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Kim Et Al. (kim + et_al)

Distribution by Scientific Domains

Medical Sciences	33%
Mathematics and Statistics	33%

Selected Abstracts

Augmented Lagrangian coordination for distributed optimal design in MDO

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 13 2008
S. Tosserams
Abstract Quite a number of coordination methods have been proposed for the distributed optimal design of large-scale systems consisting of a number of interacting subsystems. Several coordination methods are known to have numerical convergence difficulties that can be explained theoretically. The methods for which convergence proofs are available have mostly been developed for so-called quasi-separable problems (i.e. problems with individual subsystems coupled only through a set of linking variables, not through constraints and/or objectives). In this paper, we present a new coordination approach for multidisciplinary design optimization problems with linking variables as well as coupling objectives and constraints. Two formulation variants are presented, offering a large degree of freedom in tailoring the coordination algorithm to the design problem at hand. The first, centralized variant introduces a master problem to coordinate coupling of the subsystems. The second, distributed variant coordinates coupling directly between subsystems. Our coordination approach employs an augmented Lagrangian penalty relaxation in combination with a block coordinate descent method. The proposed coordination algorithms can be shown to converge to Karush,Kuhn,Tucker points of the original problem by using the existing convergence results. We illustrate the flexibility of the proposed approach by showing that the analytical target cascading method of Kim et al. (J. Mech. Design-ASME 2003; 125(3):475,480) and the augmented Lagrangian method for quasi-separable problems of Tosserams et al. (Struct. Multidisciplinary Opt. 2007, to appear) are subclasses of the proposed formulations. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Albumin dialysis in cirrhosis with superimposed acute liver injury: possible impact of albumin dialysis on hospitalization costs

LIVER INTERNATIONAL, Issue 2003
T. Hassanein
Abstract Albumin dialysis using the Molecular Adsorbents Recirculating System (MARS) has been found to be beneficial in the treatment of cirrhotic patients with acute decompensation to improve survival as well as reduce associated complications. The present study attempts to analyze the costs involved, and compare it to the benefit as a result of the MARS therapy, thus evaluating its cost-effectiveness. Using the results of a study by Kim et al. (Hepatology 2001) describing the effects of complications on the cost of hospitalization in alcoholic liver disease patients, the expenditure incurred in a group of 11 patients treated with standard medical therapy (five survivors) and a group of 12 patients treated with MARS in addition (11 survivors) (Heemann et al., Hepatology 2002) were analyzed. MARS resulted in a reduction of in-hospital deaths, as well as liver disease-related complications. Both these factors led to a substantial reduction of costs in the MARS group, which was enough to counterbalance the extra costs associated with extra-corporeal therapy. In the control group, the total hospitalization cost per survivor were calculated to be at $35 904. In the MARS group, the overall expenditure per survivor including standard medical therapy plus additional MARS liver support therapy were $32 036 , a saving of nearly $4000 compared to the control group. Therefore, it appears that the benefits of MARS therapy are enough to justify the cost of treatment and safe hospital costs, at least in the described population. However, further studies are needed to confirm these results. [source]

An Independence Test for Doubly Censored Failure Time Data

BIOMETRICAL JOURNAL, Issue 5 2004
Jianguo Sun
Abstract The analysis of doubly censored failure time data has recently attracted a great deal of attention and for this, a number of methods have been proposed (De Gruttola and Lagakos, 1989; Kim et al., 1993; Pan, 2001; Sun, 2004). To simplify the analysis, most of these methods make an independence assumption: the distribution of the survival time of interest is independent of the occurrence of the initial event that defines the survival time. Although it is well-known that the assumption may not be true, there does not seem to be any existing research discussing the checking of the assumption. In this article, a Wald test is developed for testing this assumption and the method is applied to an AIDS cohort study. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Regression Analysis of Doubly Censored Failure Time Data Using the Additive Hazards Model

