Depolarization Index Research Articles

Clear imaging method for underwater targets based on the second Lorentz depolarization index

Underwater target information is submerged in background scattered light due to the scattering effect of suspended particles in turbid water. In order to improve the quality of target imaging in turbid water, this paper proposes a method for achieving clear underwater target imaging using the second Lorentz depolarization index based on a dual division of focal plane Mueller matrix imaging system. This method can directly quantify the attenuation of light in water, and then solve a clear image of the target. Experimental results on underwater targets of different materials (plastic, paper, metal) show that the method proposed can effectively remove background scattering light while enhancing image contrast, ultimately improving the imaging quality of targets in turbid water.

Mueller matrix polarimetry approach for noninvasive glucose sensing with absorbance and anisotropic parameters on fingertips.

A Mueller matrix polarimetry system at 532 nm wavelength is developed for noninvasive glucose sensing in turbid media such as human's fingertip. The system extracts mean absorbance and anisotropic properties, demonstrated numerically and experimentally with phantom glucose samples. It is found that mean absorbance ( ), depolarization index (Δ), and linear dichroism (LD) show linear variation with glucose concentration 100-500 mg/dL. In addition, LightTools simulations indicate proportional scaling of scattering effects with , Δ, and LD. Real-world tests on fingertip show a strong correlation between these properties and blood glucose levels with a mean absolute relative deviation (MARD) of 12.56% and a correlation coefficient (R2) of 0.875 in prediction by a neural network (NN) model, highlighting the advantages of Mueller matrix in extracting more parameters related to blood glucose.

Gold nanoparticle-based biosensor for Lysozyme-DNA detection utilizing decomposition Mueller matrix polarimetry

Lysozyme serves as a crucial biomarker in the identification of several diseases, that includes breast cancer, Alzheimer’s disease, meningitis, and rheumatoid arthritis. This study proposes an innovative method for the detection of Lysozyme using a gold nanoparticle based biosensor and decomposition Muller matrix polarimetry. In the proposed study, the DNA aptamer is used as the recognition element, while the gold nanoparticles are used as a sensing element. The sensed signal is taken as the input to a Mueller matrix calculation process, which determines three optical characteristics that yield optimal results of the gold nanoparticle colloidal solution, namely the degree of depolarization, the linear diattenuation, and the depolarization index. The results have shown that all three optical parameters vary linearly with the concentration of Lysozyme throughout a broad dynamic range spanning from 0.01 to 500 pM with a limit of detection of 1.24 fM. Overall, the proposed technique provides potential tool for the detection of Lys.

Characterization of polarization properties of colorectal cancer using decomposition Mueller matrix method

Rectal cancer is the third most prevalent cancer diagnosed and is traditionally screened using colonoscopy. Meanwhile, polarization characteristic measurement has emerged as an attractive alternative in recent years owing to its deep analysis of the structure of samples and non-invasive nature. Accordingly, this study employed the Mueller matrix decomposition method to measure the effective optical parameters of 100 slices from 20 healthy rectal tissue samples and 100 slices from 20 cancerous rectal tissue samples. The mean values and expression levels of the linear birefringence, circular birefringence, linear dichroism, circular dichroism, and depolarization index properties of the samples were compared using t-tests and ANOVA tests. The experimental results showed that the linear birefringence, orientation angle of linear dichroism, and values of linear dichroism and circular dichroism showed significant differences between the different tissue types. Thus, these parameters may serve as useful biomarkers for the diagnosis of rectal cancer.

Alleviating negative group polarization with the aid of social bots

When group polarization is combined with intense negative emotions, it can have detrimental consequences such as online and offline riots. To address this issue, this paper proposes a framework called MNGP (Mitigating Negative Group Polarization) that utilizes both human guidance and social robot assistance. MNGP comprises three main modules: data collection, data mining, and robot embedding. In the data collection module, relevant data capturing group polarization with negative emotions is collected, filtered, and stored. Subsequently, in the data mining module, user and comment characteristics that can help mitigate group polarization are extracted using a novel depolarization index. Finally, in the robot embedding module, a set of social bots are deployed to emulate these characteristics and post neutral or positive comments under manual supervision. Experimental results demonstrate that, over a span of 28 days, with the assistance of 20 social bots across four topics, there were a total of 1039 user interactions and 2349 comments received. Furthermore, the presence of social bots led to a 20 percent reduction in group polarization compared to scenarios where no bots were utilized.

Estimation of Medium Depolarization Index with Noise Immunity in Catheter-Based PS-OCT toward Vascular Plaques Detection.

