• Title/Summary/Keyword: resistance mechanism

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Resilience and Resistance of Biological Community : Application for Stream Ecosystem Health Assessment (생물 군집의 회복력 및 저항력 : 하천생태계 건전성 평가를 위한 응용성)

  • Ro, Tae-Ho
    • Journal of Environmental Policy
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    • v.1 no.1
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    • pp.91-110
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    • 2002
  • Ecosystem health assessment is an emerging concept regarded as a useful diagnostic tool for evaluating ecosystems. The stability of ecosystem is the main theme in the assessment. Generally, two components - resilience and resistance - are involved in the mechanism of ecosystem stability. In this study, relative degrees of the resistance and the resilience were quantified for most aquatic Insects Inhabiting running waters in Korea. A total of 34 groups were newly categorized based on previous studies, and a conceptual model has been produced. The model was applied for the aquatic insect communities inhabiting different streams and demonstrated that each stream ecosystem possessed different degrees of stability. This study also indicated that it was possible to compare stabilities of different ecosystems using relative degrees of resilience and resistance. Using the conceptual model, suitable conservation and management strategies could be recommended in ecological assessments. The model can be used as a stepping-stone for developing more comprehensive methodology that objectively diagnoses and evaluates the ecosystem stability.

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Effects of Vinorelbine on Cisplatin Resistance Reversal in Human Lung Cancer A549/DDP Cells

  • Zhou, Yu-Ting;Li, Kun;Tian, Hui
    • Asian Pacific Journal of Cancer Prevention
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    • v.14 no.8
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    • pp.4635-4639
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    • 2013
  • Multi-drug resistance (MDR) is an essential aspect of human lung cancer chemotherapy failure. Recent studies have shown that vinorelbine is involved in underlying processes in human tumors, reversing the MDR inseveral types of cancer cells. However, the roles and potential mechanism are not fully clear. In this study, we explored effects of vinorelbine in multi-drug resistance reversal of human lung cancer A549/DDP cells. We found that vinorelbine increased drug sensitivity to cisplatin and intracellular accumulation of rhodamine-123, while decreasing expression of P-glycoprotein (P-gp), multi-drug resistance-associated protein (MRP1) and glutathione-S-transferase ${\pi}$ (GST-${\pi}$) in A549/DDP cells. At the same time, we also established downregulation of p-Akt and decreased transcriptional activation of NF-${\kappa}B$ and twist after vinorelbine treatment. The results indicated that vinorelbine might be used as a potential therapeutic strategy in human lung cancer.

Azole Resistance Caused by Increased Drug Efflux in Candida glabrata Isolated from the Urinary Tract of a Dog with Diabetes Mellitus

  • Kim, Minchul;Lee, Hyekyung;Hwang, Sun-Young;Lee, Inhyung;Jung, Won Hee
    • Mycobiology
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    • v.45 no.4
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    • pp.426-429
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    • 2017
  • A yeast-like organism was isolated from a urine sample of a 6-year-old neutered male miniature poodle dog with urinary tract infection, diabetes ketoacidosis, and acute pancreatitis. We identified the yeast-like organism to be Candida glabrata and found that this fungus was highly resistant to azole antifungal drugs. To understand the mechanism of azole resistance in this isolate, the sequences and expression levels of the genes involved in drug resistance were analyzed. The results of our analysis showed that increased drug efflux, mediated by overexpression of ATP transporter genes CDR1 and PDH1, is the main cause of azole resistance of the C. glabrata isolated here.

Endothelium-derived Relaxing Factors of Small Resistance Arteries in Hypertension

  • Kang, Kyu-Tae
    • Toxicological Research
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    • v.30 no.3
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    • pp.141-148
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    • 2014
  • Endothelium-derived relaxing factors (EDRFs), including nitric oxide (NO), prostacyclin ($PGI_2$), and endothelium-derived hyperpolarizing factor (EDHF), play pivotal roles in regulating vascular tone. Reduced EDRFs cause impaired endothelium-dependent vasorelaxation, or endothelial dysfunction. Impaired endothelium-dependent vasorelaxation in response to acetylcholine (ACh) is consistently observed in conduit vessels in human patients and experimental animal models of hypertension. Because small resistance arteries are known to produce more than one type of EDRF, the mechanism(s) mediating endothelium-dependent vasorelaxation in small resistance arteries may be different from that observed in conduit vessels under hypertensive conditions, where vasorelaxation is mainly dependent on NO. EDHF has been described as one of the principal mediators of endothelium-dependent vasorelaxation in small resistance arteries in normotensive animals. Furthermore, EDHF appears to become the predominant endothelium-dependent vasorelaxation pathway when the endothelial NO synthase (NOS3)/NO pathway is absent, as in NOS3-knockout mice, whereas some studies have shown that the EDHF pathway is dysfunctional in experimental models of hypertension. This article reviews our current knowledge regarding EDRFs in small arteries under normotensive and hypertensive conditions.

