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Based on wind profile radar data, this paper aims at different typhoon processes landed and affected Fujian from 2011 to 2019, according to the nature of typhoon rainstorm, it can be classified into outer precipitation before typhoon landed, main body precipitation and precipitation at the rear of typhoon, the change of the characteristic quantities in approaching time of the occurrence of short-term heavy rainfall was analyzed, and the typhoon case in 2020 was back calculated. The results show that, the characteristics of low-level jet streams (maximum wind speed at low altitude, minimum height of jet streams, and low-level jet stream index), as well as the magnitude of vertical wind shear below 700 hPa, have important indicative significance for the occurrence of short-term heavy rainfall. (1) More than 80 % of short-term heavy rainfall occurred 3 h before the low-level jet stream already existed. The maximum wind speed below 2 km was basically close to a normal distribution, and the occurrence of heavy precipitation showed a bimodal pattern. The percentage of wind speed between 8 and 32 m/s was the highest, exceeding 85 %. The wind direction of the strong wind is mainly NE, SE, and SW. Classification analysis showed that the distribution characteristics of wind speed of the main precipitation were the same as before, but the wind direction SE was higher than NE. The wind speed of pre-landfall precipitation was basically skewed, and the occurrence time of heavy precipitation followed a normal distribution. The percentage of wind speed between 16 and 32 m/s was the highest, and the wind direction was the same as before classification. The maximum wind speed of precipitation in the rear was basically bimodal distribution, with a relatively even distribution, and the wind direction was mainly SE and SW. (2) In the 3 h before the occurrence of short-term heavy precipitation, there was an increase in the maximum wind speed value, a decrease in the minimum extension height, and an increase in the low-level jet stream index I. As short-term heavy rainfall approached, the intensity of the low-level jet stream remained high and its proportion increased. The minimum achievable extension height gradually decreased and remained stable at a low value. In the first 2 h of heavy rainfall, the wind speed reached its maximum, the extension height was the lowest, and the lowlevel jet stream index I was the highest. Classifying and discussing it, the precipitation in the rear was different, and the lowest height decreased to the lowest at the time of occurrence, at which point the I value reached its maximum. The characteristics of the other two categories were the same as before the classification. (3) The vertical wind shear from the ground to different isobaric surfaces gradually decreased with the increase of height. With the approach of short-term heavy rainfall, the vertical wind shear of each layer basically decreased gradually, after the beginning of heavy rainfall, which decreased to the minimum. The characteristics of main body precipitation were the same as before the classification. Pre-landfall precipitation, in addition to the gradual decrease of vertical wind shear from the ground to 925 hPa, both 850 hPa and 700 hPa increased first and then decreased, vertical wind shear decreased to the minimum after the beginning of heavy rainfall. Precipitation at rear of typhoon, vertical wind shear from ground to 700 hPa increased compared with that before the occurrence of heavy rainfall, while wind shear from ground to 925 hPa and 850 hPa showed the characteristics of decreasing when heavy rainfall occurred. (4)The median values of various physical quantities before the occurrence of typhoon short-term heavy rainfall were selected as the thresholds of short-term heavy rainfall will occur. The intensity of LLJ is about 21 m/s, the lowest height is about 0.65 km, the LLJ index I is about 36 x 10-3s-1. Vertical wind shear from the ground to 925 hPa, 850 hPa and 700 hPa are respectively about 15.9 x 10-3s-1, 11.2 x 10-3s-1 and 5.1 x 10-3s-1. [ABSTRACT FROM AUTHOR]

• Using a cut-off value for a short cervix introduces selection bias and affects the normal distribution and incidence of a short cervical length. • Irrespective of the chosen cut-off value, the deviation from a normal distribution is most pronounced around this threshold. • If essential decisions depend on a cut-off value, healthcare providers should be aware of potential bias and measure with caution. A prior study suggested that implementing a cut-off value of ≤30 mm for a short cervical length (CL) could potentially introduce selection bias and alter the distribution of CL measurements. As such, the objective of this study is to evaluate how CL distribution and incidence of short CL are affected when using different cut-off values for a short CL. This is a secondary analysis of the Quadruple P (QP) Screening study; a prospective cohort study that included low-risk patients with singleton pregnancies undergoing fetal anomaly scan at 18–22 weeks of gestation, including a CL measurement. Patients with a short cervix, defined as ≤35 mm, were subsequently counseled for the QP trial; a randomized controlled trial (RCT) comparing progesterone to cervical pessary for the prevention of preterm birth. If participation to the RCT was refused, patients with a CL ≤25 mm were advised to use progestogen. The primary objective of this current study was to assess the normal distribution of CL across the entire cohort and to assess the incidence of short CL when using the cut-off values of ≤35 and ≤25 mm. Normal distributions for CL were simulated based on mean and standard deviation(SD) of the original data. The Kolmogorov-Smirnov test was used to evaluate the distribution of the CL measurements. Moreover, to evaluate the motives behind ultrasound measurements around the cut-off value, sonographers were asked to fill out a qualitative questionnaire. The total cohort included 19.171 eligible participants who underwent CL measurement, with a mean CL of 43.9 mm (±8.1 SD). The distribution of all CL observed measurements deviated significantly from the normal distribution (p < 0.001). A total of 1.852 (9.7%) patients had short CL ≤35 mm, which was significantly lower than expected when compared to the simulated normal distribution (n = 2.661, 13.9%; p < 0.001). The incidence of short CL ≤25 mm in our cohort statistically differed from the simulated normal distribution (238, 1.2% vs 177, 0.9%; p=0.003). When comparing our data to the simulated normal distribution, the difference in distributions is most pronounced when examining the difference between 35 and 36 mm. Results of the questionnaire reveal sonographers claimed not to be influenced by a cut-off value for study participation or progesterone treatment. This study demonstrates that using any cut-off value for a short CL influences the incidence and distribution of CL. When using a cut-off value of ≤35 mm for study inclusion, the incidence of measurements of a short CL is lower than the anticipated incidence compared to a normal distribution. However, when using a cut-off value of ≤25 mm for progesterone treatment, the frequency of CL measurements is higher than expected below this threshold compared to a normal distribution. This study highlights the risk of introducing selection bias, most likely unintentionally, when cut-off values for short CL are used, regardless of the specific value chosen. Therefore healthcare providers should measure the CL with caution if essential decisions depend on a specific cut-off value. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the value and age- and gender-specific threshold values of bone mineral density (BMD) by quantitative computed tomography (QCT) for the prediction of spontaneous thoracolumbar vertebral fractures and thoracolumbar junction fractures accompanying distant vertebral fractures. Methods: Among the 556 patients included, 68 patients had thoracolumbar vertebral fractures (12 patients with distant vertebral fractures, 56 patients without distant vertebral fractures) and 488 patients had no vertebral fractures. All patients were grouped by gender and age. According to the principle of Youden index, the threshold values were calculated from receiver operating characteristic (ROC) curves. Results: The threshold values for predicting thoracolumbar vertebral fractures were 89.8 mg/cm3 for all subjects, 90.1 mg/cm3 for men, and 88.6 mg/cm3 for women. The threshold values for men aged < 60 years old and ≥ 60 years old were 117.4 mg/cm3 and 87.5 mg/cm3, respectively. The threshold values for women aged < 60 years old and ≥ 60 years old were 88.6 and 68.4 mg/cm3, respectively. The threshold value for predicting spontaneous thoracolumbar junction fractures with distant vertebral fractures was 62.7 mg/cm3. Conclusions: QCT provides a good ability to predict age- and gender-specific spontaneous thoracolumbar vertebral fractures, and to further predict spontaneous thoracolumbar junction fractures with distant vertebral fractures. [ABSTRACT FROM AUTHOR]

