Integration of software reliability into systems reliability optimization

Reliability optimization originally developed for hardware systems is extended to incorporate software into an integrated system reliability optimization. This hardware-software reliability optimization problem is formulated into a mixed-integer programming problem. The integer variables are the number of redundancies, while the real variables are the components reliabilities;To search a common framework under which hardware systems and software systems can be combined, a review and classification of existing software reliability models is conducted. A software redundancy model with common-cause failure is developed to represent the objective function. This model includes hardware redundancy with independent failure as a special case. A software reliability-cost function is then derived based on a binomial-type software reliability model to represent the constraint function;Two techniques, the combination of heuristic redundancy method with sequential search method, and the Lagrange multiplier method with the branch-and-bound method, are proposed to solve this mixed-integer reliability optimization problem. The relative merits of four major heuristic redundancy methods and two sequential search methods are investigated through a simulation study. The results indicate that the sequential search method is a dominating factor of the combination method. Comparison of the two proposed mixed-integer programming techniques is also studied by solving two numerical problems, a series system with linear constraints and a bridge system with nonlinear constraints. The Lagrange multiplier method with the branch-and-bound method has been shown to be superior to all other existing methods in obtaining the optimal solution;Finally an illustration is performed for integrating software reliability model into systems reliability optimization

Developmental Stages of Preschool Educators: A Study of Junior College Students in Taiwan

The present study applies early field experience theory and developmental stages theory as the basis of teacher training in a junior college program in Taiwan. Two hundred sixty-six junior college students from two junior colleges were surveyed in order to ascertain what factors had an effect on the concept of teaching concerns. Comparisons were made among the following : with/ without preschool education background in senior high school, grade, school, age, fathers\u27 educational levels, mothers\u27 educational levels, and fathers\u27 yearly income. The results indicate that early field experiences had a direct effect on teaching concerns. The students\u27 year of study (freshmen vs sophomore) in junior college made a difference depending on whether they had been exposed to an early field experience. The groups that had a preschool education background had higher mean developmental-teaching-stage scores, in first (freshmen) study year, but lower mean scores in the second (sophomore) study year. The mean developmental teaching- stage scores for both study years of junior college students with preschool education background were very close to each other. Junior college students without a preschool education background in senior high had a higher mean developmental-teaching-stage score in the second year than in the first year

GPER-induced signaling is essential for the survival of breast cancer stem cells.

G protein-coupled estrogen receptor-1 (GPER), a member of the G protein-coupled receptor (GPCR) superfamily, mediates estrogen-induced proliferation of normal and malignant breast epithelial cells. However, its role in breast cancer stem cells (BCSCs) remains unclear. Here we showed greater expression of GPER in BCSCs than non-BCSCs of three patient-derived xenografts of ER- /PR+ breast cancers. GPER silencing reduced stemness features of BCSCs as reflected by reduced mammosphere forming capacity in vitro, and tumor growth in vivo with decreased BCSC populations. Comparative phosphoproteomics revealed greater GPER-mediated PKA/BAD signaling in BCSCs. Activation of GPER by its ligands, including tamoxifen (TMX), induced phosphorylation of PKA and BAD-Ser118 to sustain BCSC characteristics. Transfection with a dominant-negative mutant BAD (Ser118Ala) led to reduced cell survival. Taken together, GPER and its downstream signaling play a key role in maintaining the stemness of BCSCs, suggesting that GPER is a potential therapeutic target for eradicating BCSCs

Understanding the Gap of Reading Performance between ELL and EOL Children from Low-Income Families in Elementary School Years

This study explored reading development in low income children of English Language learners (ELLs) from kindergarten to the fourth grade. Data used in this study came from the Early Childhood Longitudinal Study, Kindergarten Class of 2010-2011 (ECLS-K: 2011). A sample size was 3,451 students below the poverty threshold. The independent variables were the indicators of home language and gender. The six dependent variables were students’ reading item response theory (IRT) scale scores in the fall and spring semester of the kindergarten year and all the spring semesters from the first to the fourth grade. Six full 2-way analysis of variance (ANOVA) models were used for the statistical analyses. The results found there is a gender difference in children’s reading performance, with female doing slightly better than male students. The low-income children’s performance in reading IRT scores has shown differences among the three groups. The English Only Learners (EOL) had the highest mean scores throughout the five years. The group of Multilingual Learners (ML) and English Language Learner (ELL) group had mixed results of the second or lowest scores among these three groups. Among the six subgroups the EOL female had the highest mean scores throughout the five years

