Baseline Maps Research Articles

Non-invasive detection of slow conduction with cardiac magnetic resonance imaging for ventricular tachycardia ablation.

Non-invasive myocardial scar characterization with cardiac magnetic resonance (CMR) has been shown to accurately identify conduction channels and can be an important aid for ventricular tachycardia (VT) ablation. A new mapping method based on targeting deceleration zones (DZs) has become one of the most commonly used strategies for VT ablation procedures. The aim of the study was to analyse the capability of CMR to identify DZs and to find predictors of arrhythmogenicity in CMR channels. Forty-four consecutive patients with structural heart disease and VT undergoing ablation after CMR at a single centre (October 2018 to July 2021) were included (mean age, 64.8 ± 11.6 years; 95.5% male; 70.5% with ischaemic heart disease; a mean ejection fraction of 32.3 ± 7.8%). The characteristics of CMR channels were analysed, and correlations with DZs detected during isochronal late activation mapping in both baseline maps and remaps were determined. Overall, 109 automatically detected CMR channels were analysed (2.48 ± 1.15 per patient; length, 57.91 ± 63.07 mm; conducting channel mass, 2.06 ± 2.67 g; protectedness, 21.44 ± 25.39 mm). Overall, 76.1% of CMR channels were associated with a DZ. A univariate analysis showed that channels associated with DZs were longer [67.81 ± 68.45 vs. 26.31 ± 21.25 mm, odds ratio (OR) 1.03, P = 0.010], with a higher border zone (BZ) mass (2.41 ± 2.91 vs. 0.87 ± 0.86 g, OR 2.46, P = 0.011) and greater protectedness (24.97 ± 27.72 vs. 10.19 ± 9.52 mm, OR 1.08, P = 0.021). Non-invasive detection of targets for VT ablation is possible with CMR. Deceleration zones found during electroanatomical mapping accurately correlate with CMR channels, especially those with increased length, BZ mass, and protectedness.

Mapping high marsh and salt pannes/flats along the northern Gulf of Mexico coast

Coastal wetlands are predicted to undergo extensive transformation due to climate and land use change. Baseline maps of coastal wetlands can be used to help assess changes. Found in the upper portion of the estuarine zone, high marsh and salt pannes/flats provide ecosystem goods and services and are particularly important to fish and wildlife. We developed the first map of high marsh and salt pannes/flats along the northern Gulf of Mexico using regional models that included spectral indices related to greenness and wetness from optical satellite imagery, elevation data, irregularly flooded wetland probability information, and synthetic aperture radar backscatter. We found the greatest relative coverage of high marsh along the Texas coast (30% to 65%) and the Florida Panhandle (40%), whereas the greatest relative coverage of salt pannes/flats was along the lower Texas coast (74%) and the middle Texas coast (15%). As part of this effort, we also developed a map that highlighted irregularly flooded wetlands dominated by Juncus roemerianus (black needlerush) for part of the study area. Both maps had an overall accuracy of around 80%. Our results advance the understanding of estuarine marsh zonation and provide a baseline for assessing future transformations.

Impact of cardiac magnetic resonance channels to localize deceleration zones during VT ablation

Abstract Funding Acknowledgements Type of funding sources: None. Background Cardiac magnetic resonance has demonstrated to accurately identify voltage conduction channels and it is nowadays an important tool to analyze the arrhythmic substrate, to predict ventricular tachycardia (VT) events and to aid VT ablation. The characteristics of CMR channels (CMR-CCs) that predicts the presence of deceleration zone (DZ) have not been explored. Methods Forty-four consecutive patients with scar-related VT undergoing ablation after CMR (October 2018-July 2021) were included (medium age 64.8±11.6 years; 95.5% male; 70.5% ischemic heart disease, mean ejection fraction of 32.3±7.8). Characteristics of CMR-CCs were analyzed and correlation with DZs both in baseline maps and remaps were performed. Patients were prospectively followed for VT recurrence for one year. Results Overall, 129 automatically detected CMR-CCs were analyzed (2.89±1.83 per patient; length: 52.72±65.44mm (0.18–376.73), CC mass: 1.76±2.46grams (0.01–14.59); protectedness 19.02±24.51% (0.01–143.51)). Overall, 73.6% of CMR-CCs were associated with a DZ: 58.1% CMR-CCs in baseline map and 15.5% with a DZs not observed initially but in remaps. The univariate analysis showed that channels associated with DZs were longer (61.83±73.43 vs. 29.96±32.55, OR 1.01, p0.004), with higher border zone mass (2.02±2.75 vs. 1.09±1.44, OR 1.28, p0.031) and more protectedness (21.90±27.23 vs. 11.46±14.20, OR1.02, p0.036). VT recurrence after one-year follow up was 21.95%. Conclusions Pre ablation CMR can accurately identify channels that correlates with DZs that could be targets for ablation, especially those CMR-CCs with higher length, border zone mass and protectedness. Additionally, some channels not related with DZ in the first map have a clear DZ after abolishing the first region of slow conduction, suggesting a very useful role of CMR to detect potential DZs.

