• Title/Summary/Keyword: Activation Functions

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A Simulation of the Myocardium Activation Process using the Discrete Event Cell Space Model (DEVCS 모델을 사용한 심근 활성화과정의 시뮬레이션)

  • Kim Gwang-Nyeon;Jung Dong-Keun;Kim Gi-Ryon;Choi Byeong-Cheol;Lee Jung-Tae;Jeon Gye-Rok
    • Journal of the Korea Society for Simulation
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    • v.13 no.4
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    • pp.1-16
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    • 2004
  • The modelling and simulation of the activation process for the heart system is meaningful to understand special excitatory and conductive system in the heart and to study cardiac functions because the heart activation conducts through this system. This thesis proposes two dimensional cellular automaton(CA) model for the activation process of the myocardium and conducted simulation by means of discrete time and discrete event algorithm. In the model, cells are classified into anatomically similar characteristic parts of the heart and each of cells has a set of cells with preassigned properties. Each cell in this model has state variables to represent the state of the cell and has some state transition rules to change values of state variables executed by state transition function. The state transition rule is simple as follows. First, the myocardium cell at rest stay in passive state. Second, if any one of neighborhood cell in the myocardium cell is active state then the state is change from passive to active state. Third, if cell's state is an active then automatically go to the refractory state after activation phase. Four, if cell's state is refractory then automatically go to the passive state after refractory phase. These state transition is processed repeatedly in all cells through the termination of simulation.

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JNK activation induced by ribotoxic stress is initiated from 80S monosomes but not polysomes

  • Kim, Tae-Sung;Kim, Hag Dong;Park, Yong Jun;Kong, EunBin;Yang, Hee Woong;Jung, Youjin;Kim, YongJoong;Kim, Joon
    • BMB Reports
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    • v.52 no.8
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    • pp.502-507
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    • 2019
  • Translation is a costly, but inevitable, cell maintenance process. To reduce unnecessary ATP consumption in cells, a fine-tuning mechanism is needed for both ribosome biogenesis and translation. Previous studies have suggested that the ribosome functions as a hub for many cellular signals such as ribotoxic stress response, mammalian target of rapamycin (mTOR), and ribosomal S6 kinase (RSK) signaling. Therefore, we investigated the relationship between ribosomes and mitogen-activated protein kinase (MAPK) activation under ribotoxic stress conditions and found that the activation of c-Jun N-terminal kinases (JNKs) was suppressed by ribosomal protein knockdown but that of p38 was not. In addition, we found that JNK activation is driven by the association of inactive JNK in the 80S monosomes rather than the polysomes. Overall, these data suggest that the activation of JNKs by ribotoxic stress is attributable to 80S monosomes. These 80S monosomes are active ribosomes that are ready to initiate protein translation, rather than polysomes that are already acting ribosomes involved in translation elongation.

Difference in Lung Functions according to Genetic Polymorphism of Tobacco Substance Metabolizing Enzymes of Korean Smokers (한국인 흡연자들의 담배 물질 대사 효소의 유전자 다형성에 따른 폐기능 차이)

  • Kang, Yun-Jung
    • Journal of Convergence for Information Technology
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    • v.10 no.5
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    • pp.134-142
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    • 2020
  • This study aimed to determine whether there was a difference in lung functions of smokers according to the presence of carcinogenic genetic-metabolizing enzymes by comparing the results of lung functions and the presence of genetic metabolizing enzymes that metabolize tobacco substances. To achieve this, 31 smokers without no illness and no psychiatric history were selected (28 males and 3 females); they were aged 20 to 27 years and were physically and mentally healthy students attending K University. Their lung functions were measured, and gene polymorphisms of cytochrome P-450 1A1 (CYP1A1) related to metabolic activation of tobacco components and gene polymorphism of tumor protein 53 (TP53) related to lung cancer were analyzed. As a result, the mean values of lung function of TT and Arg / Arg without genetic mutations were the highest, and ANOVA analysis of CYP1A1 and lung functions showed that the P-value of FVC was 0.049, which was different between groups. In other words, there is no high mutation in Cytochrome P-450 1A1 (CYP1A1) gene, which is associated with the metabolic activation of tobacco components. In other words, In the absence of the mutant Cytochrome P-450 1A1 (CYP1A1) gene, which is associated with the metabolic activation of tobacco components, the value of FVC was high.

