Hasil untuk "physics.med-ph"

J. Dressman, R. Berardi, Lambros C. Dermentzoglou et al.

P. Dunfield, R. Knowles, R. Dumont et al.

E. Fourest, J. Roux

Jan M. Antosiewicz, J. McCammon, Michael K. Gilson

Marco Ferreira, Ana Belchior, Teresa Pinheiro et al.

LiDRoSIS is an automated MATLAB-Python software suite for the segmentation and quantification of lipid droplets (LDs) and reactive oxygen species (ROS) in fluorescence microscopy images of irradiated A549 and MCF7 cells exposed to gold-based nanoparticles. It combines classical image processing algorithms with statistical post-analysis through a companion Python tool, StatLysis. The platform enables reproducible, high-throughput analysis of morphological and spectral parameters linked to nanoparticle-enhanced radiobiological responses. By bridging imaging and quantitative analytics, LiDRoSIS provides a robust framework for nanomedicine and radiation biology research.

Baptiste Hériard-Dubreuil, Emma Brenner, Benjamin Rio et al.

Wave velocity is a key parameter for imaging complex media, but in vivo measurements are typically limited to reflection geometries, where only backscattered waves from short-scale heterogeneities are accessible. As a result, conventional reflection imaging fails to recover large-scale variations of the wave velocity landscape. Here we show that matrix imaging overcomes this limitation by exploiting the quality of wave focusing as an intrinsic guide star. We model wave propagation as a trainable multi-layer network that leverages optimization and deep learning tools to infer the wave velocity distribution. We validate this approach through ultrasound experiments on tissue-mimicking phantoms and human breast tissues, demonstrating its potential for tumour detection and characterization. Our method is broadly applicable to any kind of waves and media for which a reflection matrix can be measured.

Uzi Harush, Ravid Straussman, Baruch Barzel

When confronted with an undesired cell population, such as bacterial infections or tumors, we seek the most effective treatment, designed to eliminate the population as rapidly as possible. A common practice is to monitor the cells short-term response to the treatment, and from that, extrapolate the eventual treatment outcome, i.e. will it eradicate the cells, and if yes at what timescales. Underlying this approach is the assumption that the cells exhibit a homogeneous response to the treatment, and hence the early response patterns can be naturally extended to later times. Recent experiments on cancer cell populations, however, indicate a significant level of cellular heterogeneity, undermining this classic assessment protocol of treatment efficacy. We, therefore, develop here a stochastic framework, to analytically predict the temporal dynamics of a heterogeneous cell population. Quite often, we find, the average cellular parameters, governing the short-term response, fail to predict the actual treatment outcome. In contrast, our analysis, which also incorporates the populations variability, helps identify the relevant statistical parameters, which in turn, enable us to predict the full trajectory of the cell population, and specifically - the likelihood and typical timescales for remission.

W. Charman, C. Porter, Sabena D. Mithani et al.

Vincent Hickl, Abid Khan, René M. Rossi et al.

The spread of microbial infections is governed by the self-organization of bacteria on surfaces. Limitations of live imaging techniques make collective behaviors in clinically relevant systems challenging to quantify. Here, novel experimental and image analysis techniques for high-fidelity single-cell segmentation of bacterial colonies are developed. Machine learning-based segmentation models are trained solely using synthetic microscopy images that are processed to look realistic using state-of-the-art image-to-image translation methods, requiring no biophysical modeling. Accurate single-cell segmentation is achieved for densely packed single-species colonies and multi-species colonies of common pathogenic bacteria, even under suboptimal imaging conditions and for both brightfield and confocal laser scanning microscopy. The resulting data provide quantitative insights into the self-organization of bacteria on soft surfaces. Thanks to their high adaptability and relatively simple implementation, these methods promise to greatly facilitate quantitative descriptions of bacterial infections in varied environments.

Akihiro Haga

Objective: Despite recent advancements in quantum computing, the limited number of available qubits has hindered progress in CT reconstruction. This study investigates the feasibility of utilizing quantum annealing-based computed tomography (QACT) with current quantum bit levels. Approach: The QACT algorithm aims to precisely solve quadratic unconstrained binary optimization (QUBO) problems. Furthermore, a novel approach is proposed to reconstruct images by approximating real numbers using the variational method. This approach allows for accurate CT image reconstruction using a small number of qubits. The study examines the impact of projection data quantity and noise on various image sizes ranging from 4x4 to 24x24 pixels. The reconstructed results are compared against conventional reconstruction algorithms, namely maximum likelihood expectation maximization (MLEM) and filtered back projection (FBP). Main result: By employing the variational approach and utilizing two qubits for each pixel of the image, accurate reconstruction was achieved with an adequate number of projections. Under conditions of abundant projections and lower noise levels, the image quality in QACT outperformed that of MLEM and FBP. However, in situations with limited projection data and in the presence of noise, the image quality in QACT was inferior to that in MLEM. Significance: This study developed the QACT reconstruction algorithm using the variational approach for real-number reconstruction. Remarkably, only 2 qubits were required for each pixel representation, demonstrating their sufficiency for accurate reconstruction.

Zhen Hua, John Turek, Mike Childress et al.

