Research

The growth rate of bacterial flagella

Bacterial flagellar structure, fluorescent imaging and the growth model
Bacterial flagella are thin protein filaments as helical propellers of bacterial swimming. We developed single cell real-time observation techniques to understand the growth rate and growth mechanism of these self-assembled nano-filaments.
Length-dependent flagellar growth rate of Vibrio alginolyticus revealed by real time fluorescent imaging 
M.T. Chen, Z.Y. Zhao, J.Yang, P. Kai, M.A.B. Baker, F. Bai and C.-J. Lo 
eLife e22140 (2017)

 

Reviewer-thrilled laser phase locking

 
By electronics feedback, we achieved sub-mHz level offset locking
By our novel electronic design, we achieved phase error of 10^-19 rad. per duty cycle for two laser mutual coherence, which made the reviewer of optics express “thrilled”
Robust sub-millihertz-level offset locking for transferring optical frequency accuracy and for atomic two-photon spectroscopy 
Wang-Yau Cheng*, Ting-Ju Chen, Chia-Wei Lin, Bo-Wei Chen, Ya-Po Yang and Hung Yi Hsu 
Optics Express 25, 2752 (2017)

 

Dust acoustic rogue wave

 研究成果伊林
Spatial dust density (nd) distribution in the xy plane, normal to the wave propagation direction z, at different time τ, showing the sudden emergence of a rogue wave event, labeled by the arrow at τ = 0, from the previous nd distribution one wave period ahead (i.e. τ = -32.5 ms). 
We reported the first experimental demonstration of spatially and temporally localized rogue wave events in weakly disordered 3D dust acoustic waves. By tracking dust particle trajectories and waveform evolutions, we identify that the 3D particle focusing by the distorted waveform is the key for rogue wave generation.
Generation of acoustic rogue waves in dusty plasmas through three-dimensional particle focusing by distorted waveforms Ya-Yi Tsai, Jun-Yi Tsai, and Lin I
Nature Physics (2016), doi:10.1038/nphys3669

 

Frequency Enhancement in Coupled Noisy Excitable Elements

The mean frequency of a coupled excitable system can be enhanced in some coupling regime as the system approaches synchronization.
The novel phenomenon of frequency enhancement in coupled excitable elements is discovered and explained which can account For in vitro cardiac experiments. Our work opens a new avenue of understanding how a biological system can regulate its rhythm.
Frequency Enhancement in Coupled Noisy Excitable Elements W.Y. Chiang, Pik-Yin Lai*, and C. K. Chan* Phys. Rev. Lett. 106, p.254102-1~4 (2011)

 

Process of inducing pores in membranes by melittin

Process of inducing pores in membranes by melittin
We clarified the process of inducing pores in membranes by melittin and determined the pore structure . Not only the new developed hybrid techniques were used to study the interaction between bio-molecules and membranes but also the result provided useful information in drug design, disease therapy and nonvirus delivery
Process of inducing pores in membranes by melittin  Ming-Tao Lee, Tzu-Lin Sun, Wei-Chin Hung, and Huey W. Huang  Proceedings of the National Academy of Sciences 110, 14243-14248 (2013) .

 

Left-right symmetry breaking in bacterial gliding motility ?

Adhesion proteins move along a closed loop on the surface of F. johnsoniae. At sufficient high adhesin speed, the bacterium glides by breaking left-right symmetry.
A theoretical model for bidirectional motion of Flavobacterium johnsoniae is proposed by Hsuan-Yi Chen (NCU Physics) and Hirofumi Wada (Ritsumeikan University). For a sufficiently large adhesion speed, bidirectional motion arises from spontaneous symmetry breaking. Close to the bifurcation point, the direction of motion could be sensitively regulated in response to environmental cues.
Bidirectional Bacterial Gliding Motility Powered by the Collective Transport of Cell Surface Proteins H. Wada, D. Nakane , Hsuan-Yi ChenPhys. Rev. Lett . 101, 248102(2013)

 

Kinetics of a sodium-driven bacterial flagellar motor

Kinetics of Bacterial Flagellar Motor
Bacterial flagellar motor is a powerful natural nanomachine powered by a transmembrane electrochemical potential difference. We directly measure the mechanical output, torque and speed curves, of this ion-driven protein complex over a wide of electrochemical potential. The motor requires at least 37 ± 2 ions per revolution. We use a 4-state kinetic model to understand the kinetic process.
The mechanism and kinetics of a sodium-driven bacterial flagellar motor C.-J. Lo, Y. Sowa, T. Pilizota . and RM Berry Proceedings of the National Academy of Sciences 110, E2544-E2551 (2013)

 

Optical frequency of cesium 6S-8S transition

Cesium 6S-8S two-photon spectrum in which the natural linewidth of 932 kHz is deduced. Note that the error bar of each data point is much smaller than the red dot. The magnified fitting residual is actually 100 times smaller than the signal height and is highly symmetric, showing our experimental result is in high agreement with theory
Cesium 6S-8S transition offers an excellent basis for observing the physics of parity non-conservation and for testing the electroweak theory. By using a comb laser and a novel quantum interference spectrum, we have obtained the most precise transition frequency in literature. Our result was selected as “Spotlight on Optics August, 2013” by Optical Society of America (OSA)
The absolute frequency of cesium 6S-8S 822-nm two-photon transition by a high-resolution scheme Chien -Ming Wu, Tze -Wei Liu, Ming- Hsuan Wu, Ray- Kuang Lee and Wang- Yau Cheng Opt . Lett . 38 , 3186(2013)

 

Search for Darkmatter in the Universe with the AMS experiment

The picture shows the AMS detector on the International Space Station. Inserted diagram shows the result of Positron fraction measurement.
AMS measured the positron fraction in the cosmic rays with high precision. The data show that the positron fraction is steadily increasing from 10 to 250 GeV. However, from 20 to 250 GeV, the slope decreases by an order of magnitude.
First Result from the AMS on the ISS: Precision Measurement of the Positron Fraction in Primary Cosmic Rays of 0.5 – 350 GeV ” The AMS Collaboration, Phys. Rev. Lett . 110, 141102 (2013)

 

Search for the Higgs boson and new physics with CMS

The event shows characteristics expected from the decay of the SM Higgs boson to a pair of photons
CMS observed a newparticle with mass around 125 GeV which agrees with the SM Higgs prediction within the statistical error。
Observation of a new boson at a mass of 125 GeV with the CMS experiment at the LHC The CMS Collaboration Physics Letters B 716 (2012) 30

 

Building Foundations for Looking into Unknowns at CMS

Left: Inclusive photon production cross section as a function of photon transverse energy. Right: The ratios of data to theory predictions
Using the early LHC data collected in 2010, CMS performed the first measurement of inclusive photon production. This result established the benchmark of photon identification and background estimation. This paper is also the first CMS photon physics paper.
Measurement of the Isolated Prompt Photon Production Cross Section in pp Collisions at sqrt (s)= 7 TeV The CMS Collaboration Phys. Rev. Lett . 106, 082001 (2011)