• 제목/요약/키워드: memory effect

검색결과 1,631건 처리시간 0.03초

Ethanol Extract of Soybean Ameliorates Scopolamine-Induced Memory Impairment in Mice

  • Yoo, Dae-Hyoung;Woo, Jae-Yeon;Kim, Dong-Hyun
    • Natural Product Sciences
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    • 제19권4호
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    • pp.324-328
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    • 2013
  • Soy (Glycine max, family Leguminosae) contains isoflavones and saponins as main constituents. In our preliminary study, soybean ethanol extract (SE) ameliorated scopolamine-induced memory impairment in mice in the passive avoidance task. Therefore, to confirm its ameliorating effect for memory impairments, we measured its effect in scopolamine-induced memory-impaired mice in Morris water maze task. SE significantly prevented scopolamine-induced memory impairment in the Morris water maze task. SE also increased the swimming time within quadrant section of the platform on the day after the final training session test. SE protected the reduction of brain-derived neurotrophic factor (BDNF) expression and cAMP response element-binding protein (CREB) phosphorylation in the hippocampi of scopolamine-treated mice. However, SE did not inhibit acetylcholinesterase. To understand the possible role of soysaponins in memory impairments, we prepared soyasaponins-rich (butanol) fraction of soybean (SRF) and investigated its protective effect against in the passive avoidance and Morris water maze tasks. SRF ameliorated scopolamine-induced memory impairment in mice. The memory impairment-ameliorating effect of SRF was more effective than that of SE. Based on these findings, soybean may improve memory impairment by regulating CREB phosphorylation and BDNF expression.

전력증폭기의 비선형 특성과 Memory Effect를 보상하기 위한 Look-up Table 방식의 Digital Pre-distorter (Look-up Table type Digital Pre-distorter for Linearization Power Amplifier with Non-linearity and Memory Effect)

  • 최홍민;김왕래;유재우;안광은
    • 한국정보통신설비학회:학술대회논문집
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    • 한국정보통신설비학회 2008년도 정보통신설비 학술대회
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    • pp.218-222
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    • 2008
  • RF power amplifier requires linearization in order to reduce adjacent channel interference. And most of the existing linearization algorithms assume that a PA has memory-less nonlinearity. But for the wider bandwidth signal, the memory effect of PA cannot be ignored. This paper investigates digital pre-distortion by use of a memory polynomial model which compensates for amplifier nonlinearity and memory effect. The look-up table based implementation scheme is used to reduce the computational complexity of the pre-distortion block. The linearization performance is demonstrated on wideband CDMA signal and class AB high power amplifier.

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Design and Performance Analysis of Pre-Distorter Including HPA Memory Effect

  • An, Dong-Geon;Lee, Il-Jin;Ryu, Heung-Gyoon
    • Journal of electromagnetic engineering and science
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    • 제9권2호
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    • pp.71-77
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    • 2009
  • OFDM(Orthogonal Frequency Division Multiplexing) signals sutler serious nonlinear distortion in the nonlinear HPA(High Power Amplifier) because of high PAPR(Peak Average Power Ratio). Nonlinear distortion can be improved by a pre-distorter, but this pre-distorter is insufficient when the PAPR is very high in an OPFDM system. In this paper, a DFT(Discrete Fourier Transform) transform technique is introduced for PAPR reduction. It is especially important to consider the memory effect of HPA for more precise predistortion. Therefore, in this paper, we consider two models, the TWTA(Traveling-Wave Tube Amplifier) model of Saleh without a memory effect and the HPA memory polynomial model that has a memory effect. We design a pre-distorter and an adaptive pre-distorter that uses the NLMS(Normalized Least Mean Square) algorithm for the compensation of this nonlinear distortion. Without the consideration of a memory effect, the system performance would be degraded, even if the pre-distorter is used for the compensation of the nonlinear distortion. From the simulation results, we can confirm that the proposed system shows an improvement in performance.

