Ultrafast imaging of surface-exclusive carrier dynamics in silicon

Understanding the dynamics of charge carriers at the semiconductor surfaces and interfaces is fundamental to the further development of photocatalytic, photovoltaic, and optoelectronic devices. Here, we study the surface photovoltage (SPV) dynamics in intrinsic and doped silicon using scanning ultrafast electron microscopy (SUEM). SUEM is a surface sensitive technique that allows the direct imaging of carriers at ultrafast time scales, thereby elucidating their spatiotemporal response to optical excitation. We first discuss the mechanism of image formation in SUEM. We then use these images to show that carrier dynamics on the silicon surface depends strongly on the doping type and concentration, though not always dictated by SPV. The numerical simulation of the drift-diffusion model suggests that this is due to the formation of complex transport processes, driven by intrinsic and photoinduced fields in the excited volume. This work refines our current understanding of the surface-exclusive dynamics in semiconductors by introducing a means to study their evolution in space and time and providing a model to explain the underlying mechanism

Investigating the dimensions, components and key indicators of supply chain management based on digital technologies

Purpose: Over the past decade, the advent of digital technologies has led to dramatic changes in the nature of business processes, and the introduction of the concept of digital developments has greatly affected various aspects of the business. New digital technologies are being prepared to transform all areas of what we call "traditional business processes." With the help of digital technologies, the speed, accuracy, and precision of processes in various businesses have been dramatically optimized, which has saved time, energy, and resources in organizations and businesses. Methodology: Supply Chain Management (SCM), as the core business priority of any manufacturing company, has placed itself in the focus of business owners. Suppliers, organizations, and supply chain agencies use the information and share it with others while generating information. Findings: In this regard, considering the importance and fundamental role of the supply chain in the organization and business, as well as the important effects that digital technologies can have on it, this paper reviews library dimensions, components, and key indicators of a chain by reviewing the library resources. Supply based on digital technologies. Originality/Value: This study provides a conceptual framework for the digital supply chain that demonstrates the importance of this chain

Carrier density oscillation in the photoexcited semiconductor

The perturbation of a semiconductor from the thermodynamic equilibrium often leads to the display of non-linear dynamics and formation of spatiotemporal patterns due to the spontaneous generation of competing processes. Here, we use scanning ultrafast electron microscopy to show that the transport of hot carriers in the strongly excited semiconductor slows down by turning into an oscillatory process; this is evidenced by the expansions and contractions in the second moment of the distribution. We attribute such a response to the electric field generated by the spatial separation of photo-excited electrons and holes under intrinsic and photo-induced fields; we then introduce a transport model that mimics the experimental observation. Our finding provides a direct imaging evidence for the electrostatic oscillation of hot carriers in the highly excited semiconductor and offers new insights into their dynamics in space and time

A Comparison of Selective Classification Methods in DNA Microar¬ray Data of Cancer: Some Recommendations for Application in Health Promotion

Background: The aim of this study was to apply a new method for se¬lecting a few genes, out of thousands, as plausible markers of a disease.Methods: Hierarchical clustering technique was used along with Support Vector Machine (SVM) and Naïve Bayes (NB) classifiers to select marker-genes of three types of breast cancer. In this method, at each step, one sub¬ject is left out and the algorithm iteratively selects some clusters of genes from the remainder of subjects and selects a representative gene from each cluster. Then, classifiers are constructed based on these genes and the accu¬racy of each classifier to predict the class of left-out subject is recorded. The classifier with higher precision is considered superior.Results: Combining classification techniques with clustering method re¬sulted in fewer genes with high degree of statistical precision. Although all classifiers selected a few genes from pre-determined highly ranked genes, the precision did not decrease. SVM precision was 100% with 22 genes instead of 50 genes while the NB resulted in higher precision of 97.95% in this case. When 20 highly ranked genes selected to be fed to the algorithm, same precision was obtained using 6 and 5 genes with SVM and NB clas¬sifiers respectively.Conclusion: Using hybrid method could be effective in choosing fewer number of plausible marker genes so that the classification precision of these markers is increased. In addition, this method enables detecting new plausible markers that their association to disease under study is not bio¬logically proved