Medium depolarization imaging by catheter-based polarization-sensitive optical coherence tomography (PS-OCT) can provide valuable insight into significant features of lipid, macrophages, and cholesterol crystals in atherosclerotic vulnerable plaques. In this paper, we demonstrate a method to achieve an accurate estimation of the medium depolarization index (EMDI) with noise immunity in catheter-based PS-OCT. EMDI is calculated by an iterative approximation based on Lu-Chipman matrix decomposition and Frobenius norm judgment of incoherent averaging of Mueller matrices. Monte Carlo simulation results verify that the medium depolarization measurement by EMDI is 3.3 times more accurate compared with those of the depolarization index (DI) and degree of polarization uniformity (DOPU). In experiments, we design a microsphere suspension with various concentrations and measure EMDI under different additive noise. Consistently, the measurement accuracy by EMDI is increased 2.85 times compared to those by DI and DOPU. For vascular plaques detection, we use protein and cholesterol gel as plaque phantoms. Based on PS-OCT images of plaque phantom in vitro and in ex vivo porcine coronary artery, the recognition rate of plaque by EMDI is 2.99 to 4.65 times higher than those by DI and DOPU evaluated by spatial response of the Laplacian operator (SRLO).

Mueller-Polarimetry of Barley Leaves I: Depolarization Metrics

In this paper, Mueller polarimetry is applied to study the three groups of common barley leaf samples (Hordeum vulgare) in the visible spectrum (λ = 632.8 nm): Chlorina mutant, Chlorina etiolated mutant and Cesaer varieties. These samples differed in internal leaf structure from genetic mutation or by illumination during growth. Our main concern is to discriminate and characterize these three groups of leaf samples by depolarization metrics: degree of polarization (DoP), average degree of polarization (Average DoP), depolarization index (DI(M)), and Q(M) and R(M) metrics. The results obtained show that all depolarization metrics are sensitive to the sample’s polarization properties. The most effective observable is the Q(M) metric in both forward and backward scattering. The DoP metric showed presence of depolarization anisotropy, which is significantly different for forward and backward scattering for all three groups of samples. Dichroism is observed for both forward and backward scattering, with lower dichroism in forward scattering.

Skin cancer detection using effective optical parameters and the classification and regression tree algorithm: A novel framework

Early detection of skin cancer matters because diagnosis, prognosis and treatment plan differ for each skin cancer type at their stages. Medical imaging taking the advantages of the non-invasive and non-ionizing polarized light is emerging as a tool for the development of screening and diagnotic tests. In this work, we proposed a novel framework to classify human melanoma and nonmelanoma skin cancer using the Classification and Regression Tree algorithm (CART). The samples were prepared from twenty-four non-melanoma skin cancer samples (consisting of twelve squamous cell carcinoma and twelve basal cell carcinoma samples); and three melanoma skin cancer samples. We calculated ten optical parameters from anisotropic biological tissues, namely the LB orientation angle (α), the LB phase retardance (β), the CB optical rotation angle (γ), the LD orientation angle (θd), the linear dichroism (D), the circular dichroism (R), the degrees of linear depolarization (e1 and e2), the degree of circular depolarization (e3), and the depolarization index (∆) using Stokes-Mueller matrix formalism. All effective optical parameters of biological tissue were then input into the CART classifier as predictors. The model yielded an accuracy of 92.6%, which is desirable for any robust and interpretable classification model. The results showed that for biological tissue samples, linear polarization properties dominate over circular ones due to the cellular microstructural composition of tissue, especially under anomalous growth as seen in skin cancer. This novel framework can potentially assist physicians in making timely and well-informed medical decisions.

Depolarizing metrics in the biomedical field: Vision enhancement and classification of biological tissues

Polarimetry encompasses a collection of optical techniques broadly used in a variety of fields. Nowadays, such techniques have provided their suitability in the biomedical field through the study of the polarimetric response of biological samples (retardance, dichroism and depolarization) by measuring certain polarimetric observables. One of these features, depolarization, is mainly produced by scattering on samples, which is a predominant effect in turbid media as biological tissues. In turn, retardance and dichroic effects are produced by tissue anisotropies and can lead to depolarization too. Since depolarization is a predominant effect in tissue samples, we focus on studying different depolarization metrics for biomedical applications. We report the suitability of a set of depolarizing observables, the indices of polarimetric purity (IPPs), for biological tissue inspection. We review some results where we demonstrate that IPPs lead to better performance than the depolarization index, which is a well-established and commonly used depolarization observable in the literature. We also provide how IPPs are able to significantly enhance contrast between different tissue structures and even to reveal structures hidden by using standard intensity images. Finally, we also explore the classificatory potential of IPPs and other depolarizing observables for the discrimination of different tissues obtained from ex vivo chicken samples (muscle, tendon, myotendinous junction and bone), reaching accurate models for tissue classification.