대전입자형 디스플레이 소자의 점유면적 평가방법에 의한 구동특성 및 메모리 효과 분석 (Analysis of Driving Characteristics and Memory Effect by Occupation Area Evaluation Method of Charged Particle Type Display Device)

  • 김진선;김영조
    • 한국전기전자재료학회논문지
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    • 제24권8호
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    • pp.669-673
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    • 2011
  • The charged particle type display is a kind of the reflectivity type display and shows an image by absorption and reflection of external light source, which has keep an image without additional electric power because of bistability. In this paper, we made a device whose cell gap is $56\;{\mu}m$ and also analyzed driving and memory characteristics by applied driving voltages. As a result, we found that the driving voltage and memory effect depend on q/m(charge to mass ratio) of charged particle. In this case of breakdown voltage, the devices showed degradation of reflectivity and memory effect due to irregular movement of overcharged particles. In addition, contrast ratio of the device varies with memory effect. Thus, we consider that device needs uniform q/m for improvement of electric and optical properties and memory effect.

Effect of Intensity of Unconditional Stimulus on Reconsolidation of Contextual Fear Memory

  • Kwak, Chul-Jung;Choi, Jun-Hyeok;Bakes, Joseph T.;Lee, Kyung-Min;Kaang, Bong-Kiun
    • The Korean Journal of Physiology and Pharmacology
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    • 제16권5호
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    • pp.293-296
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    • 2012
  • Memory reconsolidation is ubiquitous across species and various memory tasks. It is a dynamic process in which memory is modified and/or updated. In experimental conditions, memory reconsolidation is usually characterized by the fact that the consolidated memory is disrupted by a combination of memory reactivation and inhibition of protein synthesis. However, under some experimental conditions, the reactivated memory is not disrupted by inhibition of protein synthesis. This so called "boundary condition" of reconsolidation may be related to memory strength. In Pavlovian fear conditioning, the intensity of unconditional stimulus (US) determines the strength of the fear memory. In this study, we examined the effect of the intensity of US on the reconsolidation of contextual fear memory. Strong contextual fear memory, which is conditioned with strong US, is not disrupted by inhibition of protein synthesis after its reactivation; however, a weak fear memory is often disrupted. This suggests that a US of strong intensity can inhibit reconsolidation of contextual fear memory.

Memory Effect를 최소화한 C-대역 내부 정합 GaAs 전력증폭기 (C-Band Internally Matched GaAs Power Amplifier with Minimized Memory Effect)

  • 최운성;이경학;어윤성
    • 한국전자파학회논문지
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    • 제24권11호
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    • pp.1081-1090
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    • 2013
  • 본 논문에서는 C-대역에서 입출력 정합 회로가 패키지에 내장된 10 W급 내부 정합 증폭기 설계 및 제작을 하였다. 전력증폭기 설계에 사용한 트랜지스터로 GaAs pHEMT bare-chip을 사용하였다. 트랜지스터 패드 위치와 커패시터 크기를 고려한 와이어 본딩 해석으로 정확도 높은 설계를 하였다. 패키지와 정합 회로를 함께 EM simulation하여 패키지가 정합 회로에 미치는 영향을 해석하였다. 2-tone 측정 시 memory effect로 인해 발생되는 IMD3의 비대칭성을 줄이기 위한 memory effect 감쇄 바이어스 회로를 제안 및 설계하였다. 측정 결과, 7.1~7.8 GHz 대역에서 $P_{1dB}$는 39.8~40.4 dBm, 전력 이득은 9.7~10.4 dB, 효율은 33.4~38.0 %을 얻었고, 제안된 memory effect 감쇄 바이어스 회로로 IMD3(Upper)와 IMD3(Lower)차는 0.76 dB 이하를 얻었다.

TiNi/A16061 형상기억복합재료의 피로균열진전에 대한 냉간압연효과 (Effect of Cold Rolling on Fatigue Crack Propagation of TiNi/A16061 Shape Memory Composite)

  • 이진경;박영철;이규창;이상필;조윤호;이준현
    • 대한기계학회논문집A
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    • 제29권10호
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    • pp.1315-1320
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    • 2005
  • TiNi alloy fiber was used to recover the original shape of materials using its shape memory effect. The shape memory alloy plays an important role within the metal matrix composite. The shape memory alloy can control the crack propagation in metal matrix composite, and improve the tensile strength of the composite. In this study, TiNi/A16061 shape memory alloy(SMA) composite was fabricated by hot press method, and pressed by a roller for its strength improvement. The four kinds of specimens were fabricated with $0\%,\;3.2\%,\;5.2\%\;and\;7\%$ and volume fraction of TiNi alloy fiber, respectively. A fatigue test has performed to evaluate the crack initiation and propagation for the TiNi/A16061 SMA composite fabricated by かis method. In order to study the shape memory effect of the TiNi alloy fiber, the test has also done under both conditions of the room temperature and high temperature. The relationship between the crack growth rate and the stress intensity factor was clarified for the composite, and the cold rolling effect was also studied.