Determining the role of greatness plan on learning the manners and skills of Islamic life by students in the opinion of teachers and principals of elementary schools in Jarghoyeh district

The aim of present research is to determine the role of greatness plan on learning the manners and skills of Islamic life by students in the opinion of teachers and principals of elementary schools in Jarghoyeh district in 2011-1391(2011-2012). The present study has been descriptive –traverse one and its statistical population included all principals and teachers of elementary schools in Jarghoyeh district (old and new Jarghoyeh) consisting 175 individuals. The statistical sample of this study included 120 individuals who were selected by Kockarn sampling method formula and in random categorical manner proportional to sample volume. The study tool was researcher-made questionnaire which was adjusted based on Likert’s 5- point scale (very much, much, good, medium, little).Data resulting from research were analyzed by using uni- variable T test and also LSD follow up test in SPSS software environment. The results of this study showed that the effect of teaching greatness plan is more than medium level in learning any of the skills of making relation with God, effective relationship, interpersonal relations, dignity, empathy, decision making, social order, self-esteem , thought, and self-consciousness in students but its effectiveness in learning emotion management skill by the students is in lower level. Key words: instruction, students, greatness plan, life skills, learnin

Studying the Relationship between Learning Styles and Progressive Teaching Methods among High Schools Students in the city of Isfahan

The purpose of this study is to investigate the relationship between learning styles and progressive teaching methods among high schools students in the city of Isfahan. This study is a practical research from purpose view and is a descriptive-correlation one from research methodology perspective. The statistical population of this study includes all of the male and female students of high schools in the city of Isfahan in 2010-2011 academic year. This population consists of 86142 students. A sample of 150 students has been selected from this population through multi-stages cluster sampling. This sample consists of 79 female students and 71 male ones. In order to collect the research data, a standard questionnaire and a self-administrated questionnaire has been used. The first questionnaire that has been developed by Reid was used for examining learning styles among students and the second self-administrated one has been used for investigating the teaching methods. The reliability of the questionnaires has been examined through Cronbachs’ Alpha Coefficient. The coefficient was 0.68 and 0.94 for our questionnaire and confirms reliability of the questionnaires. Also the supervisor and other professors have been asked to review and modify the questionnaire and thereby its face validity has been examined and confirmed. The results of this study revealed that there is not any significant relationship between individual learning style and students’ preferred teaching methods. Also the results indicated that there is not any significant relationship between collective learning styles and students’ preferred teaching methods. Another part of the results showed that the relationship between project learning style and students’ preferred teaching methods is significant. Finally, the observed difference between students’ average of learning styles and their preferred teaching methods in terms of gender was significant. Keywords: Learning, Learning Styles, Teaching Method

Ontological Foundations of Multicultural Education

This research was conducted with the aim of examining the ontological foundations of multicultural education by way of a qualitative method of a philosophical research: conceptual analysis. The research scope included all the books, journals, documents, and writings, where for sampling due to a plurality of sources in this area all the printed and digital writings available for the researches were applied. In this research, to collect the information sample notes designed by the researcher were used. The analysis in this paper was done by way of concept analysis, concept interpretation and theoretical inference. Research findings revealed two major philosophical roots and foundations of the multicultural education which are: postmodernism and critical theory. Postmodernism involves implications that explicitly imply multicultural education. These implications are: attention to "another", "honoring the distinction", and "protection of minorities". According to the research findings, ontological foundations of multicultural education: insisting on removing and ending metaphysics; denying absolute, fixed and priori realities; emphasis on differences bout realities; denying a concrete and independent reality; formation of realities in line with needs, interest and cultural traditions; and attention to "virtual reality". Keywords: Education, Multicultural education, Philosophical Foundations of multicultural education, Ontological Foundations of Multicultural Education