Attenuation Pattern Research Articles

Freshwater salinization syndrome limits management efforts to improve water quality.

Freshwater Salinization Syndrome (FSS) refers to groups of biological, physical, and chemical impacts which commonly occur together in response to salinization. FSS can be assessed by the mobilization of chemical mixtures, termed "chemical cocktails", in watersheds. Currently, we do not know if salinization and mobilization of chemical cocktails along streams can be mitigated or reversed using restoration and conservation strategies. We investigated 1) the formation of chemical cocktails temporally and spatially along streams experiencing different levels of restoration and riparian forest conservation and 2) the potential for attenuation of chemical cocktails and salt ions along flowpaths through conservation and restoration areas. We monitored high-frequency temporal and longitudinal changes in streamwater chemistry in response to different pollution events (i.e., road salt, stormwater runoff, wastewater effluent, and baseflow conditions) and several types of watershed management or conservation efforts in six urban watersheds in the Chesapeake Bay watershed. Principal component analysis (PCA) indicates that chemical cocktails which formed along flowpaths (i.e., permanent reaches of a stream) varied due to pollution events. In response to winter road salt applications, the chemical cocktails were enriched in salts and metals (e.g., Na+, Mn, and Cu). During most baseflow and stormflow conditions, chemical cocktails were less enriched in salt ions and trace metals. Downstream attenuation of salt ions occurred during baseflow and stormflow conditions along flowpaths through regional parks, stream-floodplain restorations, and a national park. Conversely, chemical mixtures of salt ions and metals, which formed in response to multiple road salt applications or prolonged road salt exposure, did not show patterns of rapid attenuation downstream. Multiple linear regression was used to investigate variables that influence changes in chemical cocktails along flowpaths. Attenuation and dilution of salt ions and chemical cocktails along stream flowpaths was significantly related to riparian forest buffer width, types of salt pollution, and distance downstream. Although salt ions and chemical cocktails can be attenuated and diluted in response to conservation and restoration efforts at lower concentration ranges, there can be limitations in attenuation during road salt events, particularly if storm drains bypass riparian buffers.

Abnormal sense of agency in eating disorders

The feeling of controlling one’s own actions and, through them, impacting the external environment (i.e. Sense of Agency—SoA) can be relevant in the eating disorders (EDs) symptomatology. Yet, it has been poorly investigated. This study aims to implicitly assess SoA exploiting the Sensory Attenuation paradigm in two groups of EDs patients (Anorexia Nervosa Restrictive and Anorexia Nervosa Binge-Purging or Bulimia Nervosa) compared to a control group. We find that controls perceive self-generated stimuli as less intense than other-generated ones showing the classic pattern of sensory attenuation. By contrast, EDs patients show the opposite pattern, with self-generated perceived as more intense than other-generated stimuli. This result indicates an alteration of the implicit component of the feeling of control in EDs patients, thus suggesting a potential implication of these results for the clinical practice and the treatment of EDs symptomatology.

Effects of a large-scale dam structure on upstream and downstream lateral hyporheic exchange and residence time distributions – The Xinglong Water Conservancy Dam, China