Enrolling patients in clinical trials to obtain fresh tumor biopsies to profile anticancer agents can be slow and expensive. However, if flash-frozen biopsies can be thawed to produce viable living tissue with relevant biodynamic profiles, then a large reservoir of tissue-banked samples could become available for phenotypic library building. Here, we report biodynamic profiles acquired from revived flash-frozen canine B-cell lymphoma biopsies using digital speckle holography. We compared the thawed-tissue drug-response spectrograms to spectrograms from fresh tissues in a study of canine B-cell lymphoma. By compensating for tissue trauma in the thawed sample, patient clustering of both the fresh and thawed samples were found to be in general agreement with clinical outcomes. This study indicates that properly frozen tumor specimens are a viable proxy for fresh specimens in the context of chemosensitivity testing, and that thawed samples from tissue banks contain sufficient viable cells to evaluate phenotypic drug response.

Xiao-Ping Li, A. Gilmore, S. Caffarri et al.

The biochemical, biophysical, and physiological properties of the PsbS protein were studied in relation to mutations of two symmetry-related, lumen-exposed glutamate residues, Glu-122 and Glu-226. These two glutamates are targets for protonation during lumen acidification in excess light. Mutation of PsbS did not affect xanthophyll cycle pigment conversion or pool size. Plants containing PsbS mutations of both glutamates did not have any rapidly inducible nonphotochemical quenching (qE) and had similar chlorophyll fluorescence lifetime components as npq4-1, a psbS deletion mutant. The double mutant also lacked a characteristic leaf absorbance change at 535 nm (ΔA535), and PsbS from these plants did not bind dicyclohexylcarbodiimide (DCCD), a known inhibitor of qE. Mutation of only one of the glutamates had intermediate effects on qE, chlorophyll fluorescence lifetime component amplitudes, DCCD binding, and ΔA535. Little if any differences were observed comparing the two single mutants, suggesting that the glutamates are chemically and functionally equivalent. Based on these results a bifacial model for the functional interaction of PsbS with photosystem II is proposed. Furthermore, based on the extent of qE inhibition in the mutants, photochemical and nonphotochemical quenching processes of photosystem II were associated with distinct chlorophyll fluorescence life-time distribution components.

Pavel Seregin, Oleg Burmistrov, Georgiy Solomakha et al.

Specialized radio-frequency coils and sensors placed inside the magnetic resonance imaging (MRI) scanner considerably extend its functionality. However, since cable connected in-bore devices have several disadvantages compared to wireless ones, the latter currently undergo active development. One of the promising concepts in wireless MRI coils is energy harvesting that relies on converting the energy carried by the radio-frequency MRI field without the need for additional transmitters as in common wireless power transfer realizations. In this Article, we propose a compact harvesting coil design based on the combination of the loop and butterfly coils that allows energy harvesting of a circularly polarized field. By performing numerical simulations and experiments with commonly used Siemens Espree and Avanto 1.5 Tesla MRI scanners, we demonstrate that the proposed approach is safe, efficient, does not decrease the quality of MRI images, and allows doubling the harvested voltage compared to linearly polarized setups.

Rick Orij, J. Postmus, Alexander Ter Beek et al.

Miriam Menzel, Silvania F. Pereira

Previous simulation studies by Menzel et al. [Phys. Rev. X 10, 021002 (2020)] have shown that scattering patterns of light transmitted through artificial nerve fiber constellations contain valuable information about the tissue substructure such as the individual fiber orientations in regions with crossing nerve fibers. Here, we present a method that measures these scattering patterns in monkey and human brain tissue using coherent Fourier scatterometry with normally incident light. By transmitting a non-focused laser beam (wavelength of 633 nm) through unstained histological brain sections, we measure the scattering patterns for small tissue regions (with diameters of 0.1-1 mm), and show that they are in accordance with the simulated scattering patterns. We reveal the individual fiber orientations for up to three crossing nerve fiber bundles, with crossing angles down to 25°.

P. S. Grinchuk, E. I. Fisenko, S. P. Fisenko et al.

It is shown that the evaporation rate of a liquid sample containing the culture of coronavirus affects its survival on a substrate. Possible mechanisms of such influence can be due to the appearance of large, about 140 bar, non comprehensive capillary pressures and the associated dynamic forces during the movement of the evaporation front in a sample with the virus. A simulation of isothermal evaporation of a thin liquid sample based on the Stefan problem was performed. The comparison of simulation data and recent experiments on the coronavirus survival on various surfaces showed that the rate of isothermal evaporation of aqueous samples, which is higher for heat-conducting materials, correlates well with the lifetime of the coronavirus on these surfaces.

Nozomi Nishizawa, Bassam Al-Qadi, Takahiro Kuchimaru

Depolarization of circularly polarized light scattered from biological tissues depends on structural changes in cell nuclei, which can provide valuable information for differentiating cancer tissues concealed in healthy tissues. In this study, we experimentally verified the possibility of cancer identification using scattering of circularly polarized light. We investigated the polarization of light scattered from a sliced biological tissue with various optical configurations. A significant difference between circular polarizations of light scattered from cancerous and healthy tissues is observed, which is sufficient to distinguish a cancerous region. The line-scanning experiments along a region incorporating healthy and cancerous parts indicate step-like behaviors in the degree of circular polarization corresponding to the state of tissues, whether cancerous or normal. An oblique and perpendicular incidence induces different resolutions for identifying cancerous tissues, which indicates that the optical arrangement can be selected according to the priority of resolution.

C. López-Vázquez, A. Oehmen, C. M. Hooijmans et al.

E. Gianazza, P. Righetti

Elena Aznar, M. Marcos, R. Martínez‐Máñez et al.