Degree Of Depolarization Research Articles

Quantum Tunneling-Induced Membrane Depolarization Can Explain the Cellular Effects Mediated by Lithium: Mathematical Modeling and Hypothesis.

Lithium imposes several cellular effects allegedly through multiple physiological mechanisms. Membrane depolarization is a potential unifying concept of these mechanisms. Multiple inherent imperfections of classical electrophysiology limit its ability to fully explain the depolarizing effect of lithium ions; these include incapacity to explain the high resting permeability of lithium ions, the degree of depolarization with extracellular lithium concentration, depolarization at low therapeutic concentration, or the differences between the two lithium isotopes Li-6 and Li-7 in terms of depolarization. In this study, we implemented a mathematical model that explains the quantum tunneling of lithium ions through the closed gates of voltage-gated sodium channels as a conclusive approach that decodes the depolarizing action of lithium. Additionally, we compared our model to the classical model available and reported the differences. Our results showed that lithium can achieve high quantum membrane conductance at the resting state, which leads to significant depolarization. The quantum model infers that quantum membrane conductance of lithium ions emerges from quantum tunneling of lithium through the closed gates of sodium channels. It also differentiates between the two lithium isotopes (Li-6 and Li-7) in terms of depolarization compared with the previous classical model. Moreover, our study listed many examples of the cellular effects of lithium and membrane depolarization to show similarity and consistency with model predictions. In conclusion, the study suggests that lithium mediates its multiple cellular effects through membrane depolarization, and this can be comprehensively explained by the quantum tunneling model of lithium ions.

Inhibitory effect of the selective serotonin reuptake inhibitor paroxetine on human Kv1.3 channels

Paroxetine is one of the most effective selective serotonin reuptake inhibitors used to treat depressive and panic disorders that reduce the viability of human T lymphocytes, in which Kv1.3 channels are highly expressed. We examined whether paroxetine could modulate human Kv1.3 channels acutely and directly with the aim of understanding the biophysical effects and the underlying mechanisms of the drug. Kv1.3 channel proteins were expressed in Xenopus oocytes. Paroxetine rapidly inhibited the steady-state current and peak current of these channels within 6 min in a concentration-dependent manner; IC50s were 26.3 μM and 53.9 μM, respectively, and these effects were partially reversed by washout, which excluded the possibility of genomic regulation. At the same test voltage, paroxetine blockade of the steady-state currents was higher than that of the peak currents, and the inhibition of the steady-state current increased relative to the degree of depolarization. Paroxetine decreased the inactivation time constant in a concentration-dependent manner, but it did not affect the activation time constant, which resulted in the acceleration of intrinsic inactivation without changing ultrarapid activation. Blockade of Kv1.3 channels by paroxetine exhibited more rapid inhibition at higher activation frequencies showing the use-dependency of the blockade. Overall, these results show that paroxetine directly suppresses human Kv1.3 channels in an open state and accelerates the process of steady-state inactivation; thus, we have revealed a biophysical mechanism for possible acute immunosuppressive effects of paroxetine.

Effect of elastic anisotropy on thermally induced distortions of a laser beam in single cubic syngony crystals with radial cooling. Part III

We report a study of thermally induced depolarisation of a laser beam in single cubic syngony crystals of 23 and m3 symmetry groups with an anisotropic elastic stiffness tensor. For active elements in the form of a long rod and a thin disk with radial cooling under uniform volume pumping, we investigate the effect of anisotropy of elastic properties on the dependence of the degree of depolarisation in the crystal on the orientation of the crystallographic axes, as well as on the position of the critical orientation in the crystallographic coordinate system.

Effect of elastic anisotropy on thermally induced distortions of a laser beam in single cubic syngony crystals with radial cooling. Part II

We report a study of thermally induced depolarisation of a laser beam in single cubic syngony crystals of 432, , and m3m symmetry groups with an anisotropic elastic stiffness tensor. For active elements in the form of a long rod and a thin disk with radial cooling under uniform volume pumping, we investigate the effect of anisotropy of elastic properties on the dependence of the degree of depolarisation in the crystal on the orientation of the crystallographic axes, as well as on the position of the critical orientation in the crystallographic coordinate system.