Anthropogenic in-stream structures such as large dams can alter stream hydrodynamics and cause river stage fluctuations that have the potential to affect hyporheic exchange flow (HEF) patterns between rivers and groundwater. However, the development of HEF patterns and residence time distribution (RTD) in dam-regulated riverbank aquifers has mostly been studied focusing on areas downstream of large dam structures while upstream areas have often been neglected. In order to investigate the HEF and RTD patterns under the influence of a large dam in upstream and downstream areas simultaneously, groundwater level data was collected from thirteen monitoring wells distributed over three monitoring profiles both upstream and downstream of XingLong water conservancy dam (XLD), in the Han river, China. Based on field observations, a two-dimensional, horizontal numerical model was built to assess the spatiotemporal evolution of lateral hyporheic exchange flow, the spatial extent of the hyporheic zone (HZ) and groundwater RTD under the influence of the XLD. Our results demonstrate that the impact of the XLD is different in upstream and downstream aquifer regions. The storage effect induced by the XLD caused significant groundwater recharge upstream of the dam over long period of model, while significant groundwater discharge occurs downstream of the dam. As the stage of the regulated Han River varies, the HZ along the upstream river boundary significantly enhanced by the dam whereas substantial HEF downstream was observed in response to rising or high river stage. Furthermore, the operation of the XLD resulted in some substantial flow around the dam characterized by short flow path lengths and high flow velocity, which consequently resulted in the development of a significant HZ in the perimeter surrounding the XLD. Residence time distributions showed that the water in the HZ downstream of the XLD is dominated by rejuvenated (younger) groundwater, whereas the HZ upstream of the XLD comprises a mix of older and younger waters. HEF in the immediate vicinity of the dam comprises both aged and rejuvenated discharged groundwater. Our findings emphasize the need to more holistically consider river stage dynamics in river corridors where large dams are operated to better assess and understand the consequences on riverbank storage as well as flow, transport and attenuation patterns in connected floodplain aquifers and their impact on the aquatic environment.

Study on the penetration capability of GPR for the steel-fibre reinforced concrete (SFRC) segment based on numerical simulations and model test

The SFRC segment is gaining attention in shield tunnels due to their better mechanical properties. However, the existence of steel fibres poses a greater difficulty when attempting to utilize ground penetrating radar (GPR) for nondestructive quality inspection compared to conventional reinforced concrete segments. This paper presented a refined numerical model of SFRC segments with gprMax software, to investigate the penetration characteristics of GPR. The numerical model incorporated four different steel fibre contents, namely 0%, 0.5%, 2.5%, and 5%. The model also included an internal void and a surface metal plate to compare and analyze the waveform characteristics of GPR with the normal sections of the segment. The orthogonal test of numerical simulation investigates the imaging characteristics, power attenuation patterns, and imaging features of three different GPR frequency gradients: 200 MHz, 500 MHz, and 1000 MHz. This analysis helps in selecting the appropriate detection frequency based on the observed energy attenuation patterns and imaging characteristics. Then, the model test was conducted at the selected frequency to study the penetration performance of GPR. The research results indicate that the numerical model established in this paper demonstrates good effectiveness in studying the waveform characteristics of steel fibre-reinforced concrete under various conditions. The numerical model established in this paper realized the study of the penetration characteristics and imaging features of different steel fibre contents, GPR frequencies, and detection targets. Analysis of waveform characteristics, power attenuation, and imaging results indicates that GPR at 500 MHz exhibits better detection performance for SFRC segments. The results of the numerical simulation were verified through model tests of real SFRC segments, demonstrating that 500 MHz has good penetration performance for SFRC segments. This paper also proposed a calculation method for equivalent relative dielectric constant (ERDC) based on the model test results and validated its rationality through the analysis of numerical simulation results and real GPR waveforms.

Explosion of high pressure hydrogen tank in fire: Mechanism, criterion, and consequence assessment

This study published experimental data on the catastrophic rupture consequences of high-pressure hydrogen storage tanks in fire environments. It made up for the lack of actual explosion data for verification of the traditional theoretical prediction models and numerical simulations. To reveal the mechanism of high-pressure tank explosion and corresponding characteristics of hydrogen explosion, the fireball parameters, fragment characteristics, and blast wave attenuation patterns resulting from tank rupture were analyzed. The results indicated that the hazard of hydrogen storage tank explosion was coupled with the combined contribution of physical and chemical explosion energies. The failure pressure of a 6.8 L – 30 MPa tank under fire conditions decreased by 60.3 % compared to that at room temperature. Following tank explosion, the duration of hydrogen-air deflagration was only about 2 s, and the maximum diameter of the fireball was nearly 4.48 m. A portion of the mechanical energy generated by tank explosion was converted into the kinetic energy of projectile fragments, with the farthest discovered fragment distance reaching 46.0 m. Additionally, the measured peak overpressure decreased from 875.33 kPa to 7.52 kPa at distances ranging from 2 m to 15 m from the explosion source. To evaluate blast wave overpressure in high-pressure hydrogen tanks for engineering applications, a standardized and generalized procedure was innovatively proposed, and its effectiveness was validated by experimental data. Furthermore, the hazardous distances defined by the peak overpressure were utilized to delineate risk zones. The distances of 61.6 m and 17.3 m from the explosion source were identified as zones without injury to human and without damage to structures, respectively. The proposed methodology and the results of the experiments were of practical importance for ensuring the safety of high-pressure hydrogen storage systems in various applications.

