Evolution of the curvature perturbation during and after multi-field inflation

We study the evolution of the curvature perturbation on the super-horizon scales starting from the inflationary epoch until there remains only a single dynamical degree of freedom, presureless matter, in the universe. We consider the cosmic inflation driven by a multiple number of the inflaton fields, which decay into both radiation and pressureless matter components. We present a complete set of the exact background and perturbation equations which describe the evolution of the universe throughout its history. By applying these equations to the simple but reasonable model of multi-field chaotic inflation, we explicitly show that the total curvature perturbation is continuously varying because of the non-adiabatic components of the curvature perturbation generated by the multiple inflaton fields throughout the whole evolution of the universe. We also provide an useful analytic estimation of the total as well as matter and radiation curvature perturbations, assuming that matter is completely decoupled from radiation from the beginning. The resulting isocurvature perturbation between matter and radiation is at most sub-percent level when the masses of the inflaton fields are distributed between $10^{-6}m_{pl}$ and $10^{-5}m_{pl}$. We find that this result is robust unless we use non-trivial decay rates, and that thus, in general, it is hard to obtain large matter-radiation isocurvature perturbation. Also, by using the $\delta{N}$ formalism, we point out that the inflationary calculation, especially when involving multiple inflaton fields, is likely to lose the potentially important post-inflationary evolution which can modify the resulting curvature perturbation.Comment: 31 pages, 6 figures, Final version to appear in JCAP. Add calculation of power spectrum and spectral index. We provide more discussio

Measuring efficiency of lean six sigma project implementation using data envelopment analysis at NASA

Purpose: This study aims to review the implementation of the Lean Six Sigma project methodology in the Johnson Space Center (JSC) business environment of National Aeronautics and Space Administration (NASA) with an objective of evaluating performance of individual projects and to develop recommendation for strategies to improve operational efficiencies based on Data Envelopment Analysis (DEA). Design/methodology/approach: In this study, authors propose the Lean Six Sigma project performance evaluation model (LSS-PPEM) based on Data DEA where Critical Success Factors (CSFs) and Total Team Hours serve as inputs while Process Sigma and Cost avoidance are used as outputs. The CSFs are factors that critically affect the performance of LSS at JSC. Six of those are identified by the Black Belts through Analytical Hierarchical Process, and the values of those are decided by project leaders and Green Belts through survey. Eighteen LSS projects are evaluated, and their results are analyzed. Findings and Originality/value: Eventually, four out of the six CSFs are adopted for this study based upon Pearson correlation analysis, and those four include Project execution and follow up of results; Top management’s commitment and participation; The use of data analysis with easily obtainable data; Attention given to both long and short term targets. Using data between the years 2009 and 2011, seven of the eighteen projects are found to be efficient. The benchmark analysis and slack analysis are conducted to provide further recommendation for JSC managers. Three out of those seven efficient projects are most frequently used as an efficient peer. Practical implications: Traditionally, DEA has been considered as a data-driven approach. In this study, authors incorporate the survey-based CSFs into the DEA frame. Since many organizations may have different CSFs, the framework presented in this study can be easily applied to other organizations. Originality/value: This study provides a DEA-based framework and case study of LSS project evaluation in the government sector, which is very unique application to author’s best knowledge. The framework is unique in terms of its input factor selection and quantification procedures.Peer Reviewe

Application of a concept development process to evaluate process layout designs using value stream mapping and simulation

Purpose: We propose and demonstrate a concept development process (CDP) as a framework to solve a value stream mapping (VSM) related process layout design optimization problem. Design/methodology/approach: A case study approach was used to demonstrate the effectiveness of CDP framework in a portable fire extinguisher manufacturing company. To facilitate the CDP application, we proposed the system coupling level index (SCLI) and simulation to evaluate the process layout design concepts. Findings: As part of the CDP framework application, three process layout design concepts - current layout (CL), express lane layout (ELL) and independent zone layout (IZL) - were generated. Then, the SCLI excluded CL and simulation selected IZL as the best concept. The simulation was also applied to optimize the performance of IZL in terms of the number of pallets. Based on this case study, we concluded that CDP framework worked well. Research limitations/implications: The process layout design optimization issue has not been well addressed in the VSM literature. We believe that this paper initiated the relevant discussion by showing the feasibility of CDP as a framework in this issue. Practical implications: The CDP and SCLI are very practice-oriented approaches in the sense that they do not require any complex analytical knowledge. Originality/value: We discussed a not well-addressed issue with a systematic framework. In addition, the SCLI presented was also unique.Peer Reviewe