At present, the tobacco baking process in China mainly relies on manual monitoring, which has problems of subjectivity, fuzziness and high cost. Research on using machine vision methods to monitor and judge real-time changes in tobacco quality during the baking process is gradually increasing. Real time monitoring needs to be based on efficient and accurate segmentation of roasted tobacco leaf images, so the research on segmentation of roasted tobacco leaf images has become particularly important. A segmentation method for roasted tobacco leaf images based on K-means clustering algorithm was proposed. Firstly, the image was read and RGB was converted to the CYMK color space. Then, the grayscale image of the K-channel in the CYMK color space was extracted. We clustered the single channel image again, determined the image segmentation threshold based on the cluster center, and finally used image processing methods to segment the image. We compared three clustering methods of K-means, fuzzy C-means clustering (FCM) and Gaussian mixture clustering (GMM). The results showed that the pixel accuracy of the K-means algorithm was 97. 8%, the intersection to union ratio was 96. 43%, and the Dice coefficient was 98. 2%, all of which were better than the other two methods. The K-means algorithm could better extract the contour of tobacco leaves, remove redundant information and make the segmentation results clearer. [ABSTRACT FROM AUTHOR]

Background: Soil is important medium of all living beings. Due to the high doses of fertilizers application soil heath is getting deteriorated. Soil fertility variation restricts efficient fertilizer N management when broad based blanket recommendations are used in maize (Zea mays L.). Site-specific fertilizer nitrogen management (SSNM) could be the best management option to avoid excessive and untimely nitrogen (N) applications in maize. Methods: A field experiment was conducted at Agronomy Farm, Lovely Professional University, Phagwara during kharif season of 2020 and 2021 to study the nitrogen management using leaf colour chart (LCC) and chlorophyll meter in maize (Zea mays L.). Colour (of the first top maize leaf with fully exposed collar) as measured by comparison with different shades of green colour on a leaf colour chart (LCC) and also by SPAD meter. Need based fertilizer application at LCC5 and SPAD 50 significantly improved growth and yield attributes viz., plant height, dry matter accumulation plant-1, number of leaves plant-1, stem diameter, number of internodes plant-1, leaf area index, cob length, cob girth, number of cobs plant-1, number of grains cob-1, grain weight plant-1 and 1000-grain weight along with higher grain and stover yields, grain protein content over fixed time application of 1200 kg N ha-1. Result: Evaluation of the established threshold leaf greenness revealed that fertilizer N management using LCC 5 and SPAD 50 starting from six-leaf stage to before silking stage resulted in improved agronomic efficiency in maize. There was no response to fertilizer N application at silking stage. The study concluded that in maize, fertilizer N can be more efficiently managed by applying fertilizer N dose based on leaf colour as measured by LCC than blanket recommendation. [ABSTRACT FROM AUTHOR]

In this article, we develop a Hepatitis B virus model with six compartments affected by environmental fluctuations since the Hepatitis B virus produces serious liver infections in the human body, putting many people at high risk. The existence of a global positive solution is shown to prove the positivity of solutions. We demonstrate that the system experiences the extinction property for a specific parametric restriction. Besides that, we obtain the stochastic stability region for the proposed model through the stationary distribution. To determine the appearance and disappearance of infection in the population, we find and analyze the reproduction ratio R0S$$ {R}_0&#x0005E;S $$. In addition, we have verified the condition of the reproduction ratio through the graphical simulations. [ABSTRACT FROM AUTHOR]

The dielectric constant and the dispersion relation of the Ordinary mode (O-mode) instability has been discussed by using the Vlasov kinetic model in the presence of the Heaviside distribution function. The Heaviside distribution includes relativistic effects for both the parallel and perpendicular streaming. It is noted that the relativistic effects play a destabilizing role for the O-mode at higher magnetic field in comparison to the non-relativistic case. The growth rate of O-mode instability is calculated analytically for different values of parallel and perpendicular streaming. It is shown that the parallel streaming destabilizes the O-mode where as the perpendicular streaming provides a stabilizing effect. The results of the non-relativistic O-mode instability have been retrieved under limiting case. [ABSTRACT FROM AUTHOR]

Background: It is mandatory to label food products with the 14 main allergens in the EU. Reasonable allergen labeling requires knowledge of population‐based thresholds derived from food challenges. The aim of this study was to evaluate the threshold‐distribution in clinically verified food allergic patients for allergens mandatory for labeling. Methods: All positive open oral food challenges and double‐blind placebo‐controlled food challenges (DBPCFC) performed at the Allergy Center, Odense University Hospital, Denmark (2000–2022) were included. For each included challenge, the cumulative threshold (LOAEL) was obtained and NOAEL estimated. Data were modelled as an interval censored log‐normal distribution. Results: Overall, 38 of all 2612 challenges (1.5%) in 1229 patients (717 male, 986 children) reacted to <5 mg protein. The majority of the most sensitive patients reacted with a Sampson severity score of 2–3. Using interval censored log‐normal models only five groups (hens´ egg, fish, peanut, milk, tree‐nuts) elicited reactions after ingestion of 0.5 mg protein and in low frequencies of the population. Hen's egg was the most potent allergen, with reactivity to <0.5 mg protein in 0.24% [0.13–0.44%] of egg allergic patients while the estimated fraction of allergic patients reacting to a eliciting dose on 0.5 mg protein for most other allergens were below 0.04%. Conclusion: Our data demonstrates that the majority of food allergic patients as expected tolerating traces of allergenic foods without developing severe allergic symptoms and signs. Hen's egg appears to be the food most likely to elicit reactions in the most sensitive individuals at very low doses. [ABSTRACT FROM AUTHOR]

Determining background aerosol optical depth threshold value (BAOD) is critical to aerosol type identification and air pollution control. This study presents a statistical method to select the best BAOD threshold value using the VIIRS DB AOD products at 1 × 1 degree resolution from 2012 to 2019 as a major testbed. A series of multiple lognormal distributions with 1 to 5 peaks are firstly applied to fit the AOD histogram at each grid point, and the distribution with the highest correlation coefficient (R) gives preliminary estimations of BAOD, which is defined as either the intersection point of the first two normal distribution curves when having multiple peaks, or the midpoint between the peak AOD and the first AOD with non-zero probability when the mono peak is the best fit. Then, the lowest 1st to 100th percentile AOD distributions are compared with the preliminary BAOD distribution on a global scale. The final BAOD is obtained from the best cutoff percentile AOD distributions with the lowest bias compared with preliminary BAOD. Results show that the lowest 30th percentile AOD is the best estimation of BAOD for different AOD datasets and different seasons. Analysis of aerosol chemical information from MERRA-2 further supports this selection. Based on the BAOD, we updated the VIIRS aerosol type classification scheme, and the results show that the updated scheme is able to achieve reliable detection of aerosol type change in low aerosol loading conditions. [ABSTRACT FROM AUTHOR]