PO-04-122 IMPACT OF CARDIAC MAGNETIC RESONANCE CHANNELS TO LOCALIZE DECELERATION ZONES DURING VT ABLATION

Cardiac magnetic resonance has demonstrated to accurately identify voltage conduction channels and it is nowadays an important tool to analyze the arrhythmic substrate, to predict ventricular tachycardia (VT) events and to aid VT ablation. The characteristics of CMR channels (CMR-CCs) that predicts the presence of deceleration zone (DZ) have not been explored. To analyze the correlation between CMR-CCs and deceleration zones in isochronal late activation maps. Forty-four consecutive patients with scar-related VT undergoing ablation after CMR (October 2018-July 2021) were included (medium age 64.8±11.6 years; 95.5% male; 70.5% ischemic heart disease, mean ejection fraction of 32.3±7.8). Characteristics of CMR-CCs were analyzed and correlation with DZs both in baseline maps and remaps were performed. Patients were prospectively followed for VT recurrence for one year. Overall, 129 automatically detected CMR-CCs were analyzed (2.89±1.83 per patient; length: 52.72±65.44mm (0.18–376.73), CC mass: 1.76±2.46grams (0.01–14.59); protectedness 19.02±24.51% (0.01–143.51)). Overall, 73.6% of CMR-CCs were associated with a DZ: 58.1% CMR-CCs in baseline map and 15.5% with a DZs not observed initially but in remaps. The univariate analysis showed that channels associated with DZs were longer (61.83±73.43 vs. 29.96±32.55, OR 1.01, p0.004), with higher border zone mass (2.02±2.75 vs. 1.09±1.44, OR 1.28, p0.031) and more protectedness (21.90±27.23 vs. 11.46±14.20, OR1.02, p0.036). VT recurrence after one-year follow up was 21.95%. Pre ablation CMR can accurately identify channels that correlates with DZs that could be targets for ablation, especially those CMR-CCs with higher length, border zone mass and protectedness. Additionally, some channels not related with DZ in the first map have a clear DZ after abolishing the first region of slow conduction, suggesting a very useful role of CMR to detect potential DZs.Tabled 1Univariate analysis of channels characteristics and the primary endpoint (slow conduction properties) (PO-04-122)Total (n=129)Slow conduction (n=95)Non-slow conduction (n=34)ORpLength per channel (mm)52.72±65.44 (0.18–376.73)61.83±73.4329.96±32.551.01 (1-1.03)0.004Mass per channel (grams)1.76±2.46 (0.01–14.59)2.02±2.751.09±1.441.28 (0.97-1.7)0.031Width per channel (mm)4.94±1.91 (0.01–9.34)4.97±1.894.67±2.041.08 (0.88-1.31)0.465Protectedness per channel (mm)19.02±24.51 (0.01–143.51)21.90±27.2311.46±14.201.02 (1-1.05)0.036Layers:- Endocardium- Mesocardium- Epicardium- Endo/Meso- Meso/Epi- Transmural.48 (37.2%)7 (5.4%)26 (20.2%)21 (16.3%)8 (6.2%)19 (14.7%).3052215717.1824612.0.41 (0.18-0.91)0.89 (0.16-4.81)2.26 (0.72-7.12)0.88 (0.31-2.48)2.63 (0.31-22.16)3.49 (0.76-15.97).0.030.890.160.360.360.09Number of layers per channel3.05±2.32 (1–9)3.32±2.462.50±1.801.16 (0.96-1.4)0.104Number of AHA segments per channel2.28±1.20 (1–8)2.47±1.361.85±1.031.56 (1.01-2.4)0.028 Open table in a new tab