Commonalities between mind wandering and task-set switching: An event-related potential study

Previous research has established that mind wandering does not necessarily disrupt one's task-switching performance. Here we investigated the effects of mind wandering on electrophysiological signatures, measured using event-related potentials (ERPs), during a switching task. In the current study, a final sample of 22 young adults performed a task-switching paradigm while electroencephalography was continuously recorded; mind wandering was assessed via thought probes at the end of each block. Consistent with previous research, we found no significant disruptive effects of mind wandering on task-switching performance. The ERP results showed that at the posterior electrode sites (P3, Pz, and P4), P3 amplitude was higher for mind-wandering switch trials than on-task switch trials, thus opposing the typical pattern of P3 attenuation during periods of mind wandering relative to on-task episodes. Considering that increased P3 amplitude during higher-order switch trials (e.g., response rule switching) may reflect the implementation of new higher-order task sets/rules, the current findings seem to indicate similar executive control processes underlie mind wandering and task-set switching, providing further evidence in favor of a role for switching in mind wandering.

Optical Attenuation Coefficient Optimization Algorithm for Deep Tissue Signals in Optical Coherence Tomography Based on Kalman Filter

Optical coherence tomography (OCT) attenuation imaging is a technique that uses the optical attenuation coefficient (OAC) to distinguish the types or pathological states of tissues and has been increasingly used in basic research and clinical diagnosis. With the increasing application of swept-source OCT, scholars are increasingly inclined to explore deep tissues. Unfortunately, the accuracy of OAC calculation when exploring deep tissues has yet to be improved. Existing methods generally have the following problems: overestimation error, underestimation error, severe fluctuation, or stripe artifacts in the OAC calculation of the OCT tail signal. The main reason for this is that the influence of the noise floor on the OCT weak signal at the tail-end is not paid enough attention. The noise floor can change the attenuation pattern of the OCT tail signal, which can lead to severe errors in the OAC. In this paper, we proposed a Kalman filter-based OAC optimal algorithm to solve this problem. This algorithm can not only eliminate the influence of the noise floor, but can also effectively protect the weak signal at the tail-end from being lost. The OAC of deep tissues can be calculated accurately and stably. Numerical simulation, phantom, and in vivo experiments were tested to verify the algorithm’s effectiveness in this paper. This technology is expected to play an essential role in disease diagnosis and in the evaluation of the effectiveness of treatment methods.

Dynamic Assessment of Spatiotemporal Population Distribution Based on Mobile Phone Data: A Case Study in Xining City, China

High-resolution, dynamic assessments of the spatiotemporal distributions of populations are critical for urban planning and disaster management. Mobile phone big data have real-time collection, wide coverage, and high resolution advantages and can thus be used to characterize human activities and population distributions at fine spatiotemporal scales. Based on six days of mobile phone user-location signal (MPLS) data, we assessed the dynamic spatiotemporal distribution of the population of Xining City, Qinghai Province, China. The results show that strong temporal regularity exists in the daily activities of local residents. The spatiotemporal distribution of the local population showed a significant downtown-suburban attenuation pattern. Factors such as land use types, holidays, and seasons significantly affect the spatiotemporal patterns of the local population. By combining other spatiotemporal trajectory data, high-resolution and dynamic real-time population distribution evaluations based on mobile phone location signals could be better developed and improved for use in urban management and disaster assessment research.

