High-resolution Mode Research Articles

Anti-reflux surgical treatment for Barrett’s oesophagus

The aim of the study. To improve the effectiveness of surgical treatment for patients with hiatal hernia (HH) and gastro-esophageal reflux disease (GERD) in combination with Barrett’s esophagus by developing a new method for surgical correction of the physiological cardia incompetence. Materials and methods. The study was conducted in the Department of Digestive Surgery of the State Institution “Institute of Gastroenterology of the National Academy of Medical Sciences of Ukraine” in 2020–2021 and involved 56 patients with HH and GERD, among them axial HH was detected in 42 patients (75.0 %) – type I; paraesophageal HH – in 6 patients (10.7 %) – type II; mixed HH – in 8 patients (14.3 %) – type III (code ICD-10 – K44). The diagnosis was established using esophagogastroduodenoscopy (by high-resolution NBI mode), X-ray and histological examinations, manometry. Results. When the diagnosis of HH in combination with Barrett’s esophagus was confirmed, a two-stage treatment was performed. During the first stage, argonoplasmic coagulation of the altered esophageal mucosa was done. Anti-reflux procedures constituted the second stage to remove HH and restore an excessive dilatation of the esophageal orifice of the diaphragm by cruroraphy with correction of anti-reflux function of the cardia by fundoplication, angle of His reconstruction and providing free food passage. 11 (19.6 %) patients underwent surgery according to a new technique that provided reliable recovery of cardia physiological functions and preservation of the anatomical relation between the diaphragm and the esophageal-gastric junction and included cruroraphy and fundoplication. Conclusions. Thus, the proposed two-stage method of surgical treatment for patients with HH and GERD in combination with Barrett’s esophagus is highly effective. The application of the proposed method provides the elimination of pathological changes which are visible on conventional endoscopy in the esophageal mucosa, reliable restoration of cardia physiology and preservation of the anatomical relation between the diaphragm and the esophageal-gastric junction. In the post-surgical period, the proposed method of surgical treatment reduces the likelihood of recurrent failure of cardia physiological functions, dysphagia and Barrett’s esophagus.

On the Processing of Dual-Channel Receiving Signals of the LuTan-1 SAR System

LuTan-1 (LT-1) is an innovative spaceborne radar Earth observation mission including two satellites equipped with synthetic aperture radar (SAR) which will be launched in 2022. Active phased array antennas that can be divided into two physical channels are equipped on each satellite. The signal can be transmitted through the full antenna without broadening and recorded by each channel. Therefore, two methods can be used to preprocess the dual-channel receiving signals, referred to as dual-channel echo reconstruction and dual-channel echo synthesis. The former is inherited from the traditional high-resolution wide-swath mode and the latter is a method that takes coherent superposition as the reference. This paper researches the impacts of the two methods in system performance and imaging quality. Principles and theoretical models are firstly given. Furthermore, the system performance under the “L1A_SM_S” working mode of the LT-1 is simulated to compare the differences between the two methods, which mainly focuses on azimuth ambiguity-to-signal ratio, noise equivalent sigma zero, and the performance of block adaptive quantization. Afterwards, the test data acquired by the ground validation system of the LT-1 are used for the hardware-in-the-loop simulation to demonstrate the imaging quality between the two methods. Finally, a quantitative comparison is given.

Case study of a moisture intrusion over the Arctic with the ICOsahedral Non-hydrostatic (ICON) model: resolution dependence of its representation