Study of colloidal gold nanorods in liquid dispersions using light scattering methods

Five samples of liquid dispersions of colloidal gold nanorods having various aspect ratios have been studied using light scattering methods. Transmission electron microscopy has been employed as a reference method. Advantages and drawbacks of dynamic light scattering and nanoparticle tracking analysis methods for study of nanoparticle geometrical parameters and concentration, sample monodispersity degree and detection of large particle aggregations and quasispherical impurities have been demonstrated. We show that depolarized dynamic light scattering method can be used for analysis of geometrical parameters of colloidal gold nanorods in liquid dispersions. The measurement results depend largely on the presence of large impurity particles or particle aggregations in samples. In turn the presence of large particles in dispersions can be detected using dynamic light scattering methods or nanoparticle tracking analysis. Dynamic light scattering method is more sensitive to the presence of even small quantities of large impurities or aggregations in samples. The monodispersity degree of nanorod liquid dispersions can also be assessed using dynamic light scattering and nanoparticle tracking analysis methods, and the measurement results can be considered more statistically significant in comparison with electron microscopy because a larger number of particles are analyzed. An increase in the concentration of spherical particles in compound dispersions of colloidal gold nanospheres and nanorods leads to a decrease in the contribution of the rotational mode to the overall scattering intensity. Data on the concentration of quasispherical impurities in samples of colloidal gold nanorod liquid dispersions have been reported on the basis of scattered light depolarization degree measurements.

Polarized Laser Backscattering of Atmospheric Cloud Distribution Based on Simulated Annealing Algorithm

Meteorological forecasting can not only reduce the losses caused by natural disasters to human society but also has a very important significance in the fields of water conservancy, aviation, and transportation. In order to improve the accuracy of meteorological forecasting, we should focus on the in-depth optical analysis of atmospheric cloud distribution. Compared with forward-scattered laser light, backscattered laser light can save more optical information. Therefore, this paper studies the backscattering of polarized laser light distributed in atmospheric clouds. In this study, a simulated annealing algorithm was used to invert the data of spaceborne lidar to obtain the depolarization degree and backscattering coefficient of atmospheric clouds and aerosols at different heights. Finally, based on the radar measurement example, the simulated annealing algorithm was used to analyze the atmospheric information of sunny, cloudy, and hazy weather in summer and winter, and the atmospheric depolarization and backscattering coefficients corresponding to different weather heights were obtained. The corresponding cloud layer type was judged. The research results prove the feasibility of the simulated annealing algorithm in the study of polarized laser backscattering in atmospheric cloud distribution. This study provides new ideas for radar data processing methods and provides a theoretical basis for further research in the field of meteorological forecasting.

Antimicrobial photodynamic inactivation with curcumin against Staphylococcus saprophyticus, in vitro and on fresh dough sheet

Photodynamic inactivation (PDI), as a new non-thermal decontamination and preservation technology, exhibits the advantages of low cost, free of residue and non-microbial resistance. Curcumin (CUR) as a natural photosensitizer could effectively inactivate food spoilage bacteria at an absorbance wavelength (420–470 nm) light illumination. In this study, the in vitro influence of PDI process parameters on the inactivation of Staphylococcus saprophyticus and the antimicrobial mechanism was analyzed. Approximate 5 log CFU/ml reduction was obtained when treated with 25 μM CUR and 4.32 J/cm2 of blue LED. Obvious cell wrinkles, cell membrane disruption, intracellular contents leakage and increased membrane permeability of S. saprophyticus cell were observed after CUR-PDI treatment. Further, generation of intracellular reactive oxygen species, along with decreased intracellular enzyme activities and increased degree of cell membrane depolarization verified cell damage. The in vivo photo-antibacterial effect (1.04 log CFU/g and 0.81 log CFU/g) was validated on fresh millet dough sheet at two initial bacterial loads (5 log CFU/g and 3 log CFU/g, respectively). These findings illustrated that CUR mediated PDI could be applied to inhibit S. saprophyticus growth and possibly prevent spoilage of fresh dough products.

