Joanna E. Laszczyk and Andrzej J Nowak
The purpose of this paper is to present the computational model of the neonate’s brain cooling process. The main aim of the analysis is to tune the developed computational model…
Abstract
Purpose
The purpose of this paper is to present the computational model of the neonate’s brain cooling process. The main aim of the analysis is to tune the developed computational model, make it convergent and representing the hypothermia therapy reasonably. To find the appropriate model parameters the trial of an inverse analysis, based on the standard least-square method, is performed. Having partially validated model the number of numerical simulations are carried out to compare their results with measurements made during real therapy.
Design Methodology Approach
The geometrical model of the newborn’s body is built using MRI and CT scans utilizing Mimics software and the Design Modeler while Ansys Fluent with its User Defined Function capability was used to implement the whole model and to carry out simulations. To model the bioheat transfer the Pennes bioheat equation is applied. In the mathematical model blood perfusion rate, metabolic heat generation rate as well as the arterial blood temperature are dependent on the tissue temperature. In order to determine the proper values of model parameters of bioheat transport in neonate’s body the attempt to inverse analysis is also performed.
Findings
The performed inverse analysis resulted in the values of model parameters (metabolic heat sources, blood perfusions etc.). Tuned model was then applied to simulate brain cooling process with reasonable accuracy. Obtained model parameters were also compared to the data obtained from neonatologists.
Research limitations implications
The presented numerical model still requires tests and simulations. The results from the inverse analysis based on the real measurements can be very valuable.
Practical implications
The determination of the proper parameters of the bioheat transfer in the neonatal body can finally be used to control the numerical simulations of the brain cooling process. The simulation of the re-warming process after hypothermic therapy can be improved considerably.
Social implications
The performance of the numerical simulations of the brain cooling process in the proper way can finally helps protect newborns’ health and life.
Originality Value
In the paper 3-D real geometrical model of the newborn’s body includes head, torso and limbs and different types of tissues are distinguished in the model. The considered bioheat transfer problem is also fully 3-D. This model is then utilised together with inverse analysis in order to determine the model parameters for the newborn’s body.
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THE status of the flight simulator for aircrew training has increased considerably the world over during the last five years to the extent that most major airlines now possess any…
Abstract
THE status of the flight simulator for aircrew training has increased considerably the world over during the last five years to the extent that most major airlines now possess any number of simulators between one and twenty or so depending on the variety of aircraft types used and fleet size. Today even second and third level operators are looking to the flight simulator, not only as a means of reducing costs but also to increase standards of safety.
I ENTERED the literary world late in the immediate post‐war years when changes of literary taste and loyalty were already in the air. The first broadcast I gave was, I remember…
Abstract
I ENTERED the literary world late in the immediate post‐war years when changes of literary taste and loyalty were already in the air. The first broadcast I gave was, I remember, an attack upon Virginia Woolf. Her books had nurtured me as an adolescent, and I was in reaction against her influence.
Qi Flora Dong, Yiting Cao, Xin Zhao and Ashutosh Deshmukh
The effect of tax policy on the repatriation of foreign earnings is a topic of ongoing discussion among policymakers, academics, and the popular press. It has become more salient…
Abstract
The effect of tax policy on the repatriation of foreign earnings is a topic of ongoing discussion among policymakers, academics, and the popular press. It has become more salient due to the 2017 Tax Cuts and Jobs Act (TCJA), which permanently removed repatriation tax. This paper synthesizes the academic literature examining US multinational firms’ responses to the repatriation tax holiday initiated by the 2004 American Jobs Creation Act (AJCA), which temporarily reduced the tax on the repatriation of foreign earnings. By synthesizing firm responses to the temporary tax reduction, we identify similarities and differences in: (1) theories about why and when repatriation tax affects firms’ repatriation decisions; (2) empirical evidence of whether repatriation tax affects firms’ repatriation decisions; and (3) empirical evidence of whether repatriation tax affects firms’ investment decisions. The analyses provide insights into the effect of the permanent removal of repatriation tax under the TCJA and explore avenues for future research. This synthesis of the AJCA literature informs tax research and practice as well as policymaking.