Abstract. The Arctic is warming faster than the global average and any other region of a similar size. One important factor in this is the poleward atmospheric transport of heat and moisture, which contributes directly to the surface and air warming. In this case study, the atmospheric circulation and spatio-temporal structure of a moisture intrusion event is assessed, which occurred from 5 to 7 June 2017 over the Nordic seas during an intensive measurement campaign over Svalbard. This analysis focuses on high-spatial-resolution simulations with the ICON (ICOsahedral Non-hydrostatic) model which is put in context with coarser-resolution runs as well the ERA5 reanalysis. A variety of observations including passive microwave satellite measurements is used for evaluation. The global operational ICON forecasts from the Deutscher Wetterdienst (DWD) at 13 km horizontal resolution are used to drive high-resolution Limited-Area Mode (LAM) ICON simulations over the Arctic with 6 and 3 km horizontal resolutions. The results show the skilful capacity of the ICON-LAM model to represent the observed spatio-temporal structure of the selected moisture intrusion event and its signature in the temperature, humidity and wind profiles, and surface radiation. In several aspects, the high-resolution simulations offer a higher accuracy than the global simulations and the ERA5 reanalysis when evaluated against observations. One feature where the high-resolution simulations demonstrated an advanced skill is the representation of the changing vertical structure of specific humidity and wind associated with the moisture intrusion passing Ny-Ålesund (western Svalbard); the humidity increase at 1–2 km height topped by a dry layer and the development of a low-level wind jet are best represented by the 3 km simulation. The study also demonstrates that such moisture intrusions can have a strong impact on the radiative and turbulent heat fluxes at the surface. A drastic decrease in downward shortwave radiation by ca. 500 W m−2 as well as an increase in downward longwave radiation by ca. 100 W m−2 within 3 h have been determined. These results highlight the importance of both moisture and clouds associated with this event for the surface energy budget.

A Flexible Image-Guided Shape Reconstruction Framework for Electrical Impedance Tomography

Electrical Impedance Tomography (EIT) owns the advantages of safety, high temporal resolution and functional imaging characteristics, thus is considered as a promising medical/ industrial imaging modality. However, due to the ill-posedness of its inverse problem, the spatial resolution of EIT is low, which is greatly impeded its practical applications. A flexible image-guided shape reconstruction framework for EIT is proposed to alleviate the problem. A statistical inverse problem framework for image-guided inclusion boundary reconstruction is established to directly reconstruct the inclusion boundary and the corresponding conductivity distribution. The morphology prior information is extracted from the images obtained from other high resolution modes and is used to guide the boundary reconstruction process in the form of a conditional probability model. A series of simulation and experimental studies are carried out for different application backgrounds. The lung EIT imaging guided by CT image and EIT inclusion detection guided by B-ultrasound image are simulated and analyzed respectively. The results show that the proposed method has high applicability to prior images of different modes. It not only achieves high-precision shape reconstruction but also high-precision conductivity estimation under the guidance of accurate prior images. Meanwhile, the proposed method has high robustness to the possible influence of noise in prior images or incomplete structural information. Even if the information in the prior image is biased or incomplete, the proposed method can still achieve high precision boundary reconstruction and conductivity estimation. The results of quantitative analysis show that compared with the method without image prior, the proposed method has an average reduction of 70% in area error, while the conductivity estimation error is reduced by about 5 times on average.

An Electromagnetic Simulator for Sentinel-3 SAR Altimeter Waveforms Over Land—Part I: Bare Soil

ALtimetry for BIOMass (ALBIOM) is a Permanent Open Call Project funded by the European Space Agency (ESA) to explore the possibility of forest biomass retrieval by using Copernicus Sentinel-3 (S-3) Synthetic Aperture Radar Altimeter (SRAL) in low- and high-resolution mode at Ku- and C-bands. It represents an original work in the research of new techniques for vegetation observation using altimetry data. Because of the complexity of the land surfaces, no algorithm has been developed for a specific retracking of the altimetric land waveform. This calls for the development of a model able to reproduce the acquisition system and the target scattering phenomena to simulate the interaction of the radar pulse with the land. In this first work we present the electromagnetic simulator of S-3 SRAL altimeter measurements over bare soil scenarios realized through a modification of the SAVERS (Soil And Vegetation Reflection Simulator) simulator developed by the team for GNSS-R reflectometry over land. The impact of topography has been also taken into account. We demonstrate that SAVERS for S-3 SRAL proved its capability to reproduce altimeter waveforms’ main attributes for both flat and topography scenarios.

Concurrent Imaging for TerraSAR-X: Wide-Area Imaging Paired With High-Resolution Capabilities

The concurrent imaging technique enables parallel acquisitions with different beams or modes, e.g., a wide area Stripmap mode with a High-Resolution Spotlight mode. Such a concurrent Stripmap/Spotlight imaging technique is investigated for TerraSAR-X. This technique employs a pulse-to-pulse interleaving scheme to acquire two acquisitions-even of disjunctive areas-at the same time, offering products with different resolution and coverage portfolios. This capability is especially interesting for customers interested in an overview of a larger area but at the same time observing an area of interest with higher resolution, e.g., for infrastructure monitoring or reconnaissance applications. The basic concepts, as well as the driving system parameters, are discussed in detail, together with a coverage analysis revealing the high availability rate of the mode combinations on a global scale. A processing approach re-using a substantial part of the existing infrastructure is described and exemplary acquisitions are shown, together with a detailed performance analysis with respect to resolution and ambiguities.

