scholarly journals Spontaneous circulation of active microtubules confined by optical traps

2021 ◽  
Author(s):  
Stephen E Martin ◽  
Matthew E Brunner ◽  
Joshua M Deutsch
Keyword(s):  
Power Spectrum ◽  
Symmetry Breaking ◽  
First Principles ◽  
Optical Trap ◽  
Spontaneous Circulation ◽  
Optical Traps ◽  
Far Field ◽  
Angular Momenta ◽  
Surrounding Fluid

AbstractWe propose an experiment to demonstrate spontaneous ordering and symmetry breaking of kinesin-driven microtubules confined to an optical trap. Calculations involving the feasibility of such an experiment are first performed which analyze the power needed to confine microtubules and address heating concerns. We then present the results of first-principles simulations of active microtubules confined in such a trap and analyze the types of motion observed by the microtubules as well as the velocity of the surrounding fluid, both near the trap and in the far-field. We find three distinct phases characterized by breaking of distinct symmetries and also analyze the power spectrum of the angular momenta of polymers to further quantify the differences between these phases. Under the correct conditions, microtubules were found to spontaneously align with one another and circle the trap in one direction.

Surface roughness and substrate induced symmetry-breaking: influence on the plasmonic properties of aluminum nanostructure arrays

Nanoscale ◽  
2020 ◽  
Author(s):  
Feifei ZHANG ◽  
Jérôme Plain ◽  
Davy Gerard ◽  
Jérôme Martin
Keyword(s):  
Surface Roughness ◽  
Optical Properties ◽  
Symmetry Breaking ◽  
Surface Topography ◽  
Metallic Nanoparticles ◽  
Far Field ◽  
Al Nanoparticles ◽  
Nanostructure Arrays

The surface topography is known to play an important role on the near- and far- field optical properties of metallic nanoparticles. In particular, aluminum (Al) nanoparticles are commonly fabricated through...

Optimal trap velocity in a dynamic holographic optical trap using a nematic liquid crystal spatial light modulator

2022 ◽  
Author(s):  
Karuna Sindhu Malik ◽  
Bosanta Ranjan Boruah
Keyword(s):  
Liquid Crystal ◽  
Nematic Liquid Crystal ◽  
Spatial Light Modulator ◽  
Optical Trap ◽  
Optical Element ◽  
Optical Traps ◽  
Light Modulator ◽  
Step Size ◽  
Microscopic Object ◽  
Optimal Velocity

Abstract A dynamic holographic optical trap uses a dynamic diffractive optical element such as a liquid crystal spatial light modulator to realize one or more optical traps with independent controls. Such holographic optical traps provide a number of flexibilities and conveniences useful in various applications. One key requirement for such a trap is the ability to move the trapped microscopic object from one point to the other with the optimal velocity. In this paper we develop a nematic liquid crystal spatial light modulator based holographic optical trap and experimentally investigate the optimal velocity feasible for trapped beads of different sizes, in such a trap. Our results show that the achievable velocity of the trapped bead is a function of size of the bead, step size, interval between two steps and power carried by the laser beam. We observe that the refresh rate of a nematic liquid crystal spatial light modulator is sufficient to achieve an optimal velocity approaching the theoretical limit in the respective holographic trap for beads with radius larger than the wavelength of light.

Acoustic Design of a Local Scatterer in a Phase-Space

1995 ◽  
Author(s):  
John J. McCoy ◽  
Ben Zion Steinberg
Keyword(s):  
Mechanical Property ◽  
Phase Space ◽  
Mass Density ◽  
Sound Field ◽  
Design Strategy ◽  
Local Region ◽  
Small Scale ◽  
Far Field ◽  
Acoustic Design ◽  
Surrounding Fluid

Abstract A spatially local region of mechanical property heterogeneity is a source of scattering, by which a structure-borne mechanical wavefield is released as sound, to a surrounding fluid. We consider the case of a scatterer which is of the order of the size of the wavelength of a plate-wave field for a frequency which is below coincidence. A design strategy for reducing the strength of the scattered sound field in the fluid, at far-field distances from the scatterer, by adding a small-scale structure to the heterogenity, is presented. The design is accomplished in a wavelet-based phase-space. Emphasized is a significant distinction required of the added structure, depending on the heterogeneity applying to a measure of the local mass density or the local bending stiffness.

Noise analysis of the turbojet and turbofan engine tests

2013 ◽  
Vol 228 (13) ◽  
pp. 2414-2423
Author(s):  
Jingjing Huang ◽  
Longxi Zheng
Keyword(s):  
Power Spectrum ◽  
Noise Reduction ◽  
Spectrum Analysis ◽  
Test Bench ◽  
Power Spectrum Analysis ◽  
Noise Power ◽  
Far Field ◽  
Turbofan Engine ◽  
Turbojet Engine ◽  
Field Noise