Background: Food allergy is common in childhood with some children having a low threshold and being difficult to protect from accidental ingestion of the offending food. Therapies for this potentially life‐threatening condition are highly needed. The aim of this study was to evaluate the efficacy of Omalizumab in food‐allergic children. Methods: This is a single‐center, double‐blind, placebo‐controlled study. Food allergic children with a cumulative threshold ≤443 mg food protein at DBPCFC were randomized to Omalizumab (asthma dose) or placebo (3:1). After 3 months, a second DBPCFC was performed (steps 3, 10, 30, 100, 300, 1000, and 3000 mg food protein), followed by a separate open challenge up to 10,000 and 30,000 mg food protein if negative. Responders were defined as ≥2‐step increases in threshold. Non‐responders received high‐dose Omalizumab. A third DBPCFC was performed after 6 months. Skin testing, blood samples, and the severity of atopic co‐morbidity were registered during the study and 3 months after treatment. Results: In total, 20 children were evaluated at 3 months (14 Omalizumab, 6 placebo). All treated with Omalizumab increased their threshold at least two steps and with a significant difference between the Omalizumab and the placebo group (p =.003), although the intended number of included children was not reached. The threshold before Omalizumab treatment was 13–443 mg food protein while the threshold after 3 months of treatment increased up to 44,000 mg (1143–44,000). In the placebo group, two children improved threshold during the study. Conclusion: An increase in the threshold level during Omalizumab treatment significantly improve patient safety and protected all children against small amount of allergen. [ABSTRACT FROM AUTHOR]

Solar radio bursts are intense radio radiation sources that occur during the energy-release process and represent a hot topic in solar-physics and space-weather research. In this paper, we present a multimode prediction model for daily solar radio bursts. The model uses deep learning and machine learning to obtain data information from different dimensions and to establish the relationship between the characteristics of the solar active region on the solar surface and solar radio bursts. For this model, we use data from the Solar and Heliospheric Observatory (SOHO)/Michelson Doppler Imager (MDI) total solar magnetic map, the Royal Observatory of Belgium World Data Centre in Brussels, and NOAA sunspot parameters (including number, area, and type of sunspots) as inputs. The output results are then compared with the list of solar radio bursts recorded by the Radio Solar Telescope Network (RSTN) to determine whether solar radio bursts are present and to determine the key parameters for determining radio bursts. Based on 5449 days of observational data, we find that the prediction accuracy of the model is 0.898 ± 0.011, and that the number of sunspots is a key parameter in determining the occurrence of solar radio bursts. Specifically, when the number of sunspots is greater than 15, the probability of occurrence of solar radio bursts is greater than 90%. We have identified the key parameters and thresholds for determining solar radio bursts and highlighted the key parameters for space-weather prediction. In addition, the prediction model can also be used for predicting in other fields. [ABSTRACT FROM AUTHOR]

Providing adequate green cover in the form of trees, parks and gardens is a nature-based solution which every city must adopt to address the urbanization and its impacts, as it helps to reduce the temperature, maintain the ecology and biodiversity, provide recreational facilities for the city inhabitants and many more. Accurate mapping and monitoring of Urban Green Spaces (UGS) through satellite images is essential to check whether a city has adequate green cover or not. Studies on UGS have mostly used Landsat and Sentinel-2A satellite images for extracting the green covered areas in cities. Though it is advantageous to use these freely available images, however the accuracy of extraction is a major concern as the images are of >10m spatial resolution. Distinguishing the various green cover types, such as trees, shrubs, cropland, etc. is not an easy task in low and medium resolution satellite images. To overcome these drawbacks, one has to use high (1-10m) and very-high resolution (<1m) images for extracting the UGS accurately, however, purchasing such 'cm' resolution satellite images is a costly affair. In order to balance between the cost and resolution, the best and viable option is to use the Google earth (GE) imagery and the same was attempted in the present study by proposing a simple threshold-based approach to extract the UGS and its types from GE imagery. To illustrate the proposed method, 15 sites from the city of Vellore, India were taken and the latest cloud free GE imagery was then downloaded, projected and carefully checked for its range of pixel values in different types of UGS classes. The threshold values of each UGS type were then used to reclassify the original GE image and finally the accuracy assessment was performed on the reclassified UGS map. The results were promising as the overall accuracy (OA) was > 90% at 12 sites and only 3 out of 15 sites exhibits OA in the range of 75-86%. In order to assess the performance of the proposed approach at other locations, 5 cities across the globe [2 from India (Bangalore and Hyderabad) and 3 from abroad (Barcelona, Kuala Lumpur, New York)] were taken and the results revealed that the proposed method performs well in extracting the UGS and its types as the OA was found to be above 90% at all the 5 cities. The proposed approach can be used by civic authorities not only to check whether the city has adequate green cover or not but also can monitor whether UGS has increased or decreased over the years using the historical GE images. [ABSTRACT FROM AUTHOR]

With the widespread application of the modular multilevel converter (MMC) in the fields of electronic and electrical engineering, the open-circuit failure problem of the power devices in submodules (SMs) has become the main factor restricting its stable operation. Therefore, power device open-circuit fault diagnosis is widely studied as the main means to ensure the ongoing and stable operation of MMCs. The existing fault diagnosis approaches on the basis of voltage of capacitor change are only applicable to fault diagnosis under active power conditions. However, in reactive power scenarios, MMC systems have very important applications, such as power grid steady-state reactive power regulation and transient reactive power support. Therefore, an effective fault diagnosis method based on the capacitance voltage change rate is put forward for the diagnosis of faults under reactive conditions. This method differentiates the capacitor voltage and compares it with the threshold to diagnose faults under reactive power operation. The proposed method is simulated using PSCAD simulation software. Simulation results verify the practicability of the presented approach. [ABSTRACT FROM AUTHOR]

An image processing-based Firebug Swarm Optimization (FSO) algorithm is developed in this article to detect maximum power point tracking (MPPT) under shadowing conditions on PV arrays. After capturing an image and applying image processing techniques, the proposed method can detect the shading portion of photovoltaic array (PV). The image processing results can then be used to modify the current rating in power equations. The Firebug swarm optimization (FSO) algorithm is metaheuristic algorithm that identifies and controls switching configurations under partial shading patterns by detecting the maximum global peak point (GPP) of output power generated by multiple configurations. This research is proposed with an image processing edge detection algorithm called the Otsu-Canny algorithm for detecting the partial shade on PV array. The FSO algorithm is used to rearrange the shaded photovoltaic array to significantly reduce the power and efficiency losses. MATLAB simulations were carried out using a 280 W PV panel to verify the efficiency of the proposed FSO MPPT technique with an image processing-based algorithm. The proposed FSO MPPT scheme's performance is compared to current cutting-edge MPPT methods. Under partial shading conditions, the proposed algorithm successfully detected the maximum peak point of a photovoltaic array, increasing power output and efficiency. [ABSTRACT FROM AUTHOR]