Evaluation of the Accuracy of the Displayed Average Glandular Dose in Mammography

We aimed to clarify the error of displayed value against the measured value of the average glandular dose (AGD) in two-dimensional (2D) mammography and digital breast tomosynthesis (DBT) and evaluate the accuracy of the displayed AGD as an index to estimate AGD. Polymethyl methacrylate (PMMA) phantoms with thicknesses varying from 20 to 80 mm were imaged, and the values displayed on the mammography system were used as the displayed AGD. The incident air kerma and the half-valued layer were measured, and the measured AGD in 2D mammography was calculated using the equation by Dance et al. On the other hand, the measured AGD in DBT was calculated by correcting for different projection angles. The relative error to the PMMA thickness was evaluated by assessing the relative error of the displayed AGD against the measured AGD. The maximum relative error of the displayed AGD against the measured AGD was 17.3% in 2D mammography, 19.1% in the standard (ST) mode, and 19.8% in the high-resolution (HR) mode. The relative error of the displayed AGD against the measured AGD tended to increase with increase in PMMA thickness. This tendency was especially noticeable for PMMA with thicknesses of 70 and 80 mm in DBT.

A Digital Filter Bank Based Method for Data Reduction in Spaceborne SAR Electronics

On-board data reduction is a major concern in designing of a spaceborne synthetic aperture radar (SAR) system since the volume of acquired SAR data is generally much higher than the downlink capability to the ground-station. The dechirp-on-receive (DoR) method is considered the state-of-the-art SAR data reduction technique. If there is deramping hardware in the SAR instrument, DoR is an effective method to reduce the volume of images for high resolution modes. In this paper, we use a digital signal processing method which applies a modified discrete Fourier transform (MDFT) filter bank for SAR data reduction. We call this method MDFT band selection filter (MDFT-BSF). This paper presents a quantitative analysis of the MDFT-BSF on data reduction performance. In addition, we provide a relationship between the data reduction performance and the number of sub-bands (M), and show that there is an optimal value of M that minimizes the volume of on-board SAR data. An evaluation of MDFT-BSF including a comparison with the DoR method presents that MDFT-BSF has an advantage for SAR data reduction. We show that MDFT-BSF can be implemented and operated on commercial space-grade FPGAs by the development of a spaceborne SAR digital receiver.

The performance of neutron diffractometers at long and short pulse spallation sources: Comparison between ESS and J-PARC

The general performance of diffractometers at the first long pulse spallation source ESS, is compared with their counterparts at J-PARC, a short pulse spallation source. The difference in the inherent pulse structure of these neutron sources presents opportunities for new concepts for instrumentation, where performance does not scale simply with source power. The article describes advantages and disadvantages of those diffractometers, adapting to the very different source characteristics. We find that the two sources offer comparable performance in flux and resolution when operating in high-resolution mode. ESS offers significant advantages in tunability and flexibility, notably in the ability to relax resolution in order to increase flux for a given experiment. The slow repetition rate of ESS favors long instruments. On the other hand, J-PARC instruments perform very well in spite of the lower source power and allow better access to epithermal neutrons, of particular interest for PDF analysis of diffraction data.

Improving Small-Molecule Force Field Parameters in Ligand Binding Studies.

Small molecules are major players of many chemical processes in diverse fields, from material science to biology. They are made by a combination of carbon and heteroatoms typically organized in system-specific structures of different complexity. This peculiarity hampers the application of standard force field parameters and their in silico study by means of atomistic simulations. Here, we combine quantum-mechanics and atomistic free-energy calculations to achieve an improved parametrization of the ligand torsion angles with respect to the state-of-the-art force fields in the paradigmatic molecular binding system benzamidine/trypsin. Funnel-Metadynamics calculations with the new parameters greatly reproduced the high-resolution crystallographic ligand binding mode and allowed a more accurate description of the binding mechanism, when the ligand might assume specific conformations to cross energy barriers. Our study impacts on future drug design investigations considering that the vast majority of marketed drugs are small-molecules.

