Use of a local cone model to predict essential CSF light adaptation behavior used in the design of luminance quantization nonlinearities

2015 ◽  
Author(s):  
Scott Daly ◽  
S. A. Golestaneh
Keyword(s):  
Light Adaptation ◽  
Cone Model ◽  
Local Cone

A Hydrogen Bond Between Linear Tetrapyrrole and Conserved Aspartate Causes the Far-Red Shifted Absorption of Phytochrome Photoreceptors

2020 ◽  
Author(s):  
Egle Maximowitsch ◽  
Tatiana Domratcheva
Keyword(s):  
Hydrogen Bond ◽  
Light Adaptation ◽  
Positive Charge ◽  
Pyrrole Ring ◽  
Md Simulations ◽  
Spectral Shift ◽  
Specific Domain ◽  
Study Guides ◽  
Rational Engineering ◽  
Tuning Mechanism

Photoswitching of phytochrome photoreceptors between red-absorbing (Pr) and far-red absorbing (Pfr) states triggers light adaptation of plants, bacteria and other organisms. Using quantum chemistry, we elucidate the color-tuning mechanism of phytochromes and identify the origin of the Pfr-state red-shifted spectrum. Spectral variations are explained by resonance interactions of the protonated linear tetrapyrrole chromophore. In particular, hydrogen bonding of pyrrole ring D with the strictly conserved aspartate shifts the positive charge towards ring D thereby inducing the red spectral shift. Our MD simulations demonstrate that formation of the ring D–aspartate hydrogen bond depends on interactions between the chromophore binding domain (CBD) and phytochrome specific domain (PHY). Our study guides rational engineering of fluorescent phytochromes with a far-red shifted spectrum.

Conical SNA using fuzzy k-medoids based on user experience

2021 ◽  
pp. 002072092098849
Author(s):  
Poonam Rani ◽  
MPS Bhatia ◽  
Devendra K Tayal
Keyword(s):  
Social Networks ◽  
Social Network ◽  
User Experience ◽  
Three Dimensional ◽  
Experimental Results ◽  
Dynamic Parameters ◽  
Clustering Method ◽  
Cone Model ◽  
Intelligent Approach ◽  
Conical Model

The paper presents an intelligent approach for the comparison of social networks through a cone model by using the fuzzy k-medoids clustering method. It makes use of a geometrical three-dimensional conical model, which astutely represents the user experience views. It uses both the static as well as the dynamic parameters of social networks. In this, we propose an algorithm that investigates which social network is more fruitful. For the experimental results, the proposed work is employed on the data collected from students from different universities through the Google forms, where students are required to rate their experience of using different social networks on different scales.

Comparison of the responses of AII amacrine cells in the dark- and light-adapted rabbit retina

1999 ◽  
Vol 16 (4) ◽  
pp. 653-665 ◽  
Author(s):  
DAIYAN XIN ◽  
STEWART A. BLOOMFIELD
Keyword(s):  
Receptive Field ◽  
Light Adaptation ◽  
Amacrine Cells ◽  
Bipolar Cells ◽  
Rabbit Retina ◽  
Response Component ◽  
Synaptic Inputs ◽  
Field Organization ◽  
Receptive Field Organization ◽  
Aii Amacrine Cells

We studied the light-evoked responses of AII amacrine cells in the rabbit retina under dark- and light-adapted conditions. In contrast to the results of previous studies, we found that AII cells display robust responses to light over a 6–7 log unit intensity range, well beyond the operating range of rod photoreceptors. Under dark adaptation, AII cells showed an ON-center/OFF-surround receptive-field organization. The intensity–response profile of the center-mediated response component followed a dual-limbed sigmoidal function indicating a transition from rod to cone mediation as stimulus intensities were increased. Following light adaptation, the receptive-field organization of AII cells changed dramatically. Light-adapted AII cells showed both ON- and OFF-responses to stimulation of the center receptive field, but we found no evidence for an antagonistic surround. Interestingly, the OFF-center response appeared first following rapid light adaptation and was then replaced gradually over a 1–4 min period by the emerging ON-center response component. Application of the metabotropic glutamate receptor agonist APB, the ionotropic glutamate blocker CNQX, 8-bromo-cGMP, and the nitric oxide donor SNAP all showed differential effects on the various center-mediated responses displayed by dark- and light-adapted AII cells. Taken together, these pharmacological results indicated that different synaptic circuits are responsible for the generation of the different AII cell responses. Specifically, the rod-driven ON-center responses are apparently derived from rod bipolar cell synaptic inputs, whereas the cone-driven ON-center responses arise from signals crossing the gap junctions between AII cells and ON-center cone bipolar cells. Additionally, the OFF-center response of light-adapted AII cells reflects direct synaptic inputs from OFF-center cone bipolar cells to AII dendritic processes in the distal inner plexiform layer.

scholarly journals Correction to: Experimental investigation of blunt cone model at hypersonic Mach number 7.25

2021 ◽  
Vol 43 (7) ◽  
Author(s):  
Saiprakash Mani ◽  
C. Senthilkumar ◽  
G. Kadam Sunil ◽  
Singh Prakash Rampratap ◽  
V. Shanmugam ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Mach Number ◽  
Blunt Cone ◽  
Cone Model

A unique low light adaptation mechanism inRhodobacter azotoformans

2014 ◽  
Vol 54 (12) ◽  
pp. 1350-1357 ◽  
Author(s):  
Kai Li ◽  
Chungui Zhao ◽  
Huiying Yue ◽  
Suping Yang
Keyword(s):  
Light Adaptation ◽  
Low Light ◽  
Adaptation Mechanism

scholarly journals A Homogeneous Field for Light Adaptation

1968 ◽  
Vol 26 (2) ◽  
pp. 521-522
Author(s):  
Henry W. Mertens
Keyword(s):  
Light Adaptation ◽  
Space Perception ◽  
Stray Light ◽  
Homogeneous Field

A light-adaptation device which creates a homogeneous field is described. It can be used easily between observations in space perception experiments to reduce sensitivity of the eyes to stray light in the experimental display and does not itself introduce extraneous cues.

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