Coordinate Transformation and Polynomial Chaos for the Bayesian Inference of a Gaussian Process with Parametrized Prior Covariance Function

This paper addresses model dimensionality reduction for Bayesian inference based on prior Gaussian fields with uncertainty in the covariance function hyper-parameters. The dimensionality reduction is traditionally achieved using the Karhunen-\Loeve expansion of a prior Gaussian process assuming covariance function with fixed hyper-parameters, despite the fact that these are uncertain in nature. The posterior distribution of the Karhunen-Lo\`{e}ve coordinates is then inferred using available observations. The resulting inferred field is therefore dependent on the assumed hyper-parameters. Here, we seek to efficiently estimate both the field and covariance hyper-parameters using Bayesian inference. To this end, a generalized Karhunen-Lo\`{e}ve expansion is derived using a coordinate transformation to account for the dependence with respect to the covariance hyper-parameters. Polynomial Chaos expansions are employed for the acceleration of the Bayesian inference using similar coordinate transformations, enabling us to avoid expanding explicitly the solution dependence on the uncertain hyper-parameters. We demonstrate the feasibility of the proposed method on a transient diffusion equation by inferring spatially-varying log-diffusivity fields from noisy data. The inferred profiles were found closer to the true profiles when including the hyper-parameters' uncertainty in the inference formulation.Comment: 34 pages, 17 figure

Magnetic Nanoparticles as MRI Contrast Agents

Magnetic Resonance Imaging (MRI) is a non-invasive imaging modality that offers both anatomical and functional information. Intrinsic longitudinal and transverse relaxation times (T1 and T2, respectively) provide tools to manipulate image contrast. Additional control is yielded when paramagnetic and magnetic particulate materials are used as contrast materials. Superparamagnetic particles are mostly synthesized from iron oxide and are usually coated with polymers and functional particles to offer multifunctional biomedical applications. The latter include not only MRI but also cancer treatment through drug delivery and hyperthermia. This Chapter reviews the fundamental dipole–dipole diamagnetic proton relaxation mechanism dominant in water followed by a brief description of the use of gadolinium complexes as MRI contrast agent. Finally, a description of the important chemical and physical properties of magnetic nanoparticle (MNP) that define their use as MRI relaxation enhancing agents especially for T2. The main governing models are described for the different motional regimes with few simulation results demonstrating the applicability of the given equations

Epidemiology of antibiotic resistance in culture-positive hospitalized patients in selected hospitals in Khartoum, Sudan

Objective: To study the prevelence of antibiotic resistance and the prevalent bacterial isolates in hospitalized patients in Khartoum hospitals. Materials & Methods: A cross-sectional prevalence study was carried out during the period of April–November 2015 in Khartoum; 226 bacterial cultures were included. Identification of isolates using standard biochemical tests and antibiotic susceptibilities were determined using disc diffusion method. Results were interpreted according to the standards of the British society of antimicrobial chemotherapy. Results: Eight bacterial species were isolated: Staphylococcus aureus, Enterococcus faecalis, Streptococcus spp., Klebsiella pneumoniae, Pseudomonas spp., Escherichia coli, Proteus spp., and Acinetobacter spp. S. aureus was the most prevalent, the majority of which were resistant to methicillin/oxacillin (MRSA). Cultures in our study were mainly from urine (36.7%), blood samples (37.2%), and wound cultures (19%). More than 90% of the tested isolates were resistant to cefuroxime; 54% and 73.8% of Gram-positive and Gram-negative isolates, respectively, were resistant to ceftazidime. Furthermore, there was a high meropenem resistance among Gram-negative isolates tested. Multi-resistant Acinetobacter spp. as well as vancomycin-resistant S. aureus was isolated. Gram-negative isolates showed good susceptibilities to aminoglycosides as well as ciprofloxacin. However, the high resistance rate to these antibiotics was observed in Gram-positive isolates in these hospitals. Conclusion: Methicillin-resistant S. aureus was the most prevalent organism. Gramnegative isolates showed good susceptibilities to aminoglycosides and ciprofloxacin. There were high resistance rates to cefuroxime, ceftazidime, and meropenem. Five vancomycin-resistant S. aureus were identified

THE EFFECTIVENESS OF ETHICS-TRAINING PROGRAMS IN THE BANKING SECTOR: The mediation effects of ethical culture, supervision, and enforcement

Academic and professional interest in organizational ethics-training is on the rise as advances in technology and global reach create increasing opportunities for violations of moral standards. To mitigate risks associated with moral hazard, organizations strive to create an ethical culture by offering formal ethics-training programs. Notably, the literature is rich with studies that confirm a positive effect of ethics-training programs on employee ethical behavior. However, such programs may become mere cosmetics in the presence of a weak ethical culture, a non-ethics oriented supervisor, and lack of policy enforcement. This study investigates the roles played by the afore-mentioned factors on the relationship between formal ethics-training and employee ethical intentions. The quantitative approach is used and data are analyzed using structural equation modeling with IBM’s Amos. Important findings are reported and relevant implications suggested

Evaluation of Treatment Methods Used for Construction on Expansive Soils in Egypt