Road Surface Recognition at mm-Wavelengths Using a Polarimetric Radar

We demonstrate detection of ice formations on a road surface using a polarimetric radar operating at 87.5-92.5 GHz. The radar measures the scattering parameters of the surface at horizontal and vertical polarizations and their cross-polarization components. We demonstrate detection of ice for radar beam directed at up to 45 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sup> angle of incidence with respect to the surface which allows for road surface characterization in front of a vehicle. The method used is based on a statistical approach where the 2-port scattering parameters are measured multiple times and used to calculate an average scatter coherence matrix representing the surface. The coherence matrix is then decomposed to eigenvalues/vectors, which are used to estimate polarimetric attributes such as target entropy(degree of randomness) and polarimetric pedestal (degree of depolarization). Through measurements of dry, ice-covered and wet road surfaces, we show that both entropy and depolarization are increased with respect to dry surface when a thin ice layer is formed, while their value decrease for the case of wet surface. It is also shown that these polarimetric attributes are not sensitive to surface roughness in dry conditions, minimizing the probability of false alarm due to road surface wear.

3D Mueller matrix mapping of layered distributions of depolarisation degree for analysis of prostate adenoma and carcinoma diffuse tissues

Prostate cancer is the second most common cancer globally in men, and in some countries is now the most diagnosed form of cancer. It is necessary to differentiate between benign and malignant prostate conditions to give accurate diagnoses. We aim to demonstrate the use of a 3D Mueller matrix method to allow quick and easy clinical differentiation between prostate adenoma and carcinoma tissues with different grades and Gleason scores. Histological sections of benign and malignant prostate tumours, obtained by radical prostatectomy, were investigated. We map the degree of depolarisation in the different prostate tumour tissues using a Mueller matrix polarimeter set-up, based on the superposition of a reference laser beam with the interference pattern of the sample in the image plane. The depolarisation distributions can be directly related to the morphology of the biological tissues. The dependences of the magnitude of the 1st to 4th order statistical moments of the depolarisation distribution are determined, which characterise the distributions of the depolarisation values. To determine the diagnostic potential of the method three groups of histological sections of prostate tumour biopsies were formed. The first group contained 36 adenoma tissue samples, while the second contained 36 carcinoma tissue samples of a high grade (grade 4: poorly differentiated—4 + 4 Gleason score), and the third group contained 36 carcinoma tissue samples of a low grade (grade 1: moderately differentiated—3 + 3 Gleason score). Using the calculated values of the statistical moments, tumour tissues are categorised as either adenoma or carcinoma. A high level (> 90%) accuracy of differentiation between adenoma and carcinoma samples was achieved for each group. Differentiation between the high-grade and low-grade carcinoma samples was achieved with an accuracy of 87.5%. The results demonstrate that Mueller matrix mapping of the depolarisation distribution of prostate tumour tissues can accurately differentiate between adenoma and carcinoma, and between different grades of carcinoma. This represents a first step towards the implementation of 3D Mueller matrix mapping for clinical analysis and diagnosis of prostate tumours.

Three-Dimensional Distribution Of Fundus Depolarization and Associating Factors Measured Using Polarization-Sensitive Optical Coherence Tomography.

PurposeTo investigate the three-dimensional distribution and associating demographic factors of depolarization, using polarization-sensitive optical coherence tomography (PS-OCT), to evaluate melanin pigmentation in the retinal pigment epithelium (RPE) and choroid in healthy eyes.MethodsIn total, 39 unaffected healthy eyes of 39 subjects were examined using a PS-OCT clinical prototype. The degree of depolarization, expressed as the polarimetric entropy, was assessed in the RPE, the superficial and the total choroid layer, especially in the center, the inner, or the outer areas centered at the fovea. The values and their association with the demographic data were analyzed. Near-infrared fundus autofluorescence (NIRAF) was also used, in the same manner, for the comparison. Twenty-eight of 39 eyes were measured twice to evaluate intrasession repeatability.ResultsBoth the polarimetric entropy in the RPE and the gray level in NIRAF, decreased from the center to the periphery (P < 0.001). The polarimetric entropy in the RPE was significantly associated with age in each area (P ≤ 0.001). In the RPE and the superficial choroid, the polarimetric entropy was negatively associated with axial length in each area (P ≤ 0.002). The intraclass correlation coefficient of the polarimetric entropy in the same session was excellent in each area of the RPE, superficial choroid, or total choroid layer (0.94–0.98).ConclusionsThe distribution of fundus melanin pigment-related depolarization was evaluated using PS-OCT. The depolarization was associated with the subjects’ demographic data, such as age or axial length.Translational RelevanceThe presented information in healthy eyes provides an essential basis for the investigation into a variety of chorioretinal pathologies.

