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The article is devoted to the problem of air pollution and its impact on human health and the environment. The paper considers methods of air pollution analysis based on the use of neural networks, taking into account the variety of data from the Internet. The authors emphasize the different effects of pollutants depending on the type, duration and level of exposure, as well as other factors, including individual risks to human health and the combined effects of different pollutants and stress factors. Special attention is paid to the two most common types of air pollution - smog and soot. The uneven distribution of the negative effects of air pollution, which are most often felt in low-income and colored communities, as well as the Air quality Index (AQI) developed by the Environmental Protection Agency, which informs the population about the current state of atmospheric air and its impact on human health, are considered separately. As a result of the work, the criteria for analyzing air quality, including pollution parameters and weather conditions, are presented, and the structure of future data is developed.

The purpose of the study is labor saving, productivity gain of work and ball screws quality design pursuant to the use in numerical control machines. The article is devoted to the problem of automation of the designing of ball screws with return ports. These ball screws are an important element of the mechatronic modules of numerically controlled machines, as they affect the accuracy of linear displacement. Research methods: system-oriented analysis, structural analysis, methods of functional and object-matching programming, simulation. The novelty of the work: a method of three-dimensional parametric simulation of nuts of ball screws and a computation algorithm for a ball screw based on the synthesis of well-known techniques, has been developed. Research results: a software product consisting of modules that together automate the design process of nuts, screws, rigid supports, tilting saddles and ball screw coupling elements, has been developed. Conclusions: the developed methods for calculation of basic ball screw parameters can be used as the algorithmic basis of software products. Since the process for designing ball screw nuts with return ports has been automated, there are grounds for developing automation methods for other types of nuts.

This paper summarizes emerging practice and research issues in the health insurance industry. We provide an industry overview, epitomize business analytics applications, and outline current and emerging problems of interest to key stakeholders and researchers in information systems, operations management, and healthcare management. Specifically, we focus on three areas of research that are of importance to the health insurance industry as well as the healthcare system: (i) management and evaluation of intervention programs, (ii) creation of effective provider networks, and (iii) emerging issues such as the impact of a pandemic, patient communication and steering, and technological innovations in health care. We lay out brief details of how each of these problems can be formulated, where the data can be acquired (public and/or proprietary data sets), and provide guidance for solving them. For several of these problems, we provide models that span causal modeling, predictive modeling, and prescriptive modeling. [ABSTRACT FROM AUTHOR]

A complementary safety assessment of the specific absorption rate (SAR) of the electromagnetic energy was performed in a prototype 8Tx/16Rx RF array for cardiac magnetic resonance imaging (MRI) at 7 T. The study aimed to address two critical aspects of 7‐T SAR safety not always explicitly examined by coil vendors: (i) the influence of an RF‐array position on a peak SAR value, and (ii) the risk of exceeding the permitted maximal SAR in the tissue surrounding conductive passive implants. The full‐wave 3D electromagnetic simulations for the thorax with shifted array position and the whole‐body volume in the presence of a dental retainer, an intrauterine contraceptive device (IUD), and a hip joint implant, were performed for two human voxel models. The effect of the array displacement on the SAR was simulated for seven array locations on the thorax shifted from the central position in different directions on 50 mm. The peak SAR values for both models were analyzed for the three phase‐only transmit vectors optimized for B1+ homogeneity and transmit efficiency. Peak SAR values due to the shifts of the array position increase up to ≈50%. The worst‐case peak SAR value for a dental retainer was found to be in the range of 10% of the maximal SAR in the tissue within the array's borders. For the IUD and artificial hip joint implants the effect was found to be negligible (peak SAR < 1% of the SAR within array borders). In addition to simulations for cardiac MRI, we performed a preliminary B1+ shimming and SAR‐safety analysis for the same RF‐array at various positions lower on the body trunk to assess a potential application in imaging abdominopelvic organs (prostate, kidney, and liver). The most promising target for an ad hoc alternative application of the array was found to be the prostate. [ABSTRACT FROM AUTHOR]

B0 inhomogeneity leads to imaging artifacts in cardiac magnetic resonance imaging (MRI), in particular dark band artifacts with steady‐state free precession pulse sequences. The limited spatial resolution of MR‐derived in vivo B0 maps and the lack of population data prevent systematic analysis of the problem at hand and the development of optimized B0 shim strategies. We used readily available clinical computed tomography (CT) images to simulate the B0 conditions in the human heart at high spatial resolution. Calculated B0 fields showed consistency with MRI‐based B0 measurements. The B0 maps for both the simulations and in vivo measurements showed local field inhomogeneities in the vicinity of lung tips with dominant Z3 spherical harmonic terms in the field distribution. The presented simulation approach allows for the derivation of B0 field conditions at high spatial resolution from CT images and enables the development of subject‐ and population‐specific B0 shim strategies for the human heart. [ABSTRACT FROM AUTHOR]

