Mean Relative Difference Research Articles

Comparisons of the vertical distributions of aerosols in the CALIPSO and GEOS-Chem datasets in China

Abstract In this study, we compared the aerosol profiles derived from the Cloud-Aerosol Lidar Infrared Pathfinder Satellite Observations (CALIPSO) over China with those simulated by the Global 3-D Atmospheric Chemical Transport model (GEOS-Chem) for the period of 2007–2014. Multiple steps were implemented in the data analysis. First, we validated CALIPSO and GEOS-Chem aerosol optical depth (AOD) using Moderate Resolution Imaging Spectroradiometer (MODIS) products, both CALIPSO and GEOS-Chem AOD were found to 30%∼50% underestimations in eastern China and 60%∼80% underestimations in western China. Second, MODIS AOD was introduced to normalize the aerosol extinction coefficient (AEC) of both CALIPSO and GEOS-Chem in each 1-km layer below 10 km to achieve a uniform comparison. Linear regression analysis between the normalized CALIPSO and GEOS-Chem AECs yielded better correlation coefficients and lower mean relative differences than the direct comparisons from the original data. Finally, we investigated the vertical distributions of aerosol components over the North, South, Northwest and Tibet regions of China. Our findings are summarized based on different aerosol components as the following. Dust aerosols: The percentages of CALIPSO polluted dust to total dust in the North and South regions (50%∼68% in different seasons) are higher than those in the Northwest and Tibet regions (25%∼45%). Thus, the polluted dust classification significantly affects our comparisons in the North and South. For CALIPSO pure dust, its concentrations in the higher layers are larger than those of GEOS-Chem. Continental/sulfate, nitrate, and ammonium (SNA) aerosols: The percentages of CALIPSO continental aerosols to total aerosols are almost negligible throughout the four regions (

Temporal stability of soil apparent electrical conductivity (ECa) in managed podzols

The spatial variability in soil physical and hydraulic properties for a managed podzol was assessed using soil apparent electrical conductivity (ECa). Two EMI sensors, the multi-coil (MC) and multi-frequency (MF), were adopted for measurement of ECa on a silage- corn experimental plot in western Newfoundland, Canada. Results demonstrated a significant relationship between the ECa mean relative differences (MRD) and the soil moisture content MRD (R2 = 0.33 to 0.70) for both MC and MF sensors. The difference in depth sensitivity between MC and MF sensors accounted for the variation (0.015 to 0.09) in ECa standard deviation of the relative differences. A significant linear relationship was found between the ECa MRD and sand (R2 = 0.35 and 0.53) or silt (R2 = 0.43), but not with clay (R2 = 0.06 and 0.16). The spatial variability of the ECa-based predictions (CV = 3.26 to 27.61) of soil properties was lower than the measured values (CV = 5.56 to 41.77). These results inferred that the temporal stability of ECa might be a suitable proxy to understand the spatial variability of soil physical and hydraulic properties in agricultural podzols.

Relative efficacy of interventions in the treatment of second-line non-small cell lung cancer: a systematic review and network meta-analysis