Influence of Joint on Retrofitting Effect by Exterior Steel Frames of Existing RC Buildings (외부접합공법의 내진보강효과에 미치는 접합부의 영향)

  • Ahn, Choong Weon;Min, Chan Gi;Noh, Eun Choul;Han, Hong Soo;Kim, Tae Wan
    • Journal of the Earthquake Engineering Society of Korea
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    • v.19 no.4
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    • pp.183-194
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    • 2015
  • In this paper, Nonlinear Static Pushover analysis method(NSP) is proposed which apply to RC buildings reinforced by external retrofit for seismic performance. Based on previous analysis and research, NSP is more developed by connection nonlinearity according to shear resistance mechanism such as dowel and adhesive resistance as major shear resistance elements. According to the proposed method, structural analysis for example buildings was carried out to evaluate seismic performance of buildings. And, it was confirmed that depending on shear strain and characteristics of joint resistant of external retrofitting are different from internal retrofitting. Furthermore, the strength reduction coefficient of the anchor needs to be considered at the joint design.

The Effect of Individual Features on the Innovative Resistance in FinTech Service (핀테크 서비스에서 개인적 특성이 혁신저항요인에 미치는 영향)

  • Son, Dal-Ho
    • The Journal of Information Systems
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    • v.28 no.3
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    • pp.123-139
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    • 2019
  • Purpose With the development of information and communication technologies. fintech industry is rapidly growing as a major financial service. Previous research literatures mainly focused on overall characteristics and technical aspects of fintech including security issues. Therefore, this study investigated the effect of individual features influencing the resistance of adopting a fintech service. Moreover, this paper included the guidelines in practical development of fintech mechanism. Design/methodology/approach For research purposes, this study developed research hypotheses in order to empirically examine the effect of the factors that might have a significant effect on the resistance of the wearable device. The empirical research was based on a survey which carried through 359 participants. Research hypotheses were evaluated via SPSS Statistics 21.0 and AMOS 19 statistical package program. Findings Results showed that self-efficacy and individual innovation had a significant effect on the technostress and switching cost. In addition, technostress, security and switching cost had a significant effect on the resistance of adopting a fintech service. However, more factors are needed to including in research model to generalize these results.

The Finite Element Analysis and Experiment of Flexible Media Separation Mechanism (유연매체 분리기구의 유한요소해석과 실험)

  • Yoon, You-Hoon;Baek, Yoon-Kil;Yoon, Joon-Hyun
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.05a
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    • pp.322-325
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    • 2005
  • The separation mechanism is installed to separate a note one by one from the stacked notes and the overlap type, one of separation mechanism, has been used a lot in financial equipments like ATM. This paper has compared and estimated analysis results using finite element method with experimental results over various parameters such as conditions of note, overlap value, roller shapes, which affect the friction force (resistance) exerting on notes between rollers. Consequently, the effect of various parameters on the performance of overlap type separation mechanism can be known and optimal shape and overlap value can be obtained.

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A Study on Voltage Collapse Mechanism in Electric Power Systems (전력계통에서의 전압붕괴 매카니즘에 관한 연구)

  • Kim, Do-Hyung;Ryu, Heon-Su;Moon, Young-Hyun;Choi, Byoung-Kon;Park, Jung-Do
    • Proceedings of the KIEE Conference
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    • 2001.07a
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    • pp.171-174
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    • 2001
  • In this paper, an EMM(Equivalent Mechanical Model) is developed to explain the voltage collapse mechanism by reflecting the effects of reactive powers. The proposed EMM exactly represents the voltage instability mechanism described by the system equations. By the use of the EMM model the voltage collapse mechanism has been illustrated by showing the exactness of the results. It is also discussed a system transform in technique to eliminate the resistance component of the Thevenin equivalent impedance for practical applications.

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A Study on Voltage Collapse Mechanism using Equivalent Mechanical Model

  • Kim, Do-Hyung;Ryu, Heon-Su;Lee, Jong-Gi;Moon, Young-Hyun
    • KIEE International Transactions on Power Engineering
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    • v.12A no.1
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    • pp.6-14
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    • 2002
  • In this paper, an EMM(Equivalent Mechanical Model) Is developed to explain the voltage collapse mechanism by reflecting the effects of reactive powers. The proposed EMM exactly represents the voltage instability mechanism described by the system equations. By the use of the EMM model, the voltage collapse mechanism has been illustrated by showing the exactness of the results. The stable region has been investigated with a reactive-power-controlled two-bus system, which shows that special alerts are required when the system operates with leading power factor. It is also discussed a system transform technique to eliminate the resistance component of the Thevenin equivalent impedance for practical applications. Finally, the results adopting the proposed method fur sample systems which were transformed are listed

Experimental study on stripping mechanism of tension controlled bolts (TC볼트의 스트리핑 메카니즘에 대한 실험적 연구)

  • 신근하
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.9 no.1
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    • pp.111-118
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    • 2000
  • Over tightening experiments of the tension-controlled bolts are carried out and the stripping mechanism is reviewed base on the observed results. There are two modes of bolt failure due to the over tightening : one the fracture of the bolt the other the thread stripping Bifurcation between these two modes is rather delicate but it seems being related with the elastic flexibility of the bolt which depends upon the unused thread length. The fracture mode occurs in the bolts with good flexibility while the latter with bad one. According to the ISO Standard some meter coarse threads like M20 and M22 have the same pitch which causes bigger fastener to less resistance in shear and bending compared with the smaller one. however since UNC thread system adapts different pitch for different nominal diameter unified coarse threads show better stripping resistance than their corresponding meter threads.

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