Polarization scattering imaging experiment based on Mueller matrix

Polarimetry is today a widely used and powerful tool for nondestructive analysis of the structural and morphological properties of a great variety of material samples, including aerosols and hydrosols, among many others. For each given scattering measurement configuration, absolute Mueller polarimeters provide the most complete polarimetric information, intricately encoded in the 16 parameters of the corresponding Mueller matrix. Thus, the determination of the mathematical structure of the polarimetric information contained in a Mueller matrix constitutes a topic of great interest. In this work, besides a structural decomposition that makes explicit the role played by the diattenuation-polarizance of a general depolarizing medium, a universal synthesizer of Muller matrices is developed. This is based on the concept of an enpolarizing ellipsoid, whose symmetry features are directly linked to the way in which the polarimetric information is organized.

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Brain networks underlying the processing of sound symbolism related to softness perception

Scientific Reports ◽

10.1038/s41598-021-86328-6 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Ryo Kitada ◽

Jinhwan Kwon ◽

Ryuichi Doizaki ◽

Eri Nakagawa ◽

Tsubasa Tanigawa ◽

...

Keyword(s):

Inferior Frontal Gyrus ◽

Sensory Modality ◽

Brain Regions ◽

Sound Symbolism ◽

Matching Task ◽

Unique Contribution ◽

Superior Frontal Gyrus ◽

Symbolic Information ◽

Object Properties ◽

Imaging Experiment

AbstractUnlike the assumption of modern linguistics, there is non-arbitrary association between sound and meaning in sound symbolic words. Neuroimaging studies have suggested the unique contribution of the superior temporal sulcus to the processing of sound symbolism. However, because these findings are limited to the mapping between sound symbolism and visually presented objects, the processing of sound symbolic information may also involve the sensory-modality dependent mechanisms. Here, we conducted a functional magnetic resonance imaging experiment to test whether the brain regions engaged in the tactile processing of object properties are also involved in mapping sound symbolic information with tactually perceived object properties. Thirty-two healthy subjects conducted a matching task in which they judged the congruency between softness perceived by touch and softness associated with sound symbolic words. Congruency effect was observed in the orbitofrontal cortex, inferior frontal gyrus, insula, medial superior frontal gyrus, cingulate gyrus, and cerebellum. This effect in the insula and medial superior frontal gyri was overlapped with softness-related activity that was separately measured in the same subjects in the tactile experiment. These results indicate that the insula and medial superior frontal gyrus play a role in processing sound symbolic information and relating it to the tactile softness information.

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Optical Chirality Determined from Mueller Matrices

Applied Sciences ◽

10.3390/app11156742 ◽

2021 ◽

Vol 11 (15) ◽

pp. 6742

Author(s):

Hans Arwin ◽

Stefan Schoeche ◽

James Hilfiker ◽

Mattias Hartveit ◽

Kenneth Järrendahl ◽

...

Keyword(s):

Circular Dichroism ◽

Constitutive Relations ◽

Mueller Matrix ◽

Optical Path ◽

Electromagnetic Modeling ◽

Structural Effects ◽

Polarization Effects ◽

Optical Chirality ◽

Mueller Matrices ◽

Circular Dichroïsm

Optical chirality, in terms of circular birefringence and circular dichroism, is described by its electromagnetic and magnetoelectric material tensors, and the corresponding optical activity contributes to the Mueller matrix. Here, spectroscopic ellipsometry in the spectral range 210–1690 nm is used to address chiral phenomena by measuring Mueller matrices in transmission. Three approaches to determine chirality parameters are discussed. In the first approach, applicable in the absence of linear polarization effects, circular birefringence and circular dichroism are evaluated directly from elements of a Mueller matrix. In the second method, differential decomposition is employed, which allows for the unique separation of chirality parameters from linear anisotropic parameters as well as from depolarization provided that the sample is homogeneous along the optical path. Finally, electromagnetic modeling using the Tellegen constitutive relations is presented. The last method also allows structural effects to be included. The three methods to quantify optical chirality are demonstrated for selected materials, including sugar solutions, α-quartz, liquid crystals, beetle cuticle, and films of cellulose nanocrystals.

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