Full waveform inversion (FWI) is a nonlinear data fitting process that can derive high-resolution model parameters through iteration. In this process, step length is related to inversion accuracy and computational efficiency. It can be calculated efficiently with the inexact line search method, which does not require a misfit function to achieve the exact minimum. This method is aimed toward obtaining the appropriate descent using evaluation conditions and initial step length. Moreover, it does not depend on the form of the misfit function. In the inexact line search method, the evaluation condition and initial step length are obviously important factors. In this work, the classical Armijo, Wolfe, and Goldstein evaluation conditions in solving optimization problems in mathematics are studied and compared in detail. Numerical examples from the synthetic data of the overthrust model show that the convergence characteristics of Armijo and Goldstein are similar and that the computational efficiency is high and conducive to seismic FWI. In addition, the adaptive Barzilai-Borwein (ABB) method is adopted in FWI. The ABB method maximizes the changes in model parameters and gradients to adaptively calculate the initial step length. The threshold value of the ABB method for the initial step length estimation is also studied to explore a suitable threshold value that can ensure that large and small step lengths are frequently adopted in FWI. Numerical examples from the synthetic data of the overthrust model demonstrate the validity of the ABB method. Moreover, the inversion is superior when the threshold value is less than 0.5. [ABSTRACT FROM AUTHOR]

Background: Endometrial proliferative lesions (EPL) usually refer to endometrial hyperplasia (EH) and endometrial cancer (EC). Among patients with premenopausal EPL who wish to preserve their fertility, only those with EH and early-stage EC have the possibility to undergo fertility preservation therapy. However, there is currently a lack of specific and reliable screening criteria and models for identifying these patients. Methods: This study utilized a retrospective diagnostic study design. The training set included medical record information that met the criteria between August 2017 and October 2022, while the validation set consisted of medical record information that met the criteria from November 2022 to May 2023. The endometrial pathological test served as the gold standard. The serum anti-Mullerian hormone (AMH) level before endometrial sampling and a regression model were employed to predict EPL. Results: The study included a total of 1209 patients with PCOS (1119 in the control group and 90 in the endometrial proliferative lesion group) and 5366 women without PCOS (5249 in the control group and 117 in the proliferative lesion group). In the case of PCOS patients aged 20–39 years, the most effective screening threshold for AMH was found to be a serum AMH level of ≤5.39 ng/mL. The model used for this group was logit(p) = −2.562 − 0.430 × AMH + 0.127 × BMI + 1.512 × hypertension + 0.956 × diabetes −1.145 × regular menstruation. On the other hand, for non-PCOS women aged 20–39 years, the optimal screening threshold for AMH was determined to be a serum AMH value of ≤2.18 ng/mL. The model used for this group was logit(p) = −3.778 − 0.823 × AMH + 0.176 × BMI + 2.660 × diabetes −1.527 × regular menstruation −1.117 × dysmenorrhea. It is important to note that all of these findings have successfully passed internal verification. Conclusion: For PCOS and non-PCOS women aged 20–39 years, the serum AMH test and related multiple regression models were obtained for the warning of EPL. [ABSTRACT FROM AUTHOR]

Proton nuclear magnetic resonance (NMR) is widely applied to characterize the microscopic properties of hydrogen‐containing porous media. The transverse relaxation time cutoff (T2c) value is the crucial parameter for the quantitative analysis of NMR data. Currently, there is no universal method for the determination of the T2c in clayey soils. This study aimed to develop a laboratory method for determining the T2c of remoulded loess by the freezing point of loosely bound water. Malan loess, a kind of typical clayey silt, was used as test material. Based on the soil freezing characteristic, NMR measurements were performed on remoulded loess with different macro‐parameter controls during the cooling process to obtain the T2 spectrum at each target temperature. By analysing the variation of unfrozen water content with temperature reduction, the freezing point of loosely bound water and the T2c value within the freezing‐point range was determined. The freezing point of loosely bound water in remoulded loess is about −3 to −5°C and that of firmly bound water is less than −5°C. Accordingly, the T2c value of remoulded loess is determined to be 1.5–1.8 ms. The assessment of heating and cooling process and different methods for determining the T2c shows that the laboratory method by the freezing point is effective and reliable, and the T2c determined by statistical methods is worthy of further study and improvement. The saturated permeability of remoulded loess is evaluated according to the determined T2c, and two NMR‐based permeability equations can well reflect pore water distribution in remoulded loess, but to a certain extent, both equations ignore soil microstructure, pore connectivity and chemical effects of pore solution. The laboratory method by the freezing point and the determined T2c value of remoulded loess fill the gap of NMR measurement in loess analysis and are of great significance for low‐plastic clays and clay types. [ABSTRACT FROM AUTHOR]

Lettuce (Lactuca sativa) is one of the most consumed vegetables in Colombia and department of Cundinamarca ranks first in terms of production. One of the problems that has been detected in the Bogotá savanna is that, although producers usually apply fertilizers in excess, the average yield obtained is well below the potential, largely because there is no tool to determine the appropriate nutritional status. This research proposed to determine the norms of the Diagnosis and Recommendation Integrated System (DRIS) for lettuce cultivation in the savanna of Bogotá, to balance the plant nutritional status previously selecting, using Monte Carlo analysis techniques, one of eight different methods to divide the population sample into high and low yield. Field data were collected from farms representing 12% of the area planted in 2018 according to Cundinamarca statistics. Plant nutritional status was determined at early vegetative growth using established laboratory techniques, and crop yield was recorded at the end. The splitting methods showed that the maximum difference with the lowest variance was obtained using the Cate and Nelson proposal applied on the predicted values of a regression analysis between yield and plant nutrient concentration, taking care that the size of the subpopulations was greater than or equal to 25% of the sample size. Once the DRIS standards were determined, DRIS indices were calculated for each sampling point and, as a result, potassium and phosphorus were the most frequent deficient elements due to imbalance, while iron and copper were the most frequent elements in excess. [ABSTRACT FROM AUTHOR]

EMF has a variety of biological impacts and has an impact on the metabolic process in the human body. Antenna towers, anechoic chambers, and other sources can all produce this. Some of the human populations live very close to the EMF-emitting antenna towers. We can make humans aware of the EMF radiation and protect from diseases if there is a proper method to anticipate the EMF radiation of antennas installed in different places. For the study of telecom data and EMF emission, many machine learning and deep learning techniques have been developed in recent years. Predictive analytics played a bigger part in this. For prediction, it comprises advanced statistics, modeling and more machine learning methodologies. However, the appropriate hyper parameters must be established for the model's effective prediction, but this cannot be guaranteed in a dynamic environment where the data is always changing. The learning model's performance improves when these parameters are optimized. The goal of this study is to use the Telecom dataset to create a novel hybrid deep learning model for forecasting the trend of EMF radiations. The patterns were first discovered using Artificial Neural Networks (ANN) and Multilayer Perceptron (MLP) combined with the Particle Swarm Optimization method (PSO). Later to boost its performance the hybrid approach (MLP-RFD-PSO) was developed and 98.8% accuracy was achieved. [ABSTRACT FROM AUTHOR]