BackgroundLocally advanced or metastatic non-small cell lung cancer (NSCLC) that has progressed after first-line treatment has a poor prognosis. Recent randomized clinical trials (RCTs) have demonstrated survival benefits of alternative treatments to docetaxel. However, information is lacking on which patients benefit the most and what drug or regimen is optimal. We report a systematic review and network meta-analysis (NMA) of second-line treatments in all subgroup combinations determined by histology, programmed death ligand 1 (PD-L1) expression, and epidermal growth factor receptor (EGFR) mutation.MethodsMEDLINE, PubMed, EMBASE, Biosciences Information Service (using the Dialog Platform), Cochrane Library, and abstracts from scientific meetings were searched for RCTs published up to September 2015. Key outcomes were overall survival (OS) and progression-free survival (PFS). Bayesian hierarchical exchangeable NMAs were conducted to calculate mean survival times and relative differences for eight subgroups, using docetaxel as the reference comparator. For OS, the NMA was based on hazard ratios applied to a first-order fractional polynomial model fitted to the reference treatment. For PFS, a second-order fractional polynomial model was fitted to reconstructed patient-level data for the entire network of evidence.ResultsThe search identified 30 studies containing 17 different treatment regimens. Docetaxel plus ramucirumab was associated with a significant improvement in OS and PFS, relative to docetaxel, regardless of patient type. Docetaxel plus nintedanib showed similar efficacy to docetaxel plus ramucirumab in the nonsquamous populations. EGFR tyrosine kinase inhibitors (TKIs) erlotinib and gefitinib showed superior levels of efficacy in EGFR mutation-positive populations and the one PD-1 immunotherapy (nivolumab) studied showed superior efficacy in the populations exhibiting high PD-L1 expression.ConclusionsIn the absence of head-to-head comparisons, we performed a mixed-treatment analysis to synthesize evidence of the efficacy of each treatment. Benefits are optimized by targeting specific treatments to individual patients guided by histology, PD-L1 expression, and EGFR mutation status.Systematic review registrationThis review is registered in PROSPERO (registration number: CRD42014013780 available at www.crd.york.ac.uk/PROSPERO).

Applicability of Taylor’s Hypothesis for Estimating the Mean Streamwise Length Scale of Large-Scale Structures in the Near-Neutral Atmospheric Surface Layer

A field investigation of the mean streamwise length scale Lx of large-scale structures and the convection velocity is performed in a high-Reynolds-number (Reτ ~ 106) atmospheric surface layer (ASL). Based on selected high-quality synchronous data obtained at different streamwise positions, the length scale Lx and global convection velocity Uc are extracted in the logarithmic region of the near-neutral ASL at heights of 0.9 m, 1.71 m, 3.5 m, and 5 m. It is found that Uc values are approximately 16% greater than the local mean streamwise velocity component U, and the value of Lx obtained from spatially-separated measurements is greater than the results estimated from Taylor’s hypothesis using the value of U at the four heights. The mean relative difference between the value of Lx and the results estimated by Taylor’s hypothesis using the value of U is approximately 15%. However, the relative difference between the value of Lx and the results estimated from Taylor’s hypothesis using the convection velocity Uc instead of the mean streamwise velocity component U is reduced to 1 ± 6% (≈ zero). Thus, the convection velocity Uc is more appropriate than the mean streamwise velocity component U in obtaining Lx values in the near-neutral ASL.

Accuracy of a Point-of-Care Hemoglobin A1c Assay.

Point-of-care test (POCT) HbA1c assays provide rapidly available results for clinical decision-making. Accuracy and precision must be established. Venous blood samples from 300 patients were assayed for HbA1c by a laboratory technician ("laboratory assessment") with the POCT Alere Afinion™ assay and a laboratory (Premier AffinityTM) assay. POCT results from 402 patients' fingerstick samples assayed by nine nontechnician staff ("clinical assessment") were compared with the laboratory assay. The laboratory assessment showed tight correlation (r2 = .977, P < .001) between the assays. Mean absolute and relative differences were 0.01 percentage points and 2.1%, respectively. CVs for the POCT and laboratory assays were <2% and <1%, respectively. The clinical assessment also showed a tight correlation between the assays (r2 = .978, P < .001), with mean absolute and relative differences of 0.2 percentage points and 3.41%, respectively. CV for the POCT assay was <2%. The POCT performed acceptably compared to the laboratory assay under realistic clinical conditions.

A Soft Ring-Shaped Actuator for Radial Contracting Deformation: Design and Modeling.