To improve parallel transmit (pTx) and receive performance for cardiac MRI (cMRI) in pigs at 7 T, a dedicated transmit/receive (Tx/Rx), 16‐element antisymmetric dipole antenna array, which combines L‐shaped and straight dipoles, was designed, implemented, and evaluated in both cadavers and animals in vivo. Electromagnetic‐field simulations were performed with the new 16‐element dipole antenna array loaded with a pig thorax‐shaped phantom and compared with an eight‐element array of straight dipoles. The new dipole array was interfaced to a 7 T scanner in pTx mode (8Tx/16Rx). Imaging performance of the novel array was validated through MRI measurements in a pig phantom, an 85 kg pig cadaver, and two pigs in vivo (74 and 81 kg). Due to the improved decoupling between interleaved L‐shaped and straight dipole elements, the 16‐element dipole array fits within the same outer dimensions as an eight‐element array of straight dipoles. This provides improvement of both transmit and receive characteristics and additional degrees of freedom for B1+ shimming. The antisymmetric dipole array demonstrated efficient suppression of destructive interferences in the B1+ field, with up to 25% improvement in the B1+ homogeneity achieved using static pTx‐RFPA B1+ shimming in comparison with the hardware‐adjusted state, which was optimized for single transmit. High‐resolution (0.5 × 0.5 × 4 mm3) anatomical images of the heart after cardiac arrest proved good transmit and receive characteristics of the novel array design. Parallel imaging with an acceleration factor up to R = 6 was possible while maintaining a mean g factor of 1.55 within the pig heart. CINE images acquired in vivo in two pigs demonstrated SNR and parallel imaging capabilities similar to those of a reference 8Tx/16Rx dedicated loop array for cMRI in pigs. [ABSTRACT FROM AUTHOR]

Background: To investigate the effects of B1-shimming and radiofrequency (RF) parallel transmission (pTX) on the visualization and quantification of the degree of stenosis in a coronary artery phantom using 7 Tesla (7 T) magnetic resonance imaging (MRI). Methods: Stenosis phantoms with different grades of stenosis (0%, 20%, 40%, 60%, 80%, and 100%; 5 mm inner vessel diameter) were produced using 3D printing (clear resin). Phantoms were imaged with four different concentrations of diluted Gd-DOTA representing established arterial concentrations after intravenous injection in humans. Samples were centrally positioned in a thorax phantom of 30 cm diameter filled with a custom-made liquid featuring dielectric properties of muscle tissue. MRI was performed on a 7 T whole-body system. 2D-gradient-echo sequences were acquired with an 8-channel transmit 16-channel receive (8 Tx / 16 Rx) cardiac array prototype coil with and without pTX mode. Measurements were compared to those obtained with identical scan parameters using a commercially available 1 Tx / 16 Rx single transmit coil (sTX). To assess reproducibility, measurements (n = 15) were repeated at different horizontal angles with respect to the B0-field. Results: B1-shimming and pTX markedly improved flip angle homogeneity across the thorax phantom yielding a distinctly increased signal-to-noise ratio (SNR) averaged over a whole slice relative to non-manipulated RF fields. Images without B1-shimming showed shading artifacts due to local B1+-field inhomogeneities, which hampered stenosis quantification in severe cases. In contrast, B1-shimming and pTX provided superior image homogeneity. Compared with a conventional sTX coil higher grade stenoses (60% and 80%) were graded significantly (p<0.01) more precise. Mild to moderate grade stenoses did not show significant differences. Overall, SNR was distinctly higher with B1-shimming and pTX than with the conventional sTX coil (inside the stenosis phantoms 14%, outside the phantoms 32%). Both full and half concentration (10.2 mM and 5.1 mM) of a conventional Gd-DOTA dose for humans were equally suitable for stenosis evaluation in this phantom study. Conclusions: B1-shimming and pTX at 7 T can distinctly improve image homogeneity and therefore provide considerably more accurate MR image analysis, which is beneficial for imaging of small vessel structures. [ABSTRACT FROM AUTHOR]

Purpose: Inhomogeneities of the static magnetic B0 field are a major limiting factor in cardiac MRI at ultrahigh field (≥ 7T), as they result in signal loss and image distortions. Different magnetic susceptibilities of the myocardium and surrounding tissue in combination with cardiac motion lead to strong spatio‐temporal B0‐field inhomogeneities, and their homogenization (B0 shimming) is a prerequisite. Limitations of state‐of‐the‐art shimming are described, regional B0 variations are measured, and a methodology for spherical harmonics shimming of the B0 field within the human myocardium is proposed. Methods: The spatial B0‐field distribution in the heart was analyzed as well as temporal B0‐field variations in the myocardium over the cardiac cycle. Different shim region‐of‐interest selections were compared, and hardware limitations of spherical harmonics B0 shimming were evaluated by calibration‐based B0‐field modeling. The role of third‐order spherical harmonics terms was analyzed as well as potential benefits from cardiac phase–specific shimming. Results: The strongest B0‐field inhomogeneities were observed in localized spots within the left‐ventricular and right‐ventricular myocardium and varied between systolic and diastolic cardiac phases. An anatomy‐driven shim region‐of‐interest selection allowed for improved B0‐field homogeneity compared with a standard shim region‐of‐interest cuboid. Third‐order spherical harmonics terms were demonstrated to be beneficial for shimming of these myocardial B0‐field inhomogeneities. Initial results from the in vivo implementation of a potential shim strategy were obtained. Simulated cardiac phase–specific shimming was performed, and a shim term‐by‐term analysis revealed periodic variations of required currents. Conclusion: Challenges in state‐of‐the‐art B0 shimming of the human heart at 7 T were described. Cardiac phase–specific shimming strategies were found to be superior to vendor‐supplied shimming. [ABSTRACT FROM AUTHOR]