Fatigue damage of welded joints is gradually becoming one of the key problems affecting the service safety of steel bridges under repeated vehicle loads. The fatigue crack growth rate (FCGR) tests of compact tensile (CT) specimens of two plate thicknesses under three stress ratios were carried out with Q690D high strength steel (HSS) butt weld (BW) in this paper. The FCGR and fatigue crack growth threshold (FCGT) under different stress ratios were obtained. Expressions for the FCGR and FCGT that can synthesize the effects of stress ratio were established. A new method to determine the crack closure parameters of Q690D HSS BW was also given. On the basis of McEvily model, the calculation formula of FCG for Q690D HSS BW was derived. The results show that the Q690D HSS BW of this batch have good FCG performance. And the greater the plate thickness, the better the FCG performance of the specimens taken perpendicular to the rolling direction. The FCGR recommended by BS7910 specification is 1.71–2.92 times that of the Q690 HSS BW in this study. The FCGR increases with the increase of stress ratio. When the stress ratio increases from 0.1 to 0.2, the FCGR increases by 49.48 %, whereas FCGR increases by 129.65 % when the stress ratio increases from 0.2 to 0.5. The stress ratio has a greater influence on the FCGR parameters for plates of smaller thickness. And the FCGT decreases linearly with the increase of stress ratio. • The fatigue crack growth rate tests were conducted on CT specimens of Q690D high strength steel butt weld with two plate thicknesses at three stress ratios. • The fatigue crack growth threshold tests of Q690D high strength steel butt weld were carried out with two plate thicknesses at three stress ratios. • Fatigue crack closure parameter U of Q690D high strength steel butt weld was proposed. • The fracture types and fracture mechanisms were analyzed by the microscopic morphology of the specimens. • The calculation formula of FCG for Q690D HSS welded joints was derived. [ABSTRACT FROM AUTHOR]

The computational modeling of fractures in solids using damage mechanics faces challenge when dealing with complex crack topologies. One effective approach to address this challenge is by reformulating damage mechanics within a variational framework. In this paper, we present a novel variational damage model that incorporates a threshold value to prevent damage initiation at low energy levels. The proposed model defines fracture energy density (ϕ ˜) and damage field (s) based on the energy density (ϕ), crack energy release rate (G c), and crack length scale (ℓ). Specifically, if ϕ ≤ G c 2 ℓ , then ϕ ˜ = ϕ and s = 0 ; otherwise, ϕ ˜ = − G c 2 4 ℓ 2 1 ϕ + G c ℓ and s = 1 − G c 2 ℓ 1 ϕ. Furthermore, we extend the model with a threshold value to a higher-order version. Utilizing this functional, we derive the governing equation for fractures that evolve automatically with ease. The formulation can be seamlessly integrated into conventional finite element methods for elastic solids with minimal modifications. The proposed formulation offers sharper crack interfaces compared to phase field methods using the same mesh density. We demonstrate the capabilities of our approach through representative numerical examples in both 2D and 3D, including static fracture problems, cohesive fractures, and dynamic fractures. The open-source code is available on GitHub via the link https://github.com/hl-ren/vdm. • A variational damage model with a threshold prevents damage at low energy levels. • The VDM expresses the damage field as a piecewise function of energy density. • The VDM is generalized into an arbitrary order, and into other physical fields. • The static fractures, cohesive fractures and dynamic fractures in 2D or 3D are modeled. [ABSTRACT FROM AUTHOR]

A stochastic epidemic model with random noise transmission is taken into account, describing the dynamics of the measles viral infection. The basic reproductive number is calculated corresponding to the stochastic model. It is determined that, given initial positive data, the model has bounded, unique, and positive solution. Additionally, utilizing stochastic Lyapunov functional theory, we study the extinction of the disease. Stationary distribution and extinction of the infection are examined by providing sufficient conditions. We employed optimal control principles and examined stochastic control systems to regulate the transmission of the virus using environmental factors. Graphical representations have been offered for simplicity of comprehending in order to further verify the acquired analytical findings. [ABSTRACT FROM AUTHOR]

The coronavirus disease (COVID-19) is a dangerous pandemic and it spreads to many people in most of the world. In this paper, we propose a COVID-19 model with the assumption that it is affected by randomness. For positivity, we prove the global existence of positive solution and the system exhibits extinction under certain parametric restrictions. Moreover, we establish the stability region for the stochastic model under the behavior of stationary distribution. The stationary distribution gives the guarantee of the appearance of infection in the population. Besides that, we find the reproduction ratio R 0 S for prevail and disappear of infection within the human population. From the graphical representation, we have validated the threshold conditions that define in our theoretical findings. [ABSTRACT FROM AUTHOR]

Site-specific fertilizer nitrogen (N) management using chlorophyll meter (SPAD meter) can help drawing in-season need-based N topdressing decisions. However, SPAD meter based threshold chlorophyll value to trigger supplement N in spring maize is indistinct. Field studies were conducted for two years in sub-tropical and sub-humid climate to study variations in spectral properties and to establish threshold SPAD value for need-based N management in spring maize cultivars. Results specified that N concentration of topmost fully expanded leaf was closely correlated with SPAD meter readings from six-leaf stage (V6) to tasseling stages (VT). The Cate-Nelson plot expressed SPAD 50 as the threshold value to determine plant N need at different growth stages. Need-based topdressings of 30 kg N ha−1, whenever SPAD reading fell below the threshold 50 improved grain yield production by 7.6 to 10.2 per cent over soil test-based N application. SPAD threshold 45 guided N management was inadequate to meet plant N demand, whereas SPAD threshold 55 guided N application lead to N doses in excess of crop requirement without yield benefits. SPAD threshold 50 guided N management ensured better demand-supply synchrony throughout the growth stages and thus reported better N recovery and agronomic efficiencies over soil test-based N management. [ABSTRACT FROM AUTHOR]

The establishment of the reference ambient background concentrations (ABCs) and quality reference values (QRVs) for trace metal (TM) concentrations in soils are required for the environmental assessment and any implementation of a protective action. This information is lacking for soils of the eastern Mitidja plain, which is an important agricultural production area in Algeria. Data for the aqua regia extractable Cd, Cr, Cu, Fe, Ni, Pb and Zn concentrations from 180 composite topsoil samples taken across the Mitidja plain in a stratified random pattern were statistically analysed. Descriptive statistical methods and linear regression equations were applied to determine the upper limit of the ABCs for the TMs. After removal of outliers, the derived QRVs were: Cd 0.24, Cr 62.1, Cu 99.3, Fe 45 590, Ni 47.7, Pb 33 and Zn 115 mg/kg. Iron is a macro element in the soils, but is included as its concentration can be used to normalise the concentrations of the other elements. The derived QRVs are similar or less than those reported for other regions of the world, apart from Cu, where a wide range (36 to 206 mg/kg) is reported. These reference values can be used to identify areas that may require follow-up surveys or to identify priority sites for decision making. [ABSTRACT FROM AUTHOR]