Exploratory Mapping of Blue Ice Regions in Antarctica Using Very High-Resolution Satellite Remote Sensing Data

Mapping spatiotemporal changes in the distribution of blue ice regions (BIRs) in Antarctica requires repeated, precise, and high-resolution baseline maps of the blue ice extent. This study demonstrated the design and application of a newly-developed semi-automatic method to map BIRs in the Antarctic environment using very high-resolution (VHR) WorldView-2 (WV-2) satellite images. We discussed the potential of VHR satellite data for the mapping of BIRs in the Antarctic environment using a customized normalized-difference blue-ice index (NDBI) method devised using yellow, green, and near-infrared spectral bands of WV-2 data. We compared the viability of the newly developed customized NDBI approach against state-of-the-art target detection (TD), spectral processing (SP) and pixel-wise supervised (PSC) feature extraction (FE) approaches. Four semi-automatic FE approaches (three existing plus one newly developed) consisting of 16 standalone FE methods (12 existing + four customized) were evaluated using an extensive quantitative and comparative assessment for mapping BIRs in the vicinity of Schirmacher Oasis, on the continental Antarctic coastline. The results suggested that the customized NDBI approach gave a superior performance and the highest statistical stability when compared with existing FE techniques. The customized NDBI generally rendered the lowest level of misclassification (average RMSE = 654.48 ± 58.26 m2), followed by TD (average RMSE = 987.81 ± 55.05 m2), SP (average RMSE = 1327.09 ± 127.83 m2) and PSC (average RMSE = 2259.43 ± 115.36 m2) for mapping BIRs. Our results indicated that the use of the customized NDBI approach can greatly improve the semi-automatic mapping of BIRs in the Antarctic environment. This study presents the first refined map of distribution of BIRs around the Schirmacher Oasis. The total area of blue ice in the study area was estimated to be 106.875 km2, approximately 61% of the study area. The WV-2 derived BIR map area presented in this study locally refined the existing BIR map derived using Landsat Enhanced Thematic Mapper Plus (ETM+) and the Moderate Resolution Imaging Spectroradiometer (MODIS)-based mosaic of Antarctica (MOA) dataset by ~31% (~33.40 km2). Finally, we discussed the practical challenges and future directions in mapping BIRs across Antarctica.

Preclinical assessment of the feasibility, safety and lesion durability of a novel 'single-shot' pulsed field ablation catheter for pulmonary vein isolation.

Single-shot pulmonary vein isolation can improve procedural efficiency. To assess the capability of a novel, expandable lattice-shaped catheter to rapidly isolate thoracic veins using pulsed field ablation (PFA) in healthy swine. The study catheter (SpherePVI; Affera Inc) was used to isolate thoracic veins in two cohorts of swine survived for 1 and 5 weeks. In Experiment 1, an initial dose (PULSE2) was used to isolate the superior vena cava (SVC) and the right superior pulmonary vein (RSPV) in six swine and the SVC only in two swine. In Experiment 2, a final dose (PULSE3) was used for SVC, RSPV, and left superior pulmonary vein (LSPV) in five swine. Baseline and follow-up maps, ostial diameters, and phrenic nerve were assessed. Pulsed field ablation was delivered atop the oesophagus in three swine. All tissues were submitted for pathology. In Experiment 1, all 14/14 veins were isolated acutely with durable isolation demonstrated in 6/6 RSPVs and 6/8 SVC. Both reconnections occurred when only one application/vein was used. Fifty-two and 32 sections from the RSPVs and SVC revealed transmural lesions in 100% with a mean depth of 4.0 ± 2.0 mm. In Experiment 2, 15/15 veins were isolated acutely with 14/15 veins (5/5 SVC, 5/5 RSPV, and 4/5 LSPV) durably isolated. Right superior pulmonary vein (31) and SVC (34) sections had 100% transmural, circumferential ablation with minimal inflammation. Viable vessels and nerves were noted without evidence of venous stenosis, phrenic palsy, or oesophageal injury. This novel expandable lattice PFA catheter can achieve durable isolation with transmurality and safety.

Solanum elaeagnifolium (Solanaceae) Invading One in Five Natura 2000 Protected Areas of Greece and One in Four Habitat Types: What Is Next?