A Study of the Sermon as Bible Study Materials for Small Group and Church Growth: With a Focus on Singing Hope Church

This study will suggest that the Sunday Service sermons are essential elements for church growth and the sermons can be used as Bible study materials in the small group meetings. Korean churches kept on growing after the Pyeongyang Great Revival in 1907. However, Korean churches stopped growing since 2000, at which point they started to decline in numbers. One of the reasons is that the congregants do not live according to the Word of God that is proclaimed from the pulpit. There are various reasons for church growth. The researcher observed that continuously applying Sunday sermons to church members is essential to church growth. The researcher has been using Sunday sermons as materials for small group Bible studies and will thus study the relationship between Sunday sermons and church growth. Then the researcher will analyze the materials, books, and case studies of small groups that used sermons as Bible study materials. There will be presented samples of Bible study materials that the researcher used which will demonstrate how Sunday sermons can be made into small group discipling materials. The researcher will explain how Sunday sermon messages can continuously impact Korean churches through the form of small group Bible study materials

IDEF method-based simulation model design and development

The purpose of this study is to provide an IDEF method-based integrated framework for a business process simulation model to reduce the model development time by increasing the communication and knowledge reusability during a simulation project. In this framework, simulation requirements are collected by a function modeling method (IDEF0) and a process modeling method (IDEF3). Based on these requirements, a common data model is constructed using the IDEF1X method. From this reusable data model, multiple simulation models are automatically generated using a database-driven simulation model development approach. The framework is claimed to help both requirement collection and experimentation phases during a simulation project by improving system knowledge, model reusability, and maintainability through the systematic use of three descriptive IDEF methods and the features of the relational database technologies. A complex semiconductor fabrication case study was used as a testbed to evaluate and illustrate the concepts and the framework. Two different simulation software products were used to develop and control the semiconductor model from the same knowledge base. The case study empirically showed that this framework could help improve the simulation project processes by using IDEF-based descriptive models and the relational database technology. Authors also concluded that this framework could be easily applied to other analytical model generation by separating the logic from the dataPeer Reviewe

Assessment of satellite rainfall nowcasting based on extrapolation technique

Póster presentado en: 3rd European Nowcasting Conference, celebrada en la sede central de AEMET en Madrid del 24 al 26 de abril de 2019

Effects of Genetic and Pharmacologic Inhibition of COX-2 on Colitis-associated Carcinogenesis in Mice

COX-2 has been inappropriately overexpressed in various human malignancies, and is considered as one of the representative targets for the chemoprevention of inflammation-associated cancer. In order to assess the role of COX-2 in colitis-induced carcinogenesis, the selective COX-2 inhibitor celecoxib and COX-2 null mice were exploited in an azoxymethane (AOM)-initiated and dextran sulfate sodium (DSS)-promoted murine colon carcinogenesis model. The administration of 2% DSS in drinking water for 1 week after a single intraperitoneal injection of AOM produced colorectal adenomas in 83% of mice, whereas only 27% of mice given AOM alone developed tumors. Oral administration of celecoxib significantly lowered the incidence as well as the multiplicity of colon tumors. The expression of COX-2 and inducible nitric oxide synthase (iNOS) was upregulated in the colon tissues of mice treated with AOM and DSS, and this was inhibited by celecoxib administration. Likewise, celecoxib treatment abrogated the DNA binding of NF-kappa B, a key transcription factor responsible for regulating expression of aforementioned pro-inflammatory enzymes, which was associated with suppression of I kappa B alpha degradation. In the COX-2 null (COX-2(-/-)) mice, there was about 30% reduction in the incidence of colon tumors, and the tumor multiplicity was also markedly reduced (7.7 +/- 2.5 vs. 2.43 +/- 1.4, P < 0.01). As both pharmacologic inhibition and genetic ablation of COX- 2 gene could not completely suppress colon tumor formation following treatment with AOM and DSS, it is speculated that other pro-inflammatory mediators, including COX-1 and iNOS, should be additionally targeted to prevent inflammation-associated colon carcinogenesis.