Lipid Profiles of Human Brain Tumors Obtained by High-Resolution Negative Mode Ambient Mass Spectrometry

Alterations in cell metabolism, including changes in lipid composition occurring during malignancy, are well characterized for various tumor types. However, a significant part of studies that deal with brain tumors have been performed using cell cultures and animal models. Here, we present a dataset of 124 high-resolution negative ionization mode lipid profiles of human brain tumors resected during neurosurgery. The dataset is supplemented with 38 non-tumor pathological brain tissue samples resected during elective surgery. The change in lipid composition alterations of brain tumors enables the possibility of discriminating between malignant and healthy tissues with the implementation of ambient mass spectrometry. On the other hand, the collection of clinical samples allows the comparison of the metabolism alteration patterns in animal models or in vitro models with natural tumor samples ex vivo. The presented dataset is intended to be a data sample for bioinformaticians to test various data analysis techniques with ambient mass spectrometry profiles, or to be a source of clinically relevant data for lipidomic research in oncology.

Rotatable LYSO-GAPD DEXA detector for providing improved spatial resolution

A rotatable lutetium-yttrium-oxyorthosilicate-Geiger-mode-avalanche photodiode (LYSO-GAPD) DEXA detector that can be configured into either a normal-resolution or a high-resolution mode, was proposed and examined. A 3 × 3 × 2 mm3 LYSO was coupled to a 3 × 3 mm2 GAPD. The versatile transformation of the high-resolution mode was possible by employing the rotating controller for the DEXA detector on its own axis, and the intrinsic resolution in this mode was improved by ∼ 33% compared to the normal-resolution mode. Dual-energy X-ray spectra and imaging capabilities were evaluated in both acquisition modes. The respective peak positions of low- and high-energy-beam of normal-resolution mode (high-resolution mode) were 1330 mV (1262 mV) and 2347 mV (2267 mV). The respective peak-to-valley ratios of low- and high-energy-beam of normal-resolution mode (high-resolution mode) were ∼ 2.8 (∼ 2.9) and ∼ 1.2 (∼ 1.1). Considerable improvements in phantom images such as overall contrast and fine-spot detectability were observed in the high-resolution mode. It should be noted that spatial resolution was improved by reducing the detection-area from 3 × 3 mm2 to 2 × 3 mm2 in the high-resolution mode, but count rate was also decreased. These results demonstrated that a rotatable LYSO-GAPD DEXA detector allows to provide high versatility for both high-resolution mode and normal-resolution mode with a single detector.

High level of integration of front-end imaging optics system for electron cyclotron emission imaging diagnostics on the DIII-D tokamak

The optics system of the Electron Cyclotron Emission Imaging (ECEI) diagnostics on the DIII-D tokamak has been developed and installed for high-resolution temperature fluctuations measurement in the previous decade. The System-on-Chip approach upgrade was finished in June 2019 with high integrated receiver array with 20 individual modules. In this paper, we design new optics with high-level integration. In the new optics system, there will be two mirrors from plasma to receiver array, including one replaceable curved mirror out of the vacuum and one fixed curved mirror in the vessel. There are two options with 1:1 and 1:2 magnifications for high poloidal resolution and larger poloidal window modes. The new optics system has multiple improvements, including lighter weight, smaller size, more flexible installation and alignment. The synthetic ECEI module is used to evaluate the new optics system.

Ten-mega-pixel snapshot compressive imaging with a hybrid coded aperture

High-resolution images are widely used in our everyday life; however, high-speed video capture is more challenging due to the low frame rate of cameras working at the high-resolution mode. The main bottleneck lies in the low throughput of existing imaging systems. Toward this end, snapshot compressive imaging (SCI) was proposed as a promising solution to improve the throughput of imaging systems by compressive sampling and computational reconstruction. During acquisition, multiple high-speed images are encoded and collapsed to a single measurement. Then, algorithms are employed to retrieve the video frames from the coded snapshot. Recently developed plug-and-play algorithms made the SCI reconstruction possible in large-scale problems. However, the lack of high-resolution encoding systems still precludes SCI’s wide application. Thus, in this paper, we build, to the best of our knowledge, a novel hybrid coded aperture snapshot compressive imaging (HCA-SCI) system by incorporating a dynamic liquid crystal on silicon and a high-resolution lithography mask. We further implement a PnP reconstruction algorithm with cascaded denoisers for high-quality reconstruction. Based on the proposed HCA-SCI system and algorithm, we obtain a 10-mega-pixel SCI system to capture high-speed scenes, leading to a high throughput of 4.6 × 109 voxels per second. Both simulation and real-data experiments verify the feasibility and performance of our proposed HCA-SCI scheme.

