• International Journal of Concrete Structures and Materials
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• 제6권2호
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• pp.79-85
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• 2012

This paper presents the differences in growth of time-dependent strain values in reinforced cement concrete (RCC) and pre-stressed concrete (PSC) flexural members through experiment. It was observed that at any particular age, the time-dependent strain values were less in RCC beams than in PSC beams of identical size and grade of concrete. Variables considered in the study were percentage area of reinforcement, span of members for RCC beams and eccentricity of applied pre-stress force for PSC beams. In RCC beams the time-dependent strain values increases with reduction in percentage area of reinforcement and in PSC beams eccentricity directly influences the growth of time-dependent strain. With increase in age, a non-uniform strain develops across the depth of beams which influence the growth of concave curvature in RCC beams and convex curvature in PSC beams. The experimentally obtained strain values were compared with predicted strain values of similar size and grade of plane concrete (PC) beam using ACI 318 Model Code and found more than RCC beams but less than PSC beams.

• Asian-Australasian Journal of Animal Sciences
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• 제7권1호
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• pp.119-124
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• 1994

Experiments were performed to determine age-associated changes in ornithine decarboxylase (ODC) gene and Ha-ras cellular oncogene expression in tissues of female rats. In the kidney, ODC mRNA levels did not show age-associated changes, while ODC enzyme activities were decreased with advancing age from 3 to 10 months. These results suggest that post-transcriptional mechanism (s) are involved in the age-dependent decrease in renal ODC enzyme activity. In addition, we found no correlation between testosterone-induced renal ODC expression and DNA methylation pattern. Ha-ras mRNA levels in brain decreased as animals aged from 3 to 6 months, while renal Ha-ras mRNA levels were not influenced by age. Results demonstrate the age-dependent expression of Ha-ras in a tissue-specific manner.

• The Korean Journal of Physiology and Pharmacology
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• 제22권2호
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• pp.193-201
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• 2018

Connective tissue growth factor (CTGF) is a novel fibrotic mediator, which is considered to mediate fibrosis through extracellular matrix (ECM) synthesis in diabetic cardiovascular complications. Statins have significant immunomodulatory effects and reduce vascular injury. We therefore examined whether fluvastatin has anti-fibrotic effects in vascular smooth muscle cells (VSMCs) and elucidated its putative transduction signals. We show that advanced glycation end products (AGEs) stimulated CTGF mRNA and protein expression in a time-dependent manner. AGE-induced CTGF expression was mediated via ERK1/2, JNK, and Egr-1 pathways, but not p38; consequently, cell proliferation and migration and ECM accumulation were regulated by CTGF signaling pathway. AGE-stimulated VSMC proliferation, migration, and ECM accumulation were blocked by fluvastatin. However, the inhibitory effect of fluvastatin was restored by administration of CTGF recombinant protein. AGE-induced VSMC proliferation was dependent on cell cycle arrest, thereby increasing G1/G0 phase. Fluvastatin repressed cell cycle regulatory genes cyclin D1 and Cdk4 and augmented cyclin-dependent kinase inhibitors p27 and p21 in AGE-induced VSMCs. Taken together, fluvastatin suppressed AGE-induced VSMC proliferation, migration, and ECM accumulation by targeting CTGF signaling mechanism. These findings might be evidence for CTGF as a potential therapeutic target in diabetic vasculature complication.

• 수면정신생리
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• 제15권2호
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• pp.77-81
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• 2008

