ismail et al, AandR, accepted for publication). Our group has described a panel of mechano-sensitive inflammatory genes that are up-regulated early following destabilization of the medial meniscus (DMM). These same genes are also induced in vitro by cytokine challenge or by mechanical injury to hip cartilage. Here we examine the importance of JNK2 in the regulation of these genes
A Framework for Personalized Content Recommendations to Support Informal Learning in Massively Diverse Information WIKIS
No full textPersonalization has proved to achieve better learning outcomes by adapting to specific learners’ needs, interests, and/or preferences. Traditionally, most personalized learning software systems focused on formal learning. However, learning personalization is not only desirable for formal learning, it is also required for informal learning, which is self-directed, does not follow a specified curriculum, and does not lead to formal qualifications. Wikis among other informal learning platforms are found to attract an increasing attention for informal learning, especially Wikipedia. The nature of wikis enables learners to freely navigate the learning environment and independently construct knowledge without being forced to follow a predefined learning path in accordance with the constructivist learning theory. Nevertheless, navigation on information wikis suffer from several limitations. To support informal learning on Wikipedia and similar environments, it is important to provide easy and fast access to relevant content. Recommendation systems (RSs) have long been used to effectively provide useful recommendations in different technology enhanced learning (TEL) contexts. However, the massive diversity of unstructured content as well as user base on such information oriented websites poses major challenges when designing recommendation models for similar environments. In addition to these challenges, evaluation of TEL recommender systems for informal learning is rather a challenging activity due to the inherent difficulty in measuring the impact of recommendations on informal learning with the absence of formal assessment and commonly used learning analytics. In this research, a personalized content recommendation framework (PCRF) for information wikis as well as an evaluation framework that can be used to evaluate the impact of personalized content recommendations on informal learning from wikis are proposed. The presented recommendation framework models learners’ interests by continuously extrapolating topical navigation graphs from learners’ free navigation and applying graph structural analysis algorithms to extract interesting topics for individual users. Then, it integrates learners’ interest models with fuzzy thesauri for personalized content recommendations. Our evaluation approach encompasses two main activities. First, the impact of personalized recommendations on informal learning is evaluated by assessing conceptual knowledge in users’ feedback. Second, web analytics data is analyzed to get an insight into users’ progress and focus throughout the test session. Our evaluation revealed that PCRF generates highly relevant recommendations that are adaptive to changes in user’s interest using the HARD model with rank-based mean average precision (MAP@k) scores ranging between 100% and 86.4%. In addition, evaluation of informal learning revealed that users who used Wikipedia with personalized support could achieve higher scores on conceptual knowledge assessment with average score of 14.9 compared to 10.0 for the students who used the encyclopedia without any recommendations. The analysis of web analytics data show that users who used Wikipedia with personalized recommendations visited larger number of relevant pages compared to the control group, 644 vs 226 respectively. In addition, they were also able to make use of a larger number of concepts and were able to make comparisons and state relations between concepts
The impact of structural adjustment on trade unions in Egypt
No full textThe following research focuses on trade union organisations, and in particular trade union officialdom in Egypt. The study examines the extent to which trade union officials at the various levels of the trade union hierarchy are reacting to reforms instigated by structural adjustment policies. The adoption of structural adjustment and economic reform measures as proposed by the World Bank and IMF have resulted in the government's withdrawal of some of the benefits and privileges it accorded to workers. Public sector workers are particularly affected by these changes, thereby posing a challenge to trade union officialdom, since the bulk of trade union membership is within the public sector. Trade union officials are reacting to the reform measures by trying to balance their role as representatives of workers' interests and their role in administering state policy. Whereas in the past these two roles were reconcilable, however, with liberalisation of the economy and the adoption of structural adjustment measures that is no longer tenable. Trade unionism has been weakened by the incorporation of union officials within government corporate structures, making it more difficult for trade union officialdom to challenge the reform measures adopted by the government. Rather, trade union officials are opting for `co-operation' both with the government and with management in enterprises, to the cost of workers. In enterprises, trade union officials emphasise that the interests of work and workers are inseparable. At the level of the confederation and general unions, union officials present