Bioinspired movements such as elongation/shortening and bending are extensively studied in the field of soft robotics. However, radial contracting deformation has been overlooked, another typical deformation in nature, such as the constrictive deformation in the human esophagus and bladder. We present a novel soft ring-shaped actuator that generates radial contraction and examine its quasi-static performance under pressurization. This actuator consists of a soft ring-shaped body and a rigid casing. A single circular air chamber embedded concentrically inside the actuator is created through the lost-wax method. A theoretical model of the quasi-static state of the actuator's contracting deformation was formulated in light of the minimum total potential energy principle. Meanwhile, a finite-element method (FEM) model was constructed to stimulate the radial contraction of the actuator. In addition, experiments were conducted to identify the maximum input pressure and measure the deformations at the specific input pressure. When the actuators were pressurized under 20.0 kPa, axisymmetric contractions were achieved. The theoretical model and FEM models produced the predictions in good agreement with experimental results, with slight mean relative differences regarding peak points, 3.4% and 5.4%, respectively. In addition, pilot tests suggest that the ring-shaped actuator can achieve the key tasks of robotic manipulators, such as gripping and holding.

QPSMA: Semiautomatic Software for Whole-Body Tumor Burden Assessment in Prostate Cancer Using 68Ga-PSMA11 PET/CT.

Our aim was to introduce and validate qPSMA, a semiautomatic software package for whole-body tumor burden assessment in prostate cancer patients using 68Ga-prostate-specific membrane antigen (PSMA) 11 PET/CT. Methods: qPSMA reads hybrid PET/CT images in DICOM format. Its pipeline was written using Python and C++ languages. A bone mask based on CT and a normal-uptake mask including organs with physiologic 68Ga-PSMA11 uptake are automatically computed. An SUV threshold of 3 and a liver-based threshold are used to segment bone and soft-tissue lesions, respectively. Manual corrections can be applied using different tools. Multiple output parameters are computed, that is, PSMA ligand-positive tumor volume (PSMA-TV), PSMA ligand-positive total lesion (PSMA-TL), PSMA SUVmean, and PSMA SUVmax Twenty 68Ga-PSMA11 PET/CT data sets were used to validate and evaluate the performance characteristics of qPSMA. Four analyses were performed: validation of the semiautomatic algorithm for liver background activity determination, assessment of intra- and interobserver variability, validation of data from qPSMA by comparison with Syngo.via, and assessment of computational time and comparison of PSMA PET-derived parameters with serum prostate-specific antigen. Results: Automatic liver background calculation resulted in a mean relative difference of 0.74% (intraclass correlation coefficient [ICC], 0.996; 95%CI, 0.989;0.998) compared with METAVOL. Intra- and interobserver variability analyses showed high agreement (all ICCs > 0.990). Quantitative output parameters were compared for 68 lesions. Paired t testing showed no significant differences between the values obtained with the 2 software packages. The ICC estimates obtained for PSMA-TV, PSMA-TL, SUVmean, and SUVmax were 1.000 (95%CI, 1.000;1.000), 1.000 (95%CI, 1.000;1.000), 0.995 (95%CI, 0.992;0.997), and 0.999 (95%CI, 0.999;1.000), respectively. The first and second reads for intraobserver variability resulted in mean computational times of 13.63 min (range, 8.22-25.45 min) and 9.27 min (range, 8.10-12.15 min), respectively (P = 0.001). Highly significant correlations were found between serum prostate-specific antigen value and both PSMA-TV (r = 0.72, P < 0.001) and PSMA-TL (r = 0.66, P = 0.002). Conclusion: Semiautomatic analyses of whole-body tumor burden in 68Ga-PSMA11 PET/CT is feasible. qPSMA is a robust software package that can help physicians quantify tumor load in heavily metastasized prostate cancer patients.