Thermo-hydrological modeling of temperature variations in the spring waters of a headwater catchment (Strengbach critical zone Observatory–France)

This study is geared towards evaluating the hydrological information that can be extracted from spring water temperature variations in shallow and thin aquifers of headwater catchments. A series of temperature variations (from 2013 to 2017) in four spring water sources at the Strengbach Critical Zone Observatory (CZO) was analyzed and interpreted by relying upon a coupled two-dimensional unsaturated–saturated flow and heat transfer model specifically designed for the study. Temperature variations of spring waters at the Strengbach catchment obey a seasonal non-phased and attenuated cyclicity compared with temperature inputs from the air or very shallow waters in soils. Simulation results show that, within the shallow subsurface horizons, heat transfer is mainly controlled by thermal conduction and not by fluid flow. The results also emphasize that the depth and temperature value of the thermal invariance zone are key parameters to surface temperature attenuation patterns in the first meters beneath the surface. The average maximum porosity (or saturated water content) is another important parameter impacting heat transfers in the shallow subsurface. Stronger attenuations and delays of the thermal signal occur as the porosity increases. These different results indicate that temperature variations in the spring waters, especially the attenuation and phase shift of the signals compared with incoming air-surface water temperatures, do not bring information on hydrological transfers. In very shallow systems, characteristics, such as flow velocities and water residence times, cannot be inferred from temperature variations. Nevertheless, this study suggests that spring water temperature variations could become a way of identifying the usually poorly known saturated water content and its spatial variability at the catchment scale.

Multi-window spectrum analysis of Búzios oil field PSDM seismic data applied to frequency attenuation study

The intrinsic attenuation is often quantified using the inverse quality factor Q. Methods to estimate Q are mainly based on time domain or frequency domain and sensitive to amplitude and/or frequency band variations. In this sense, noise, signal artifacts or processing steps can alter the amplitude, frequency content and the waveform, what may lead to inaccurate calculations of Q. A way to better understand the frequency band variation in seismic data and verify patterns or problems occurring in the signal frequency band is performing layered or window-by-window spectrum analysis. This work describes a multi-window spectrum analysis method used to better understand the frequency attenuation process as the seismic wave travels through the sediments from the sea bottom down to the reservoir depths in a 3D Kirchhoff Pre-Stack Depth Migrated (PSDM) seismic data from Búzios oil field. To perform the spectral analysis in frequency domain, the PSDM volume was converted to time domain using the same interval velocity volume used to depth-migrate the data. The variation of frequency band as the signal propagates through the sediment package was analyzed dividing the studied crossline sections in 13 layers of 200 ms each, from sea bottom down to the base of pre-salt reservoir formations. The results suggest that most part of higher frequency loss has been occurred in post-salt package. This may be an indication of significant viscoelastic behavior or strong stratigraphic filtering of this interval. Sequentially, higher frequency content is lost slowly from salt top down to the last layer located inside pre-salt formation. Very slight frequency spectrum variation below salt top indicates elastic behavior of the salt formation and underling pre-salt formation in this interval. The spectrum analysis method proposed here has shown to be useful and efficient to identify intervals of different attenuation patterns in seismic data. Additionally, the frequency band study produced by our spectrum analysis can be used to quality-control Q-factor estimation computed by different methods.

Scalable 3D mapping of cities using computer vision and signals of opportunity

Three-dimensional (3D) maps are used extensively in a variety of applications, from air and noise pollution modelling to location-based services such as 3D mapping-aided Global Navigation Satellite Systems (GNSS), and positioning and navigation for emergency service personnel, unmanned aerial vehicles and autonomous vehicles. However, the financial cost associated with creating and updating 3D maps using the current state-of-the-art methods such as laser scanning and aerial photogrammetry are prohibitively expensive. To overcome this, researchers have proposed using GNSS signals to create 3D maps. This paper advances that family of methods by proposing and implementing a novel technique that avoids the difficult step of directly classifying GNSS signals into line-of-sight and non-line-of-sight classes by utilising edge detection techniques adapted from computer vision. This prevents classification biases and increases the range of environments in which GNSS-based 3D mapping methods can be accurately deployed. Being based on the patterns of blockage and attenuation of GNSS signals that are freely and globally available to receive by many mobile phones, makes the proposed technique a free, scalable and accessible solution. This paper also identifies some key indicators affecting data collection scalability and efficiency of the 3D mapping solution.

