• 제목/요약/키워드: Activation Functions

검색결과 666건 처리시간 0.03초

Anti-Inflammatory Role of TAM Family of Receptor Tyrosine Kinases Via Modulating Macrophage Function

  • Lee, Chang-Hee;Chun, Taehoon
    • Molecules and Cells
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    • 제42권1호
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    • pp.1-7
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    • 2019
  • Macrophage is an important innate immune cell that not only initiates inflammatory responses, but also functions in tissue repair and anti-inflammatory responses. Regulating macrophage activity is thus critical to maintain immune homeostasis. Tyro3, Axl, and Mer are integral membrane proteins that constitute TAM family of receptor tyrosine kinases (RTKs). Growing evidence indicates that TAM family receptors play an important role in anti-inflammatory responses through modulating the function of macrophages. First, macrophages can recognize apoptotic bodies through interaction between TAM family receptors expressed on macrophages and their ligands attached to apoptotic bodies. Without TAM signaling, macrophages cannot clear up apoptotic cells, leading to broad inflammation due to over-activation of immune cells. Second, TAM signaling can prevent chronic activation of macrophages by attenuating inflammatory pathways through particular pattern recognition receptors and cytokine receptors. Third, TAM signaling can induce autophagy which is an important mechanism to inhibit NLRP3 inflammasome activation in macrophages. Fourth, TAM signaling can inhibit polarization of M1 macrophages. In this review, we will focus on mechanisms involved in how TAM family of RTKs can modulate function of macrophage associated with anti-inflammatory responses described above. We will also discuss several human diseases related to TAM signaling and potential therapeutic strategies of targeting TAM signaling.

MRI 이미지 기반의 알츠하이머 치매분류 알고리즘 (Algorithm for Classifiation of Alzheimer's Dementia based on MRI Image)

  • 이재경;서진범;조영복
    • 한국정보통신학회:학술대회논문집
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    • 한국정보통신학회 2021년도 추계학술대회
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    • pp.97-99
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    • 2021
  • 최근 고령화 사회가 지속됨에 따라, 치매(Dementia)에 대한 관심이 높아지고 있다. 그 중에서 알츠하이머병(Alzheimer's disease)는 전체 치매 환자의 50~60%로 가장 많은 비율을 차지하는 퇴행성 뇌질환으로, 현재 의료계에선 알츠하이머병에 대한 명확한 예방법 및 치료법에 대해 내놓지 못하고 있으며, 치매 발병 전 조기 치료 및 조기 예방법에 대한 중요성이 강조되고 있다. 본 논문에서는 정상인과 알츠하이머병에 걸린 환자의 MRI 데이터셋을 활용하여 컨볼루션 신경망을 중심으로 여러 가지 활성화 함수를 접목시켜, 가장 효율적인 활성화 함수를 찾고자 한다. 또한 알츠하이머 치매분류 모델링을 통해 향후 의료분야에 적합한 치매 구분 모델링으로 활용하고자 한다.

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APPROXIMATION ORDER TO A FUNCTION IN Lp SPACE BY GENERALIZED TRANSLATION NETWORKS

  • HAHM, NAHMWOO;HONG, BUM IL
    • 호남수학학술지
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    • 제28권1호
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    • pp.125-133
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    • 2006
  • We investigate the approximation order to a function in $L_p$[-1, 1] for $0{\leq}p<{\infty}$ by generalized translation networks. In most papers related to neural network approximation, sigmoidal functions are adapted as an activation function. In our research, we choose an infinitely many times continuously differentiable function as an activation function. Using the integral modulus of continuity and the divided difference formula, we get the approximation order to a function in $L_p$[-1, 1].

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The Biofeedback Scapular Stabilization Exercise in Stroke Patients Effect of Muscle Activity and Function of the Upper Extremity

  • Yang, Dae-Jung;Uhm, Yo-Han;Kim, Je-Ho
    • The Journal of Korean Physical Therapy
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    • 제27권5호
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    • pp.325-331
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    • 2015
  • Purpose: This study attempts to understand the effect of stabilization exercise of biofeedback scapular on muscle activity and functional evaluation of the upper extremity in stroke patients. Methods: Patients were divided into two groups; a biofeedback scapular stabilization exercise group comprised of 8 patients and a task-oriented training group including another 8 patients, and 30-minute exercise was performed 5 times a week for 8 weeks. Electromyogram was used to measure muscular activity of lower trapezius, deltoid middle, and serratus anterior. Fugl-Meyer Assessment and Manual Function Test were used to evaluate functions of the muscles mentioned. Results: Significant difference was observed in the comparison group before and after exercise in muscular activity of lower trapezius, deltoid middle, and serratus anterior, Fugl-Meyer Assessment, and Manual Function Test. Conclusion: Therefore, we could see that biofeedback scapular stabilization exercise is more effective than task-oriented training in facilitating muscle activation and functional capacity of upper limb.

Formation Kinetic Study of Thermal Products of Tocopherols

  • Chung, Hae-Young
    • Preventive Nutrition and Food Science
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    • 제12권3호
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    • pp.131-134
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    • 2007
  • The kinetic analyses for thermal products of alpha-, gamma- and delta-tocopherols during heating as functions of temperature and time were studied. Alpha-, gamma- and delta-tocopherols dissolved in glycerol were heated at $100{\sim}200^{\circ}C$ for $5{\sim}60$ min. The thermal products were separated by hexane extraction and analyzed by HPLC using a reversed phase ${\mu}-Bondapak$ $C_{18}-column$ with two kinds of elution solvents in a gradient mode. The formation kinetics of thermal products of tocopherols followed a first-order kinetic model. The formation rate of thermal products of tocopherols was dependent on heating temperatures and heating times. The activation energy and enthalpy for the thermal products of ${\gamma}-and$ ${\delta}-tocopherols$ were higher than those for ${\alpha}-tocopherol$ as in the case of the oxidative degradation kinetics of tocopherol. The magnitude order of the activation energy was ${\gamma}->{\delta}->{\alpha}-tocopherol$.

