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Search Results: 1 - 10 of 1475 matches for " Sehwan Jang "
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Zidovudine (AZT) and Hepatic Lipid Accumulation: Implication of Inflammation, Oxidative and Endoplasmic Reticulum Stress Mediators
Atrayee Banerjee, Mohamed A. Abdelmegeed, Sehwan Jang, Byoung-Joon Song
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0076850
Abstract: The clinical effectiveness of Zidovudine (AZT) is constrained due to its side-effects including hepatic steatosis and toxicity. However, the mechanism(s) of hepatic lipid accumulation in AZT-treated individuals is unknown. We hypothesized that AZT-mediated oxidative and endoplasmic reticulum (ER) stress may play a role in the AZT-induced hepatic lipid accumulation. AZT treatment of C57BL/6J female mice (400 mg/day/kg body weight, i.p.) for 10 consecutive days significantly increased hepatic triglyceride levels and inflammation. Markers of oxidative stress such as protein oxidation, nitration, glycation and lipid peroxidation were significantly higher in the AZT-treated mice compared to vehicle controls. Further, the levels of ER stress marker proteins like GRP78, p-PERK, and p-eIF2α were significantly elevated in AZT-treated mice. The level of nuclear SREBP-1c, a transcription factor involved in fat synthesis, was increased while significantly decreased protein levels of phospho-acetyl-CoA carboxylase, phospho-AMP kinase and PPARα as well as inactivation of 3-keto-acyl-CoA thiolase in the mitochondrial fatty acid β-oxidation pathway were observed in AZT-exposed mice compared to those in control animals. Collectively, these data suggest that elevated oxidative and ER stress plays a key role, at least partially, in lipid accumulation, inflammation and hepatotoxicity in AZT-treated mice.
The Distribution of Multiple Shot Noise Process and Its Integral  [PDF]
Jiwook Jang
Applied Mathematics (AM) , 2014, DOI: 10.4236/am.2014.53047
Abstract:

In this paper, we study multiple shot noise process and its integral. We analyse these two processes systematically for their theoretical distributions, based on the piecewise deterministic Markov process theory developed by Davis [1] and the martingale methodology used by Dassios and Jang [2]. The analytic expressions of the Laplace transforms of these two processes are presented. We also obtain the multivariate probability generating function for the number of jumps, for which we use a multivariate Cox process. To derive these, we assume that the Cox processes jumps, intensity jumps and primary event jumps are independent of each other. Using the Laplace transform of the integral of multiple shot noise process, we obtain the tail of multivariate distributions of the first jump times of the Cox processes, i.e. the multivariate survival functions. Their numerical calculations and other relevant joint distributions numerical values are also presented.

Solvent-Induced Phase-Inversion and Electrical Actuation of Dielectric Copolymer Films  [PDF]
Yeonju Jang, Toshihiro Hirai
Materials Sciences and Applications (MSA) , 2011, DOI: 10.4236/msa.2011.23023
Abstract: Block copolymers posses inherently the ability of form a variety of phase-separated microdomain structures. The lengths of block segments and the selectivity of the solvent are primary factors affecting the resultant morphology. This paper investigated the effect of casting solvents on the morphologies and electrical actuation of poly(methyl methacrylate)-poly(n-butyl acrylate)-poly(methyl methacrylate) (PMMA-PnBA-PMMA) triblock copolymer films comprising PMMA hard segment and PnBA soft segment. Transmission electron microscopy and confocal laser scanning microscopy observation revealed that PMMA and PnBA segments were assembled into various micro- and nano-sized phase structures where either of them formed continuous phase. This implies that continous phase could be inversed by used casting solvents. Solvent-dependent phase morphologies had a significant effect on the electrical actuation results. Increase of the PnBA contents and the continuous phases of PnBA soft segments improved both of electrical actuation and dielectric constant, indicating that solvent-induced phase separation modulates the electrical actuation of dielectric films. The significance of the role of solvent selectivity and the major continuous phase of the polymer in defining the morphology and electrical actuation of the self-assembled block copolymer structure are discussed.