Characterization of vine, Vitis vinifera, leaves by Mueller polarimetric microscopy

In this work, we present the study of vine leaves, Vitis vinifera, performed by imaging polarimetry in the visible (at the wavelength of 530 nm). The purpose is to demonstrate, on a case study example, the high potential of imaging polarimetry and of polarimetric microscopy, in particular, for the characterization of vegetal tissues. The analysis of the Mueller matrix image of the sample provided by the polarimetric microscope by means of a matrix decomposition protocol yields a series of observables that are directly related to the fundamental physical properties that characterize the sample. Birefringence and dichroism are related to the structural properties of the medium and can be advantageously used as non-chemical, non-contact, non-destructive and non-toxic markers to highlight the presence of specific structures in the probed sample. Polarimetric images may also be used to enhance the contrast of the measured images. Specifically, we use the polarimetric properties and the depolarization indices to unveil the presence of structures such as raphides, some of them invisible under non-polarized light, and to investigate their properties.

A novel receptor-interacting protein-1 (RIP1) inhibitor (547) protects human cardiac cells from ischemia/reperfusion-triggered necroptotic cell death

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): M.M.C.P. is supported by a Netherlands Cardiovascular Research Initiative (CVON) grant (REMAIN 2014B27) and J.P.G.S is supported by Horizon2020 ERC-2016-COG-EVICARE [725229] and BRAVE (grant number 874827. Purpose Restoring perfusion, either by coronary angioplasty or bypass anastomosis, is performed around 2 million times per year throughout Europe to treat patients after myocardial infarction. Although this treatment is highly efficient to resolve myocardial ischemia, reperfusion is accompanied by damage through the release of reactive oxygen species (ROS). This ischemia/reperfusion (I/R) injury is manifested by cardiomyocyte death, caused to a certain extent by necroptosis. As a potential means of cardioprotection, we applied the small molecule compound 547 inhibiting RIP1-kinase, a central mediator of the necroptosis pathway, in an in vitro model of human cardiac I/R injury. Methods Human foetal cardiomyocyte progenitor cells (hfCPCs) were cultured and characterized for cell type defining markers before being subjected to simulated I/R damage using hydrogen peroxide (H2O2). Cardioprotective effects of 547 were assessed 24 hours after induction of damage and application of the compound. Cell viability and necroptosis pathway activation were assessed by flow cytometry, immunocytochemistry, and western blotting. Furthermore, mitochondrial damage was determined by JC-1 staining. Results hfCPCs expressed indicative markers SCA1, GATA4, PECAM-1, VEGF and C-KIT. Treatment with compound 547 significantly protected hfCPCs from H2O2 induced damage (viable cells: 84,3 ± 4,3% vs 1,6 ± 0,31%; P<0,0001). 547 decreased the necrotic cell population (DAPI+ AnnV-) (3,0 ± 1,1% vs 10,1 ± 1,5%, P<0,0001) and reduced phosphorylation of necrosome components RIP1 (1,3 ± 0,35 fold vs 3,7 ± 0,78 fold; P< 0,01), RIP3 (1,0 ± 0,46 fold vs 4,3 ± 1,5 fold; P< 0,05), and MLKL (1,1 ± 0,15 fold vs 5,7 ± 1,7 fold; P< 0,01) without decreasing unphosphorylated protein or mRNA levels. Interestingly, 547 treatment prevented oxidative stress induced loss of nuclear RIP1 and RIP3 as measured by immunocytochemistry and western blotting of cell fractions (nuclear/cytoplasmic ratio RIP1: 0,80 ± 0,0006 [Control] vs 1,5 ± 0,17 fold [547]; P< 0,01; nuclear/cytoplasmic ratio RIP3: 0,76 ± 0,10 [Control] vs 1,6 ± 0,18 fold [547]; P< 0,01). Remarkably, compound 547 also decreased H2O2–induced mitochondrial depolarization (JC-1 staining/membrane depolarization index: 4,5 ± 0,85% vs 1,2 ± 0,38%; P< 0,05)) and expression and activation of CAMKII (0,46 ± 0,13 fold; P<0,01), a protein mediating mitochondria-dependent cell death. Conclusions Administration of compound 547 led to inhibition of necroptosis, increased cell viability and reduced mitochondrial damage in an in vitro human cardiac I/R injury model, emphasizing the potential of necroptosis inhibition for cardioprotection. Assessing clinical applicability will require further studies in relevant in vivo models.

