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At least 793 records · Page 44

Image-to-Image Wildfire Detection via Quantum-Compatible Variational Segmentation from Remotely-sensed Data

Over the last decade, the incidence of wildfires has surged, causing widespread destruction globally. To better comprehend and manage these incidents, remote sensing and aerial missions have been implemented in recent efforts. However, this has resulted in an exponential rise in the amount of remote sensing data utilization, leading to a need for intelligent automation of data extraction in wildfire studies. Machine learning provides an accurate automated approach for detecting these natural anomalies and facilitates decision-makers to take prompt actions. To make insightful decisions in wildfire management, it is imperative to move beyond simple detection and explore the potential of probabilistic generative machine learning for creating "what-if" scenarios for various wildfire conditions. Such models offer improved representation of the stochastic nature of wildfire events. However, the optimization of these models can be computationally expensive, especially when using classical computers. Quantum computers have recently emerged as a promising solution to reduce the computational cost of training such models and improve their performance. In this study, we aim to utilize quantum-compatible machine learning techniques to implement our probabilistic generative approach. To that end, we propose a supervised probabilistic variational model consisting of a U-NET-based image-to-image component along with encoder and decoder networks which work as a variational autoencoder (VAE) component. Additionally, we explore the type of latent distribution type in the VAE component and implement different means for modeling the prior distribution. We further investigate the quantum-compatible versions of the model compared to the classical counterpart and benchmark potential benefits of quantum compatibility over the classical model.

quantum machine learning↗

Particle Imaging Velocimetry Technique Development for Laboratory Measurement of Fracture Flow Inside a Pressure Vessel Using Neutron Imaging

This paper will describe recent progress made in developing neutron imaging based particle imaging velocimetry techniques for visualizing and quantifying flow structure through a high pressure flow cell with high temperature capability (up to 350 degrees C). This experimental capability has great potential for improving the understanding of flow through fractured systems in applications such as enhanced geothermal systems (EGS). For example, flow structure measurement can be used to develop and validate single phase flow models used for simulation, experimentally identify critical transition regions and their dependence on fracture features such as surface roughness, and study multiphase fluid behavior within fractured systems. The developed method involves the controlled injection of a high contrast fluid into a water flow stream to produce droplets that can be tracked using neutron radiography. A description of the experimental setup will be provided along with an overview of the algorithms used to automatically track droplets and relate them to the velocity gradient in the flow stream. Experimental results will be reported along with volume of fluids based simulation techniques used to model observed flow.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Methods, compositions and kits for imaging cells and tissues using nanoparticles and spatial frequency heterodyne imaging

Methods, compositions, systems, devices and kits are provided herein for preparing and using a nanoparticle composition and spatial frequency heterodyne imaging for visualizing cells or tissues. In various embodiments, the nanoparticle composition includes at least one of: a nanoparticle, a polymer layer, and a binding agent, such that the polymer layer coats the nanoparticle and is for example a polyethylene glycol, a polyelectrolyte, an anionic polymer, or a cationic polymer, and such that the binding agent that specifically binds the cells or the tissue. Methods, compositions, systems, devices and kits are provided for identifying potential therapeutic agents in a model using the nanoparticle composition and spatial frequency heterodyne imaging.

59 BASIC BIOLOGICAL SCIENCES↗

Cardiac Function After Multimodal Breast Cancer Therapy Assessed With Functional Magnetic Resonance Imaging and Echocardiography Imaging