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Felipe Sant'Anna Nunes, Helcio R.B. Orlande and Andrzej J. Nowak
This study deals with the computational simulation and inverse analysis of the cooling treatment of the hypoxic-ischemic encephalopathy in neonates. A reduced-order model is…
Abstract
Purpose
This study deals with the computational simulation and inverse analysis of the cooling treatment of the hypoxic-ischemic encephalopathy in neonates. A reduced-order model is implemented for real-time monitoring of the internal body temperatures. The purpose of this study is to sequentially estimate the transient temperatures of the brain and other body regions with reduced uncertainties.
Design/methodology/approach
Pennes’ model was applied in each body element, and Fiala’s blood pool concept was used for the solution of the forward bioheat transfer problem. A state estimation problem was solved with the Sampling Importance Resampling (SIR) algorithm of the particle filter method.
Findings
The particle filter method was stable and accurate for the estimation of the internal body temperatures, even in situations involving large modeling and measurement uncertainties.
Research limitations/implications
The proposed reduced-order model was verified with the results of a high-fidelity model available in the literature. Validation of the proposed model and of the solution of the state estimation problem shall be pursued in the future.
Practical implications
The solution of the state estimation problem with the reduced-order model presented in this paper has great potential to perform as an observer of the brain temperature of neonates, for the analysis and control of the systemic cooling treatment of neonatal hypoxic-ischemic encephalopathy.
Social implications
The main treatment for hypoxic-ischemic encephalopathy in neonates is the cooling of affected regions. Accurate and fast models might allow the development of individualized protocols, as well as control strategies for the cooling treatment.
Originality/value
This paper presents the application of the SIR algorithm for the solution of a state problem during the systemic cooling of a neonate for the treatment of the hypoxic-ischemic encephalopathy.
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We study the information content of issuer credit rating changes announced by a group of six Chinese credit rating agencies. We conduct an event study, and we use multivariate…
Abstract
We study the information content of issuer credit rating changes announced by a group of six Chinese credit rating agencies. We conduct an event study, and we use multivariate regression analyses to identify factors driving abnormal stock returns. Our results confirm prior findings for Western countries that downgrades are associated with significant negative abnormal returns. However, upgrades and positive or negative rating outlooks do not seem to have information content. While we cannot find differences in information content conditional on which rating agency issues the downgrade, we find that abnormal returns may vary with the target firm’s industry. In addition, the magnitude of stock price reactions to rating downgrades seems to be related to the business cycle to some extent. With respect to the role of the industry in explaining the information content of rating changes, our results may be biased due to small sample size. Nevertheless, they illustrate that the role the industry plays in explaining investor behavior may deserve special attention in future research. Our findings imply that new rating information seems to be processed quickly in the Chinese stock market, and that market reactions to rating signals are largely in line with what has been observed for Western stock markets. Both observations lend credibility to observable stock prices. The chapter sheds new light on the relevance of Chinese credit rating agencies from an equity investor’s perspective and confirms similarities between the Chinese and Western stock markets with respect to the way rating signals are processed by investors.
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This paper empirically examines whether dividends are value‐relevant in Japan by employing Ohlson’s (1995) accounting‐based equity valuation technique. The substantial U.S.‐based…
Abstract
This paper empirically examines whether dividends are value‐relevant in Japan by employing Ohlson’s (1995) accounting‐based equity valuation technique. The substantial U.S.‐based literature on dividends has confirmed the signalling role of dividends in mitigating information asymmetry between managers and investors, and is consistent with an environment characterized by dispersion of ownership. However, the most important corporate governance characteristic that distinguishes Japan from the U.S. is the predominance of inter‐corporate, interlocking ownership in Japan, which reduces information asymmetry and is therefore likely to diminish the role of dividends in mitigating such asymmetries. Pooled regression results provide evidence consistent with this hypothesis. However, even in such an environment, dividends are value relevant for firms that incur losses whilst paying dividends, and also for firms with permanent earnings.