A pattern mining approach for information filtering systems

It is a big challenge to clearly identify the boundary between positive and negative streams for information filtering systems. Several attempts have used negative feedback to solve this challenge; however, there are two issues for using negative relevance feedback to improve the effectiveness of information filtering. The first one is how to select constructive negative samples in order to reduce the space of negative documents. The second issue is how to decide noisy extracted features that should be updated based on the selected negative samples. This paper proposes a pattern mining based approach to select some offenders from the negative documents, where an offender can be used to reduce the side effects of noisy features. It also classifies extracted features (i.e., terms) into three categories: positive specific terms, general terms, and negative specific terms. In this way, multiple revising strategies can be used to update extracted features. An iterative learning algorithm is also proposed to implement this approach on the RCV1 data collection, and substantial experiments show that the proposed approach achieves encouraging performance and the performance is also consistent for adaptive filtering as well

Distances to Planetary Nebulae Using Astrometric Data of Gaia DR2

The present work is dedicated to deriving the distances of Galactic planetary nebulae using the parallax measurements of Gaia Data Release 2 (DR2). By applying an accurate calibrating sample of distances derived from Gaia DR2, we aim to examine the consistency between Gaia DR2 trigonometric distance and prior trigonometric distances as well as other individual methods usually used for distance determination. We started by searching the literatures for confirmed planetary nebulae (PNe), known up to this time, followed by discussing the method used for selecting PNe central stars from Gaia DR2. We were able to identify 2170 Gaia DR2 sources classified as PNe, from which we ignored all sources with negative parallax values, unmeasured parallax, and unmeasured colours. Only true CSs with parallax uncertainties less than 25% were adopted. As a result, a sample composed of roughly 200 PNe with highly accurate parallax measurements was selected. By comparing Gaia DR2 trigonometric distances with the previous ground-based trigonometric distances and those obtained by the Hubble Space Telescope we found that: (1) The ground-based trigonometric distances obtained by Pottasch (1996) [1] and Gutiérrez-Moreno et al. (1999) [15] perfectly matched Gaia DR2 distances. However, the trigonometric distances given by Harris et al. (2007) [5] show somewhat smaller values; (2) The space-based distances, using HST [16], are slightly higher than that of Gaia DR2 with an average ratio of 1.1. By comparing Gaia DR2 trigonometric distances with other individual distance methods we concluded that the spectroscopic method is the best subsequent method for determining the PN distance after the trigonometric method. Applying other methods should take with care especially the gravity method

Using Student-Generated Problems (SGP) As An Instructional Strategy To Enhance Undergraduate Engineering Students’ Knowledge Application Ability And Problem-Solving Skills

The Student-Generated Problems (SGP) instructional strategy represents an exclusive area of real-world practice used by some educators to give powerful support and responsibility to college students for their learning experience (Mestre, 2002; Zurcher, Coppola, & McNeil, 2016). Undergraduate Engineering students often have difficulty applying gained knowledge in real-world settings and are reportedly underprepared for workplace challenges (Luo et al., 2015; Negro et al. 2019). This study examined the effects of the SGP instructional strategy used in an undergraduate Electrical Engineering course to determine students’ abilities to apply conceptual knowledge and problem-solving skills in real problem lab activities. The need for this study was to prepare students to be able to function well in the workplace environment in the future. The study also investigated whether there were relationships between students’ skills in SGP and their problem-solving skills, conceptual, and application knowledge of Electrical Engineering concepts under study. This investigation employed a quantitative approach, using a within-subject design with pre-post testing. A single group of participants experienced both the regular and SGP instructional strategy. This study’s independent variables were the type of instructional strategy–traditional class instruction and the SGP approach. The dependent variables are the students’ learning outcomes. This quantitative study used knowledge test (pre and post) to test the students’ conceptual knowledge, a Problem-Solving Inventory (PSI) survey to assess the students’ self-perception of problem-solving skills, and a problem identification rubric to assess students’ knowledge application in the SGP activity. Limited differences were revealed in the control and experimental group participants’ responses of their conceptual knowledge, knowledge application abilities, and self- perception of problem-solving skills. Test scores in the knowledge areas did not have a statistically significant overall relationship with the most of study variables. However, the test revealed that the difference in the test scores for the approach avoidance style construct was statistically significant. Further investigation on the connections between these study variables and the SGP instructional strategy is needed to provide a more insightful depiction of the effects of the Student-Generated Problems approach on students’ development of conceptual knowledge, knowledge application, and problem-solving skills in electrical engineering concepts. Although this study did not report a significant difference between the SGP and the traditional group, there appears to be a difference between the mean scores among the two groups. Hence, it can be implied that SGP has the potential to promote knowledge utilization and problem-solving skills among engineering students. This is because SGP enables students to connect and relate classroom concepts to real-world problems, and as a result contextualizing their learning. The findings of this study are significant for engineering instructors who intend to promote knowledge application and problem-solving skills in their teaching. Also, SGP is a constructivist learning approach and the results from this study suggest that it may offer alternative instructions to the traditional teacher-centered approach, thereby helping instructors better prepare their students for their future workplace challenges

