scholarly journals Evolutionary Acquisition of the Low Thermal Noise of Frog’s Cone Pigments for Scotopic Vision

2018 ◽  
Vol 58 (4) ◽  
pp. 209-210 ◽  
Author(s):  
Keiichi KOJIMA
Keyword(s):  
Thermal Noise ◽  
Scotopic Vision ◽  
Cone Pigments

scholarly journals Scotopic rod vision in tetrapods arose from multiple early adaptive shifts in the rate of retinal release

2019 ◽  
Vol 116 (26) ◽  
pp. 12627-12628 ◽  
Author(s):  
Yang Liu ◽  
Yimeng Cui ◽  
Hai Chi ◽  
Yu Xia ◽  
Haonan Liu ◽  
...  
Keyword(s):  
Release Rate ◽  
Spectral Properties ◽  
Light Conditions ◽  
Release Rates ◽  
Low Light ◽  
Scotopic Vision ◽  
Recent Innovation ◽  
Cone Pigments ◽  
Early Vertebrates ◽  
Adaptive Shifts

The ability of vertebrates to occupy diverse niches has been linked to the spectral properties of rhodopsin, conferring rod-based vision in low-light conditions. More recent insights have come from nonspectral kinetics, including the retinal release rate of the active state of rhodopsin, a key aspect of scotopic vision that shows strong associations with light environments in diverse taxa. We examined the retinal release rates in resurrected proteins across early vertebrates and show that the earliest forms were characterized by much faster rates of retinal release than more recent ancestors. We also show that scotopic vision at the origin of tetrapods is a derived state that arose via at least 4 major shifts in retinal release rate. Our results suggest that early rhodopsin had a function intermediate to that of modern rod and cone pigments and that its well-developed adaptation to low light is a relatively recent innovation since the origin of tetrapods.

scholarly journals Adaptation of cone pigments found in green rods for scotopic vision through a single amino acid mutation

2017 ◽  
Vol 114 (21) ◽  
pp. 5437-5442 ◽  
Author(s):  
Keiichi Kojima ◽  
Yuki Matsutani ◽  
Takahiro Yamashita ◽  
Masataka Yanagawa ◽  
Yasushi Imamoto ◽  
...  
Keyword(s):  
Amino Acid ◽  
Color Vision ◽  
Mutational Analysis ◽  
Thermal Isomerization ◽  
Single Amino Acid ◽  
Single Type ◽  
Amphibian Species ◽  
Scotopic Vision ◽  
Visual Threshold ◽  
Cone Pigments

Most vertebrate retinas contain a single type of rod for scotopic vision and multiple types of cones for photopic and color vision. The retinas of certain amphibian species uniquely contain two types of rods: red rods, which express rhodopsin, and green rods, which express a blue-sensitive cone pigment (M1/SWS2 group). Spontaneous activation of rhodopsin induced by thermal isomerization of the retinal chromophore has been suggested to contribute to the rod’s background noise, which limits the visual threshold for scotopic vision. Therefore, rhodopsin must exhibit low thermal isomerization rate compared with cone visual pigments to adapt to scotopic condition. In this study, we determined whether amphibian blue-sensitive cone pigments in green rods exhibit low thermal isomerization rates to act as rhodopsin-like pigments for scotopic vision. Anura blue-sensitive cone pigments exhibit low thermal isomerization rates similar to rhodopsin, whereas Urodela pigments exhibit high rates like other vertebrate cone pigments present in cones. Furthermore, by mutational analysis, we identified a key amino acid residue, Thr47, that is responsible for the low thermal isomerization rates of Anura blue-sensitive cone pigments. These results strongly suggest that, through this mutation, anurans acquired special blue-sensitive cone pigments in their green rods, which could form the molecular basis for scotopic color vision with normal red rods containing green-sensitive rhodopsin.

Ultra-spatially resolved synchrotron powered FT-IR microspectroscopy of individual cells of biological material

1995 ◽  
Vol 53 ◽  
pp. 884-885
Author(s):  
David L. Wetzel ◽  
John A. Reffner ◽  
Gwyn P. Williams
Keyword(s):  
Thermal Noise ◽  
Spot Size ◽  
Acquisition Time ◽  
Thermal Source ◽  
Signal To Noise ◽  
Spatially Resolved ◽  
Good Spatial Resolution ◽  
Small Spot ◽  
Ft Ir ◽  
Ir Microspectroscopy