Biocompatible CuInS2 Nanoparticles as Potential Antimicrobial, Antioxidant, and Cytotoxic Agents.

A simple hydrothermal route is employed to synthesize pure copper indium disulfide (CIS) and CIS nanoparticles (NPs) mediated by various natural plant extracts. The plant extracts used to mediate are Azadirachta indica (neem), Ocimum sanctum (basil), Cocos nucifera (coconut), Aloe vera (aloe), and Curcuma longa (turmeric). The tetragonal unit cell structure of as-synthesized NPs is confirmed by X-ray diffraction. The analysis by energy-dispersive X-rays shows that all the samples are near-stoichiometric. The morphologies of the NPs are confirmed by high-resolution scanning and transmission modes of electron microscopy. The thermal stability of the synthesized NPs is determined by thermogravimetric analysis. The optical energy band gap is determined from the absorption spectra using Tauc’s equation. The antimicrobial activity analysis and the estimation of the minimum inhibitory concentration (MIC) value of the samples are performed for Escherichia coli, Pseudomonas aeruginosa, Proteus vulgaris, Enterobacter aerogenes, and Staphylococcus aureus pathogens. It shows that the aloe-mediated CIS NPs possess a broad inhibitory spectrum. The best inhibitory effect is observed against S. aureus, whereas the least effect was exhibited against P. vulgaris. The least MIC value is found for aloe-mediated CIS NPs (0.300 mg/mL) against S. aureus, P. aeruginosa, and E. aerogenes, along with basil-mediated NPs against E. coli. The antioxidant activity study showed that the IC50 value to inhibit the scavenging activity is maximum for the control (vitamin C) and minimum for pure CIS NPs. The in vivo cytotoxicity study using brine shrimp eggs shows that the pure CIS NPs are more lethal to brine shrimp than the natural extract-mediated CIS NPs. The in vitro cytotoxicity study using the human lung carcinoma cell line (A549) shows that the IC50 value of turmeric extract-mediated CIS NPs is minimum (15.62 ± 1.58 μg/mL). This observation reveals that turmeric extract-mediated CIS NPs are the most potent in terms of cytotoxicity toward the A549 cell line.

High-resolution mass spectrometry reveals a complex ganglioside pattern and novel polysialylated structures associated with the human motor cortex.

We have developed here a superior methodology based on high-resolution mass spectrometry for screening and fragmentation analysis of gangliosides extracted and purified from the human motor cortex . The experiments, conducted on a nanoelectrospray Orbitrap mass spectroscope in the negative ion mode, allowed the discrimination in the native mixture extracted from human motor cortex of no less than 83 different gangliosides, which represents the highest number of structures identified so far in this brain region. The spectral data, acquired in high-resolution mass spectrometry mode with a remarkable sensitivity and an average mass accuracy of 4.48 ppm, also show that the gangliosidome of motor cortex is generally characterized by species exhibiting a much higher degree of sialylation than previously known. Motor cortex was found dominated by complex structures with a sialylation degree ≥3, exhibiting long saccharide chains, in the G1 class. Fucogangliosides and species with the glycan chain elongated by either O-acetylation and/or acetate anion attachments were also detected; the later modification was for the first time discovered in this brain region. Of major significance is the identification of hepta and octasialylated species of GS1 and GO1 type, which are among the structures with the longest oligosaccharide chain discovered so far in the human brain. In the last stage of research, tandem mass spectrometry performed by higher energy collision dissociation provided structural data documenting the occurrence of GT1b (d18:1/20:0) isomer in the human motor cortex.