The spatial scope of agglomeration economies in Brazil

AbstractThis paper provides evidence about location and colocation patterns of manufacturing entrepreneurship and spatial scope of agglomeration economies in the context of a developing country. Using microgeographic data for all Brazilian manufacturing activities and distance‐based measures, we find clear patterns of colocalization between entrants and existing establishments, and that these patterns occur mainly at short distances. For activities presenting colocalization between entrants and existing establishments, our results also indicate that a greater number of incumbent establishments in a given location positively affects the number of entrant establishments that decide to locate there, an effect that attenuates rapidly with distance (generally disappearing after 5 km). This pattern of attenuation is robust to both the inclusion of a comprehensive set of controls for observable and unobservable local characteristics and the use of instrumental variables to address remaining endogeneity concerns.

Modulus attenuation of semi-rigid asphalt pavement layer in accelerated pavement testing with MLS66

This research aimed to investigate the attenuation mode of the layer modulus of asphalt pavement in accelerated pavement testing (APT). A full-scale experimental section was constructed and tested using the APT facility. Two non-destructive testing (NDT) methods, named falling weight deflectometer (FWD) technique and portable seismic property analyzer (PSPA) test, were used to obtain the layer moduli of asphalt pavement during the APT test. The variation patterns of layer moduli obtained by FWD and PSPA tests were calculated and compared after the temperature was corrected to 20 ℃. It was found that the variation pattern of surface layer modulus based on field FWD measurements was consistent with the one measured from PSPA tests. That is the modulus of the surface layer increases with the APT load repetitions firstly and then decreases with the rise of the repetitions. The modulus values of the surface layer measured from PSPA tests are obviously larger than those backcalculated based on deflection basins. The ratio of the measured surface layer modulus based on the PSPA test to the backcalculated one based on the FWD test ranges between 2.06 and 2.71. The backcalculated base layer modulus always declines with the increasing loading repetitions. The attenuation patterns of the surface layer modulus and the base layer modulus in the damage stage are described as Ea=421100*N-0.6119 and Eb=128000*N-0.1096, respectively.

Ground motion model for Peninsular India using an artificial neural network

Ground motion models (GMMs) are an essential tool for seismic hazard analysis. They are used for developing predictive relationships to estimate the expected levels of seismic ground shaking through the ground motion parameters (GMPs). There is limited recorded data on the stable continental regions (SCR) such as Peninsular India (PI), and Central and North Eastern America (CENA), and GMMs are developed either by hybrid or stochastic methods. In this study, an effort has been made to develop a GMM for the PI region by compiling the recorded data from the CENA and PI regions, as well as from the Near Source Strong (NESS) data. An artificial neural network coupled with the genetic algorithm is considered to develop GMMs. So, the GMP-1 model is developed for various GMPs for both RotD50 and vertical components, while the GMP-2 model is developed for RotD50 components of peak ground acceleration (PGA), peak ground velocity (PGV), and the 5% damped pseudo-spectral acceleration (PSA) for periods between 0.01 and 3 s. The developed models are valid for magnitudes between 2–7.7 Mw and 0 to 1500 km Joyner–Boore distance. In addition, a parametric study is performed with the developed models for various combinations of predictor variables, and it is noticed that both the models capture the trend and attenuation pattern observed in the recorded data for all the GMPs. Moreover, the GMP-2 model predictions agree well with the recorded data compared with the candidate GMMs developed in the NGA-EAST project. A comparison of the GMP-2 models with the recorded data in the PI region indicates the robustness and effectiveness of the developed model in providing reasonable estimates of GMPs, implying its applicability to tectonic environments similar to the CENA region.