BIOMETRICS, Issue 3 2004
Liuquan Sun
Summary Doubly censored failure time data arise when the survival time of interest is the elapsed time between two related events and observations on occurrences of both events could be censored. Regression analysis of doubly censored data has recently attracted considerable attention and for this a few methods have been proposed (Kim et al., 1993, Biometrics49, 13,22; Sun et al., 1999, Biometrics55, 909,914; Pan, 2001, Biometrics57, 1245,1250). However, all of the methods are based on the proportional hazards model and it is well known that the proportional hazards model may not fit failure time data well sometimes. This article investigates regression analysis of such data using the additive hazards model and an estimating equation approach is proposed for inference about regression parameters of interest. The proposed method can be easily implemented and the properties of the proposed estimates of regression parameters are established. The method is applied to a set of doubly censored data from an AIDS cohort study. [source]

In this issue: Biotechnology Journal 9/2010

BIOTECHNOLOGY JOURNAL, Issue 9 2010
Article first published online: 10 SEP 2010
Linking obesity and colorectal cancer Sung and Bae, Biotechnol. J. 2010, 5, 930,941 Obesity is known as one of the most closely related risk factors of colorectal cancer (CRC). However, due to the complicated nature of the diet, it has been very difficult to provide clear explanations and molecular mechanisms for the role of dietary components in carcinogenesis. Nutrigenomics has become a powerful tool to study the relationships between food components and genes. It includes nutrigenetics (dealing with genetic variations related to phenotypic changes in response to diet), nutritional epigenomics and nutritional transcriptomics/proteomics/metabolomics. This review summarizes data on genes, proteins and metabolites that are related to either obesity or CRC and candidate molecules that may link obesity and CRC. The application of bioinformatics helps to perform large-scale network analysis to study cause-effect relationships between dietary components and CRC in the future. Hepatoprotective effects of oleuropein Kim et al., Biotechnol. J. 2010, 5, 950,960 Oleuropein, an active constituent of olive leaf, has a variety of pharmacological activities associated with its capacity to scavenge reactive oxygen species and has a protective effect against non-alcoholic fatty liver disease (NAFLD) in vivo. To gain insights into the molecular mechanisms of its hepatoprotective action the group of Taesun Park (Seoul, Korea) fed mice with a high fat diet supplemented with oleuropein. Then, liver tissue was subjected to DNA microarray analysis. Oleuropein in high fat diet reduced the mRNA level of regulators of hepatic fatty acid uptake and transport. The expression of a number of genes involved in oxidative stress responses, detoxification of lipid peroxidation products and proinflammatory cytokine genes were reduced, while highly regulated transcription factors were implicated in the lipogenesis, inflammation, insulin resistance and fibrosis, underlying the multifactorial effect of oleuropein on NAFLD. Genetic variations in obesity and diabetes Varma et al., Biotechnol. J. 2010, 5, 942,949 Obesity is a state of metabolic deregulation and a leading cause for development of type 2 diabetes, which are complex polygenic diseases. Here, authors from the National Centre of Toxicological Research at the FDA (Jefferson, Arizona, USA) used a data mining approach to evaluate the role of carbohydrate metabolic pathway genes in the development of obesity and type 2 diabetes. Data from public databases were used to map the position of these genes to known quantitative trait loci (QTL) and to find sequence and structural genetic variants such as single nucleotide polymorphisms (SNPs). The results demonstrated that a majority of carbohydrate metabolic pathways genes are associated with QTL for obesity and many for type 2 diabetes. This data mining approach can establish a strategy for interpreting an individual's risk factor for disease development, instead of population attributable risks. [source]

Progressive stroke in pontine infarction

ACTA NEUROLOGICA SCANDINAVICA, Issue 4 2009
V. Saia
Objective,,, The pathogenesis of isolated pontine infarctions is still unclear, being attributed both to small or large vessel disease. The extension of infarcted tissue to the pons surface has been indicated as a possible marker of basilar branch atheromatous disease and some neuroimaging evidence confirms this finding. Methods,,, On the basis of Kim's et al., study, we performed a revision of the literature addressing this topic. Results,,, Several authors confirm an association between basilar artery branch disease and isolated pontine infarction; moreover, the enlargement of pontine lesion seems to be associated with neurological worsening. We therefore performed a brief analysis of possible mechanisms of progression. Conclusions,,, Prospective studies could be useful to evaluate predictors of neurological worsening in pontine stroke. Improvement of neuroimaging techniques is needed for a deeper comprehension of the etiopathogenesis of isolated pontine infarction. [source]