Fe-30%Mn-6% Si 합금의 형상기억효과에 미치는 Training(SIM↔γ)의 영향 (Effect of Training( SIM↔γ) on Shape Memory Effect of Fe-30%Mn-6%Si Alloy)

  • 한상호;전중환;최종술
    • 열처리공학회지
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    • 제7권2호
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    • pp.118-128
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    • 1994
  • Five alloys were selected randomly in the composition range showing the best shape memory effect in Fe-Mn-Si system reported by Murakami. The shape memory effects of those alloys were mainly investigated through the training treatment which consisted of the repetition of 2% tensile deformation at room temperature and subsequent annealing at $600^{\circ}C$ above $A_r$ temperature. At the same deformation degress in rolling $600^{\circ}C$-annealing for 1 hr. showed the best shape memory effect, and 10%-deformation degrees represented maxima of the shpae memory effects at all annealing temperatures, $500^{\circ}C$, $600^{\circ}C$ and $700^{\circ}C$. The shape memory effects of the alloys were increased by increasing training cycle up to 5 cycles. This was because a large number of dislocations introduced by training process gave rise to increase in the austenite yield stress, and acted as nucleation sites for stress induced ${\varepsilon}$ martensite. The thermal cycling treatment, repetition of cooling in nitrogen at $-196{\circ}C$ and heating to $300^{\circ}C$ for 5 min., did not improve the shape memory effect.

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유아의 의도적 통제와 작업기억이 정서조절에 미치는 영향 : 성의 조절효과 검증 (The Influences of Effortful Control and Working Memory on Emotion Regulation in Preschool Children : The Analysis of Moderating Effect of Child Sex)

  • 최은아;송하나
    • 아동학회지
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    • 제35권6호
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    • pp.65-78
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    • 2014
  • The purpose of this study was to examine the relationships between preschooler's sex, effortful control, working memory, and emotion regulation. The moderating effect of sex in the influences of effortful control and working memory on emotion regulation was also investigated. Eighty-eight children from the ages of 3 to 5 years participated in this study. A working memory task of the Korean Wechsler Intelligence Scale for Children IV(K-WISC-IV; Kwak, Oh, & Kim, 2011) was administered to the children. Their parents completed a very short form of the Children's Behavior Questionnaire(Putnam & Rothbart, 2006) and Emotion Regulation Checklist(Shields & Cicchetti, 1997). The results indicated that effortful control significantly predicted emotion regulation. Additionally the moderating effect of sex on the relationship between working memory and emotion regulation was significant. Specifically, the influence of working memory on emotion regulation was significant only in boys, but not in girls. This result suggested that effortful control has an effect on emotion regulation in a stable manner whereas working memory has different effects on the influence of emotion regulation according to sex.

Effects of Chongmyung-tang on Learning and Memory Performances in Mice

  • Lee, Seoung-Hee;Chang, Gyu-Tae;Kim, Jang-Hyun
    • 동의생리병리학회지
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    • 제20권2호
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    • pp.471-476
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    • 2006
  • Chongmyung-tang(CMT, 聰明湯), oriental herbal medicine which consists of Polygaglae Radix(遠志), Acori Graminei Rhizoma(石菖蒲) and Hoelen(白茯神) has effect on amnesia, dementia. In order to evaluate effect of CMT on memory and learning in mice, CMT extract was used for studies. This paper describes the effects of CMT extract on memory and learning processes by using the passive and active avoidance performance tests, novel object recognition task and water maze task. The CMT extract ameliorated the memory retrieval deficit induced by ethanol in the passive avoidance responses but did not affect ambulatory activity of normal mice. These results suggest that CMT has an ameliorating effect on memory retrieval impairment. CMT extract decreased spontaneous motor activity(SMA) in the latter sessions of memory registration in active avoidance responses. These results suggest that CMT has partly transquilizing or antianxiety effects. In novel object recognition task to measure visual recognition memory, CMT-administered mice enhanced in long term memory for 1-3 days. In water maze task to measure spatial learning, which requires the activation of NMDA receptors in the hippocampus, spatial learning in CMT-administered mice was faster than in wild-type mice. These results suggest that CMT enhances memory and activates NMDA receptors.