Calculation of hole spacing and surrounding rock damage analysis under the action of in situ stress and joints

In situ stress and joints have a significant impact on the propagation and attenuation pattern of blast stress waves, and they are two important factors that must be considered for tunnel blasting hole network deployment. This paper proposes a blast stress wave attenuation equation and a peripheral hole distance calculation method under the combined action of in situ stress and joints. First, the static and dynamic parameters of the jointed slate are obtained by drilling core samples in the field and conducting indoor tests. Next, considering the geometric and physical attenuation of the blast stress wave, the attenuation formula of the blast stress wave under the combined action of in situ stress and joints is derived. Based on the theory of the combined action of stress waves and explosive gas, a formula for calculating the peripheral hole distance that integrates the effects of in situ stress, joints, and tensile strength of the rock body is proposed. Finally, LS-PREPOST software is used to analyze the damage to the surrounding rock, verified by an on-site blasting test. The results show that the blast stress wave attenuation formula proposed in this paper can accurately predict the stress wave peak value under the combined action of in situ stress and joints. Combining the geological conditions and blasting parameters of the Bayueshan Tunnel study section, the optimal peripheral hole spacing is calculated to be 45 cm. The average over-excavation value of the grade IV surrounding rock is controlled within 22 cm and the over-consumption of concrete per linear meter is controlled within 100% using the peripheral hole layout method and the hole network layout parameters proposed in this paper. The research results provide a reference for the control of over-excavation and under-excavation in large-section tunnel blasting.

Pulmonary Recovery 12 Months after Non-Severe and Severe COVID-19: The Prospective Swiss COVID-19 Lung Study

Background: Lung function impairment persists in some patients for months after acute coronavirus disease 2019 (COVID-19). Long-term lung function, radiological features, and their association remain to be clarified. Objectives: We aimed to prospectively investigate lung function and radiological abnormalities over 12 months after severe and non-severe COVID-19. Methods: 584 patients were included in the Swiss COVID-19 lung study. We assessed lung function at 3, 6, and 12 months after acute COVID-19 and compared chest computed tomography (CT) imaging to lung functional abnormalities. Results: At 12 months, diffusion capacity for carbon monoxide (DLCO_corr) was lower after severe COVID-19 compared to non-severe COVID-19 (74.9% vs. 85.2% predicted, p < 0.001). Similarly, minimal oxygen saturation on 6-min walk test and total lung capacity were lower after severe COVID-19 (89.6% vs. 92.2%, p = 0.004, respectively, 88.2% vs. 95.1% predicted, p = 0.011). The difference for forced vital capacity (91.6% vs. 96.3% predicted, p = 0.082) was not statistically significant. Between 3 and 12 months, lung function improved in both groups and differences in DLCO between non-severe and severe COVID-19 patients decreased. In patients with chest CT scans at 12 months, we observed a correlation between radiological abnormalities and reduced lung function. While the overall extent of radiological abnormalities diminished over time, the frequency of mosaic attenuation and curvilinear patterns increased. Conclusions: In this prospective cohort study, patients who had severe COVID-19 had diminished lung function over the first year compared to those after non-severe COVID-19, albeit with a greater extent of recovery in the severe disease group.

Mechanical Properties and Engineering Applications of Special Soils—Dynamic Shear Modulus and Damping of MICP-Treated Calcareous Sand at Low Strains

Calcareous sand deposits are widespread along the shoreline in tropical and subtropical regions. Microbially induced calcite precipitation (MICP) treatment is a new method for improving the soil’s stiffness and strength. The small-strain shear modulus and damping ratio of MICP-treated calcareous sand, two critical parameters for predicting the dynamic behavior of soil, are little known. This study conducts a series of resonant column tests to investigate the dynamic characteristics of MICP-treated calcareous sand, emphasizing the influence of treatment duration and confining stress on the stiffness and damping characteristics. It analyzes the relationship between the initial dynamic shear modulus and unconfined compressive strength. In addition, empirical relationships between the reference shear strain and treatment duration or confining stress are provided. The results show that the normalized shear modulus G/G0 of MICP-cemented calcareous sand has a higher strain sensitivity than that of untreated sand, and the Hardin–Drnevich model can describe its attenuation pattern. The effective confining stress σc affects the degradation characteristics of the dynamic shear modulus of MICP-treated calcareous sand with a low cementation level; however, its impact decreases as the treatment duration increases. There is a linear relationship between the reference shear strain and confining stress. While the relationship between the reference shear stain and treatment duration is a power law.

