Polarimetry has a long and successful history in various forms of clear media. Driven by their biomedical potential, the use of the polarimetric approaches for biological tissue assessment has also ...recently received considerable attention. Specifically, polarization can be used as an effective tool to discriminate against multiply scattered light (acting as a gating mechanism) in order to enhance contrast and to improve tissue imaging resolution. Moreover, the intrinsic tissue polarimetry characteristics contain a wealth of morphological and functional information of potential biomedical importance. However, in a complex random medium-like tissue, numerous complexities due to multiple scattering and simultaneous occurrences of many scattering and polarization events present formidable challenges both in terms of accurate measurements and in terms of analysis of the tissue polarimetry signal. In order to realize the potential of the polarimetric approaches for tissue imaging and characterization/diagnosis, a number of researchers are thus pursuing innovative solutions to these challenges. In this review paper, we summarize these and other issues pertinent to the polarized light methodologies in tissues. Specifically, we discuss polarized light basics, Stokes-Muller formalism, methods of polarization measurements, polarized light modeling in turbid media, applications to tissue imaging, inverse analysis for polarimetric results quantification, applications to quantitative tissue assessment, etc.
Plasmonic gold nanorods (GNRs) are finding increasing use in biomedicine due to their unique electromagnetic properties, optical contrast enhancement and biocompatibility; they also show promise as ...polarization contrast agents. However, quantification of their polarization-enhancing properties within heterogeneous turbid media remains challenging. We report on polarization response in controlled tissue phantoms consisting of dielectric microsphere scatterers with varying admixtures of GRNs. Experimental Mueller matrix measurements and polarization sensitive Monte-Carlo simulations show excellent agreement. Despite the GNRs' 3D random orientation and distribution in the strong multiply scattering background, significant linear diattenuation and retardance were observed. These exclusive measurable characteristics of GNRs suggest their potential uses as contrast enhancers for polarimetric assessment of turbid biological tissue.
Extracting information-bearing signal from a noisy environment has been a practical challenge in both classical and quantum computing formalism, especially in critical signal processing applications. ...To filter out the effect of noise, we propose a quantum smoothing filter built upon quantum formalism-based circuits applied for electrocardiogram signal denoising. The proposed quantum filter is a conceptually novel framework with an advantage in computational complexity as compared to the existing classical filters, such as discrete wavelet transform and empirical mode decomposition, whereas it achieves similar performance metrics for the accuracy of the filter. Further, we exploit the penta-diagonal Toeplitz structure of the smoothing filter, which gives approximately
gate cost reduction for 10 qubit circuit compared to the standard Hamiltonian simulation without structure. The run-time complexity using the quantum matrix inversion technique for the structured matrix is given by
for condition number
of the
filter matrix within precision
. Embedding fixed sparsity of the banded matrix, the quantum filter shows potentially better run-time complexity than classical filtering techniques. For the quantifiable research results of our work, we have shown several performance metrics, such as mean-square error and peak signal-to-noise ratio analysis, with a bound of error due to observation noise, simulation error and quantum measurement uncertainty.
A number of tissue-like disordered media exhibit local anisotropy of scattering in the scaling behavior. Scaling behavior contains wealth of fractal or multifractal properties. We demonstrate that ...the spatial dielectric fluctuations in a sample of biological tissue exhibit multifractal anisotropy. Multifractal anisotropy encoded in the wavelength variation of the light scattering Mueller matrix and manifesting as an intriguing spectral diattenuation effect. We developed an inverse method for the quantitative assessment of the multifractal anisotropy. The method is based on the processing of relevant Mueller matrix elements in Fourier domain by using Born approximation, followed by the multifractal analysis. The approach promises for probing subtle micro-structural changes in biological tissues associated with the cancer and precancer, as well as for non-destructive characterization of a wide range of scattering materials.