Invasive alien plants have severe impacts on biodiversity and ecosystem services worldwide. To assess the invasion of Solanum elaeagnifolium Cav. (a major alien invasive plant; Solanaceae) in Greek protected areas (PAs), we conducted an extensive drive-by survey across the country crossing half of the Greek Natura 2000 sites. The occurrence data were then linked in GIS with (i) the boundaries of the Natura 2000 sites, (ii) the mapped habitat types in the invaded sites, and (iii) the Corine land cover, from which we calculated the ecosystem services. The results showed that approximately 24% of the investigated PAs were invaded by S.elaeagnifolium to varying degrees of extension and density of the populations. A variety of 29 different habitat types of Annex I of the Directive 92/43/EEC (including a priority habitat and seven habitat types of national importance) were found to be invaded (one in four habitat types present in Greece). In the invaded Natura 2000 sites, we recorded human activities/threats that were mostly related to agricultural activities of high intensity, while the potential in ecosystem service provision was relatively low for the category of regulating services in the invaded sites. Our study provides the first nationwide report of the distribution of S. elaeagnifolium in Natura 2000 sites of Greece, providing baseline maps and information for future monitoring. Our results highlight the need of an effective management strategy across the Natura 2000 network to effectively protect the local biodiversity, which should include management measures for invasive species, mitigating habitat fragmentation, and soil degradation, as well as the adaptation of eco-enhancing management strategies for the provision of multiple ecosystem services in agriculture.

Boosting microscopic object detection via feature activation map guided poisson blending.

Microscopic examination of visible components based on micrographs is the gold standard for testing in biomedical research and clinical diagnosis. The application of object detection technology in bioimages not only improves the efficiency of the analyst but also provides decision support to ensure the objectivity and consistency of diagnosis. However, the lack of large annotated datasets is a significant impediment in rapidly deploying object detection models for microscopic formed elements detection. Standard augmentation methods used in object detection are not appropriate because they are prone to destroy the original micro-morphological information to produce counterintuitive micrographs, which is not conducive to build the trust of analysts in the intelligent system. Here, we propose a feature activation map-guided boosting mechanism dedicated to microscopic object detection to improve data efficiency. Our results show that the boosting mechanism provides solid gains in the object detection model deployed for microscopic formed elements detection. After image augmentation, the mean Average Precision (mAP) of baseline and strong baseline of the Chinese herbal medicine micrograph dataset are increased by 16.3% and 5.8% respectively. Similarly, on the urine sediment dataset, the boosting mechanism resulted in an improvement of 8.0% and 2.6% in mAP of the baseline and strong baseline maps respectively. Moreover, the method shows strong generalizability and can be easily integrated into any main-stream object detection model. The performance enhancement is interpretable, making it more suitable for microscopic biomedical applications.

Rib cortical bone thickness variation in adults by age and sex.

Rib fractures are a common and serious outcome of blunt thoracic trauma and their likelihood is greater in older individuals. Osteoporotic bone loss is a well-documented aging phenomenon with sex-specific characteristics, but within rib bones, neither baseline maps of regional thickness nor the rates of bone thinning with age have been quantified across whole ribs. This study presents such data from 4014 ribs of 240 adult subjects aged 20-90. A validated cortical bone mapping technique was applied to clinical computed tomography scans to obtain local rib cortical bone thickness measurements over the surfaces of ribs 2 through 11. Regression models to age and sex gave rates of cortex thinning in local zones and aggregated across whole ribs. The statistical parametric mapping provided these relationships regionally as a function of rib surface location. All models showed significant reductions in bone thickness with age (p < 0.01). Average whole-rib thinning occurred at between 0.011 to 0.032 mm/decade (males) and 0.035 to 0.043 mm/decade (females), with sex and age accounting for up to 37% of population variability (R2 ). Rates of thinning differed regionally and by rib, with the highest bone loss of up to 0.074 mm/decade occurring in mid-rib cutaneous and superior regions of ribs 2-6. Rates were consistently higher in females than males (significantly so across whole ribs but not all local regions) and were more pronounced in cutaneous, superior, and inferior rib aspects (average 0.025 mm/decade difference in ribs 4-8) compared to pleural aspects which had the thickest cortices but saw only minor differences in thinning rates by sex (0.045 mm/decade for females and 0.040 mm/decade for males). Regional analysis showed male and female bone thickness differences that were not statistically significant at 20 years of age (p > 0.05 across practically all regions) but subsequent cortex thinning meant that substantial pleural and cutaneous regions were thinner (p < 0.05) in females than males by 55 years of age. The techniques and results from this study can be applied to assess rib bone content loss in clinical settings across wide populations. Additionally, average cortex thickness results can be mapped directly to finite element models of the thorax, and regression results are used to modify such models to represent the ribs of men and women across their full adult lifespan.