배 경：수면은 크게 비렘수면(non-REM sleep)과 렘수면(REM sleep)으로 나눌 수 있으며 렘수면 중에는 근력의 소실로 상기도 확장 근육의 긴장도가 저하되고 상기도 저항은 증가하여 무호흡증이 발생하거나 악화될 수 있다. 폐쇄성 수면무호흡증 자체에 대해서는 이미 많은 부분이 알려져 왔으나 렘수면에만 특이적으로 나타나는 렘수면 의존성 폐쇄성 수면무호흡증(REM-dependent OSA)은 그 중요성이 간과되어 왔다. 본 연구에서는 REM-dependent OSA 환자들의 임상 특성과 수면 변인을 살펴보고자 하였다. 방 법：2004년 3월부터 2007년 2월까지 시립은평병원 수면검사실을 방문하여 경도나 중등도의 폐쇄성 수면무호흡증으로 진단받은(5$53.7{\pm}16.7$, 남성：42명)를 대상으로 하였다. REM-dependent OSA(AHIREM/AHINREM${\ge}$2) 환자군과 No REM-dependent OSA(AHIREM/AHINREM<2) 환자군의 임상적 특성과 수면 관련변인을 비교하였다. 통계분석은 Statistica 6.0 프로그램을 사용하였으며, 유의수준은 p<0.05로 하였다. 결 과：대상군 56명 중 21명(37.5%)가 REM-dependent OSA으로 진단되었다. 두 군사이의 연령, 성별, BMI (Body Mass Index)는 유의한 차이를 보이지 않았다. 성별, 연령, BMI, PLMI를 통제한 후, 수면 관련 변인 중 REMdependent OSA 환자군에서 AHI(Apnea Hypopnea Index), ODI(Oxygen Desaturation Index)가 유의하게 낮았다($12.1{\pm}6.4$ vs. $35.9{\pm}24.7$, p=0.010; $6.0{\pm}5.3$ vs. $24.0{\pm}20.4$, p=0.006, respectively, ANCOVA). REMdependent OSA 환자군에서유의하게 높은 2단계 수면이 관찰되었다($58.5{\pm}10.3$ vs. $51.2{\pm}13.2$, p=0.031, ANCOVA). REM-dependent OSA군으로 대상군을 한정하였을 때, 성별, 연령, BMI, PLMI를 통제한 후, 렘수면중 AHI는 전체 수면중 AHI, 비렘수면중 AHI, ODI와 유의미한 양의 상관관계를 보였다(r=0.720, p=0.001；r=750, p=0.001；r=0.749, p=0.001, partial correlation, respectively). 결 론 ：본 연구에서는 폐쇄성 수면무호흡증 환자 중 37.5%를 REM-dependent OSA 환자로 진단할 수 있었다. REM-dependent OSA 환자는 더 경한 정도의 수면 무호흡증을 보이는 경향이 있었으며, 2단계 수면 분율의 증가 같은 수면구조의 변화와 연관되어 있었다. 또한, 렘수면중의 무호흡은 산소포화도 저하와 연관되어 있었다.

• Journal of applied mathematics & informatics
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• 제14권1_2호
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• pp.157-172
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• 2004

An age-dependent branching process where disasters occur as a renewal process leading to annihilation or survival of all the cells, is considered. For such a process, the total mean sojourn time of all the cells in the system is analysed using the regeneration point technique. The mean number of cells which die in time t and its asymptotic behaviour are discussed. When the disasters arrival as a Poisson process and the lifetime of the cells follows exponential distribution, elegant inter- relationships are found among the means of (i) the total number of cells which die in time t (ii) the total sojourn time of all cells in the system upto time t and (iii) the number of living cells at time t. Some of the existing results are deduced as special cases for related processes.

• International Journal of Reliability and Applications
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• 제18권1호
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• pp.9-20
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• 2017

In this paper, we consider a renewable repair-replacement warranty strategy with age-dependent minimal repair service and propose an optimal maintenance model during post-warranty period. Such model implements the repair time limit under warranty and follows with a certain form of system maintenance strategy when the warranty expires. The expected cost rate is investigated per unit time during the life period of the system as for the standard for optimality. Based on the cost design defined for each failure of the system, the expected cost rate is derived during the life period of the system, considering that a renewable minimal repair-replacement warranty strategy with the repair time limit is provided to the customer under warranty. When the warranty is finished, the maintenance of the system is the customer's responsibility. The life period of the system is defined and the expected cost rate is developed from the viewpoint of the customer's perspective. We obtain the optimal maintenance strategy during the maintenance period by minimizing such a cost rate after a warranty expires. Numerical examples using field data are shown to exemplify the application of the methodologies proposed in this paper.

• The Korean Journal of Physiology and Pharmacology
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• 제4권3호
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• pp.197-210
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• 2000