N-type amorphous silicon-germanium thin films with embedded nanocrystals as a novel thermoelectric material of elevated ZT

The state-of-art thermoelectric (TE) materials with high efficiency (i.e., ZT ~ 1) at room temperature require meeting essential features, such as being environmentally friendly (i.e., avoiding the use of rare and toxic elements), cheap to produce, and high ZT. However, the enhancement of ZT has always been a challenge because the Seebeck coefficient, electrical conductivity, thermal conductivity, and absolute temperature are interdependent. In this work, we report the fabrication of amorphous silicon-germanium (a-SiGe) thin films deposited by low-frequency plasma-enhanced chemical vapor deposition (LF-PECVD) with embedded nanocrystals that have a ZT of 2.61 at room temperature. The above is achieved by enhancing the thermoelectric power factor and, simultaneously, keeping the lowest thermal conductivity; both are in concordance with the phonon-glass electron-crystal (PGEC) approach. The power factor enhancement is accomplished by increasing the electrical conductivity through N-type doping and an annealing process at 500 °C to which thin films were subjected to improve their transport properties while avoiding crystallization. Therefore, the room-temperature electrical conductivity increased two orders of magnitude from 1.11E-01 up to 42.79 S/cm. In addition, the growth of nanocrystals (5–15 nm) embedded into the amorphous matrix contribute to the transport of charge carriers. The measured thickness and Seebeck coefficient of thin films were 200 nm and −1.038 mV/K, respectively. On the other side, the lowest thermal conductivity is reached because the material’s amorphous phase is kept despite the applied post-deposition thermal annealing. The experimental value for thermal conductivity was 0.53 W/m·K, almost half of the minimum thermal conductivity proposed by Slack. In summary, the structural characterization (developed by X-ray diffraction, Fourier transform infrared spectroscopy, and Raman spectroscopy) shows that a-SiGe material not only has an amorphous phase despite the applied thermal annealing, but it also possesses nanocrystals, which is demonstrated by transmission electron microscopy in high-resolution mode. Therefore, the a-SiGe material obtained in this research is proposed as a novel and potential thermoelectric material because it has optimized TE properties and meets desirable features, such as being inexpensive, non-hazardous, and environmentally friendly for energy harvesting applications.

Tooth biomarkers to characterize the temporal dynamics of the fetal and early-life exposome.

Background:Teeth have unique histology that make this biomatrix a time-capsule for retrospective exposure analysis of fetal and early life. However, most analytic methods require pulverizing the whole tooth, which eliminates exposure timing information. Further, the range of chemicals and endogenous exposures that can be measured in teeth has yet to be fully characterized.Methods:We performed untargeted metabolomics on micro-dissected layers from naturally shed deciduous teeth. Using four liquid-chromatography high-resolution mass spectrometry analytical modes, we profiled small molecules (<1000 Da) from prenatal and postnatal tooth fractions. In addition, we employed linear regression on the tooth fraction pairs from 31 children to identify metabolites that discriminate between prenatal and postnatal exposures.Results:Of over 10,000 features measured in teeth dentin, 390 unique compounds were annotated from 62 chemical classes. The class with the largest number of compounds was carboxylic acids and their derivatives (36%). Of the annotated exogenous metabolites (phthalates, parabens, perfluoroalkyl compounds, and cotinine) and endogenous metabolites (fatty acids, steroids, carnitines, amino acids, and others), 91 are linked to 256 health conditions through published literature. Differential analysis revealed 267 metabolites significantly different between the prenatal and the postnatal tooth fractions (adj. p-value < 0.05, Bonferroni correction), and 21 metabolites exclusive to the prenatal fraction.Conclusions:The prenatal and early postnatal exposome revealed from dental biomarkers represents a broad range of endogenous and exogenous metabolites for a comprehensive characterization in environmental health research. Most importantly, this technology provides a direct window into fetal exposures that is not possible by maternal biomarkers. Indeed, we identified several metabolites exclusively in the prenatal fraction, suggesting unique fetal exposures that are markedly different to postnatal exposures. Expansion of databases that include tooth matrix metabolites will strengthen biological interpretation and shed light on exposures during gestation and early life that may be causally linked with later health conditions.