Global crop calendars of maize and wheat in the framework of the WorldCereal project

ABSTRACT Crop calendars provide valuable information on the timing of important stages of crop development such as the planting or Start of Season (SOS) and harvesting dates or End of Season (EOS). This information is critical for many crop monitoring applications such as crop-type mapping, crop condition monitoring, and crop yield estimation and forecasting. Spatially detailed information on the crop calendars provides an important asset in this respect, as it allows the algorithms to account for specific local circumstances while also maximizing their robustness and global applicability. Existing global crop calendar products, as produced by the Group on Earth Observations’ Global Agricultural Monitoring (GEOGLAM) Crop Monitor, the United States Department of Agriculture Foreign Agricultural Service (USDA-FAS), the Food and Agriculture Organization (FAO), and the European Commission Joint Research Center’s Anomaly hot Spots of Agricultural Production (ASAP), generally provide this information only at national or subnational level. In this work, we present gridded SOS and EOS maps for wheat and maize that represent the crop calendars’ spatial variability at 0.5° spatial resolution. These maps are generated in the framework of WorldCereal, which is a European Space Agency (ESA) funded project whose cropland and crop-type wheat and maize algorithms at global scale and at 10 m spatial resolution require this information. The proposed maps are built leveraging the above noted global products (Crop Monitor, USDA-FAS, FAO, ASAP) whose datasets are combined into a baseline map and sampled to train a Random Forest algorithm based on climatic and geographic data. Their evaluation against test data from the baseline maps set aside for validation purposes show a good performance with SOS (EOS) R 2 of 0.87 (0.92) and a root mean square error (RMSE) of 27 (26) days for wheat, showing the lowest errors (RMSE <15 days) in North America, Central Europe, South Africa, and Australia, all critical areas for global wheat production and trade. Meanwhile, the largest errors (RMSE between 40 and 60 days) occurred in regions of South America close to the Amazon Forest and in Africa close to the Congo Basin. In the case of maize, the SOS (EOS) evaluation shows an R 2 of 0.88 (0.79) and an RMSE of 24 (28) days for maize, with the best performing regions (RMSE < 15 days) located in the Northern Hemisphere, South Africa, and Australia, important areas for global maize production and trade. Meanwhile, the worst performing regions were in Brazil, Saudi Arabia and India. Additionally, the crop calendars were evaluated using a simple Land Surface Phenology (LSP) model based on Sentinel-2 and Landsat 8 Earth Observation data from Sentinel-2 and Landsat 8 over known wheat and maize fields. The results show a SOS (EOS) R 2 of 0.75 (0.88) and an RMSE of 25 (18) days for wheat and SOS (EOS) R 2 of 0.80 (0.88) and an RMSE of 35 (24) days for maize. Therefore, the presented calendars present an advancement over the existing crop calendar products in terms of capturing spatial coverage and variability and reporting their accuracy.

A new approach to assess the degree of contamination and determine sources and risks related to PTEs in an urban environment: the case study of Santiago (Chile)

In 2017, a geochemical survey was carried out across the Commune of Santiago, a local administrative unit located at the center of the namesake capital city of Chile, and the concentration of a number of major and trace elements (53 in total) was determined on 121 topsoil samples. Multifractal IDW (MIDW) interpolation method was applied to raw data to generate geochemical baseline maps of 15 potential toxic elements (PTEs); the concentration–area (C-A) plot was applied to MIDW grids to highlight the fractal distribution of geochemical data. Data of PTEs were elaborated to statistically determine local geochemical baselines and to assess the spatial variation of the degree of soil contamination by means of a new method taking into account both the severity of contamination and its complexity. Afterwards, to discriminate the sources of PTEs in soils, a robust Principal Component Analysis (PCA) was applied to data expressed in isometric log-ratio (ilr) coordinates. Based on PCA results, a Sequential Binary Partition (SBP) was also defined and balances were determined to generate contrasts among those elements considered as proxies of specific contamination sources (Urban traffic, productive settlements, etc.). A risk assessment was finally completed to potentially relate contamination sources to their potential effect on public health in the long term. A probabilistic approach, based on Monte Carlo method, was deemed more appropriate to include uncertainty due to spatial variation of geochemical data across the study area. Results showed how the integrated use of multivariate statistics and compositional data analysis gave the authors the chance to both discriminate between main contamination processes characterizing the soil of Santiago and to observe the existence of secondary phenomena that are normally difficult to constrain. Furthermore, it was demonstrated how a probabilistic approach in risk assessment could offer a more reliable view of the complexity of the process considering uncertainty as an integral part of the results.