Light depolarization based on dispersion degree of polarization.

The dispersion degree of polarization, a new definition of the depolarization degree of partially polarized beams, is first proposed, to the best of our knowledge, to measure the performance of fiber depolarizers. First, the description of the polarization based on the Poincaré sphere is introduced. Then, the modified Delaunay triangulation algorithm is introduced, and the calculation formula of the dispersion degree of polarization is given based on this algorithm. The experimental device was set up, and the dispersion degree of polarization of the depolarized light after the fiber depolarizer was measured to be 47.3%. The components and proportions of polarization in the depolarized light were also obtained. Compared with the degree of polarization, the dispersion degree of polarization can quantitatively analyze the light polarization evaluation in the time dimension and provide a numerical reference for improving the depolarizer, thus increasing the fiber sensor's accuracy.

Imaging of a retinal pigment epithelium aperture using polarization-sensitive optical coherence tomography.

To evaluate cases with a retinal pigment epithelium (RPE) aperture using polarization-sensitive optical coherence tomography (PS-OCT). Retrospective consecutive case series. A retrospective study that included three eyes (three patients) with RPE aperture and age-related macular degeneration (AMD) evaluated at the Macular Clinic in Tokyo University Hospital. A three-dimensional dataset of depolarization information was obtained with a clinical prototype of PS-OCT. All patients were categorized as intermediate AMD. RPE apertures were identified with PS-OCT as discontinuities of depolarization in the RPE layer of the pigment epithelial detachment (PED). A nonuniform decrease of depolarization in the RPE layer was also observed around the aperture. Two findings were observed above the aperture, intraretinal focal areas with high reflectivity and increased depolarization and subretinal bands with moderate reflectivity and low depolarization. Retinal sensitivity according to fundus microperimetry measured at 25 points was significantly associated with the degree of depolarization at the corresponding area (r-square = 0.60, p = 0.0001). The RPE aperture was characterized as a round discontinuity of depolarization. The findings with PS-OCT suggest atrophic changes in the overlying RPE of the PED. The degree of depolarization was associated with retinal sensitivity. The current results indicate that RPE apertures developed within the spectrum of atrophic AMD.

Stochasticity in radiative polarization of ultrarelativistic electrons in an ultrastrong laser pulse

Stochasticity effects in the spin (de)polarization of an ultrarelativistic electron beam during photon emissions in a counterpropoagating ultrastrong focused laser pulse in the quantum radiation reaction regime are investigated. We employ a Monte Carlo method to describe the electron dynamics semiclassically, and photon emissions as well as the electron radiative polarization quantum mechanically. While in the latter the photon emission is inherently stochastic, we were able to identify its imprints in comparison with the new developed semiclassical stochasticity-free method of radiative polarization applicable in the quantum regime. With an initially spin-polarized electron beam, the stochastic spin effects are seen in the dependence of the depolarization degree on the electron scattering angle and the electron final energy (spin stochastic diffusion). With an initially unpolarized electron beam, the spin stochasticity is exhibited in enhancing the known effect of splitting of the electron beam along the propagation direction into two oppositely polarized parts by an elliptically polarized laser pulse. The considered stochasticity effects for the spin are observable with currently achievable laser and electron beam parameters.