Density of biofuel mixtures (Dibutyl ether + Heptane) at temperatures from (298.15–393.15) K and at pressures up to 140 MPa: Experimental data and PC-SAFT modeling

Density has been reported to binary mixtures (552 points) of dibutyl ether (DBE) + heptane in the composition range (4 compositions; 0.325 ≤ dibutyl ether mole fraction x ≤ 0.85), between 298.15,393.15 K, and for 23 pressures ranging from 0.1 MPa to 140 MPa.These experimental measurements were carried out using an apparatus, comprising a vibrating tube densimeter Anton Paar, calibrated with an uncertainty of about 0.7 kg· m-3.The volumetric behavior and excess molar volume of DBE + heptane were modeled using PC-SAFT equation. The PC-SAFT parameters of DBE and heptane were optimized using experimental density data at atmospheric pressure. The density of the mixture was reasonably well predicted, with a mean relative difference between 0.0009% and 1.99%. Whereas the excess molar volume not satisfactorily predicted.A Tait equation was used to adjust the experimental density data. In addition, from this equation the isobaric thermal expansion and the isothermal compressibility were derived.

Where to monitor the soil-water potential for scheduling drip irrigation in Populus tomentosa plantations located on the North China Plain?

Determining the optimal tensiometer placement is crucial for scheduling irrigation based on soil water potential (SWP) in poplar plantations. However, such work has never been done. The stand-age effect on the tensiometer placement is still unknown, hindering the development of a dynamic irrigation regime. In a surface drip irrigated Populus tomentosa, short-rotation plantation on sandy loam soil, the variation of SWP at different positions [hereafter expressed in spatial coordinates (distance from dripper in cm, depth in cm)] within the soil wetting volume (WV), and the daily tree growth rates were continuously monitored in one growing season. Whereas, the transpiration and fine root distribution were measured in two growing seasons. The HYDRUS model was calibrated using soil water and transpiration data from one growing season and validated using data in another growing season. Then the model was applied to simulate sixty scenarios, which were combinations of different SWP measurement positions (ten scenarios), root distribution patterns (three scenarios; mainly using rooting depth as a proxy for trees at different ages), and irrigation thresholds (two scenarios). Based on the simulation results, we estimated the ratio of actual to potential transpiration (Ta/Tp) and irrigation efficiency (IE; calculated as (Ta/Tp)/irrigation amount) for each scenario. The absolute value of the mean relative difference of SWP was smaller at (15, 10) than at any other positions within the WV. The proportion of variation in growth (R2 = 0.294) and transpiration rates (R2 = 0.247) explained by root water-uptake was also highest at (15, 10). Fine roots concentrated on both sides of dripper as the trees grew bigger, with the maximal root density finally occurring at about (15, 10) and (−15, 10). Under the (−15, 10), (0, 10), (15, 10) and (0, 30) position scenarios, the Ta/Tp was at a high level relative to other scenarios, while the IE were at a middle level. As rooting depth increased, the ranks of different tensiometer positions in Ta/Tp and IE changed only a little, and Ta/Tp decreased slightly, implying the optimal placement should not vary with stand age. Therefore, tensiometer was recommended to place at 10 cm depth and about 15 cm distance from the dripper to schedule drip irrigation in different-aged P. tomentosa plantations on sandy loam soil. This will bring benefits to minimizing the use of irrigation water and maximizing production. Besides, the comprehensive approach used in this study can be adopted, when determining the optimal soil water measurement positions for scheduling irrigation for other plant species growing on other soil types.

On the remote estimation of Ulva prolifera areal coverage and biomass

Since the outbreak of a large-scale Ulva prolifera bloom in the Yellow Sea during the Qingdao Olympic Sailing Competition in summer 2008, Ulva blooms have been a marine hazard every summer. Accurate and timely information on Ulva areal coverage and biomass is of critical importance for governmental responses, decision making, and field studies. Previous studies have shown that satellite remote sensing is the most effective method for this purpose, yet Ulva areal coverage has been estimated in different ways with significantly different results. The objective of this paper is to determine the lower and upper bounds (T0 and T1) of algae-containing pixels in Floating Algae Index images with an objective method that accurately estimates the Ulva areal coverage in individual images, and then converts coverage to biomass using a previously established conversion equation. First, a seawater background image, FAIsw, is constructed to determine T0, which varies for different algae patches. Then, T1 is determined from water tank and in situ measurements as well as radiative transfer simulations to account for different sensor configurations, solar/viewing geometry, and atmospheric conditions. Such determined T1 for MODIS 250-m resolution data is validated using concurrent and collocated 2-m resolution WorldView-2 data. Finally, Ulva areal coverage derived from MODIS data using this method are compared with those from the high-resolution data (OLI/Landsat, WFV/GaoFen-1), with a mean relative difference of 9.6%. Furthermore, an analysis of 17 same-day MODIS/Terra and MODIS/Aqua image pairs shows that large viewing angles, atmospheric turbidity, and sunglint can lead to an underestimation of Ulva coverage of up to 45% under extreme conditions.