Depolarization index from Mueller matrix descatters imaging in turbid water

Polarization underwater imaging is of great potential to target detection in turbid water. Typical methods are challenged by the requirement on degrees of polarization (DoPs) of both target light and backscattering. A polarization descattering imaging method was developed using the Mueller matrix, which in turn derived a depolarization (Dep) index from the Mueller matrix to characterize scattering media by estimating the transmittance map by combining a developed optimal function. By quantifying light attenuation with the transmittance map, a clear vision of targets can be recovered. Only using the information of scattering media, the underwater vision under diverse water turbidity was enhanced by the results of experimental data.

Mueller matrix imaging polarimetry technique for dengue fever detection

Dengue fever is one of the most common diseases in tropical and sub-tropical regions of the world, and has a variety of unpleasant and painful symptoms, including fever, bleeding, and even death. Thus, effective methods for its early-stage detection and diagnosis are urgently required. Accordingly, the present study proposes a method for detecting dengue virus through an inspection of the anisotropic polarization properties of blood serum samples, as measured using a backscattering polarimetry technique and Mueller matrix imaging method. The feasibility of the proposed approach is demonstrated using 31 real-world blood samples comprising 17 dengue-infected samples and 14 healthy non-dengue samples. It is shown that the values of the diagonal elements of the Mueller matrix for the non-dengue samples are significantly higher than those for the dengue samples. By contrast, the depolarization index of the dengue samples is higher than that of the non-dengue samples. Moreover, among the four Mueller matrix transformation (MMT) parameters considered in the present study (A, B, T and G), three of them (A, B and T) exhibit significant differences between the non-dengue and dengue samples, respectively. Thus, overall, the results indicate that the proposed method has significant potential as a rapid, low-cost, and effective technique for dengue fever diagnosis applications.

Mueller-polarimetry of soil and vegetation in the visible I: Depolarization metrics

In this paper the Mueller polarimetry is applied to study the four natural samples in visible (λ = 632.8 nm): soil, sand, clay and moss. To quantify separability of these samples based on their Mueller matrices we analyze their experimental Mueller matrices by calculating a number of single value depolarization metrics (degree of polarization, average degree of polarization, depolarization index, Q(M)-metric) for each sample in in-plane and out-of-plane geometry of experiment. The results obtained show that all depolarization metrics are sensitive to the sample's polarization properties. The most effective identifier is Q(M)-metric in both experimental geometry.

Depolarization Characteristics of Different Reflective Interfaces Indicated by Indices of Polarimetric Purity (IPPs).

Compared with the standard depolarization index, indices of polarimetric purity (IPPs) have better performances to describe depolarization characteristics of targets with different roughnesses of interfaces under different incident angles, which allow us a further analysis of the depolarizing properties of samples. Here, we use IPPs obtained from different reflective interfaces as a criterion of depolarization property to characterize and classify targets covered by organic paint layers with different roughness. We select point-light source as radiation source with wavelength as 632.8 nm, and four samples, including Cu, Au, Al and Al2O3, covered by an organic paint layer with refractive index of n = 1.46 and Gaussian roughness of α = 0.05~0.25. Under different incident angles, the values of P1, P2, P3 at divided 90 × 360 grid points and their mean values in upper hemisphere have been obtained and discussed in the IPPs space. The results show that the depolarization performances of the different reflective interfaces (materials, incident angles and surface roughness) are unique in IPPs space, providing us with a new avenue to analyze and characterize different targets.

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.

Comparing Classification Performance of Mueller Matrix Parameters for Diffuse Materials

This work compares the material classification performance of Mueller matrix polarization imaging to RGB imaging. White painted wood and white fabric samples are selected to create a classification task that is challenging for RGB imaging. A Mueller Matrix Imaging Polarimeter with a 30° full field of view is used to capture the Mueller Matrix images at nominal red, green, and blue wavelengths across multiple specular scatter angles. A Bayesian ideal observer model is used to evaluate classification performance. Performance is quantified by the Area under (AUC) the Receiver Operating Characteristic (ROC) curve. An AUC = 1 is perfect detection and AUC = 0.5 is the performance of guessing. The ensemble average AUC does not exceed 0.70 for RGB irradiance data. The ensemble average AUC for all 16 individual Mueller elements is greater than 0.95. Various combinations of Mueller matrix elements are also tested. Elements related to diattenuation and polarizance are nearly perfect classifiers for large scatter angles but the AUC minimum is 0.60 at 20°. Depolarization index is the highest performing parameter out of all tested polarization parameters for scatter angles ≥70° where AUC ≥0.98.