The soil formation in this arid area is sometimes an expansive problematic soil. Due to the lake of the construction experience on this problematic soil, many defects are appeared in the new buildings established in these arid areas. In this paper, a focusing on the treatment method using soil replacement for expansive soil formation. In the other hand, some case studies were illustrated to show the different types of problems appeared due to the different construction methods used. Finally, a conclusion about how to overcome these defects happened due to this treatment method for this problematic soil is mentioned. Some recommendations are given to civil engineers to be taken into consideration during establishing any constructions on this problematic soil

Semantic Management of E-learning in College of Engineering at Kerbala University

الإنترنت هو الأداة الأساسية لنقل المعلومات وتوفير الخدمات. الإنترنت له تأثير كبير على مختلف مجالات الحياة، بما في ذلك التعلم، حيث ظهر التعلم الإلكتروني باعتبارها واحدة من الخدمات التي تقدمها شبكة الإنترنت. التعلم الإلكتروني هو اكتساب المعرفة عن بعد باستخدام الطرق الإلكترونية، وزيادة الاعتماد عليها في العقدين الماضيين. واحدة من المشاكل التي تواجه التعلم الإلكتروني هو إدارة محتويات لأنه يختلف عن التعلم التقليدي من خلال التغلب على ظروف الزمان والمكان. الشبكة الدلالية هي إعادة هيكلة الشبكة الحالية لإدارة البيانات والموارد لتصبح أكثر فعالية للإنسان والآلة. وتستند الشبكة الدلالية على علم الأنماط الذي يعرف بأنه تمثيل وصفي للبيانات والموارد. ومن المتوقع أن تؤثر تكنولوجيات الويب الدلالي والانطولوجيا على الجيل التالي من نظم وتطبيقات التعلم الإلكتروني. إطار وصف الموارد (RDF) هو نموذج عام لتمثيل البيانات باستخدام صيغ مختلفة.  من الصيغ المستخدمة لتمثل المفردات هي FOAF وDC والي تعتمد على قواعد RDF.  يهدف هذا البحث إلى تقديم مقترح إدارة دلالية للتعليم الالكتروني في كلية الهندسة بجامعة كربلاء والتي تعتمد على علم الانطولوجيا للملفات الشخصية للمستخدمين والأنشطة العلمية والدروس. تم استخدام RDF وFOAF وDC لإنشاء جمل البيانات الوصفية. تم تقييم العمل المقترح بواسطة قييم الإرجاع والدقة لنتائج البحث ومقاييس الشبكة الاجتماعية. وتظهر النتائج أن(FOAF) هو وسيلة جيدة لتمثيل العقد والعلاقات وهذا يحسن استخدامه في البحث دون الوصول إلى قاعدة البيانات. (FOAF) لديه القدرة على جمع البيانات المشتتة الأكثر فائدة.Internet is the essential tool of transmitting information and providing services to facilitate the human daily jobs. The internet has a great impact on various fields of life, including learning, where e-learning emerged as one of the services provided by the Internet. E-learning is a distance knowledge acquisition by using electronic methods and it has increased dependence in the two decades ago. One of the problems facing e-learning is contents management because E-learning differs from traditional learning by overcoming the conditions of time and place. The semantic web is the restructuring of the current web to managing data and resources to become more effective for human and machine. The semantic web is based on an ontology which is defined as a descriptive representation of data and resources. It is expected that Semantic Web technologies and Ontologies will affect the next generation of e-learning systems and applications. Resource Description Framework (RDF) is a general modeling for data representation by using a variety of syntax. A friend of a friend (FOAF) and Dublin Core (DC) are a vocabulary description depending on RDFs' rules. This paper presents a semantic management of E-learning in College of Engineering at University of Kerbala based on ontology of users’ profile, scientific activities, and lessons. RDF, FOAF, and DC are used to create a syntax of metadata. The proposed work was evaluated according to average precision and recall of the search's results and social network metrics. The results demonstrate that FOAF is a good way to represent nodes and relations and this improves using it in searching without access the database. FOAF has the ability to gathering dispersed data into common interests

Analytical and experimental investigations of ships impact interaction with one-sided barrier

This study deals with impact interaction of ships with one-sided ice barrier during roll dynamics. An analytical model of ship roll motion interacting with ice is developed based on Zhuravlev and Ivanov non-smooth coordinate transformations. These transformations have the advantage of converting the vibro-impact oscillator into an oscillator without barriers such that the corresponding equation of motion does not contain any impact term. Such approaches, however, account for the energy loss at impact times in different ways. The present work, in particular, brings to the attention the fact that the impact dynamics may have qualitatively different response characteristics to different dissipation models. The difference between localized and distributed equivalent damping approaches is discussed. Extensive numerical simulations are carried out for all initial conditions covered by the ship grazing orbit for different values of excitation amplitude and frequency of external wave roll moment. The basins of attraction of safe operation are obtained and reveal the coexistence of different response regimes such as nonimpact periodic oscillations, modulation impact motion, period added impact oscillations, chaotic impact motion and rollover dynamics. An experimental investigation conducted on a small ship model. In particular, the experimental tests reveal complex dynamic response on multi-frequency wave motion caused by the wave reflection from the tank walls. Measured results showed a good agreement with the predicted results for small angles of the barrier relative to the ship unbiased position. However, deviation becomes significant as the angle increases. This deviation is mainly attributed to the uncertainty of the coefficient of restitution, which is found to depend on the velocity of impact in addition to the geometry and material properties of the model and barrier