Purpose: Breast intensity modulated radiation therapy (IMRT) reduces high-dose heart volumes but increases low-dose volumes. We prospectively assessed heart changes after 3D conformal RT (3DCRT) and IMRT for left-sided breast cancer. Heart dose was analyzed individually, 3DCRT patients were moderately exposed, and IMRT was performed only in patients with unacceptably high heart doses upon 3DCRT planning. Methods and Materials: In 49 patients (38 patients received 3DCRT; 11 patients received IMRT; and 20 patients received neoadjuvant or adjuvant chemotherapy) magnetic resonance imaging (MRI) and echocardiography were performed before and at 6, 12, and 24 months after treatment. Results: Mean heart dose for IMRT was 12.9 ± 3.9 Gy versus 4.5 ± 2.4 Gy for 3DCRT. Heart volumes receiving >40 Gy were 2.6% (3DCRT) versus 1.3% (IMRT); doses were >50 Gy only with 3DCRT. Temporary ejection fraction (EF) decrease was observed on MRI after 6 months (63%-59%, P=.005) resolving at 24 months. Only 3 patients had pronounced largely transient changes of EF and left ventricular enddiastolic diameter (LVEDD). Mitral (M) and tricuspid (T) annular plane systolic excursion (MAPSE and TAPSE) were reduced over the whole cohort (still within normal range). After 24 months left ventricular remodeling index decreased in patients receiving chemotherapy (0.80 vs 0.70, P=.028). Neither wall motion abnormalities nor late enhancements were found. On echocardiography, in addition to EF findings that were similar to those on MRI, global strain was unchanged over the whole cohort at 24 months after a transient decrease at 6 and 12 months. Longitudinal strain decreased in the whole cohort after 24 months in some segments, whereas it increased in others. Conclusions: Until 24 months after risk-adapted modern multimodal adjuvant therapy, only subclinical cardiac changes were observed in both 3DCRT patients with inclusion of small to moderate amounts of heart volume in RT tangents and in the patients treated with IMRT and reduced high-dose heart exposure.

62 RADIOLOGY AND NUCLEAR MEDICINE↗

Image Distortions on a Plastic Interstitial Computed Tomography/Magnetic Resonance Brachytherapy Applicator at 3 Tesla Magnetic Resonance Imaging and Their Dosimetric Impact

Purpose: To quantify magnetic resonance imaging (MRI) distortions on a plastic intracavitary/interstitial applicator with plastic needles at a field strength of 3 T and to determine the dosimetric impact, using patient data. Methods and Materials: For 11 cervical cancer patients, our clinical MRI protocol was extended with 3 scans. From the first scan, a multi-echo acquisition, a map of the magnetic field (B{sub 0}) was calculated and used to quantify the field inhomogeneity. The expected displacements of the applicator were quantified for the clinical sequence using the measured field inhomogeneity and the clinical sequence's bandwidth. The second and third scan were our routine clinical sequence (duration: <5 minutes each), acquired consecutively using opposing readout directions. The displacement of the applicator between these scans is approximately twice the displacement due to B{sub 0} inhomogeneity. The impact of the displacement on the dose was determined by reconstructing the applicator on both scans. The applicator was then shifted and rotated the same distance as the observed displacement to create a worst-case scenario (ie, twice the actual displacement due to B{sub 0} inhomogeneity). Next, the dose to 98%/90% (D{sub 98}/D{sub 90}) of the clinical target volume at high risk, as well as the dose to the most irradiated 2 cm{sup 3} for bladder and rectum, were calculated for the original plan as well as the shifted plan. Results: For a volume of interest containing the intrauterine device and the ovoids the 95th percentile of the absolute displacement ranged between 0.2 and 0.75 mm, over all patients. For all patients, the difference in D{sub 98}/D{sub 90} in the opposing readout scans with the original plan was at most 4.7%/4.3%. For the dose to the most irradiated 2 cm{sup 3} of bladder/rectum, the difference was at most 6.0%/6.3%. Conclusions: The dosimetric impact of distortions on this plastic applicator with plastic needles is limited. Applicator reconstruction for brachytherapy planning purposes is feasible at 3 T MRI.

62 RADIOLOGY AND NUCLEAR MEDICINE↗

A 7.4 kHz, 20-bit image encoder with a CMOS linear image sensor

This paper presents a unique CMOS linear image sensor for reading the pseudo-random code on the slit disc, focusing on the two aspects of low noise and readout rate. Each pixel is equipped with an exclusive integral readout circuit, and the shape of the pixel also matches the slit disc, making the output signal consistent by up to 99%. After subdivision, the absolute angle data can be captured with an angular resolution of 16 bits and a maximum speed of 7.4 kHz. In addition, decoding and subdivision methods are suitable for high-speed, inexpensive encoder systems.