The Role of Nrf2 in Cellular Innate Immune Response to Inflammatory Injury

  • Kim, Ji-Young;Surh, Young-Joon
    • Toxicological Research
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    • 제25권4호
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    • pp.159-173
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    • 2009
  • Nuclear factor erythroid derived 2-related factor-2 (Nrf2) is a master transcription regulator of antioxidant and cytoprotective proteins that mediate cellular defense against oxidative and inflammatory stresses. Disruption of cellular stress response by Nrf2 deficiency causes enhanced susceptibility to infection and related inflammatory diseases as a consequence of exacerbated immune-mediated hypersensitivity and autoimmunity. The cellular defense capacity potentiated by Nrf2 activation appears to balance the population of $CD4^+$ and $CD8^+$ of lymph node cells for proper innate immune responses. Nrf2 can negatively regulate the activation of pro-inflammatory signaling molecules such as p38 MAPK, NF-${\kappa}B$, and AP-1. Nrf2 subsequently functions to inhibit the production of pro-inflammatory mediators including cytokines, chemokines, cell adhesion molecules, matrix metalloproteinases, COX-2 and iNOS. Although not clearly elucidated, the antioxidative function of genes targeted by Nrf2 may cooperatively regulate the innate immune response and also repress the expression of pro-inflammatory mediators.

EXISTENCE AND GLOBAL EXPONENTIAL STABILITY OF A PERIODIC SOLUTION TO DISCRETE-TIME COHEN-GROSSBERG BAM NEURAL NETWORKS WITH DELAYS

  • Zhang, Zhengqiu;Wang, Liping
    • 대한수학회지
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    • 제48권4호
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    • pp.727-747
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    • 2011
  • By employing coincidence degree theory and using Halanay-type inequality technique, a sufficient condition is given to guarantee the existence and global exponential stability of periodic solutions for the two-dimensional discrete-time Cohen-Grossberg BAM neural networks. Compared with the results in existing papers, in our result on the existence of periodic solution, the boundedness conditions on the activation are replaced with global Lipschitz conditions. In our result on the existence and global exponential stability of periodic solution, the assumptions in existing papers that the value of activation functions at zero is zero are removed.

경쟁적 퍼지 다항식 뉴론을 가진 자기 구성 네트워크의 설계 (Design of Self-Organizing Networks with Competitive Fuzzy Polynomial Neuron)

  • 박호성;오성권;김현기
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2000년도 추계학술대회 논문집 학회본부 D
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    • pp.800-802
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    • 2000
  • In this paper, we propose the Self-Organizing Networks(SON) based on competitive Fuzzy Polynomial Neuron(FPN) for the optimal design of nonlinear process system. The SON architectures consist of layers with activation nodes based on fuzzy inference rules. Here each activation node is presented as FPN which includes either the simplified or regression Polynomial fuzzy inference rules. The proposed SON is a network resulting from the fusion of the Polynomial Neural Networks(PNN) and a fuzzy inference system. The conclusion part of the rules, especially the regression polynomial uses several types of high-order polynomials such as liner, quadratic and modified quadratic. As the premise part of the rules, both triangular and Gaussian-like membership functions are studied. Chaotic time series data used to evaluate the performance of our proposed model.

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Maternal effect genes: Findings and effects on mouse embryo development

  • Kim, Kyeoung-Hwa;Lee, Kyung-Ah
    • Clinical and Experimental Reproductive Medicine
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    • 제41권2호
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    • pp.47-61
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    • 2014
  • Stored maternal factors in oocytes regulate oocyte differentiation into embryos during early embryonic development. Before zygotic gene activation (ZGA), these early embryos are mainly dependent on maternal factors for survival, such as macromolecules and subcellular organelles in oocytes. The genes encoding these essential maternal products are referred to as maternal effect genes (MEGs). MEGs accumulate maternal factors during oogenesis and enable ZGA, progression of early embryo development, and the initial establishment of embryonic cell lineages. Disruption of MEGs results in defective embryogenesis. Despite their important functions, only a few mammalian MEGs have been identified. In this review we summarize the roles of known MEGs in mouse fertility, with a particular emphasis on oocytes and early embryonic development. An increased knowledge of the working mechanism of MEGs could ultimately provide a means to regulate oocyte maturation and subsequent early embryonic development.

The Effect of Hydrogen Plasma on Surface Roughness and Activation in SOI Wafer Fabrication

  • Park, Woo-Beom;Kang, Ho-Cheol;Sung, Man-Young
    • Transactions on Electrical and Electronic Materials
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    • 제1권1호
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    • pp.6-11
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    • 2000
  • The hydrogen plasma treatment of silicon wafers in the reactive ion-etching mode was studied for the application to silicon-on-insulator wafers which were prepared using the wafer bonding technique. The chemical reactions of hydrogen plasma with surface were used for both surface activation and removal of surface contaminants. As a result of exposure of silicon wafers to the plasma, an active oxide layer was found on the surface. This layer was rendered hydrophilic. The surface roughness and morphology were examined as functions of the plasma exposing time and power. In addition, the surface became smoother with the shorter plasma exposing time and power. The value of initial surface energy estimated by the crack propagation method was 506 mJ/㎡, which was up to about three times higher as compared to the case of conventional direct using the wet RCA cleaning method.

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