Objective assessment of glare at outdoor workplaces

Lighting system in a modern building environment involves many different aspects of workplaces, primarily visual comfort and health. The glare may reduce visual comfort and may be one of the indirect causes of accidents at work. Glare assessment at outdoor workplaces is a difficult task. In this instance, the Glare Rating (GR) is used as a numeric measure of glare sensation. International standards set out the rules for determining the GR as well as the required limit values of GR that provide acceptable glare sensation for specific workplaces. In practice, GR is not measured and simulation software is used to determine the GR value. However, such an assessment of the glare is not always reliable. We present the GR measurement method for outdoor workplaces using imaging luminance measuring device (ILMD). The conditions that are necessary for the proper measurement of GR were also described. The presented method was tested in laboratory conditions and in real industrial environment. Using two laboratory rooms and three different glare sources we created a set of working conditions with different glare sensation. The results of the GR measurements were consistent with the simulation in the DIALux software (mean relative difference of 2.5%). We also conducted tests in six industrial plants at 26 workplaces. In 73% of analyzed cases, the workers' subjective assessment of the glare was consistent with the results of GR measurement. A number of laboratory tests and assessments in real industrial environment confirmed the correctness of the proposed measurement method.

Reliability of bedside ultrasound of limb and diaphragm muscle thickness in critically ill children.

We evaluated the reliability of measuring muscle thickness with ultrasound in limbs and diaphragms of critically ill children and determined the sensitivity of these measures to quantitate muscle atrophy over time. An expert and trained novice sonographers prospectively measured limb and diaphragm muscle thickness in 33 critically ill children. Expert and novice intrarater and interrater reliability were similar. Intraclass correlations (ICC) and coefficients of variation (CoV) were better in limbs (ICC > 0.9; CoV 3.57%-5.40%) than in diaphragm (ICC > 0.8; CoV novice 11.88%, expert, 12.28%). Mean relative difference in all muscles was small (1%-8%). Limits of agreement of the relative difference were smaller in limb (<13%-18%) than in diaphragm (<38%) muscles. Muscle thickness is reliably measured with ultrasound by trained examiners in critically ill children. Our approach detects atrophy >13% in limb and >38% in diaphragm muscles. The smaller detectable change in limb muscles is likely due to their greater thickness. Muscle Nerve 59:88-94, 2019.

A generative model of realistic brain cells with application to numerical simulation of the diffusion-weighted MR signal

To date, numerical simulations of the brain tissue have been limited by their lack of realism and flexibility. The purpose of this work is to propose a controlled and flexible generative model for brain cell morphology and an efficient computational pipeline for the reliable and robust simulation of realistic cellular structures with application to numerical simulation of intra-cellular diffusion-weighted MR (DW-MR) signal features. Inspired by the advances in computational neuroscience for modelling brain cells, we propose a generative model that enables users to simulate molecular diffusion within realistic digital brain cells, such as neurons, in a completely controlled and flexible fashion. We validate our new approach by showing an excellent match between the morphology (no statistically different 3D Sholl metrics, P > 0.05) and simulated intra-cellular DW-MR signal (mean relative difference < 2%) of the generated digital model of brain cells and those of digital reconstruction of real brain cells from available open-access databases. We demonstrate the versatility and potential of the framework by showing a select set of examples of relevance for the DW-MR community. The computational models introduced here are useful for synthesizing intra-cellular DW-MR signals, similar to those one might measure from brain metabolites DW-MRS experiments. They also provide the foundation for a more complete simulation system that will potentially include signals from extra-cellular compartments and exchange processes, necessary for synthesizing DW-MR signals of relevance for DW-MRI experiments.