An investigation of excretion of calcium from female mice ingested with boron by using neutron activation analysis

  • Sun, Gwang Min;Lee, Jaegi;Uhm, Young Rang;Baek, Hani
    • Nuclear Engineering and Technology
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    • v.52 no.11
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    • pp.2581-2584
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    • 2020
  • Boron has been considered to play a nutritionally important role in humans and animals, but its biochemical functions are not clearly understood. Though there are signs that boron affects the mineral and hormone metabolisms, there is no comprehensive epidemiological evidence establishing a relationship between a boron intake and osteoporosis due to the excretion of calcium in the bones. In this study, we investigated the influence of boron intake on the calcium excretion of old female mice in the menopause. The concentrations of calcium in backbone, thigh bone, blood, kidney, liver, and spleen were investigated by using instrumental neutron activation analysis.

Effect of thymus extract on the activation of cytotoxic and accessory functions of tumor-associated macrophages

  • Shrivastava, Pratima;Singh, Sukh Mahendra;Singh, Nisha
    • Advances in Traditional Medicine
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    • v.4 no.1
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    • pp.9-17
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    • 2004
  • The present investigation was under taken to study whether the tumor-associated macrophages (TAM) of Daltons lymphoma (DL), a spontaneous transplantable murine T cell lymphoma can be activated to tumoricidal state by crude thymus extract. Intraperitoneal administration of thymus extract to DL-bearing mice resulted in activation of TAM with an enhanced IL-1, TNF and antigen presenting ability. It was found that treatment with thymus extract could also enhance the phagocytic and cytotoxic activity of TAM. However, only a marginal increase in arginase activity was observed. Till date to the best of our knowledge the effect of crude thymus extract on the activation of tumor associated macrophages has not been investigated, this study provides a new piece of information in the area of thymus therapy.

Improvement of learning method in pattern classification (패턴분류에서 학습방법 개선)

  • Kim, Myung-Chan;Choi, Chong-Ho
    • Journal of Institute of Control, Robotics and Systems
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    • v.3 no.6
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    • pp.594-601
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    • 1997
  • A new algorithm is proposed for training the multilayer perceptrion(MLP) in pattern classification problems to accelerate the learning speed. It is shown that the sigmoid activation function of the output node can have deterimental effect on the performance of learning. To overcome this detrimental effect and to use the information fully in supervised learning, an objective function for binary modes is proposed. This objective function is composed with two new output activation functions which are selectively used depending on desired values of training patterns. The effect of the objective function is analyzed and a training algorithm is proposed based on this. Its performance is tested in several examples. Simulation results show that the performance of the proposed method is better than that of the conventional error back propagation (EBP) method.

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A Fundamental Study on the Effect of Activation Function in Predicting Carbonation Progress Using Deep Learning Algorithm (딥러닝 알고리즘 기반 탄산화 진행 예측에서 활성화 함수 적용에 관한 기초적 연구)

  • Jung, Do-Hyun;Lee, Han-Seung
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2019.11a
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    • pp.60-61
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    • 2019
  • Concrete carbonation is one of the factors that reduce the durability of concrete. In modern times, due to industrialization, the carbon dioxide concentration in the atmosphere is increasing, and the impact of carbonation is increasing. So, it is important to understand the carbonation resistance according to the concrete compounding to secure the concrete durability life. In this study, we want to predict the concrete carbonation velocity coefficient, which is an indicator of the carbonation resistance of concrete, through the deep learning algorithm, and to find the activation function suitable for the prediction of carbonation rate coefficient as a process to determine the learning accuracy through the deep learning algorithm. In the scope of this study, using the ReLU function showed better accuracy than using other activation functions.

