logo

korean english

게시판

Home > 게시판 > 세미나

아래와 같이 콜로퀴움을 개최하오니 많이 참석해 주시기 바랍니다.

4시 20분부터 제1과학관 31214 e+강의실에서 다과를 준비하오니 많은 참석 부탁드립니다

 

아 래

 

제목: 청각의 물리학: 어떻게 노이즈를 극복하는가?

  

연사: 안  강  헌 교수님 (충남대학교, 물리학과)

 

일시: 2013년 9월 25일(수) 오후4:30

 

장소: 제1과학관 31214  e+첨단강의실 

 

초록:

Hair cells of the vertebrate inner ear are the mechanotransducers which have been proposed to amplify weak signals by generating active forces. While amplification in the mammalian cochlea is widely believed to originate from the membrane dynamics involving outer hair cell motility, non-mammalian vertebrates lack outer hair cells. Nevertheless the ear of lower vertebrates achieves acute hearing. The exact mechanism is not yet clearly known. Hair bundle motility probably underlies the amplification process. Unlike mammalian hair cells, spontaneous oscillations have been observed in individual hair cells of turtles and frogs. However, in recent experiments under more natural conditions than previously studied, frog hair bundles with an overlying membrane are found not to spontaneously oscillate, but are in fact quiescent.

 Here we introduce our recent theory[1] on the auditory transduction of the bullfrog sacculus, where  the coupling of hair bundles can induce the cessation of the spontaneous oscillation and enhanced signal-to-noise ratio. Using numerical simulations of models of bullfrog sacculi, we investigate the mechanotransduction properties of inhomogeneous hair bundles with elastic coupling and mechanical loading. We show that when inhomogeneous hair bundles are coupled with sufficient strength, all the spontaneous oscillations are suddenly quenched. This phenomenon is called amplitude death – the cessation of oscillation due to the coupling of oscillators, which was first noted in the 19th century by Rayleigh, who found that adjacent organ pipes can suppress each other's sound. We find that there exists an optimal value of the mass of the overlying membrane which gives the maximum signal-to-noise ratio. The hair bundles in this optimal condition turn out to be in the region where amplitude death is seen, which indicates the hair bundles are likely to exploit amplitude death for signal transmission.

 

[1] Ahn K-H. 2013 Enhanced signal-to-noise ratios in frog hearing can be achieved through amplitude death.  J R Soc Interface 10: 20130525.

 

 

Figure 1: Schematic figure for elastically coupled hair bundles with mechanical loading. (a)~(f) The power spectra of mechanical displacement for various inter-bundle coupling strength k and the stimulus amplitude F when 6 Hz signal is applied.

번호 제목 날짜 조회 수
공지 <12/8(Thu.) 11:00am>노벨상 소개 강연 - 2016년 노벨 물리학상: 위상 응집 물리의 탄생 2016.11.28 1058921
362 <11/13> Computer-Aided Engineering for Nucleic Acid Nanostructures 2013.11.07 106749
361 <11/6> Graphene plasmon and Plasmonics 2013.10.31 235818
360 <10/30> 광섬유 센서 2013.10.17 64288
359 <10/16> SPM Study of CVD Graphene on h-BN Film 2013.10.04 93663
358 <10/2> What's the matter? 2013.09.26 65981
» <9/25> 청각의 물리학: 어떻게 노이즈를 극복하는가? 2013.09.16 140632
356 <9/11> Epitaxial Oxygen Sponge 2013.09.09 92116
355 2013학년도 2학기 콜로퀴움 일정 2013.09.06 82430
354 <6/12> Latest Results from the IceCube Neutrino Observatory 2013.06.07 91624
353 <6/5> 물리학도가 증권가로 간 까닭은... 2013.05.29 69385
352 <5/29> Study on the electronic interactions in solids under high magnetic fields 2013.05.23 88981
351 <5/22> Computer-based Mathematical Analysis and Applications to Physics (컴퓨터 기반 수리해석과 물리학에의 응용) 2013.05.15 139199
350 <5/15> Quantum Critical Superconductivity 2013.05.09 70094
349 <5/8> Complex Networks: Through the 3D Looking Glass 2013.05.02 85317
348 <5/1> Entanglement and topological order in 1D and 2D systems 2013.04.18 109464
347 <4/17> Probing Stellar Explosions with Radioactive Beams* 2013.04.10 92375
346 <4/10> Mapulation of spins in organic compounds 2013.04.03 93291
345 <4/3> 내 안의 파장을 바꿔라! 2013.03.29 66715
344 <3/27> Proximity effects and low dimensional superconductivity of Pb nano-islands  2013.03.21 79717
343 <3/20> 빛 : 우주의 신비를 푸는 열쇠 2013.03.14 69144