Background: Aggressive lipid lowering by high-dose statin treatment has been established for the secondary prevention of coronary artery disease (CAD). Regarding the low-density lipoprotein cholesterol (LDL-C) level, however, the "The lower is the better" concept has been controversial to date. We hypothesized that there is an optimal LDL-C level, i.e., a "threshold" value, below which the incidence of cardiovascular events is no longer reduced. We undertook a subanalysis of the REAL-CAD study to explore whether such an optimal target LDL-C level exists by a novel analysis procedure to verify the existence of a monotonic relationship.Methods: For a total of 11,105 patients with CAD enrolled in the REAL-CAD study, the LDL-C level at 6 months after randomization and 5-year cardiovascular outcomes were assessed. We set the "threshold" value of the LDL-C level under which the hazards were assumed to be constant, by including an artificial covariate max (0, LDL-C - threshold) in the Cox model. The analysis was repeated with different LDL-C thresholds (every 10 mg/dl from 40 to 100 mg/dl) and the model fit was assessed by log-likelihood.Results: For primary outcomes such as the composite of cardiovascular death, non-fatal myocardial infarction, non-fatal ischemic stroke, and unstable angina requiring emergency hospitalization, the model fit assessed by log-likelihood was best when a threshold LDL-C value of 70 mg/dl was assumed. And in the model with a threshold LDL-C ≥ 70 mg/dl, the hazard ratio was 1.07 (95% confidence interval 1.01-1.13) as the LDL-C increased by 10 mg/dl. Therefore, the risk of cardiovascular events decreased monotonically until the LDL-C level was lowered to 70 mg/dl, but when the level was further reduced, the risk was independent of LDL-C.Conclusions: Our analysis model suggests that a "threshold" value of LDL-C might exist for the secondary prevention of cardiovascular events in Japanese patients with CAD, and this threshold might be 70 mg/dl for primary composite outcomes.Trial Registration: http://www.Clinicaltrials: gov . Unique identifier: NCT01042730. [ABSTRACT FROM AUTHOR]

This study aimed to describe updated information on the basic reproductive biology of Sphoeroides annulatus females and potential use of the gonadosomatic index IG as input data to assess length at 50% maturity (L50) and identify the breeding season. From April 2014 to December 2015, 767 females were analysed along the north‐west coast of the Mexican Pacific Ocean. Both immature and mature females were represented in the total length (LT), which ranged from 81 to 440 mm, and the smallest mature female was 92 mm (new record for the species). Gonadal maturity phases were assigned through histological analysis. A IG threshold value Icut was established using the lower whisker value for maturity phase spawning capable (2.06%). The monthly variation of IG supported the annual spawning seasonality, and the presence of reproductively active mature females IG≥Icut coincided with the observed periods with histological data and the peaks for both seasons 2014 and 2015. Also the presence of reproductively inactive IG

The study assesses the extent of nitrate pollution in the Densu Basin, because of its predominance in agriculture and urbanized vicinities, by employing robust techniques to estimate both the natural background and human-induced concentrations. Statistical methods used are the pre-selection method, graphical approach (probability plot), non-parametric approach (kernel density estimation), and parametric approach (Gaussian mixture model). The study shows that the Gaussian mixture model is robust enough in determining the spectral distribution and clustering of the NO3-N concentration in the basin. It estimated the natural background and human-induced concentration at 1.7 ± 1.3 and 9.8 ± 5.6 mg/L, respectively. The results show that the natural background concentration in the basin is more dominant and, hence, conducive for drinking. We found a 26% contribution from anthropogenic sources that had leaked into the natural groundwaters of the Basin. The data suggest multiple sources of NO3-N concentration in the groundwater. [ABSTRACT FROM AUTHOR]

Soil and water conservation rate is one of the evaluation indicators for building beautiful China. The soil and water conservation rates in 2006, 2011 and 2019 in the Huangfuchuan Basin were calculated based on the results of dynamic monitoring of soil and water loss in different periods and Classification and Grading Standards for Soil Erosion as well as Soil Erosion Equation in China, etc. All the circumstances were used to ascertain the threshold value of soil and water conservation rate in the Huangfuchuan River Basin in the sandy and coarse sandy area of the middle reaches of the Yellow River as well as to provide references to other tributaries on aspects of the determination of the threshold value of soil and water conservation rate and the precise control of soil and water loss in the Yellow River Basin. The current situation of soil and water loss and the difficulty of governance, natural geographical conditions, economic and social development status and eco-logical construction requirements for soil and water conservation were comprehensively considered. Retention thresholds were predicted through the studies which showed possible existences of soil erosion for a long time in the basin and the upper limit of the area with good soil and water conservation status under the premise of the year of 2019 was taken as the current base year and 2050 as the long-term target year. From 2006 to 2019, the results show that there is a "double decline" trend on the area and intensity of soil erosion in Huangfuchuan Basin. Not only the area of soil and water loss is decreased from 2 778.99 km² to 1 598.98 km², but also the area of severe and extremely strong soil erosion is decreased obviously while the area of mild soil erosion is increased distinctly. The soil and water conservation rates in 2006, 2011 and 2019 are 14.39%, 15.84% and 50.74% respectively and the threshold for the soil and water conservation rate in 2050 will be 71.39%. The area of needless treatment of soil and water loss in the Huangfuchuan Basin is 2.61 km². The completely area of soil erosion under control is 926.06 km². And the long-term soil erosion area will be 928.67 km². In order to achieve the long-term goal of soil and water conservation, the area of soil erosion should be reduced by 670.31 km² through means of prevention and control. [ABSTRACT FROM AUTHOR]

Detecting cognitive impairment in Parkinson's disease (PD) is challenging due to diverse manifestations and outdated diagnostic criteria. Cognitive screening tools, as Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA), are adopted worldwide, but despite several cutoffs has been proposed for PD, no consensus has been reached, hindered by limited sample sizes, lack of validation, and inconsistent age- and education-adjustments. Determine the optimal MMSE and MoCA cutoffs in a large PD cohort, spanning from normal cognition (PD-NC), mild cognitive impairment (PD-MCI) to dementia (PDD), and develop a decision tree model to assist physicians in cognitive workups. Our retrospective Italian multicenter study involves 1780 PD, cognitively diagnosed with a level-II assessment: PD-NC(n = 700), PD-MCI(n = 706), and PDD(n = 374). Optimal cutoffs (for raw scores) were determined through ROC analysis. Then, a machine learning approach—decision trees—was adopted to validate and analyze the possible inclusion of other relevant clinical features. The decision tree model selected as primary feature a MMSE cutoff ≤24 to predict dementia, and a score ≤ 27 for PD-MCI. To enhance PD-MCIvs.PD-NC accuracy, it also recommends including a MoCA score ≤ 22 for PD-MCI, and > 22 for PD-NC. Age and education were not selected as relevant features for the cognitive workup. Both MoCA and MMSE cutoffs exhibited high sensitivity and specificity in detecting PD cognitive statues. For the first time, a clinical decision tree model based on robust MMSE and MoCA cutoffs has been developed, allowing to diagnose PD-MCI and/or PDD with a high accuracy and short administration time. • Our decision tree model combines MMSE and MoCA for robust PD level-I cognitive workup. • Age and education were not deemed relevant features by the decision tree algorithm. • A MMSE raw score ≤ 24 identifies dementia in PD with high accuracy and reliability. • A MoCA raw score ≤ 22 effectively distinguishes PD-MCI vs. PD with normal cognition. • Combining MMSE with PD-CFRS >10 enhances accuracy for ambiguous dementia cases in PD. [ABSTRACT FROM AUTHOR]