Predictive formulas expressing relationship among dose rate, duration of exposure and mortality probability in total body irradiation in humans  [PDF]
Sung Jang Chung
Journal of Biomedical Science and Engineering (JBiSE) , 2011, DOI: 10.4236/jbise.2011.47063
Abstract: A clear and exact quantitative relationship between dose of radiation and mortality in humans is still not known because of lack of human data that would enable to determine LD50 for humans in total body irradiation. Analysis of human data has been primarily from radiation accidents, radiotherapy and the atomic bomb victims.The death rate equation derived from the 'probacent'-probability model of survival probability is employed in this study to construct the general formula of mortality probability as a function of dose rate and duration of exposure in total body irradiation in humans. There is a remarkable agreement between formula-predicted and published estimated LD50 and also between both mortality probabilities. The formulas of LD50 ans mortality probability in lethal radiation exposure for humans might be helpful in preventing radiation hazard and injury, and further for safety in radiotherapy.
Computer program of nonlinear, curved regression for ‘probacent’-probability equation in biomedicine  [PDF]
Sung Jang Chung
Journal of Biomedical Science and Engineering (JBiSE) , 2011, DOI: 10.4236/jbise.2011.49078
Abstract: On the basis of experimental observations on animals, applications to clinical data on patients and theoretical statistical reasoning, the author developed a com-puter-assisted general mathematical model of the ‘probacent’-probability equation, Equation (1) and death rate (mortality probability) equation, Equation (2) derivable from Equation (1) that may be applica-ble as a general approximation method to make use-ful predictions of probable outcomes in a variety of biomedical phenomena [1-4]. Equations (1) and (2) contain a constant, γ and c, respectively. In the pre-vious studies, the author used the least maximum- difference principle to determine these constants that were expected to best fit reported data, minimizing the deviation. In this study, the author uses the method of computer-assisted least sum of squares to determine the constants, γ and c in constructing the ‘probacent’-related formulas best fitting the NCHS- reported data on survival probabilities and death rates in the US total adult population for 2001. The results of this study reveal that the method of com-puter-assisted mathematical analysis with the least sum of squares seems to be simple, more accurate, convenient and preferable than the previously used least maximum-difference principle, and better fit-ting the NCHS-reported data on survival probabili-ties and death rates in the US total adult population. The computer program of curved regression for the ‘probacent’-probability and death rate equations may be helpful in research in biomedicine.
Predictive formulas expressing relationship between dose rate and survival time in total body irradiation in mice  [PDF]
Sung Jang Chung
Journal of Biomedical Science and Engineering (JBiSE) , 2011, DOI: 10.4236/jbise.2011.411088
Abstract: The Gompertz model is the long-time well-known mathematical model of exponential expression among mortality models in the literature that are used to describe mortality and survival data of a population. The death rate of the “probacent” model developed by the author based on animal experiments, clinical applications and mathematical reasoning was applied to predict age-specific death rates in the US elderly population, 2001, and to express a relationship among dose rate, duration of exposure and mortality probability in total body irradiation in humans. The results of both studies revealed a remarkable agreement between “probacent”-formula-predicted and published-reported values of death rates in the US elderly population or mortality probabilities in total body irradiation in humans (p - value > 0.995 in χ² test in each study). In this study, both the Gompertz and “probacent” models are applied to the Sacher’s comprehensive experimental data on survival times of mice daily exposed to various doses of total body irradiation until death occurs with an assumption that each of both models is applicable to the data. The purpose of this study is to construct general formulas expressing relationship between dose rate and survival time in total body irradiation in mice. In addition, it is attempted to test which model better fits the reported data. The results of the comparative study revealed that the “probacent” model not only fit the Sacher’s reported data but also remarkably better fit the reported data than the Gompertz model. The “probacent” model might be hopefully helpful in research in human tolerance to low dose rates for long durations of exposure in total body irradiation, and further in research in a variety of biomedical phenomena.