Suppressive role of $Na^+-Ca^{2+}$ exchange in myocardial tension generation was examined in the negative frequency-force relationship (FFR) of electric field stimulated left atria (LA) from postnatal developing rat heart and in the whole-cell clamped adult rat ventricular myocytes with high concentration of intracellular $Ca^{2+}$ buffer (14 mM EGTA). LA twitch amplitudes, which were suppressed by cyclopiazonic acid in a postnatal age-dependent manner, elicited frequency-dependent and postnatal age-dependent enhancements after $Na^+-reduced,\;Ca^{2+}-depleted$ (26 Na-0 Ca) buffer application. These enhancements were blocked by caffeine pretreatment with postnatal age-dependent intensities. In the isolated rat ventricular myocytes, stimulation with the voltage protocol roughly mimicked action potential generated a large inward current which was partially blocked by nifedipine or $Na^+$ current inhibition. 0 Ca application suppressed the inward current by $39{\pm}4%$ while the current was further suppressed after 0 Na-0 Ca application by $53{\pm}3%.$ Caffeine increased this inward current by $44{\pm}3%$ in spite of 14 mM EGTA. Finally, the $Na^+$ current-dependent fraction of the inward current was increased in a stimulation frequency-dependent manner. From these results, it is concluded that the $Ca^{2+}$ exit-mode (forward-mode) $Na^+-Ca^{2+}$ exchange suppresses the LA tension by extruding $Ca^{2+}$ out of the cell right after its release from sarcoplasmic reticulum (SR) in a frequency-dependent manner during contraction, resulting in the negative frequency-force relationship in the rat LA.

• 지역사회간호학회지
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• 제28권3호
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• pp.313-323
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• 2017

Purpose: The purpose of this study is to investigate factors affecting social problem-solving ability of alcohol-dependent patients with a focus on gender differences. Methods: Participants were 250 alcohol-dependent people(men 140, women 110) who were living in B, G and Y cities. Data were collected from January 10 to March 31, 2017 using self-report questionnaires. Abstinence self-efficacy, alcohol insight, unconditional self-acceptance, and social problem-solving ability were investigated. For data analysis, t-test, one-way ANOVA, Pearson correlation coefficients and multiple regression were employed. Results: Factors influencing social problem-solving ability for men were unconditional self-acceptance and age. The explanatory power was 28%. Factors influencing social problem-solving ability for women were unconditional self-acceptance, stress, religiousness, age, occupation and abstinence self-efficacy and the explanatory power was 72%. Unconditional self-acceptance and age were significant variables of social problem-solving ability in both men and women. Stress, occupation, religiousness and abstinence self-efficacy were significantly associated with social problem-solving ability in women but not in men. Conclusion: The results suggest that it is necessary to consider gender characteristics in order to develop effective management programs for social problem-solving ability in alcohol-dependent people.

• The Korean Journal of Physiology and Pharmacology
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• 제27권1호
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• pp.85-94
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• 2023

Ion channels regulate a large number of cellular functions and their functional role in many diseases makes them potential therapeutic targets. Given their diverse distribution across multiple organs, the roles of ion channels, particularly in age-associated transcriptomic changes in specific organs, are yet to be fully revealed. Using RNA-seq data, we investigated the rat transcriptomic profiles of ion channel genes across 11 organs/tissues and 4 developmental stages in both sexes of Fischer 344 rats and identify tissue-specific and age-dependent changes in ion channel gene expression. Organ-enriched ion channel genes were identified. In particular, the brain showed higher tissue-specificity of ion channel genes, including Gabrd, Gabra6, Gabrg2, Grin2a, and Grin2b. Notably, age-dependent changes in ion channel gene expression were prominently observed in the thymus, including in Aqp1, Clcn4, Hvcn1, Itpr1, Kcng2, Kcnj11, Kcnn3, and Trpm2. Our comprehensive study of ion channel gene expression will serve as a primary resource for biological studies of aging-related diseases caused by abnormal ion channel functions.

• Computers and Concrete
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• 제23권2호
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• pp.133-143
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• 2019

The paper presents the experimental investigations into the effect of ground granulated blast furnace slag (GGBFS) on the time-dependent tensile strength of concrete. The splitting and flexural tensile strength of concrete was determined at the ages of 3, 7, 28, 56, 90, 150 and 180 days using the cylindrical and prism specimens respectively for plain and GGBFS concrete. The amount of cement replacement by GGBFS was 0%, 40% and 60% on the weight basis. The maximum curing age was kept as 28 days. The results showed that the splitting and flexural tensile strength of concrete containing GGBFS has been found lower than the plain concrete at all ages and for all mixes. The tensile strength of 40 percent replacement has been found higher than the 60 percent at all ages and for all mixes. The rate of gain of splitting and flexural tensile strength of 40 percent GGBFS concrete is found higher than the plain concrete and 60 percent GGBFS concrete at the ages varying from 28 to 180 days. The experimental results of time-dependent tensile strength of concrete are compared with the available models. New models for the prediction of time-dependent splitting and flexural tensile strength of concrete containing GGBFS are proposed. The present experimental and analytical study will be helpful for the designers to know the time-dependent tensile properties of GGBFS concrete to meet the design requirements of liquid retaining reinforced and pre-stressed concrete structures.