Computed tomography can differentiate vaginal-origin from uterine-origin lesions in bitches.

To investigate typical computed tomography (CT) features for the differentiation of vaginal from the uterine origin in dogs. 7 healthy Beagles in the prospective study and 5 bitches in the retrospective study. In the prospective study, dual-phase CT images were obtained from sexually intact female Beagles (n = 7) during anestrus and estrus. On the CT images, the vagina and uterine horns, body, and cervix were assessed for diameter, attenuation, and contrast enhancement pattern. In the retrospective study, CT features of large vaginal lesions (leiomyoma, leiomyosarcoma, adenocarcinoma, hematocolpos, and Gartner's duct cyst) were assessed in 5 bitches. In normal bitches, the cervix was thicker with strong central enhancement compared to the uterus and vagina. The uterine artery, which enters the mesometrium at the level of the cervix, was clearly visualized and assisted in identifying the cervix. In bitches with large vaginal masses, uterine arteries were displaced by the lesions and could not be used to locate the cervix. In 4/5 dogs with vaginal masses, identification of the cervix allowed the determination of the organ of origin. In 1 dog with adenocarcinoma, CT vaginography was additionally required for determining the origin of mass. Results from this study indicate that the cervix, recognized in CT as focal thickening of the uterus with central enhancement, may be used as a landmark for the differentiation between the uterus and vagina in bitches.

The impact of climate change on the storm surges of the Mediterranean Sea: Coastal sea level responses to deep depression atmospheric systems

The impact of climate change on the storm surges of the Mediterranean Sea: Coastal sea level responses to deep depression atmospheric systems

Differentiating between adrenocortical carcinoma and lipid-poor cortical adenoma: A novel cross-sectional imaging-based score

BackgroundDiscrimination between adrenocortical carcinoma and lipid-poor cortical adenoma preoperatively is frequently difficult as these two entities have overlapping imaging characteristics. Differentiation will allow for the selection of the most appropriate operative approach and may help prevent over-treatment. We aimed to identify imaging features that could preoperatively differentiate adrenocortical carcinoma from lipid-poor cortical adenoma and use them in a novel imaging-based score. MethodsWe conducted a retrospective analysis of patients with pathologically proven adrenocortical carcinoma and lipid-poor cortical adenoma who underwent resection in a single tertiary referral center between March 1998 and August 2020. The inclusion criteria were diameter >1 cm, attenuation >10 Hounsfield units on nonenhanced computed tomography, and histopathologic diagnosis. Patients with metastatic or locally advanced adrenocortical carcinoma adenoma (stages 3–4) were excluded. We developed a score using binary logistic multivariate regression model in 5-fold derivation (∼70%) cohorts with stepwise backward conditional regression as feature selection. Standardized mean regression weight was used as variable score points. ResultsWe identified 232 adrenals resected across 211 patients. By comparing the imaging characteristics of adrenocortical carcinoma (n = 56) and lipid-poor cortical adenoma (n = 156), we revealed statistically significant differences between the groups in 9 parameters: size, attenuation, thin and thick rim enhancement patterns, heterogeneity, calcification, necrosis, fat infiltration, and lymph node prominence. The score mean performance was 100% sensitivity for the exclusion of adrenocortical carcinoma, 80% specificity (95% confidence interval, 68.3–91.5), 66% positive predictive value (95% confidence interval, 52.3–78.7), and 100% negative predictive value with area under the curve of 0.974. ConclusionWe defined and evaluated a novel 9-variable, imaging-based score. This score outperformed any single variable and could facilitate safe preoperative discrimination of adrenocortical carcinoma and lipid-poor cortical adenoma.