Linear birefringence and optical activity are two common optical polarization effects present in biological tissue, and determination of these properties has useful biomedical applications. However, ...measurement and unique interpretation of these parameters in tissue is hindered by strong multiple scattering effects and by the fact that these and other polarization effects are often present simultaneously. We have investigated the efficacy of a Mueller matrix decomposition methodology to extract the individual intrinsic polarimetry characteristics (linear retardance
and optical rotation
, in particular) from a multiply scattering medium exhibiting simultaneous linear birefringence and optical activity. In the experimental studies, a photoelastic modulation polarimeter was used to record Mueller matrices from polyacrylamide phantoms having strain-induced birefringence, sucrose-induced optical activity, and polystyrene microspheres-induced scattering. Decomposition of the Mueller matrices recorded in the forward detection geometry from these phantoms with controlled polarization properties yielded reasonable estimates for
and
parameters. The confounding effects of scattering, the propagation path of multiple scattered photons, and detection geometry on the estimated values for
and
were further investigated using polarization-sensitive Monte Carlo simulations. The results show that in the forward detection geometry, the effects of scattering induced linear retardance and diattenuation are weak, and the decomposition of the Mueller matrix can retrieve the intrinsic values for
and
with reasonable accuracy. The ability of this approach to extract the individual intrinsic polarimetry characteristics should prove valuable in diagnostic photomedicine, for example, in quantifying the small optical rotations due to the presence of glucose in tissue and for monitoring changes in tissue birefringence as a signature of tissue abnormality.
Abstract
The extraordinary concept of weak value amplification can be formulated within the realm of wave interference as nearly destructive interference between the eigenstates of the measuring ...observable. Here we report on a phenomenon of interferometric weak value amplification of small polarization rotation in Fano resonance that evolves completely
naturally
due to near destructive spectral domain interference between a continuum and a narrow resonance mode having slightly different polarization response. In order to elucidate this, we first experimentally demonstrate an interferometric weak value amplification concept by generating nearly destructive interference of two paths of an interferometer having slightly rotated linear polarization states of light. The weak value amplification of polarization rotation effect is manifested as dramatic changes in the polarization state of light, which acts as the pointer. We go on to demonstrate that the manifestation of natural interferometric weak value amplification is an important contributing factor to the observed giant Faraday rotation and ellipticity in waveguided magneto-plasmonic crystals exhibiting prominent Fano resonance. The natural weak value interpretation of the enhanced Faraday rotation in hybrid magneto-plasmonic systems enriches the existing understanding on its origin. This opens up a new paradigm of natural weak measurement for gaining fundamental insights and ensuing practical applications on various weak interaction effects in rich variety of wave phenomena that originate from fine interference effects.
Background: Individuals with sensorineural hearing loss can regain some lost auditory function with the help of hearing aids, but it may be insufficient under non – optimal condition. Future research ...aspect lies in processing strategy and training to enhance effects of auditory training and rehabilitation of patients using hearing aids. So research is done to supplement the rehabilitation process with patient centric education, counseling and auditory training to help the listener compensate for loss of auditory signal and improve communication. Whether age-related hearing loss can be decreased by auditory training along with hearing aid is to be researched as it is not clear from previous scientific works whether the outcome is significantly better than those with hearing aid who have not received training.
Aims and Objectives: The aim of the study was to determine the role of auditory training for improvement of auditory perception in aged patients with age-related sensorineural hearing loss using binaural hearing aid.
Materials and Methods: This prospective observational study was conducted in Otorhinolaryngology department of Burdwan Medical College and Hospital, Burdwan, a rural based tertiary care hospital in Burdwan for 2 months from June 2022 to July 2022 and 50 aged patients with audiologically proven age related sensorineural hearing loss using hearing aid were included in this study after through history taking and meticulous clinical examination after getting institutional ethics committee clearance. Patients were divided in two groups, 25 in experimental group (with auditory training) and 25 in control group (without auditory training) and result was analyzed.