themselves as working to keep workers' rights, but also as partners with the government in its drive for growth. By so doing trade union officials are de-politicising trade unionism, and instead focus on economic gains. Union officials are redefining their role away from workers. Trade union action at the various levels is not based on what workers want or demand, but rather on what trade union officials want, in the belief that workers do not truly know their interests. As a result, trade union action has promoted the interests of union officials rather than that of the workers. Trade unionism has become in a sense a shell without a content. However, there is evidence that there are pressures to democratise trade unionism and make it more responsive to worker demands. These pressures are from within the worker base, from trade union officials particularly at the enterprise level who are affilited to political parties, and from external forces like the Islamists. However these forces have their limitations, particularly in the face of institutionalised sectors that are capable of reproducing themselves and promoting their interests
Contribution of Clinical Biochemistry to Structural Bioinformatics
No full textAbstract Bioinformatics plays an important role in the study of human diseases with genomic data for drug development and gene therapy. Its applicative arm is clinical biochemistry that focuses on the methodology and interpretation of chemical tests performed to support diagnosis and treatment. Clinical biochemistry is one of the most important parts of laboratory diagnostics tests together with laboratory hematology, immunology, clinical serology and microbiology, clinical toxicology. It possesses the largest number of diagnostic tests that help to understand pathogenesis and etiology of different pathological processes. Clinical biochemistry is based on bioinformatics applications that have been used for tumor marker measurements, stem cell tests, gene expression, and DNA damage repair. Bioinformatics field can be derived from biochemistry. It means that biochemistry has emerged from bioinformatics applications. It is not an overstatement to say that bioinformatics is what biochemistry is evolving to become a distinct guide for quality control. This paper focuses on the point of contemporary clinical biochemistry that tends to support bioinformatics researchers. Integration between biochemistry and bioinformatics would lead to an increase in healthcare performance is thus of increasing importance in future research
Enhancing Model Selection by Obtaining Optimal Tuning Parameters in Elastic-Net Quantile Regression, Application to Crude Oil Prices
No full textRecently, there has been an increased focus on enhancing the accuracy of machine learning techniques. However, there is the possibility to improve it by selecting the optimal tuning parameters, especially when data heterogeneity and multicollinearity exist. Therefore, this study proposed a statistical model to study the importance of changing the crude oil prices in the European Union, in which it should meet state-of-the-art developments on economic, political, environmental, and social challenges. The proposed model is Elastic-net quantile regression, which provides more accurate estimations to tackle multicollinearity, heavy-tailed distributions, heterogeneity, and selecting the most significant variables. The performance has been verified by several statistical criteria. The main findings of numerical simulation and real data application confirm the superiority of the proposed Elastic-net quantile regression at the optimal tuning parameters, as it provided significant information in detecting changes in oil prices. Accordingly, based on the significant selected variables; the exchange rate has the highest influence on oil price changes at high frequencies, followed by retail trade, interest rates, and the consumer price index. The importance of this research is that policymakers take advantage of the vital importance of developing energy policies and decisions in their planning
Enhancing Model Selection by Obtaining Optimal Tuning Parameters in Elastic-Net Quantile Regression, Application to Crude Oil Prices
No full textRecently, there has been an increased focus on enhancing the accuracy of machine learning
techniques. However, there is the possibility to improve it by selecting the optimal tuning parameters,
especially when data heterogeneity and multicollinearity exist. Therefore, this study proposed a
statistical model to study the importance of changing the crude oil prices in the European Union, in
which it should meet state-of-the-art developments on economic, political, environmental, and social
challenges. The proposed model is Elastic-net quantile regression, which provides more accurate
estimations to tackle multicollinearity, heavy-tailed distributions, heterogeneity, and selecting the
most significant variables. The performance has been verified by several statistical criteria. The
main findings of numerical simulation and real data application confirm the superiority of the
proposed Elastic-net quantile regression at the optimal tuning parameters, as it provided significant
information in detecting changes in oil prices. Accordingly, based on the significant selected variables;
the exchange rate has the highest influence on oil price changes at high frequencies, followed by
retail trade, interest rates, and the consumer price index. The importance of this research is that
policymakers take advantage of the vital importance of developing energy policies and decisions in
their plannin
- …
