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Search Results: 1 - 10 of 838 matches for " Tsuyoshi Kunihama "
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Nonparametric Bayes inference on conditional independence
Tsuyoshi Kunihama,David B. Dunson
Statistics , 2014,
Abstract: In broad applications, it is routinely of interest to assess whether there is evidence in the data to refute the assumption of conditional independence of $Y$ and $X$ conditionally on $Z$. Such tests are well developed in parametric models but are not straightforward in the nonparametric case. We propose a general Bayesian approach, which relies on an encompassing nonparametric Bayes model for the joint distribution of $Y$, $X$ and $Z$. The framework allows $Y$, $X$ and $Z$ to be random variables on arbitrary spaces, and can accommodate different dimensional vectors having a mixture of discrete and continuous measurement scales. Using conditional mutual information as a scalar summary of the strength of the conditional dependence relationship, we construct null and alternative hypotheses. We provide conditions under which the correct hypothesis will be consistently selected. Computational methods are developed, which can be incorporated within MCMC algorithms for the encompassing model. The methods are applied to variable selection and assessed through simulations and criminology applications.
Bayesian modeling of temporal dependence in large sparse contingency tables
Tsuyoshi Kunihama,David B. Dunson
Statistics , 2012,
Abstract: In many applications, it is of interest to study trends over time in relationships among categorical variables, such as age group, ethnicity, religious affiliation, political party and preference for particular policies. At each time point, a sample of individuals provide responses to a set of questions, with different individuals sampled at each time. In such settings, there tends to be abundant missing data and the variables being measured may change over time. At each time point, one obtains a large sparse contingency table, with the number of cells often much larger than the number of individuals being surveyed. To borrow information across time in modeling large sparse contingency tables, we propose a Bayesian autoregressive tensor factorization approach. The proposed model relies on a probabilistic Parafac factorization of the joint pmf characterizing the categorical data distribution at each time point, with autocorrelation included across times. Efficient computational methods are developed relying on MCMC. The methods are evaluated through simulation examples and applied to social survey data.
Minocycline for Schizophrenia: A critical review  [PDF]
Tsuyoshi Miyaoka
Open Journal of Psychiatry (OJPsych) , 2012, DOI: 10.4236/ojpsych.2012.224056
Abstract: Minocycline, an antibiotic of the tetracycline family, has been shown to display neurorestoractive or neuroprotective properties in various models of neurodegenerative diseases. In particular, it has been shown to delay motor alterations, inflammation and apoptosis in models of Huntington’s disease, amyotrophic lateral sclerosis and Parkinson’s disease. Despite controversies about its efficacy, the relative safety and tolerability of minocycline have led to the launching of various clinical trials. Previously, we reported the antipsychotic effects of minocycline in patients with schizophrenia. In a pilot investigation, we administered minocycline as an open-label adjunct to antipsychotic medication to patients with schizophrenia. The results of this trial suggested that minocycline might be a safe and effective adjunct to antipsychotic medications, and that augmentation with minocycline may prove to be a viable strategy for “boosting” antipsychotic efficacy and for treating schizophrenia. Recently, in randomized double-blind placebo-controlled clinical trials, the addition of minocycline to treatment as usual early in the course of schizophrenia predominantly improves negative symptoms. The present review summarizes the available data supporting the clinical testing of minocycline for patients with schizophrenia. In addition, we extend our discussion to the potential applications of minocycline for combining this treatment with cellular and molecular therapy.
Electrodeposition of Bi-Sb alloy using Cu electrodes  [PDF]
Masato Ohmukai, Akira Tsuyoshi
Materials Sciences and Applications (MSA) , 2012, DOI: 10.4236/msa.2012.37069
Abstract: Bi-Sb alloys were grown by means of an electrodeposition method using Cu electrodes. The alloys were studied with the help of an x-ray diffractometer and an electron probe microanalysis. The both investigations have shown no trace of Cu in the obtained alloys. It can be concluded that Cu electrodes can be used for the deposition of Bi-Sb alloys; which results in an advantage of availability of the electrode.
Scoping the Possibilities: Student Preferences towards Open Textbooks Adoption for E-Learning  [PDF]
Deepak Prasad, Tsuyoshi Usagawa
Creative Education (CE) , 2014, DOI: 10.4236/ce.2014.524227
Abstract: Many universities have begun implementing e-Learning systems due to their low cost. However, publishers of expensive textbooks stand in the way of e-Learning’s ability to provide a cost-effective educational delivery model. While many universities aim to overcome this opposition and replace traditional publishers’ textbooks with free open textbooks, such plans cannot be executed successfully unless students are open to their use. As such, a study into students’ preferences towards open textbook adoption is vital to provide clear indication as to their opinions regarding open textbook use. Thus, this study conducted a study of University of the South Pacific (USP) students’ preferences towards open textbook adoption for e-Learning using a survey administered during Semester 2, 2013 which generated 1077 responses. Areas examined include: Impacts of textbook costs on students’ academic careers; preferences towards open textbook adoption; perceived barriers to and motivations for adoption of open textbooks; and preferred digital features and reading devices. Results show that textbook prices adversely impact students. Furthermore, a high level of acceptance towards the adoption of open textbooks was found. The study revealed that the preference for reading printed material was the highest rated barrier to open textbook adoption, while the free availability of open textbooks was rated the greatest motivator. Study findings are being used to inform efforts to develop open textbooks at the USP and may assist other universities seeking to start similar projects.