Characterization of healthy and cancerous human skin tissue utilizing Stokes–Mueller​ polarimetry technique

Characterizing polarization of skin pathologies is still an interested issue for the dermatology community. In a previous study, the present group proposed a Stokes–Muellermatrix polarimetry for differentiating between squamous cell carcinoma tissue and normal healthy tissue in mice. The present study extends our method to the detection of squamous cell carcinoma, basal cell carcinoma and melanoma skin cancer in humans. Using the proposed method, the orientation angle of linear birefringence (α), phase retardance (β), optical rotation angle of circular birefringence (γ), orientation angle of linear dichroism (θd), linear dichroism (D), circular dichroism (R), degrees of linear depolarization (e1 and e2), degree of circular depolarization (e3), and depolarization index (Δ) are extracted for 72 slices of 12 squamous cell carcinoma samples, 72 slices of 12 basal cell carcinoma samples, 18 slices of 3 melanoma skin cancer samples, and 36 slices of 6 healthy samples. The experimental results show that the cancerous tissue exhibits lower phase retardance (β) and linear dichroism (D) than healthy skin tissue. Overall, the proposed method provides a useful insight into the characterization optical properties of human skin cancer by Stokes–Mueller matrix polarimetry.

Study of colloidal dispersions of gold nanorods using light scattering methods

Five samples of colloidal dispersions of gold nanorods with various aspect ratio were studied using methods based on light scattering. Transmission electron microscopy was used as a reference method. The advantages and disadvantages of the dynamic light scattering and nanoparticle tracking analysis methods for determination of the geometric parameters of nanoparticles, their concentration, monodispersity, as well as for detection of large aggregates and quasispherical impurities were given. It was shown that the method of depolarized dynamic light scattering can be used for determination of the geometric parameters of liquid dispersions of colloidal gold nanorods. Moreover, it was found that the presence of large impurities or particle aggregates in the sample strongly affects the measurement results. The presence of large particles in the dispersion can be determined using dynamic light scattering or nanoparticle tracking analysis methods. The method of dynamic light scattering was also found to be more sensitive to the presence of even a small amount of large impurities or aggregates in the sample. The monodispersity of a liquid dispersion of nanorods can also be estimated by dynamic light scattering and nanoparticle tracking analysis methods, and, comparing to electron microscopy, the measurement results can be considered more statistically reliable due to the analysis of a larger number of particles. It was found that the increase of spherical particles concentration in the composite dispersion of nanospheres and nanorods leads to a decrease in the contribution of the rotational mode in the total scattering intensity. In addition, the concentration of quasispherical impurities in samples of liquid dispersions of colloidal gold nanorods was calculated based on measurements of the depolarization degree of scattered light.

Evaluating β-amyloidosis progression in Alzheimer's disease with Mueller polarimetry.

We applied the wide-field Mueller imaging polarimetry for the screening of formalin-fixed paraffin-embedded samples of mouse brain tissue at different stages of brain β-amyloidosis in Alzheimer's disease (AD). The accumulation of amyloid-beta (Aβ) deposits throughout the brain tissue is one of the key pathological hallmarks observed with the AD progression. We demonstrate that the presence of Aβ plaques influences the properties of backscattered polarized light, in particular, its degree of depolarization. By means of statistical analysis, we demonstrate that the high-order statistical moments of depolarization distributions, acquired with the multi-spectral Mueller imaging polarimetry, can be used as sensitive markers of the growing presence of Aβ plaques. The introduced label-free polarimetric approach has a potential to facilitate the current practice of the histopathology screening in terms of diagnosis accuracy, time and cost efficiency.

Suppression of Speckle Noise in Digital Holography With Spatial and Temporal Domain Depolarization

Speckle noise in digital holography has a great influence on image quality, and one of the reasons for the formation of speckle noise is that the degree of coherence for the reference light and the object light is too high and unnecessary noise is introduced to the recorded hologram. In this paper, the spatial depolarization and the temporal domain depolarization are analyzed to reduce the speckle noise. The spatial depolarization utilizes the depolarization performance of the depolarizer. By adding a quartz depolarizer to the object light, the linearly polarized light in the object light becomes randomly polarized light, thereby reducing the degree of coherence with the reference light, realizing the suppression of speckle noise, and by utilizing the characteristics of pupil parameters towards the depolarization degree, it is to realize the control for the degree of coherence. The temporal domain depolarization uses two quarter-wave plates and adjustable liquid crystal to realize the depolarization superposition. By controlling the phase delay of the liquid crystal phase variable retarder, the multi-depolarization accumulation in a short time is realized, and the experimental results show that this method preserves the detail portion of the image while better removing speckle noise. Finally, the Non-Local Means filtering algorithm is used to make the reconstructed image smoother. The method proposed in this paper has great applicable value for improving the image quality of digital holography system.