The concept of baseline is crucial for assessing natural water conditions and detecting anthropogenic influences in groundwater systems. This research proposes a methodology to define a geochemical baseline using the groundwater flow theory to develop a conceptual model, distinct from most methodologies that primarily rely on statistical techniques. The proposed methodology comprises three phases: defining a conceptual model, defining a geochemical baseline based on hydrogeochemical characterization, and identifying anthropogenic sources. This approach enhances understanding of hydrogeologic processes such as water-rock interactions, exchanges with other water bodies, redox conditions, and groundwater flow by integrating information about geology, structural geology, base level of discharge, hydrological connectivity, topography, and water table. The methodology was applied in the southern region of Mexico, specifically in the Comitán-Montebello lakes watershed characterized by complex features like the karst system and interactions with surface water bodies, providing relevant insights into the hydrogeological setting. It is a cost-effective approach that improves understanding of hydrogeological processes in data-scarce areas, thereby supporting the establishment of geochemical baselines. • Introduces a replicable methodology for establishing geochemical baselines in groundwater systems. • Provides insights into hydrogeological setting of a karst system that interacts with surface water bodies. • Establish geochemical baselines based on knowledge of geology, hydrogeology and anthropogenic activities. • Identify nitrate as the main anthropogenic indicator in the groundwater system associated with agricultural activities. [ABSTRACT FROM AUTHOR]

This study assessed the inhibitory and performance-degrading effects induced by the cationic surfactant benzalkonium chloride (BAC) on anaerobic granules during the long-term operation of a laboratory-scale expanded granular sludge bed (EGSB) reactor. To address the critical scientific problem of how BAC affects the efficiency of EGSB reactors, this research uniquely evaluated the long-term stress response to BAC by systematically comparing continuous and discontinuous inhibitor exposure scenarios. The novel comparison demonstrated that inhibitor concentration is of minor relevance compared to the biomass-specific cumulative inhibitor load in the reactor. After exceeding a critical biomass-specific cumulative inhibitor load of 6.1–6.5 mg BAC/g VS, continuous and discontinuous exposure to BAC caused comparable significant deterioration in reactor performance, including accumulation of volatile fatty acids (VFA), decreased removal efficiency, reduced methane production, as well as the wash-out, flotation, and disintegration of anaerobic granules. BAC exposures had a more detrimental effect on methanogenesis than on acidogenesis. Moreover, long-term stress by BAC led to an inhibition of protein production, resulting in a decreased protein-to-polysaccharide ratio of extracellular polymeric substances (EPS) that promoted destabilizing effects on the granules. Finally, hydrogenotrophic methanogenesis was triggered. Reactor performance could not be restored due to the severe loss of granular sludge. [Display omitted] • Inhibition of BAC on anaerobic granules and reactor performance were investigated. • Biomass-specific inhibitor load of 6.1–6.5 mg BAC/g VS resulted in reactor malfunctions. • Both exposure scenarios caused decreases in acetoclastic SMA by 85–88 %. • Decreased PN/PS due to disproportionate increase of PS under BAC exposure. • BAC shifted microbial community from acetotrophic to hydrogenotrophic methanogens. [ABSTRACT FROM AUTHOR]

Most of Kriging-based adaptive sampling approaches were focused only on the sequence architectures for producing limited (i.e., one or two) updating points, but few attention was given to the parallel sampling strategy to obtain multiple updating points in one iteration. In this study, a novel Kriging-based adaptive parallel sampling approach (KAPS-MEIGF) is proposed. This parallel sampling approach selects the first most informative update point by maximizing the expected improvement of global fit (EIGF) criterion that considers both the bias and variance information. Then the parallel sampling criterion with a threshold value is used to generate multiple potential sample points. Particularly, the cross-validation strategy is used to dynamically balance the global exploitation and local exploitation. The results of 18 test cases show that the proposed KAPS-MEIGF outperforms the EIGF sampling approach but it is worse than the maximum mean square error (MMSE) sampling approach and the combined expectation (CE) sampling approach for most of the 2-dimension test cases. However, for high-dimensional complex problems, KAPS-MEIGF exhibits significantly competing performance compared with the MMSE sampling approach and the CE sampling approach, which indicates the robustness of stability of KAPS-MEIGF. In addition, the running speed of KAPS-MEIGF is 2.8–30.9 times that of the MMSE sampling approach. Therefore, it is a very promising sampling approach to build Kriging models for the problems with diverse characteristics, especially for simulation-based high-dimensional problems. Finally, a multi-objective optimization of rotating impeller module with static cascade (RIM-SC) for rotary separated range hood illustrates the engineering application value of KAPS-MEIGF method. The result shows that the searching efficiency of KAPS-MEIGF method is about 4.4 times higher when compared to other sequence sampling strategy. For the optimized RIM-SC, both separation efficiency and exhaust airflow rate at design condition are improved by 20.3% and 63.6%, respectively, and the impeller input power is decreases by 2.8%. [ABSTRACT FROM AUTHOR]

The temporal and spatial variation characteristics of threshold value, strength and frequency of extreme high temperature in summer (June to August)of Shanxi Province were calculated and counted by percentile method, and interpolated by the methods of Inverse Distance Weight, Kriging and Anu spline based on the data of daily the maximum temperature from 67 national meteorological observational stations in Shanxi Province from 1971 to 2020. On this base, the comprehensive strength of extreme high temperature was evaluated. The study further analyzed the long term trend of the maximum temperature with the method of Theil Sen, and the mutation test of the maximum temperature was conducted by Mann Kendall test. The study results showed that the threshold values and strength of extreme high temperature were 29.4～37.7 oC and 30.2～38.4 oC respectively with an increase trend from north to south in summer of Shanxi Province from 1971 to 2020. In the past 50 years, frequency of extreme high temperature in summer was 5.8～8.0 d·a－1,which was higher in the southern Shanxi than that in the middle and north of Shanxi and that in the western Shanxi was higher than that in the eastern Shanxi. The comprehensive intensity of extreme high temperature before 1997 and around 2011 was weak, but the amplitude and extremity over⁃ all increased from 1997 to 2011 and from 2011 to 2020. The maximum temperature in most areas of Shanxi Province showed a significant increase trend, with an average rate of 0.3 oC·10 a－1 in summer during 1971－2020. The increase rate of the maximum temperature in the northern, middle and southern Shanxi were 0.3 oC·10 a－1, 0.3 oC·10 a－1 and 0.2 oC·10 a－1,respectively. The maximum temperature change abruptly in late 1990 s in the north and center of Shanxi, and the mutation occurred around the year of 2000 in southern Shanxi Province. The study results are of great significance to the prediction of extreme high temperature, impact assessment and the proposal of countermeasure in Shanxi Province, North China and the whole country in the future. [ABSTRACT FROM AUTHOR]

Brucellosis is one of the major infective and contagious bacterial diseases among animals in pastoral areas of some countries. In this paper, we introduce the effect of environment white noise in the spatial propagation process of brucellosis, and consider a stochastic two-patch brucellosis model. On one hand, we get existence and uniqueness of the global positive solution to the stochastic systems. On the other hand, by using the stochastic Lyapunov function theory we obtain a series of stochastic threshold dynamics results, incorporating extinction of the disease, existence of a unique ergodic stationary distribution of the positive solutions to systems in both patch 1 and patch 2. Furthermore, we find that stochastic perturbation is contribute to extinction of the disease to some extent by numerical simulations. [ABSTRACT FROM AUTHOR]