Synchrotron radiation is 100 to 1000 times brighter than a thermal source such as a globar. It is not accompanied with thermal noise and it is highly directional and nondivergent. For these reasons, it is well suited for ultra-spatially resolved FT-IR microspectroscopy. In efforts to attain good spatial resolution in FT-IR microspectroscopy with a thermal source, a considerable fraction of the infrared beam focused onto the specimen is lost when projected remote apertures are used to achieve a small spot size. This is the case because of divergence in the beam from that source. Also the brightness is limited and it is necessary to compromise on the signal-to-noise or to expect a long acquisition time from coadding many scans. A synchrotron powered FT-IR Microspectrometer does not suffer from this effect. Since most of the unaperatured beam’s energy makes it through even a 12 × 12 μm aperture, that is a starting place for aperture dimension reduction.

EFFECT OF CELLULAR MEMBRANE RESISTIVITY INHOMOGENEITY ON THE THERMAL NOISE-LIMIT

2015 ◽  
Vol 11 (3) ◽  
pp. 3171-3183
Author(s):  
Gyula Vincze
Keyword(s):  
Field Strength ◽  
Thermal Noise ◽  
Cellular Membrane ◽  
Thermal Limit ◽  
Low Frequencies ◽  
Membrane Resistivity ◽  
Noise Limit ◽  
The Asymmetry ◽  
Characteristic Field

Our objective is to generalize the Weaver-Astumian (WA) and Kaune (KA) models of thermal noise limit to the case ofcellular membrane resistivity asymmetry. The asymmetry of resistivity causes different effects in the two models. In the KAmodel, asymmetry decreases the characteristic field strength of the thermal limit over and increases it below the breakingfrequency (10  m), while asymmetry decreases the spectral field strength of the thermal noise limit at all frequencies.We show that asymmetry does not change the character of the models, showing the absence of thermal noise limit at highand low frequencies in WA and KA models, respectively.

scholarly journals Thermal Noise Decoupling of Micro-Newton Thrust Measured in a Torsion Balance

Symmetry ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1357
Author(s):  
Linxiao Cong ◽  
Jianchao Mu ◽  
Qian Liu ◽  
Hao Wang ◽  
Linlin Wang ◽  
...  
Keyword(s):  
Thermal Noise ◽  
Rotation Axis ◽  
Electrostatic Force ◽  
Thermal Control ◽  
Positive Temperature Coefficient ◽  
Torsion Balance ◽  
Positive Temperature ◽  
Thermal Drift ◽  
Low Thrust ◽  
Z Domain

The space gravitational wave detection and drag free control requires the micro-thruster to have ultra-low thrust noise within 0.1 mHz–0.1 Hz, which brings a great challenge to calibration on the ground because it is impossible to shield any spurious couplings due to the asymmetry of torsion balance. Most thrusters dissipate heat during the test, making the rotation axis tilt and components undergo thermal drift, which is hysteretic and asymmetric for micro-Newton thrust measurement. With reference to LISA’s research and coming up with ideas inspired from proportional-integral-derivative (PID) control and multi-timescale (MTS), this paper proposes to expand the state space of temperature to be applied on the thrust prediction based on fine tree regression (FTR) and to subtract the thermal noise filtered by transfer function fitted with z-domain vector fitting (ZDVF). The results show that thrust variation of diurnal asymmetry in temperature is decoupled from 24 μN/Hz1/2 to 4.9 μN/Hz1/2 at 0.11 mHz. Additionally, 1 μN square wave modulation of electrostatic force is extracted from the ambiguous thermal drift background of positive temperature coefficient (PTC) heater. The PID-FTR validation is performed with experimental data in thermal noise decoupling, which can guide the design of thermal control and be extended to other physical quantities for noise decoupling.

Thermal noise in contact atomic force microscopy

2021 ◽  
Vol 129 (23) ◽  
pp. 234303
Author(s):  
Chengfu Ma ◽  
Chenggang Zhou ◽  
Jinlan Peng ◽  
Yuhang Chen ◽  
Walter Arnold ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Thermal Noise ◽  
Force Microscopy ◽  
Atomic Force

scholarly journals Nano-Kelvin Thermometry and Temperature Control: Beyond the Thermal Noise Limit

2014 ◽  
Vol 112 (16) ◽  
Author(s):  
Wenle Weng ◽  
James D. Anstie ◽  
Thomas M. Stace ◽  
Geoff Campbell ◽  
Fred N. Baynes ◽  
...  
Keyword(s):  
Temperature Control ◽  
Thermal Noise ◽  
Noise Limit
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