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Hydrogen Peroxide Activates ERK in Cultured Feline Ileal Smooth Muscle Cells

  • Song, Hyun-Ju;Lee, Tai-Sang;Jeong, Ji-Hoon;Park, Joon-Hong;Choi, Tae-Sik;Lee, Doo-Won;Sohn, Uy-Dong
    • Proceedings of the PSK Conference
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    • 2002.10a
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    • pp.242.1-242.1
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    • 2002
  • H$_2$O$_2$ has been shown to act as a signaling molecule involved in many cellular functions such as oxidant-induced stress, apoptosis, proliferation. In this study, we investigated the action mechanisms of H$_2$O$_2$ on activation of Extracellular Signal-Regulated Protein Kinase(ERK) in cultured feline ileal smooth muscle cells(ISMC). Western blot analysis done with phospho-specific MAP kinases antibodies demonstrated that potent activation of ERK and moderate activation of SAPK/JNK occurred within 30 min of H$_2$O$_2$ treatment. (omitted)

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Study of nonlinear hysteretic modelling and performance evaluation for piezoelectric actuators based on activation functions

  • Xingyang Xie;Yuguo Cui;Yang Yu
    • Smart Structures and Systems
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    • v.33 no.2
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    • pp.133-143
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    • 2024
  • Piezoelectric (PZT) actuators have been widely used in precision positioning fields for their excellent displacement resolution. However, due to the inherent characteristics of piezoelectric actuators, hysteresis has been proven to greatly reduce positioning performance. In this paper, five mathematical hysteretic models based on activation function are proposed to characterize the nonlinear hysteresis characteristics of piezoelectric actuators. Then the performance of the proposed models is verified by particle swarm optimization (PSO) algorithm and the experiment data. Thirdly, the fitting performance of the proposed models is compared with the classical Bouc-Wen model. Finally, the performance of the five proposed models in modelling hysteresis nonlinearity of piezoelectric drivers is compared, in terms of RMSE, MAPE, SAPE and operation efficiency, and relevant suggestions are given.

Sternocleidomastoid and Posterior Cervical Muscle Coordination in Response to Symmetrical and Asymmetrical Jaw Functions in Normal Adults

  • Im, Yeong-Gwan;Kim, Jae-Hyung;Kim, Byung-Gook
    • Journal of Oral Medicine and Pain
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    • v.40 no.3
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    • pp.115-123
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    • 2015
  • Purpose: The aim of this study was to elucidate the coordination patterns of the sternocleidomastoid and posterior cervical muscles in response to symmetrical and asymmetrical jaw functions in normal adults. Methods: Twenty-seven healthy volunteers (8 females, 19 males; mean age, $30.4{\pm}2.5$ years) participated in this study. Surface electromyography (EMG) was used to record activities in the masseter, suprahyoid, sternocleidomastoid, and posterior cervical muscles at rest and during maximum tooth clenching, biting of a cotton roll with the anterior teeth, unilateral biting of a cotton roll with the posterior teeth, bilateral biting of cotton rolls with the posterior teeth, and jaw opening while seated. Normalized amplitude, activity indices, and asymmetry indices were compared between the muscles and the jaw tasks. Results: During symmetrical jaw functions (e.g., tooth clenching, biting with the anterior teeth, bilateral biting with the posterior teeth, jaw opening), the sternocleidomastoid and posterior cervical muscles showed elevated EMG amplitudes compared with the resting condition. The co-activation pattern of the sternocleidomastoid muscle was more pronounced than those of the posterior cervical muscles during these tasks. During asymmetrical jaw functions (e.g., unilateral biting with the posterior teeth), the ipsilateral sternocleidomastoid and masseter muscles showed higher contraction activity than did the contralateral muscles, but the contralateral posterior cervical muscles were more active than the ipsilateral muscles. Conclusions: The sternocleidomastoid and posterior cervical muscles were shown to be co-activated and coordinated anteroposteriorly or bilaterally according to symmetrical or asymmetrical jaw function. These results suggest an integrated neural control mechanism for the jaw and neck muscles, and provide further evidence supporting the intimate functional coupling between the trigeminal and cervical neuromuscular systems.