Aerogine noise leads to environment pollution largely when aerogine is tested. In this paper, the power spectrum analysis method of the aeroengine test noise was discussed, and the noise measurement and analysis experiments of a turbojet engine and a turbofan engine tests were carried out. The noise level, main noise resource, and noise characteristics of the two turbojet and turbofan engines were analyzed. Meanwhile, the indoor noise and far-field noise of the turbojet engine were both measured, the noise spread characteristics were analyzed and the noise reduction performance of the test bench was evaluated. The noise generated by the turbojet engine test had the discrete characteristic of high frequency. The higher frequencies when peak values occurred were the blade passage frequencies and the noises with lower frequencies were the broad band noises, especially the jet noise, and the maximum of the peak values occurred at the basic frequencies or harmonic frequencies of the compressor. Meanwhile, the noises generated by the turbofan engine, focused on the high frequencies and the peak values corresponded to the rotation noise of the fan blades. The experimental results were consistent with the theory basically, which indicated that the aeroengine operating status information could be identified by the noise power spectrum analysis. In addition to the aeroengine noise reduction research, the noise power spectrum analysis could also be used to diagnose the fault of the aeroengine structure and performance. On the other hand, the indoor and far-field noise measurement experimental results implied that the noise was suppressed from 136 dB to 85 dB and could provide the reference to the noise reduction design of the aeroengine test bench.

scholarly journals Symmetry Breaking in Interacting Ring-Shaped Superflows of Bose–Einstein Condensates

Symmetry ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1312 ◽  
Author(s):  
Artem Oliinyk ◽  
Igor Yatsuta ◽  
Boris Malomed ◽  
Alexander Yakimenko
Keyword(s):  
Symmetry Breaking ◽  
Rotational Symmetry ◽  
Mean Field ◽  
Spontaneous Breaking ◽  
Persistent Currents ◽  
Mean Field Model ◽  
Final State ◽  
Double Ring ◽  
Angular Momenta ◽  
Bose Einstein

We demonstrate that the evolution of superflows in interacting persistent currents of ultracold gases is strongly affected by symmetry breaking of the quantum vortex dynamics. We study counter-propagating superflows in a system of two parallel rings in regimes of weak (a Josephson junction with tunneling through the barrier) and strong (rings merging across a reduced barrier) interactions. For the weakly interacting toroidal Bose–Einstein condensates, formation of rotational fluxons (Josephson vortices) is associated with spontaneous breaking of the rotational symmetry of the tunneling superflows. The influence of a controllable symmetry breaking on the final state of the merging counter-propagating superflows is investigated in the framework of a weakly dissipative mean-field model. It is demonstrated that the population imbalance between the merging flows and the breaking of the underlying rotational symmetry can drive the double-ring system to final states with different angular momenta.

Nonlinear Proportional Plus Integral Control of Optical Traps for Exogenous Force Estimation

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
D. G. Cole ◽  
J. G. Pickel
Keyword(s):  
Optical Trap ◽  
Open Loop ◽  
Optical Force ◽  
Optical Traps ◽  
Pi Control ◽  
Force Estimation ◽  
Nonlinear Controller ◽  
Closed Loop System ◽  
Integral Control ◽  
Servo Tracking

This article explores nonlinear proportional plus integral (PI) feedback for controlling the position of an object held in an optical trap. In general, nonlinearities in the spatial dependence of the optical force complicate feedback control for optical traps. Nonlinear PI control has been shown to provide all of the benefits of integral control: disturbance rejection, servo tracking, and force estimation. The controller also linearizes the closed-loop system. More importantly, the nonlinear controller is shown to be equivalent to an estimator of the exogenous force. The ability of nonlinear PI control to lower the measurement SNR is evaluated and compared to the variational open-loop case. A simulation demonstrating the performance of the nonlinear PI control is presented.

Optically driven pumps and flow sensors for microfluidic systems

2008 ◽  
Vol 222 (5) ◽  
pp. 829-837 ◽  
Author(s):  
H Mushfique ◽  
J Leach ◽  
R Di Leonardo ◽  
M J Padgett ◽  
J M Cooper
Keyword(s):  
Fluid Flow ◽  
Optical Tweezers ◽  
Microfluidic Channel ◽  
Optical Traps ◽  
Spin Angular Momentum ◽  
Flow Sensors ◽  
Flow Sensing ◽  
Optically Trapped ◽  
Surrounding Fluid ◽  
Displace Fluid

This paper describes techniques for generating and measuring fluid flow in microfluidic devices. The first technique is for the multi-point measurement of fluid flow in microscopic geometries. The flow sensing method uses an array of optically trapped microprobe sensors to map out the fluid flow. The optical traps are alternately turned on and off such that the probe particles are displaced by the flow of the surrounding fluid and then retrapped. The particles' displacements are monitored by digital video microscopy and directly converted into velocity field values. The second is a method for generating flow within a microfluidic channel using an optically driven pump. The optically driven pump consists of two counter-rotating birefringent vaterite particles trapped within a microfluidic channel and driven using optical tweezers. The transfer of spin angular momentum from a circularly polarized laser beam causes the particles to rotate at up to 10 Hz. The pump is shown to be able to displace fluid in microchannels, with flow rates of up to 200 m−3 s−1 (200 fL s−1). In addition a flow sensing method, based upon the technique mentioned above, is incorporated into the system in order to map the magnitude and direction of fluid flow within the channel.

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