Data-driven spatiotemporal projections of shallow permafrost based on CMIP6 across the Qinghai‒Tibet Plateau at 1 km2 scale

The degradation of near-surface permafrost under ongoing climate change on the Qinghai‒Tibet Plateau (QTP) is of growing concern due to its impacts on geomorphological and ecological processes, as well as human activities. There is an increased need for an in-depth understanding of the evolution of permafrost temperature (Ttop) and active-layer thickness (ALT) at a fine scale on the QTP under climate change. This study evaluated the permafrost thermal development over the QTP for the period 1980–2100 at a 1 km2 scale using a physically analytical model accounting for both climatic and local environmental factors based on multi-source data. The model results were validated against thermal borehole measurements and baseline maps. The modeled current (2001–2018) permafrost area (Ttop ≤ 0 °C) covers 1.42 × 106 km2 (ca. 56.1% of the QTP land area), 10.1% of which thawed over the historical period 1981–2000. To assess how the ground thermal regime could develop in the future, we utilized the multi-model ensemble mean of downscaled outputs from eight climate models under three Shared Socio-economic Pathways (i.e., SSP126, 245, and 585) in CMIP6 to force the permafrost model. Model results suggest that the current (2001–2018) permafrost extent is likely to dramatically contract in the future period (2021–2100), as indicated by consistent Ttop warming and ALT increasing due to climate changing. About 26.9%, 59.9%, 80.1% of the current permafrost is likely to disappear by the end of the 21st century under SSP126, SSP245, and SSP585 scenarios, respectively. The simulation results may further provide new opportunities to assess the future impacts of climate warming on environments and engineering development over the QTP.

Spatial multicriteria approach to support water resources management with multiple sources in semi-arid areas in Brazil

Semi-arid regions often face severe drought events that reduce agricultural and livestock production. In recent years, some international studies have used multicriteria decision analysis (MCDA) approaches combined with geographic information systems (GIS-MCDA) to support decision-makers in assessing the suitability of agricultural land for irrigation in semi-arid regions. Unlike previous studies, which have only considered a single source of water for crop irrigation, this study proposes a GIS-MCDA approach that considers all potentially available local water sources (e.g., groundwater, surface water, and wastewater) as possible alternatives for better multisource water resource management (MWRM) in regions facing water shortages. The geospatial multicriteria evaluation implemented in this study considers a series of technical, environmental, and agricultural productivity criteria using the analytical hierarchy process (AHP) method. Three independent baseline maps were generated, showing the spatial distribution of suitable areas for crop irrigation for each considered water source in the studied area. Surface water, groundwater, and wastewater offered suitable crop irrigation for 83%, 70%, and 26% of the study area, respectively. Overlapping these areas produced a final map showing all the feasible areas for each crop irrigation alternative at the same time. The MWRM approach considering all water sources increased the coverage of suitable areas to be irrigated in the study area by 2.2%, 20.4%, and more than 225% compared to considering surface water, groundwater, and wastewater, respectively, independently. The GIS-MCDA framework proposed in this study provides better support for decision-makers and stakeholders, favouring a reduction in possible conflicts over water scarcity, the diversification of irrigated crops, and an improvement in the quality-quantitative management of water resources in semi-arid regions.

ASSESSMENT OF THE OUTDOOR GAMMA RADIATION LEVELS IN ALGIERS PROVINCE, ALGERIA.

The outdoor gamma radiation dose rates due to natural radioactivity and due to the artificial radionuclides released from the Chernobyl and Fukushima accidents and Algeciras incident were assessed in the Algiers province (capital of Algeria). Furthermore, the dose rates induced by the cosmic rays were analytically calculated in the province concerned. The recorded dose rates due to terrestrial outdoor gamma radiation were found to range from 14.3±0.7 to 114.3±5.7 nGy h -1, those due to cosmic rays ranged from 32.021±0.013 to 34.029±0.367 nGy h -1, while the contribution of the dose rate due to external exposure induced by 137Cs deposits, from major accidents, was estimated to be less than 0.3 nGy h-1. The spatial distributions of terrestrial and cosmic rays dose rates were mapped using QGIS software. The obtained radiological baseline maps can be used as reference information to assess any changes in the radiation exposure levels having an impact on the population health.