Structure and Physicochemical Properties of Acetonitrile–o-Dichlorobenzene Solutions

Based on an analysis of concentration dependences of the degree of depolarization and molecular light scattering coefficients, density, ultrasound speed, adiabatic compressibility, excess molar volume and adiabatic compressibility in acetonitrile–о-dichlorobenzene solutions, three ranges with different structures are distinguished: 0–0.2, 0.2–0.9, and 0.9–1.0. Molecular dynamics modeling is performed in each range to obtain a detailed description of the structure of the solutions. It is found that in the first range, the solvation of acetonitrile molecules is accompanied by the local reorientation of о-dichlorobenzene molecules from mainly parallel to mainly perpendicular arrangement. The acetonitrile molecules fall into less dense regions of the о-dichlorobenzene structure and are incorporated into the system of its nonvalent contacts. The second range is the region of the maximum heterogeneity of the solutions, in which an important role is played by both homo- and heteromolecular interactions, and there are agglomerates and conglomerates of the molecules of both components. In the third range, о-dichlorobenzene molecules are solvated, and the mechanism differs from that of the solvation of acetonitrile: о-dichlorobenzene weakly affects the acetonitrile structure and its structure remains virtually unchanged.

Characterization of optical parameters of breast cancercell line - BT474 by polarimetry technique

Breast cancer is a well-known health issue that has been a major focus for healthcare professionals for quite some time. Still, the most common noninvasive diagnostic tool - mammography - results in a high false positive rate along with risks of exposure to radiation. These disadvantages are magnified and become more severe when screenings are done repeatedly. To tackle this problem, we introduce a novel framework for uncomplicated diagnosis of breast cancer. Our method utilizes the analytical technique of Mueller matrix decomposition and Stokes vector polarimetry from a polarized light system consisting of a helium-neon laser (wavelength of 632.5 nm), a quarter-wave plate, polarizers, and a Stokes polarimeter. Thus, this technique introduces no radiation. We extracted nine optical parameters of a breast cancer cell line - BT474 - and determined the relationshipand separation power of these parameters to cancerous cells and healthy cells. Specifically, the samples were designed as a two-dimensional cellular model of malignant breast tumours that combined a range of four cell densities - 104, 105, 106, and 107 cells - per an area of 9 cm2.Nine optical parameters - orientation angle of linear birefringence (α), retardance or linear birefringence (β), optical rotation angle or circular birefringence (γ), orientation angle of linear dichroism (θd), linear dichroism (D), circular dichroism (R), degrees of linear depolarization (e1 and e2), and degree of circular depolarization (e3) - were extracted from a total of 40 samples using the polarized light system. The results revealed the positive correlations between three cell densities (104, 105, and 106) and the orientation angle of linear birefringence (R2 = 0.8038), linear birefringence (R2 = 0.8627), and linear dichroism (R2 = 0.9662). Meanwhile, both the orientation angle of linear dichroism and circular dichroism illustrated the negative correlation with that range of cell densities with R2 = 0.9983 and 0.9447, respectively. This proves that the optical parameters measured demonstrate significant association with the cells’ characteristics and thus, the proposed method could pave the way for an accessible diagnosis of breast cancer.

Compensation for Laser Beam Depolarization by Spatial Light Modulators

We propose a new method for compensating the thermally induced depolarization of laser radiation, which is based on using spatial light modulators. It is shown that using one modulator, the integral depolarization degree can be reduced by several times, whereas two modulators make it possible to almost completely rule out depolarization, regardless of its nature. The phase front of the laser beam is analyzed and it is shown that this phase front remains qualitatively unchanged when depolarization is compensated by one modulator, while in the case of compensation by two modulators the phase nonuniformity decreases, which leads to an increase in the far-field intensity.