Predicting high-resolution spatial and temporal variations in summer air temperatures and its effect on asthma and myocardial-infarctions in Montreal, Canada

BACKGROUND AND AIM: To develop and apply new high-resolution models of within-city spatiotemporal variations in summer air temperatures in Montreal, Canada and evaluate associations with emergency room visits for asthma and myocardial. METHODS: We developed a new model to predict temperatures across Montreal using a large database of temperature measurements collected from 200 sites across Montreal during the summers of 2018 and 2019. Using these data, we conducted a case crossover study of daily temperature and emergency room visits for asthmas and myocardial infractions between 2014-2018. Conditional logistic regression models were analyzed using traditional fixed-site monitors and our new high-resolution models. RESULTS:There was a positive association between daily mean temperature and myocardial infraction using both fixed-site temperature data [OR=1.076 (95% CI: 1.0081-1.149) per 5oC] as well as our new high-resolution model [OR = 1.077 (95% CI: 1.0098-1.148) per 5oC]. Among older women, temperature was more strongly associated with myocardial infarction using our new high-resolution mode (OR = 1.147 (95% CI: 1.0057, 1.309) per 5oC] compared to fixed-site measurements [OR = 1.104 (95% CI: 0.9963, 1.304) per 5oC]. There was a negative association in individuals below the median age of 57 who had asthma using the fixed temperature site [OR = 0.7001 (95% CI: 0.5315-0.9222) per 5oC] as well as the high-resolution model [OR = 0.7423 (95% CI: 0.5710-0.9649) per 5oC]. CONCLUSIONS:Daily variations in summer temperatures are positively associated with acute myocardial infarction. Stronger associations were generally observed using our new high-resolution estimates of spatio-temporal variations in temperature compared to traditional fixed site measurements. KEYWORDS: Asthma, myocardial infractions, case-crossover study, heatwaves, extreme temperatures

Quantification of airway dimensions using a high-resolution CT scanner: A phantom study.

Small airways with inner diameters less than 2mm are sites of major airflow limitations in patients with chronic obstructive pulmonary disease (COPD) and asthma. The purpose of this study is to investigate the limitations for accurate assessment of small airway dimensions using both high-resolution CT (HRCT) and conventional normal-resolution CT at low dose levels. To model the normal human airways from the 3rd to 20th generations, a cylindrical polyurethane phantom with 14 airway tubes of inner diameters (ID) ranging from 0.3 to 3.4mm and wall thicknesses (WT) ranging from 0.15 to 1.6mm was placed within an Anthropomorphic QRM-Thorax phantom. The Aquilion Precision (Canon Medical Systems Corporation) HRCT scanner was used to acquire images at 80, 100, and 120kV using high resolution mode (HR, 0.25mm×160 detector configuration) and normal-resolution (NR) mode (0.5mm×80 detector configuration). The HR data were reconstructed using a 1024×1024matrix (0.22×0.22×0.25mm voxel size) and the NR data were reconstructed using a 512×512matrix (0.43×0.43×0.50mm). Two reconstruction algorithms (filtered back projection; FBP and an adaptive iterative dose reduction 3D algorithm; AIDR 3D) and three reconstruction kernels (FC30, FC52, and FC56) were investigated. The dose values ranged from 0.2 to 6.2mGy. A refined automated full-width half-maximum (FWHM) method was used for the measurement of airway dimensions, where the density profiles were computed by radial oversampling using a polar coordinate system. Both ID and WT were compared to the known dimensions using a regression model, and the root-mean-square error (RMSE) and average error were computed across all 14 airway tubes. The results indicate that the ID can be measured within a 15% error down to approximately 0.8 and 2.0mm using the HR and NR modes, respectively. The overall RMSE (and average error) of ID measurements for HR and NR were 0.10mm (-0.70%) and 0.31mm (-2.63%), respectively. The RMSE (and average error) of WT measurements using HR and NR were 0.10mm (23.27%) and 0.27mm (53.56%), respectively. The WT measurement using HR yielded a factor of two improvement in accuracy as compared to NR. High-resolution CT can provide more accurate measurements of airway dimensions as compared with NR CT, potentially improving quantitative assessment of pathologies such as COPD and asthma. The HR mode acquired and reconstructed with AIDR3D and the FC52kernel provides most accurate measurement of airway dimensions. Low-dose HR measurements at dose level above 0.9mGy can provide improved accuracy on both inner diameters and wall thicknesses compared to full dose NR airway phantom measurements.