Accuracy of a Smartphone-based Autorefractor Compared with Criterion-standard Refraction

Uncorrected refractive error is a prevalent problem throughout the world especially among the low-income population who have limited access to professional eye care and cannot afford eyeglasses. The purpose of this study was to evaluate the accuracy and usability of a low-cost, portable, smartphone-based autorefractor (Netra, EyeNetra Inc., Somerville, MA) in adults. A cross-sectional study was conducted to compare the portable refractor with subjective (manifest and cycloplegic) refraction for sequential adult participants with best-corrected visual acuity of 20/40 or greater. For each method of refraction, the spherical equivalent was calculated. Differences between methods were tested with linear mixed regression models. A validated usability questionnaire was administered regarding ease of use (100-point scale, higher scores better) for the portable autorefractor. Eighty-seven subjects (152 eyes) were studied (age range, 20 to 90 years; mean ± standard deviation, 51.9 ± 18.3 years). Mean spherical equivalent by the portable device was -2.76 D (range, -14.75 to 3.63 D) compared with -2.49 D (range, -15.25 to 4.25 D) by manifest refraction. The mean relative difference in spherical equivalent between methods was -0.27 D (P = .001, significantly different than 0 D). The mean absolute difference between methods was 0.69 D (P < .001, significantly different than 0.5-D absolute difference). Similar results were found when comparing spherical equivalent between Netra and cycloplegic refraction methods. Subjects reported average ease of use for the Netra of 75.4 ± 19.8. The portable autorefractor had small but clinically significant differences from subjective refraction. The device's scores on the usability scale indicate good overall patient acceptance. The device may be valuable for use where there is limited access to a trained refractionist.

233. Radiotherapy treatment planning of the pelvis region using only MR pseudo-CT images

Introduction Radiotherapy treatment plannings are based on CT images that provide information of tissue density. A fusion between CT and MR images is often performed in anatomical regions characterized by soft tissue prevalence to improve contouring, considering the high contrast provided by MRI. In this study, a method for the reconstruction of pseudo-CT of pelvis region, using only T1/T2-weighted MR images, was developed to reduce radiation exposure, improve anatomical contrast and skip image fusion during planning. Materials and Methods CT and MR images of 6 patients were acquired using a GE LightSpeed Xtra and a GE Optima MR360 1.5 T Advance, respectively. A registration between MR and CT images was performed by SPM12. The images of 5 patients were segmented in 5 different regions, according to the histogram of the CT images: body surface, soft tissue, bone surface, spongy bone and compact bone. Fitting parameters were obtained by the least squares method, comparing MR and CT intensities. Akaike information criterion highlighted the polynomial function that best fitted the data for each segmented region. The evaluated fitting parameters were used to generate pseudo-CT images from the MR images of the 6th patient. Body surface and soft tissue were automatically segmented, while bone structures were identified by a semiautomatic method. For validation, corresponding CT and pseudo-CT voxel intensities were compared. Dose distribution accuracy in a direct field treatment was estimated evaluating the dose in 10 points and PDDs on both CT and pseudo-CT images by Pinnacle3. Results A mean relative intensity difference of ≈1.3% was found between CT and pseudo-CT images, mainly due to body surface and bone segmentation. The evaluated dose and PDD mean relative differences were of ≈1.2% and ≈1%, respectively. Conclusions Our preliminary results on pseudo-CT planning show the method feasibility. These could be improved implementing an automatic bone segmentation.