Mapping hourly population dynamics using remotely sensed and geospatial data: a case study in Beijing, China

ABSTRACT High spatiotemporal population data are critical for a wide range of applications (e.g. urban planning and management, risk assessment, and epidemic control). However, such data are still not widely available due to the limited knowledge of complex human activities. Here we proposed a spatiotemporal downscaling framework for estimating hourly population dynamics in Beijing by integrating remote sensing and social sensing data. First, we generated two baseline maps of population during sleep and work times using a dasymetric method. Second, we generated urban functional zones using a random forest model and derived human activity patterns from social sensing data. Finally, we estimated the hourly population dynamics at a 500-meter resolution using a temporal downscaling method. Results show the significant spatial difference of the population over time, especially between working hours (9:00 − 18:00) and sleeping hours (after 0:00). The spatial pattern of population is more homogenous within the sixth ring area in Beijing during work time compared to sleep time when there are more clusters of high population. The comparison of spatiotemporal patterns with the referenced real-time heat maps from Baidu indicates that our population data are reliable. The framework presented in this paper is transferable in other regions. The resulting dataset of hourly population dynamics is of great help for governments of emergency responses as well as for studies about human risks to environmental issues.

The Spatial Distribution of Relative Corneal Refractive Power Shift and Axial Growth in Myopic Children: Orthokeratology Versus Multifocal Contact Lens

PurposeTo determine if the spatial distribution of the relative corneal refractive power shift (RCRPS) explains the retardation of axial length (AL) elongation after treatment by either orthokeratology (OK) or multifocal soft contact lenses (MFCLs).MethodsChildren (8–14 years) were enrolled in the OK (n = 35) or MFCL (n = 36) groups. RCRPS maps were derived by computing the difference between baseline and 12-month corneal topography maps and then subtracting the apex values. Values at the same radius were averaged to obtain the RCRPS profile, from which four parameters were extracted: (1) Half_x and (2) Half_y, i.e., the x- and y-coordinates where each profile first reached the half peak; (3) Sum4 and (4) Sum7, i.e., the summation of powers within a corneal area of 4- and 7-mm diameters. Correlations between AL elongation and these parameters were analyzed by multiple linear regression.ResultsAL elongation in the OK group was significantly smaller than that in the MFCL group (p = 0.040). Half_x and Half_y were also smaller in the OK group than the MFCL group (p < 0.001 each). Half_x was correlated with AL elongation in the OK group (p = 0.005), but not in the MFCL group (p = 0.600). In an analysis that combined eyes of both groups, Half_x was correlated with AL elongation (β = 0.161, p < 0.001).ConclusionsThe OK-induced AL elongation and associated RCRPS Half_x were smaller than for the MFCL. Contact lenses that induce RCRPS closer to the corneal center may exert better myopia control.

Baseline maps of potentially toxic elements in the soils of Garhwal Himalayas, India: Assessment of their eco‐environmental and human health risks

AbstractGeochemical mapping is frequently used to identify the regions of the Planet with critical chemical elements and their natural or anthropogenic sources. In order to understand elements' geochemistry and to identify the area's potentially harmful associations, high‐resolution maps of chemical elements, physico‐chemical parameters, a noncarcinogenic hazard index, and a potential ecological risk index were modelled with soil samples collected in the Himalaya region. It is the first environmental and geochemical atlas for this region. It was found that natural processes are determining the distribution of the variable in this area. The granulometric features seem to be strongly influenced by land use, with coarser grain sizes in forest soils, contrasting with the finer grain sizes in agricultural soils. The map distribution of the noncarcinogenic hazard index showed that there is an expected hazard for some variables for both children and adults. Potential ecological risk is revealed to be low to moderate. Remediation of contaminated soils is necessary to reduce the associated risks, make the land resource available for agricultural production, enhance food security, and scale down land tenure problems arising from changes in the land use pattern. This study is subsequent implementation of natural‐based approaches to system stability in largely unspoilt area.