Computer-assisted formulas predicting cancer mortality risk after exposure to acute low dose ionizing radiation in humans  [PDF]
Sung Jang Chung
Journal of Biomedical Science and Engineering (JBiSE) , 2012, DOI: 10.4236/jbise.2012.54023
Abstract: A clear relationship between dose of radiation and mortality in humans is still not known because of lack of human data that would enable to determine human tolerance in total body irradiation. Human data for analysis have been primarily from radiation accidents, radiotherapy and the atomic bomb victims. A general formula that predicts mortality probability as a function of dose rate and duration of exposure to acute high dose ionizing radiation in humans was published by the author, applying the “probacent” model to the reported data on animal-model-predicted dose versus mortality. In this study, the “probacent” model is applied to the data on dose versus cancer mortality risk, published by the United Nations (UNSCEAR, 2010) and other investigators to construct general formulas expressing a relationship between dose and solid cancer or leukemia mortality probability after exposure to acute low dose ionizing radiation in humans. There is a remarkable agreement between formula-derived and published values of dose and solid cancer or leukemia mortality probability (p > 0.99). The general formula might be helpful in preventing radiation hazard and injury in acute low dose ionizing radiation, and for safety in radiotherapy.
The Science of Self, Mind and Body  [PDF]
Sung Jang Chung
Open Journal of Philosophy (OJPP) , 2012, DOI: 10.4236/ojpp.2012.23026
Abstract: A relationship among self, mind and body in humans is still not clearly known in philosophy and science because of lack of human data that would enable to objectively explain it. Teachings related to their relationship in religions have been given to humanity in general in terms of subjective words. Consequently, philosophers and scientists have been investigating to find objective proofs related to their relationship. The author proposed a theory in his book (2009) that there are in a human individual two selves, one, the inner self (the true self) and one, the physical self (the false self) that coexist in one individual person. McGonigal (2012) published her book in which she described two minds or two selves in one human individual, naming them “I Will” and “I WANT” self on the basis of extensive studies on adult subjects. More recent researches in neuroscience using functional magnetic resonance imaging (fMRI) discovered that the prefrontal cortex of the human brain performs self-control, emotion regulation and guiding behaviors with morality, future goals and rules. The author compared characteristic aspects of the inner and physical selves of Chung with the “I Will” and “I Want” selves of McGonigal. There is a remarkable good agreement between the inner and physical selves of Chung and the “I Will” and “I WANT” selves of McGonigal. The author proposes a theory in this study that the inner and physical selves correspond to the “I WILL” and “I WANT” selves, respectively, and that the inner self, the true self, controls the physical self, the false self, interacting with the prefrontal cortex ofthe human brain.
The Asset Pricing System  [PDF]
Yi-Jang Yu
Modern Economy (ME) , 2012, DOI: 10.4236/me.2012.35062
Abstract: Mainstream asset pricing models are all inappropriate when they consistently insist on applying one single model to deal with a reality filled with different aspects of asset pricing. In addition, those models also treat the right environ-ment variable too lightly hence can not rightly do the job of asset pricing. In this study, based on the portfolio theory and the principle of supply and demand, a more reasonable asset pricing system including five different models will be suggested to provide a necessary function of automatic price stabilization and to better serve our financial market.
Measuring Tail Dependence for Aggregate Collateral Losses Using Bivariate Compound Shot-Noise Cox Process  [PDF]
Jiwook Jang, Genyuan Fu
Applied Mathematics (AM) , 2012, DOI: 10.4236/am.2012.312A300
Abstract: In this paper, we introduce tail dependene measures for collateral losses from catastrophic events. To calculate these measures, we use bivariate compound process where a Cox process with shot noise intensity is used to count collateral losses. A homogeneous Poisson process is also examined as its counterpart for the case where the catastrophic loss frequency rate is deterministic. Joint Laplace transform of the distribution of the aggregate collateral losses is derived and joint Fast Fourier transform is used to obtain the joint distributions of aggregate collateral losses. For numerical illustrations, a member of Farlie-Gumbel-Morgenstern copula with exponential margins is used. The figures of the joint distributions of collateral losses, their contours and numerical calculations of risk measures are also provided.

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