42 ENGINEERING↗

Feasibility of hard X-ray imaging using monolithic active pixel sensors (MAPS)

Silicon detectors have been widely used in high energy physics (HEP) experiments. The outstanding properties of silicon detectors include radiation hardness, small material budget, fine spatial resolution, high speed and low cost. In this paper, we report initial results of using a single-bit Monolithic Active Pixel Sensor (MAPS), a leading candidate for the next generation trackers in high luminosity colliders, for hard X-ray imaging. The MAPS responses to X-ray with different energies are obtained and compared with simulation. The observed cluster sizes are larger than that predicted by the Continuous Slowing Down Approximation (CSDA) model, indicating that the charge diffusion process might play an important in the MAPS response to low energy electrons. In conclusion, this work paves the way towards multiple layer ultrafast silicon sensor applications in synchrotrons and XFEL beamlines.

36 MATERIALS SCIENCE↗

Thermal conductivity of ZrO2-4mol%Y2O3 thin coatings by pulsed thermal imaging method

Thin ZrO2-4mol% Y2O3 coatings were deposited onto ZrO2 substrates by electron beam-physical vapor deposition. The coated samples revealed a feather-like columnar microstructure. The main phase of the ZrO2-4mol% Y2O3 coatings was the tetragonal phase. To evaluate the influence of the coating’s thickness on the thermal conductivity of thin ZrO2-4mol% Y2O3 coatings, the pulsed thermal imaging method was employed to obtain the thermal conductivity of the coating layer in the two-layer (coating and substrate) samples with thickness between 56 and 337 micrometers. The thermal conductivity of the coating layer was successfully evaluated and compared well with those obtained by the laser flash method for similar coatings. The thermal conductivity of coatings shows an increasing tendency with an increase in the coating’s thickness.

36 MATERIALS SCIENCE↗

Single-Polymer–Particle Growth Kinetics with Molecular Catalyst Speciation and Single-Turnover Imaging

The dynamics of the local environments surrounding molecular polymerization catalysts plausibly impact turnover kinetics, but the impact of and nature of such dynamics have previously been obscured by ensemble averaging. With Grubbs’ second generation ruthenium metathesis catalyst and a precipitation polymerization system, studies at the single-particle and -turnover level establish that (1) an inverse correlation exists between rate and duration of single-polymer–particle growth of aggregates, consistent with a local environment density model for the time-variable kinetics; (2) cross-linking additives produced a small, but detectible, reduction in overall monomer incorporation; (3) total ruthenium quantity within the polymer particles (as characterized by energy dispersive X-ray spectroscopy) is differentiable from the quantity that is catalytically active (as characterized by in situ fluorescence microscopy), providing catalyst speciation information; and (4) time-resolved enyne metathesis reactions can be imaged, corresponding to single turnovers at individual molecular catalysts during polymer growth under synthetically relevant conditions. Here, these findings identify and characterize reactivity distributions likely arising from the dynamics of local environments. As such, these data provide reactivity information that is unavailable through traditional ensemble analytical methods that obscure this type of information through averaging.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Comparison of beam emission spectroscopy and gas puff imaging edge fluctuation measurements in National Spherical Torus Experiment

In this study, the close physical proximity of the Gas Puff Imaging (GPI) and Beam Emission Spectroscopy (BES) diagnostics on the National Spherical torus Experiment (NSTX) is leveraged to directly compare fluctuation measurements, and to study the local effects of the GPI neutral deuterium puff during H-mode plasmas without large Edge Localized Modes. The GPI and BES views on NSTX provide partially overlapping coverage of the edge and scrape-off layer (SOL) regions above the outboard midplane. The separation in the toroidal direction is 16°, and field lines passing through diagnostic views are separated by ∼20 cm in the direction perpendicular to the magnetic field. Strong cross-correlation is observed, and strong cross-coherence is seen for frequencies between 5 and 15 kHz. Also, probability distribution functions of fluctuations measured ∼3 cm inside the separatrix exhibit only minor deviations from a normal distribution for both diagnostics, and good agreement between correlation length estimates, decorrelation times, and structure velocities is found at the ±40% level. While the two instruments agree closely in many respects, some discrepancies are observed. Most notably, GPI normalized fluctuation levels exceed BES fluctuations by a factor of ∼9. BES mean intensity is found to be sensitive to the GPI neutral gas puff, and BES normalized fluctuation levels for frequencies between 1 and 10 kHz are observed to increase during the GPI puff.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