Common patterns of variation between femoral and tibial cartilage maps and baseline features from the osteoarthritis initiative

Common patterns of variation between femoral and tibial cartilage maps and baseline features from the osteoarthritis initiative

An improved three-dimensional concentration measurement technique using magnetic resonance imaging

Magnetic resonance concentration (MRC) was introduced by Benson et al. (Exp Fluids 49:43–55, 2010) to obtain three-dimensional, time-averaged concentration fields in complex turbulent flows without the need for optical access using magnetic resonance imaging. It has since been applied to a wide variety of flows including jet engine film cooling configurations, mixing layers, and urban dispersion cases. However, the measurement uncertainty is currently limited to about 5% of the injected concentration, irrespective of the local concentration. This work presents an advanced MRC technique to greatly reduce the uncertainty at low concentration. Best practices for conducting MRC experiments are described to establish a baseline methodology. These include the choice of scan settings and fluids, calibration procedure, mixing experiment details, and method for computing concentration fields from scan data. An advanced technique is developed to reduce the uncertainty at low concentration by combining data from multiple experiments at increasing molarity of injected fluid, using Fourier-space averaging to reduce noise, and by minimizing fluid property differences using a low flip angle to reduce the maximum injected molarity without degrading the signal-to-noise ratio. The method is flexible and can be optimized to meet the uncertainty requirements of specific applications. Experiments are performed on the turbulent mixing downstream of an isolated, rectangular building as a test case. The advanced technique is validated against the baseline method and maps of spatially dependent experimental uncertainty are presented. Less than 1% uncertainty based on a 95% confidence interval is achieved near the plume boundaries. Results from the new technique reveal dilute but non-zero concentration regions near the wall which could not be resolved using the baseline method.

Semiautomated Detection and Mapping of Vegetation Distribution in the Antarctic Environment Using Spatial-Spectral Characteristics of WorldView-2 Imagery

Effective monitoring of changes in the geographic distribution of cryospheric vegetation requires high-resolution and accurate baseline maps. The rationale of the present study is to compare multiple feature extraction approaches to remotely mapping vegetation in Antarctica, assessing which give the greatest accuracy and reproducibility relative to those currently available. This study provides precise, high-resolution, and refined baseline information on vegetation distribution as is required to enable future spatiotemporal change analyses of the vegetation in Antarctica. We designed and implemented a semiautomated customized normalized difference vegetation index (NDVI) approach for extracting cryospheric vegetation by incorporating very high resolution (VHR) 8-band WorldView-2 (WV-2) satellite data. The viability of state-of-the-art target detection, spectral processing/matching, and pixel-wise supervised classification feature extraction techniques are compared with the customized NDVI approach devised in this study. An extensive quantitative and comparative assessment was made by evaluating four semiautomatic feature extraction approaches consisting of 16 feature extraction standalone methods (four customized NDVI plus 12 existing methods) for mapping vegetation on Fisher Island and Stornes Peninsula in the Larsemann Hills, situated on continental east Antarctica. The results indicated that the customized NDVI approach achieved superior performance (average bias error ranged from ~6.44 ± 1.34% to ~11.55 ± 1.34%) and highest statistical stability in terms of performance when compared with existing feature extraction approaches. Overall, the accuracy analysis of the vegetation mapping relative to manually digitized reference data (supplemented by validation with ground truthing) indicated that the 16 semi-automatic mapping methods representing four general feature extraction approaches extracted vegetated area from Fisher Island and Stornes Peninsula totalling between 2.38 and 3.72 km2 (2.85 ± 0.10 km2 on average) with bias values ranging from 3.49 to 31.39% (average 12.81 ± 1.88%) and average root mean square error (RMSE) of 0.41 km2 (14.73 ± 1.88%). Further, the robustness of the analyses and results were endorsed by a cross-validation experiment conducted to map vegetation from the Schirmacher Oasis, East Antarctica. Based on the robust comparative analysis of these 16 methods, vegetation maps of the Larsemann Hills and Schirmacher Oasis were derived by ensemble merging of the five top-performing methods (Mixture Tuned Matched Filtering, Matched Filtering, Matched Filtering/Spectral Angle Mapper Ratio, NDVI-2, and NDVI-4). This study is the first of its kind to detect and map sparse and isolated vegetated patches (with smallest area of 0.25 m2) in East Antarctica using VHR data and to use ensemble merging of feature extraction methods, and provides access to an important indicator for environmental change.