A framework to facilitate te leadership performance improvement in the healthcare sector: the case of the kingdom of Saudi Arabia

In order to improve leadership performance and enhance effective leadership in the healthcare sector organisations in general and the Kingdom of Saudi Arabia (KSA) in particular, this study proposes a theoretical framework to address the ways in which leadership competency strengthens the relationship between leaders and followers. The research is based on a single case as a longitudinal study to allow for in-depth investigation. The research applies a constructive-interpretivism approach – inductive to gain a deep understanding and clear explanation of the leadership performance and practices in the organisational setting. The data were collected using triangulated methods—semi-structured interviews, focus groups and observation. This research applies a qualitative strategy to achieve its objectives. This approach, is most appropriate for this research, which is exploratory and interpretive in nature. This study targets participants who are experts in the phenomena of the field study. The participants represented several levels of the organisations studied. Data were collected in three stages, using issue focus in-depth interviews. The saturation level was reached after 33 interviews. A number of elements emerged as important in shaping the leadership performance in the field study, in the areas of culture, values and context. The present study suggested a framework to facilitate a culture of leadership performance improvement in the healthcare organisations. This framework was developed based on the main emerged themes of the study. This study is expected to contribute to the existing literature on leadership competencies, the process of change management and social identity by providing empirical data on the significance of leadership competency in improving performance in the healthcare sector in general, especially in the KSA and the Gulf Cooperation Council (GCC countries)

A Study On The Plasticity And Fracture Behaviors Of Inconel 718 Under Multiaxial Stress And Extremely Low Cycle Fatigue Loadings

Engineering materials and structures are usually subjected to multiaxial stress states loading due to geometrical effects, residual stresses, or multi-directional loading. Ductile fracture and Extremely Low Cycle Fatigue (ELCF), less than 100 cycles to fail, are two common and co-exist failure modes in many engineering structures. However, the linkage between these two failure modes under multi-axial loading conditions has never been systematically studied. This research summarizes an extensive work of experimental and numerical studies of ductile fracture and ELCF under different stress states for nickel-base superalloy material IN718 under room temperature. Specially designed specimens and tests were used to achieve desired multi-axial loading conditions. Four types of specimens with four different shapes, total of 16 specimens, were tested until complete fracture. Two groups of tests were conducted: (a) round bar specimens with different notches; (b) plane strain specimens. Experimental data of force-displacement curves and strain-life graph were plotted for analysis. The first part of this research focuses on a numerical study of monotonic tensile loading with different stress states. This part of the investigation deeply studies the dependency of the hydrostatic stress (related to stress triaxiality) and the normalized third invariant of the deviatoric stress (related to Lode angle parameter) in plastic behavior and ductile fracture. Constitutive plasticity model proposed by Bai & Wierzbicki and the modified Mohr-Coulomb (MMC) ductile fracture model were adapted with several extensions. The plasticity model and ductile fracture criterion were implemented into ABAQUS through a user-defined material subroutine (VUMAT). Extensive experimental results are used to calibrate the models. After setting up the parameter optimization during model calibration, the experimental results and numerical simulations were well correlated in both plasticity deformation and fracture initiation. A 3D fracture locus of Inconel 718 was constructed by knowing the strain at fracture, stress triaxiality, and normalized Lode angle of the tested samples. By introducing a suitable element post-failure behavior, not only the fracture initiation but also the fracture propagation modes are successfully predicted in finite element simulations for monotonic loading. The second part extensively investigates ELCF on IN718. The IN718 cyclic plasticity behavior and the Bauschinger effect are studied and simulated using the well-known nonlinear kinematic hardening law by J. L. Chaboche and his co-workers under different strain amplitudes and different stress states. Moreover, the Voce isotropic hardening law was applied in combination with the Bai-Wierzbicki plasticity model. The Bai-Wierzbicki plasticity model was used to capture the effect of different stress states on ELCF based on the stress triaxiality and Lode angle parameters. On the other hand, the modified Mohr–Coulomb (MMC) ductile fracture model for monotonic loading was extended by a new damage evolution rule to cover the ELCF regime. A new parameter was introduced to represent the effect of the cyclic loading at ELCF. The new parameter is responsible for capturing the change of non-proportional loading direction between the current stress and the backstress tensors. The model explores the underlying damage and fracture mechanisms through the equivalent plastic strain evolution under cycling loading. Finally, the mechanism linkage between these two failure modes was studied. A comparison between the experimental data and the finite element simulation results (by Abaqus/Explicit) shows very good correlations. In addition, fractographic examinations, analysis, and finite element simulations are presented

The Antimicrobial Resistance Plasmid Mobilome of Salmonella enterica and Related Enteric Species and Factors that Influence the Transfer Efficiency.