Results: Formal auditory training was able to improve the central auditory skills of hearing aid users. Improvement was noted in an objective neurophysiologic correlate and perceived by patients, as revealed in a self-assessment questionnaire.
Conclusion: Formal auditory training in adult hearing aid users promotes: Improvement in auditory skills for sound localization, memory for nonverbal sounds in sequence, auditory closure, and figure-to-ground for verbal sounds. Greater benefits with hearing aids in reverberant and noisy environments.
Probing volume phase transition behavior of superdiluted polymer solutions both micro- and macroscopically still persists as an outstanding challenge. In this regard, we have explored 4 × 4 spectral ...Mueller matrix measurement and its inverse analysis for excavating the microarchitectural facts about stimuli responsiveness of “smart” polymers. Phase separation behavior of thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) and pH responsive poly(N,N-(dimethylamino)ethyl methacrylate) (PDMAEMA) and their copolymers were analyzed in terms of Mueller matrix derived polarization parameters, namely, depolarization (Δ), diattenuation (d), and linear retardance (δ). The Δ, d, and δ parameters provided useful information on both macro- and microstructural alterations during the phase separation. Additionally, the two step action ((i) breakage of polymer–water hydrogen bonding and (ii) polymer–polymer aggregation) at the molecular microenvironment during the cloud point generation was successfully probed via these parameters. It is demonstrated that, in comparison to the present techniques available for assessing the hydrophobic–hydrophilic switch over of simple stimuli-responsive polymers, Mueller matrix polarimetry offers an important advantage requiring a few hundred times dilute polymer solution (0.01 mg/mL, 1.1–1.4 μM) at a low-volume format.
Purpose
To reduce the inter- and intra- rater variability as well as time and effort, a method for computer-assisted delineation of hematoma is proposed. Delineation of hematoma is done for further ...automated analysis such as the volume of hematoma, anatomical location of hematoma, etc. for proper surgical planning.
Methods
Fuzzy-based intensifier was used as a pre-processing technique for enhancing the computed tomography (CT) volume. Autoencoder was trained to detect the CT slices with hematoma for initialization. Then active contour Chan–Vese model was used for automated delineation of hematoma from CT volume.
Results
The proposed algorithm was tested on 48 hemorrhagic patients. Two radiologists have independently segmented the hematoma manually from CT volume. The intersection of two volumes was used as ground-truth for comparison with the segmentation performed by the proposed method. The accuracy was determined by using similarity matrices. The result of sensitivity, positive predictive value, Jaccard index and Dice similarity index were calculated as 0.71 ± 0.12, 0.73 ± 0.18, 0.55 ± 0.14, and 0.70 ± 0.12 respectively.
Conclusions
A new approach for delineation of hematoma is proposed. The algorithm works well with the whole volume. Similarity indices of the proposed method are comparable with the existing state of art.
The spin orbit interaction (SOI) of light has been the focus of recent research due to the fundamental consequences and potential applications in diverse systems, ranging from inhomogeneous ...anisotropic media to engineered plasmonics and metamaterial strutures. Here, we demonstrate perhaps one of the simplest means to study SOI and the spin Hall shift (SHS) using a standard Gaussian TEM00 beam in an optical trap. Our system exploits the versatility and interference generated in a stratified medium to control and manipulate SOI and transfer the resulting angular momentum to optically trapped microparticles. We show that even such a simple setup can lead to an order of magnitude enhancement in the SHS compared to the subwavelength shifts typically obtained. Importantly, this leads to the generation of doughnut-like mode structures from a fundamental Gaussian beam, as well as controlled rotation of mesoscopic particles using a linearly polarized Gaussian beam that lacks intrinsic angular momentum. The local optical torque leading to rotation of the particles is a direct measure of the local spin angular momentum (SAM) density of the field. Our measurement is the first experimental demonstration of using a probe particle to measure the SAM density for nonparaxial fields.
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