In vivo dosimetry of intraoral stent using TLD during external photon beam radiotherapy of oral cavity

Introduction: Individual oral stent is a mouth-opening device that used in head and neck cancer radiotherapy with the intention of decreasing radiation dose to health tissues. The aim of this study was to check the dose delivered to both the hard palate and tongue when patient uses the stent during radiotherapy of tongue carcinoma. Methods and materials: The intraoral stents were made for 10 patients and TLD-100 dosimeters were placed at superior and inferior parts of stent at the level of hard palate and tongue, respectively. Then patients treated with 3DCRT technique using 6MV photons, the data from the TLDs and treatment planning system calculations were analyzed. Results: The results showed that the mean (±standard deviation) relative difference between measured and calculated doses for tongue and hard palate was -4.41± 6.34, 0.57± 9.6 respectively. Conclusion: This study demonstrated the value of thermoluminescent dosimetry as a treatment verification method and its usefulness departmental quality assurance program.

Reproducibility of brain MRS in older healthy adults at 7T.

To date, the majority of MRS reproducibility studies have been conducted in healthy younger adults, with only a few conducted in older adults at 3T. With the growing interest in applying MRS methods to study the longitudinal course and effects of treatments in neurodegenerative disease, it is important to establish reproducibility in age-matched controls, especially in older individuals. In this study, spectroscopic data were acquired using a stimulated echo acquisition mode (STEAM) localization technique in two regions (anterior and posterior cingulate cortices-ACC, PCC, respectively) in 10 healthy, cognitively normal older adults (64±8.1years). Reproducibility was assessed via mean coefficients of variation (CVs) and relative differences (RDs) calculated across two visits performed 2-3months apart. Metabolites with high signal-to-noise ratio (SNR) such as NAA, tCho, and Glu had mean CVs of 10% or less and mean RDs of 15% or less across both regions. Metabolites with lower SNR such as GABA and Gln had slightly higher mean CVs of 22% or less and mean RDs of 27% or less across both regions. These results demonstrate the feasibility of acquiring MRS data at 7T in older subjects, and establish that the spectroscopic data are reproducible in both the ACC and PCC in older, healthy subjects to the same extent as in previous studies in young subjects.

Advances in representing interactive methane in ModelE2-YIBs (version 1.1)

Abstract. Methane (CH4) is both a greenhouse gas and a precursor of tropospheric ozone, making it an important focus of chemistry–climate interactions. Methane has both anthropogenic and natural emission sources, and reaction with the atmosphere's principal oxidizing agent, the hydroxyl radical (OH), is the dominant tropospheric loss process of methane. The tight coupling between methane and OH abundances drives indirect linkages between methane and other short-lived air pollutants and prompts the use of interactive methane chemistry in global chemistry–climate modeling. In this study, an updated contemporary inventory of natural methane emissions and the soil sink is developed using an optimization procedure that applies published emissions data to the NASA GISS ModelE2-Yale Interactive terrestrial Biosphere (ModelE2-YIBs) global chemistry–climate model. Methane observations from the global surface air-sampling network of the Earth System Research Laboratory (ESRL) of the US National Oceanic and Atmospheric Administration (NOAA) are used to guide refinement of the natural methane inventory. The wetland methane flux is calculated as a best fit; thus, the accuracy of this derived flux assumes accurate simulation of methane chemical loss in the atmosphere and accurate prescription of the other methane fluxes (anthropogenic and natural). The optimization process indicates global annual wetland methane emissions of 140 Tg CH4 yr−1. The updated inventory includes total global annual methane emissions from natural sources of 181 Tg CH4 yr−1 and a global annual methane soil sink of 60 Tg CH4 yr−1. An interactive methane simulation is run using ModelE2-YIBs, applying dynamic methane emissions and the updated natural methane emissions inventory that results from the optimization process. The simulated methane chemical lifetime of 10.4±0.1 years corresponds well to observed lifetimes. The simulated year 2005 global-mean surface methane concentration is 1.1 % higher than the observed value from the NOAA ESRL measurements. Comparison of the simulated atmospheric methane distribution with the NOAA ESRL surface observations at 50 measurement locations finds that the simulated annual methane mixing ratio is within 1 % (i.e., +1 % to −1 %) of the observed value at 76 % of locations. Considering the 50 stations, the mean relative difference between the simulated and observed annual methane mixing ratio is a model overestimate of only 0.5 %. Comparison of simulated annual column-averaged methane concentrations with SCIAMACHY satellite retrievals provides an independent post-optimization evaluation of modeled methane. The comparison finds a slight model underestimate in 95 % of grid cells, suggesting that the applied methane source in the model is slightly underestimated or the model's methane sink strength is slightly too strong outside of the surface layer. Overall, the strong agreement between simulated and observed methane lifetimes and concentrations indicates that the ModelE2-YIBs chemistry–climate model is able to capture the principal processes that control atmospheric methane.