The dynamic distribution of antimicrobial resistance genes in Salmonella enterica is considered a public health risk. S. enterica is one of the most important etiological agents of foodborne illness and has a critical impact on global human health. In S. enterica and related species, mobile genetic elements (MGEs) serve as primary vehicles for the dissemination of antibiotic resistance genes in the bacterial evolution. This dissemination can be impacted by different selective pressures that leads to diverse antibiotic response phenotypes. This project focusses on the dynamics of antimicrobial resistance genes, particularly exploring the transfer efficiency of multidrug resistance plasmids in S. enterica using a combination of in silico and in vitro techniques. Plasmid physiology is part of an essential genetic engineering tool has mediated the dynamic transfer and spread of antimicrobial resistance in Salmonella isolates. Several phenotypic and molecular techniques were selected in these studies to better understand the molecular biology and epidemiology of resistance plasmids. These methods included whole genome sequencing (WGS) analyses, replicon (incompatibility; Inc) typing and conjugation studies of plasmids from S. enterica and related species. Multiple in silico analyses were used to evaluate WGS and plasmid sequencing data to examine the distribution of MGEs, AMR, biocide, disinfectant, and heavy metal resistance genes across the different plasmid types and to develop a plasmid characterization database. The database supported the development of the computational algorithms to process the WGS data from S. enterica isolates and is very useful for identifying the plasmid Inc types and their specific conjugal transfer systems, which are valuable to study the diversity and dissemination of plasmids associated with AMR in S. enterica and other Enterobacteriaceae. In vitro studies explored the impact of different antimicrobial exposures on conjugal transfer potential of plasmids. For some S. enterica strains, exposure to different concentrations of tetracycline or chloramphenicol led to differences in the efficiency of AMR plasmid transfer. These data help to better understand the distribution of resistance genes and provide a useful method for a comprehensive molecular studies of plasmid transfer dynamics. The impact of these findings clarifies the role of the conjugation dynamics in the dissemination of antimicrobial resistance in S. enterica and related species, which can potentially impact the transfer of resistance genes within the gastrointestinal microbiome. Further studies are required to identify the underlying genetic mechanisms for Salmonella resistance plasmid transfer using approaches like RNA-sequencing methods to extend the understanding of the regulation of genetic pathways during conjugal transfer. Overall, the research study expands our knowledge of plasmid transfer dynamic and the provides tools that can be used to better understand AMR gene transfer among Salmonella enterica isolates which can have an impact in clinical and diagnostic laboratories as well as in epidemiological surveillance

Information Security Policy for E-government in Saudi Arabia: Effectiveness, Vulnerabilities and Threats

This study focuses on the issue of information security policy for e-government in Saudi Arabia. It evaluates the three fundamental pillars that determine data security such as effectiveness, vulnerabilities, and threats. The paper is seeking to reveal the risks of information security policy for e-government in Saudi Arabia as well as to examine the vulnerabilities and the effectiveness of the system. The methodology applied inductive approach where both qualitative and quantitative research method were used. A survey by use of questionnaires and an interview was conducted

Age effect on presence, susceptibility and treatment of erosive tooth wear

Indiana University-Purdue University Indianapolis (IUPUI)Erosive tooth wear (ETW) is a growing dental condition often associated with aging. This in-vitro project comprised three studies aiming to investigate the impact of tooth age on ETW susceptibility and prevention. In the first study, un-identified extracted premolars were collected and had their ages estimated using validated dental forensic methods. The premolars were examined to investigate the relationship between age and presence and severity of ETW, as well as other main dental-hard tissues conditions. ETW, dental caries, fluorosis, extrinsic staining and tooth color were evaluated using established clinical indices. In the second study, the tooth age impact on ETW susceptibility and response to preventive treatments (Sn+F, NaF, and de-ionized water control) were evaluated using representative samples from the initial study. Enamel and dentin specimens were prepared and subjected to daily erosion-treatmentremineralization cycling procedure. Surface loss (SL) was determined during and after the cycling, by optical profilometry. Similar protocol was adopted in the third study with the addition of toothbrushing abrasion to the model, in order to explore the interplay between age and toothpaste abrasivity on erosion-abrasion development. SL was measured during and after the erosion-toothbrushing-remineralization cycling. The relationships between age and the investigated variables were assessed using linear regression models. In conclusion: 1. The presence and severity of ETW, dental caries, and extrinsic staining increased with age, while of enamel fluorosis decreased. Tooth also showed to be darker with age. 2. Susceptibility of enamel and dentin to demineralization increased with age. Sn+F showed the highest anti-erosive efficacy, and was not affected by age. NaF showed lower efficacy on dentin, which increased with age. 3. Enamel and dentin SL increased with toothpaste abrasivity level. Dentin SL also increased with age. Age effect on enamel SL was observed only with low abrasive toothpaste. Age-related changes on enamel and dentin affected ETW development.2020-05-1