Comparison between Amorphous and Tandem Silicon Solar Cells in Practical Use  [PDF]
Masato Ohmukai, Akira Tsuyoshi
Journal of Power and Energy Engineering (JPEE) , 2017, DOI: 10.4236/jpee.2017.54002
Abstract: Solar cells are now widely used as a clean method for electric energy generation. Among various type of solar cells, we compared the ability between amorphous and tandem (amorphous and polycrystalline) silicon solar cells by means of simultaneous running test. This kind of comparison is of importance practically, because the comparison of only inherent characteristics cannot include environmental parameters such as temperature totally. It was concluded that both types of solar cells provided almost the same energy for one year. The amorphous silicon solar cell provided more energy in summer while the tandem solar cell was advantageous in winter. It is due to the fact that the decrease in energy conversion at the higher cell temperature is more noticeable in tandem solar cells.
Simulation Suggests Origin of Potential Induced Degradation of Solar Cell  [PDF]
Masato Ohmukai, Akira Tsuyoshi
Journal of Power and Energy Engineering (JPEE) , 2017, DOI: 10.4236/jpee.2017.56004
Abstract: Solar cells are well known as devices for sustainable electric energy generation. Nowadays the potential induced degradation has been brought up as an obstacle problem for practical use. In order to determine the cause of this kind of degradation, numerical simulation by a finite difference time domain method has been performed for computational electromagnetics in the case that the thunder attacks the solar modules. The results show that the dielectric breakdown in the glass covered over the solar cells triggered by the thunderstroke is critical. So it is helpful to protect the dielectric breakdown in the glass from the thunderstroke.
Effect of Parameters on Potential Induced Degradation of Solar Cell  [PDF]
Masato Ohmukai, Akira Tsuyoshi
Journal of Power and Energy Engineering (JPEE) , 2017, DOI: 10.4236/jpee.2017.56003
Abstract: Solar cells are widely used to generate electric energy even at homes. It surely has a great advantage of sustainability. However, the potential induced degradation has been found to be an obstacle problem for practical use. It was reported that the main cause is the dielectric breakdown in the glass covered over the solar cells triggered by the thunderstroke. In this paper, the effects of the parameters such as the position of thunderstroke, the wave form, the peak value and the front duration of the lightning current, were examined by means of numerical calculation. For the lightning current, a step-like waveform and an impulse waveform were examined. The effect of the induced voltage was found to be independent of the waveform. The peak value, the front duration of the lightning current greatly affects the induced voltage.
Potential Impact of Blended Learning on Teacher Education in Mongolia  [PDF]
Narangerel Jachin, Tsuyoshi Usagawa
Creative Education (CE) , 2017, DOI: 10.4236/ce.2017.89104
Abstract: Mongolia is a developing country with little infrastructure capacities, but with rapid economic growth for the past few years. Within the past few years, internet and mobile technologies have become more affordable and widespread. Even though there are improvements, it is no secret that quality in all levels of educational sector in Mongolia is inadequate. E-Learning is becoming a driving force of the pedagogical and technological innovations in the higher education institutions worldwide. The most practiced form of the e-Learning in the higher education institutions is blended learning. Some researches show that use of a blended learning course in higher education can result in better quality in instruction. Design and implementation of blended course in particular situation, revision and assessment of quality, would not only enable to share the experience with the similar higher education institutions but also contribute to the overall research in quality in higher education. This paper presents implementation and improvement of the blended “Pedagogy course,” using Moodle Learning Management System and discusses the potential impact on teacher education in Mongolia. Pilot blended “Pedagogy course” was designed and implemented during 2012-2013 school year then revised in 2014-2015 school year. To ensure effectiveness, Keller’s ARCS model of motivational design, validated by many researches was chosen. At the end of the implementation, the students’ blended learning experience survey was completed followed by focus group discussion and statistical analysis. Results show that students in blended class could achieve better grades than traditional class, with high satisfaction. The outcome of the research shows that blended learning implemen-tation can improve quality in higher education has a potential to improve teacher education and should be recommended in similar educational institu-tions in developing countries with similar situation in Mongolia.
Change in E-learning Readiness and Challenge for Myanmar Higher Education  [PDF]
Mon Mon The, Tsuyoshi Usagawa
Creative Education (CE) , 2018, DOI: 10.4236/ce.2018.99095
Abstract: The advantage of technology has paved way for innovation in higher education. Because of being cost-effective, unlimited time and place, the universities from the developing world are also trying to integrate e-learning into their traditional education system. However, as a fundamental process, they require the readiness assessment before their e-learning implementation. Moreover, the evaluation on readiness should be done as on-going process so that readiness movements are able to be confirmed, and necessary preparations in line with their updates can be effectively done. The purpose of this study was to investigate if the e-learning readiness of two Myanmar technological universities are stable or not, and to find out which items happened the highest difference between 2016 and 2017. To examine the changes in e-learning readiness, the paper-based data collection was done using questionnaires and shared toward 648 students in 2016 and 1024 students in 2017. Data analysis was done by indexes of descriptive statistics and independent t-test. Findings reveal that their readiness was a significant decline in 2017. Moreover, the items with highest changes were addressed, and the readiness levels on each studied dimension were also measured. In addition, the study points out blackout problems found in Myanmar universities. Understanding the barriers directed by e-learning readiness encourages Myanmar universities to make an e-learning effort on what kind of strategies and preparation should be emphasized.
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