Cortical Spreading Depression Phenomena Are Frequent in Ischemic and Traumatic Penumbra: A Prospective Study in Patients With Traumatic Brain Injury and Large Hemispheric Ischemic Stroke.

Spreading depolarization (SD) phenomena are waves of neuronal depolarization, which propagate slowly at a velocity of 1 to 5 mm/minute and can occur in patients with ischemic or hemorrhagic stroke, traumatic brain injury, and migraine with aura. They form part of secondary injury, occurring after spreading ischemia. The purposes of this study were to describe the frequency and characteristics of SD phenomena and to define whether a correlation existed between SD and outcome in a group of patients with TBI and large hemispheric ischemic stroke. This was a prospective observational study of 39 adult patients, 17 with malignant middle cerebral artery infarction and 22 with moderate or severe traumatic brain injury, who underwent decompressive craniectomy and multimodal neuromonitoring including electrocorticography. Identification, classification, and interpretation of SDs were performed using the published recommendations from the Cooperative Study on Brain Injury Depolarization group. The outcomes assessed were functional disability at 6 and 12 months after injury, according to the extended Glasgow outcome scale, Barthel index, and modified Rankin scale. Four hundred eighty-three SDs were detected, in 58.9% of the patients. Spreading depolarizations were more common, particularly the isoelectric SD type, in patients with malignant middle cerebral artery infarction (P < 0.04). In 65.21% of patients with SDs on electrocorticography, the "peak" day of depolarization was day 0 (the first 24 hours of recording). Spreading depolarization convulsions were present in 26.08% of patients with SDs. Patients with more SDs and higher depolarization indices scored worse on extended Glasgow outcome scale (6 months) and Barthel index (6 and 12 months) (P < 0.05). Evidence on SD phenomena is important to ensure continued progress in understanding their pathophysiology, in the search for therapeutic targets to avoid additional damage from these secondary injuries.

Scattering mechanism-based decomposition model for depolarization

As a common phenomenon caused by light-matter interactions, depolarization is a hot topic in polarized optics and statistical optics. Based on scattering mechanism, a Mueller matrix decomposition approach is proposed to detail and enrich the depolarization information of surface scattering. On the basis of the superposition of four basic scattering mechanisms, two parameters (diagonal scattering depolarization coefficient (DSDC) and cross scattering depolarization coefficient (CSDC)) are deduced to represent the effect of scattering superposition on depolarization. Further, the relationship between these two parameters and depolarization index is established to amplify the depolarization difference between different materials, making depolarization information more useful in distinguishing different materials. Through the experiments in two cases (distinguishing man-made camouflage material and natural object; distinguishing oil film on water surface), it is verified that DSDC and CSDC have excellent effect in distinguishing the depolarization of different materials. The work in this paper is promoting in the study of depolarization.

Preconditioning hippocampal slices with hypothermia promotes rapid tolerance to hypoxic depolarization and swelling: Mediation by erythropoietin

We suggested previously that hippocampal slices were protected from hypoxic depolarization and swelling by preincubating them at room temperature (Kreisman et al., 2000). We postulated that hypothermic preconditioning induced tolerance in our slices, which protected against hypoxic depolarization and swelling. Control hippocampal slices were incubated at 34–35 °C for two hours and the response to 10 min of severe hypoxia was compared to slices which were preconditioned for two hours at room temperature (22–23 °C) prior to warming to 34–35 °C. Recordings of the extracellular DC potential provided an index of tissue depolarization and changes in tissue light transmittance provided an index of swelling. Hypothermic preconditioning significantly reduced hypoxia-induced swelling, particularly in CA3 and the dentate inner blade. Since erythropoietin (EPO) had been shown to mediate hypoxic preconditioning, we tested whether EPO also mediated hypothermic preconditioning in our slices. Recombinant rat EPO (1–10 micromolar) mitigated hypoxia-induced swelling and depolarization in dentate inner blade of unconditioned slices in a dose-dependent manner. We also blocked the protective effects of hypothermic preconditioning on hypoxic depolarization and swelling in the inner blade of the dentate gyrus by administering soluble EPO receptor in the bath and treating slices with wortmannin to block phosphorylation of PI3 kinase, a critical step in the activation of the downstream neuroprotectant, Akt. These results suggest that EPO mediates tolerance to hypoxic depolarization and swelling induced by hypothermic preconditioning. They also emphasize that various preincubation protocols used in experiments with hippocampal slices may differentially affect basal electrophysiological and metabolic properties of those slices.