Curved planar reformatting and convolutional neural network-based segmentation of the small bowel for visualization and quantitative assessment of pediatric Crohn's disease from MRI.

Contrast-enhanced MRI of the small bowel is an effective imaging sequence for the detection and characterization of disease burden in pediatric Crohn's disease (CD). However, visualization and quantification of disease burden requires scrolling back and forth through 3D images to follow the anatomy of the bowel, and it can be difficult to fully appreciate the extent of disease. To develop and evaluate a method that offers better visualization and quantitative assessment of CD from MRI. Retrospective. Twenty-three pediatric patients with CD. 1.5T MRI system and T1 -weighted postcontrast VIBE sequence. The convolutional neural network (CNN) segmentation of the bowel's lumen, wall, and background was compared with manual boundary delineation. We assessed the reproducibility and the capability of the extracted markers to differentiate between different levels of disease defined after a consensus review by two experienced radiologists. The segmentation algorithm was assessed using the Dice similarity coefficient (DSC) and boundary distances between the CNN and manual boundary delineations. The capability of the extracted markers to differentiate between different disease levels was determined using a t-test. The reproducibility of the extracted markers was assessed using the mean relative difference (MRD), Pearson correlation, and Bland-Altman analysis. Our CNN exhibited DSCs of 75 ± 18%, 81 ± 8%, and 97 ± 2% for the lumen, wall, and background, respectively. The extracted markers of wall thickness at the location of min radius (P = 0.0013) and the median value of relative contrast enhancement (P = 0.0033) could differentiate active and nonactive disease segments. Other extracted markers could differentiate between segments with strictures and segments without strictures (P < 0.05). The observers' agreement in measuring stricture length was >3 times superior when computed on curved planar reformatting images compared with the conventional scheme. The results of this study show that the newly developed method is efficient for visualization and assessment of CD. 4 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:1565-1576.

Soil water content and temporal stability in an arid area with natural and planted grasslands

AbstractSoil water content (SWC) is a key factor for successful vegetation restoration in arid and semiarid regions, and vegetation has significant influences on the spatial patterns and temporal dynamics of SWC. The aim of this study was to investigate the temporal stability of SWC under different restored grasslands in an arid hilly area of Central China. SWC was measured in the 0‐ to 300‐cm soil profile in the natural grassland (Stipa capillata) and three typical planted grasslands (Medicago sativa, Agropyron cristatum, and Caragana korshinskii) over two growing seasons (from June to October 2015 and 2016) under natural rainfall conditions. The results showed that the mean SWC in the natural grassland was approximately 30% higher than those in the planted grasslands. The SWC consumption of the planted legume grasslands in the deepest soil layers (below 200 cm) was higher than that of the natural grassland, owing to the deep root system of the legumes. Both natural and planted grasslands had low SWC temporal stability in the top soil layers (0–50 cm), whereas more stable conditions were gradually observed with increasing the soil depth. The mean value of the mean relative differences of SWC in natural grassland (ca. 15%) was lower than that in the planted grasslands (A. cristatum grasslands) and much lower than that in the scrubland, highlighting the stronger temporal stability of SWC in the natural grassland. In conclusion, natural grassland could maintain higher and stable SWC and is recommended to be used for achieving sustainable vegetation restoration in arid and semiarid regions.