A Case Study on Membership Growth of a Teacher Professional Community Using the Diffusion Model

This is an exploratory case study to analyze the membership growth of a virtual community named SCTNet by using diffusion model. SCTNet (http://sctnet.edu.tw) is designed to facilitate profession communications among teachers of elementary schools and junior high schools in Taiwan. The diffusion model provides the insight of influential factors for the membership growth on the web site. According to the empirical results, the word-of-mouth has stronger effect than the mass-media advertising. In addition, the diffusion process is slower than those of general innovations or durable goods. The authors propose two possible reasons, one is that teachers belong to different homophilous groups and lack of heterophilous communications, and the other is that the isolation is a general problem surrounding the teachers. Besides, the virtual community is attributed as an interactive media; the more members gather, the more benefits can be generated such as professional advices and emotional supports among members. There should be a so-called “critical mass” in the diffusion curve for such interactive innovation. After the turning point, the membership grows explosively. However, the empirical data of this study does not appear such circumstance. Thus, several aspects that require further researched are suggested in the end of this paper

Investigating the Knowledge-Sharing Behavior ina Professional Virtual Community

This research aims at investigating the knowledge sharing-behaviors in a teachers’ professional virtual community. Logs data in the entire community and in special interest groups (SIGs) were analyzed. Some typical behaviors were identified by the clustering analysis in this study. The largest group of member belongs to inactive users. They rarely log in the system, are passive in uploading or downloading teaching materials, and almost never post or reply messages. Another group is active in receiving knowledge while reluctant to give knowledge or to respond. The third group frequently login the system, is the most active in sharing knowledge, and actively searching knowledge. However, the third group contains only a small number of members. Furthermore, fifty-five members of the knowledge-sharing group were interviewed using focus group technique to find out qualitative information as to why they are willing to share information and what are their concerns in sharing information. The results indicated that knowledge sharing is not a common behavior in professional virtual community, and knowledge-sharing culture is difficult to promote even in non-competitive professional communities. Secondly, knowledge cannot flow easily throughout the community even when certain knowledge flow promoting mechanism is provided. Thirdly, professional autonomy may hinder the frequency of interactions with others in professional virtual community. Fourthly, attitudes regarding information ownership are important factors in knowledge sharing of a professional virtual community. Finally, teaching and IT usage experiences are not major factors affecting knowledge-sharing behavior in pro fessional virtual communities

Exploring Taiwan citizens’ scientific literacy, interest in, and engagement in learning science

This study explored Taiwan citizens' scientific literacy, interest in, and engagement in learning science. By using the stratified random sampling strategy, 1,831 citizens in the age group of 18-70 years were selected to respond to a questionnaire survey along with a paper-pencil test. For exploring the relationship between Taiwan citizens' scientific literacy and their interest in science, the participants were divided into four groups on the basis of their scores for scientific literacy and interest in science. According to the essential results, the high scientific literacy and high science interest (HH) group was mainly represented by males, young citizens, and citizens with higher educational degrees. Conversely, the low scientific literacy and low science interest (LL) group was dominated by females, elderly citizens, and citizens with only a secondary school diploma. Among the four groups, citizens in the HH and LH groups exhibited higher frequency of engagement in science activities. Finally, citizens with high science interest tended to be enthusiastic in learning science and technology. This study contributed a novel insight that the interest in learning science plays a critical role in promoting adults' engagement in learning science. Future studies are recommended for focusing on the citizens in the LH group to investigate how high engagement in learning science influences their scientific literacy

Small Angle X-Ray and Neutron Scattering - Its Application to Supramolecular Solutions

Contains reports on seven research projects.Argonne National LaboratoryU.S. Department of Energy DE-FG01-90ER45429National Science FoundationUniversity of Florence, ItalyExxon FellowshipNational Science Foundation Grant INT 87-508