Some indicators for evaluating heavy metal pollution have been proposed. However, a threshold is lacking to judge if the heavy metal concentration has reached the extent that is harmful to plant health. In order to get the threshold, aerial hyperspectral images were obtained. The spatial patterns of six soil heavy metals (Cu, Zn, As, Sn, Cr and Cd) were obtained by establishing random forest inversion models. The normalized difference vegetation index (NDVI) under different soil heavy metal concentrations was analysed. Cu, Zn, As, Sn and Cr exhibited that low concentrations stimulated plant growth while high concentrations suppressed it. When the concentrations of Cu, Zn, As, Sn and Cr exceeded 19.960 mg/kg, 49.040 mg/kg, 14.049 mg/kg, 0.193 mg/kg and 89.799 mg/kg, respectively, heavy metals began to inhibit the growth of vegetation. The lower reaches of the river and the downwind area of the mining area were easily to exceed the threshold. [ABSTRACT FROM AUTHOR]

The sudden outbreak of SARS-CoV-2 has caused the shortage of medical resources around the world, especially in developing countries and underdeveloped regions. With the continuous increase in the duration of this disease, the control of migration of humans between regions or countries has to be relaxed. Based on this, we propose a two-patches mathematical model to simulate the transmission of SARS-CoV-2 among two-patches, asymptomatic infected humans and symptomatic infected humans, where a half-saturated detection rate function is also introduced to describe the effect of medical resources. By applying the methods of linearization and constructing a suitable Lyapunov function, the local and global stability of the disease-free equilibrium of this model without migration is obtained. Further, the existence of forward/backward bifurcation is analyzed, which is caused by the limited medical resources. This means that the elimination or prevalence of the disease no longer depends on the basic reproduction number but is closely related to the initial state of asymptomatic and symptomatic infected humans and the supply of medical resources. Finally, the global dynamics of the full model are discussed, and some numerical simulations are carried to explain the main results and the effects of migration and supply of medical resources on the transmission of disease. [ABSTRACT FROM AUTHOR]

We construct the existence theory for generalized fractional Bessel differential equations and find the solutions in the form of fractional or logarithmic fractional power series. We figure out the cases when the series solution is unique, non-unique, or does not exist. The uniqueness theorem in space Cp is proved for the corresponding initial value problem. We are concerned with the following homogeneous generalized fractional Bessel equation \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\sum\limits_{i = 1}^m {{d_i}{x^{{\alpha _i}}}} {D^{{\alpha _i}}}u\left(x \right) + \left({{x^\beta } - {v^2}} \right)u\left(x \right) = 0,\,{\alpha _i} >0,\,\beta >0,$$\end{document} which includes the standard fractional and classical Bessel equations as particular cases. Mostly, we consider fractional derivatives in Caputo sense and construct the theory for positive coefficients di. Our theory leads to a threshold admissible value for ν2, which perfectly fits to the known results. Our findings are supported by several numerical examples and counterexamples that justify the necessity of the imposed conditions. The key point in the investigation is forming proper fractional power series leading to an algebraic characteristic equation. Depending on its roots and their multiplicity/complexity, we find the system of linearly independent solutions. [ABSTRACT FROM AUTHOR]

This paper presents a new and mathematical method for online signature validation based on machine learning. In this way, the average values of the factors are taken into account to ensure validity. Here, seven different types of features used are x coordinates, y coordinates, time stamp, pen up and down, azimuth, height and pressure. Three new features are extracted from it, i.e., (displacement, velocity and acceleration) using the correlated extraction process to obtain dynamic feature of signature. These features are extracted from the popular dataset SVC2004. The extracted feature is then passed to various classifiers named as Naive Bayes, random forest, J48, MLP, logistic regression and PART. The result of genuine and forge signatures is obtained in terms of precision, true positive rate, false positive rate, F-score, etc. The obtained result is then compared with the existing method with respect to false acceptance rate and false rejection rate. [ABSTRACT FROM AUTHOR]

Bimagnetic α-Fe2O3/NiFe2O4 nanocomposite was synthesized via a simple and cost-effective approach, and the effect of the annealing temperature on the nanocomposite properties was discussed. Structural characterizations confirm the formation of α-Fe2O3/NiFe2O4 nanocomposite. Transmission electron microscope (TEM) characterization reveals the bimodal distribution of particles in the nanocomposites. Thermal annealing favours for the improvement of phase fraction along with the structural phase transformation of NiFe2O4 phase. Existence of percolation threshold phase fraction of NiFe2O4 in the composite sample could be responsible for the enhancement of optical band gap and magnetization. Beyond the percolation phase fraction, the magnetization decreased along with the coercivity and exchange bias. The appearance of enhanced optical property, single domain structure, ferromagnetic behaviour and high-energy product suggests the usefulness of the sample for photocatalyst, magnetic sensor and magnetic refrigerator applications. [ABSTRACT FROM AUTHOR]

We propose a nonsmooth Filippov refuge ecosystem with a piecewise saturating response function and analyze its dynamics. We first investigate some key elements to our model which include the sliding segment, the sliding mode dynamics and the existence of equilibria which are classified into regular/virtual equilibrium, pseudo-equilibrium, boundary equilibrium and tangent point. In particular, we consider how the existence of the regular equilibrium and the pseudo-equilibrium are related. Then we study the stability of the standard periodic solution (limit cycle), the sliding periodic solutions (grazing or touching cycle) and the dynamics of the pseudo equilibrium, using quantitative analysis techniques related to nonsmooth Filippov systems. Furthermore, as the threshold value is varied, the model exhibits several complex bifurcations which are classified into equilibria, sliding mode, local sliding (boundary node and focus) and global bifurcations (grazing or touching). In conclusion, we discuss the importance of the refuge strategy in a biological setting. [ABSTRACT FROM AUTHOR]

Various indices, notably rock quality designation (RQD), weighted joint density (WJD), and block quality designation (BQD) have been introduced by researchers to survey joints in boreholes, each with its own advantages and disadvantages. The idea of combining WJD and BQD to use positive features of both formed the main goal of the current study, leading to the definition of an improved BQD (B Q D I). After joint surveys of cores drilled in Kulikosh Marble Quarry, Iran, linear regressions validated by statistical tests showed that BQD is less dependent on the drilling direction than the RQD. An empirical equation was also obtained as B Q D I = 0.95 B Q D O , with the help of which one can estimate the value of B Q D I by measuring the original BQD (B Q D O). Taking into account the joint orientations, B Q D I is logically closer to reality whereby mining engineers can assess block productivity of stone quarries more accurately. [ABSTRACT FROM AUTHOR]

The goals of this study were to determine the concentrations of Cu in the soil of olive orchards grown on the Terra rossa and to examine how close the Cu concentration is to contamination limits defined by different soil quality standards. A total of 40 composite topsoil (0–25 cm) samples were collected in the traditional dry farming and highly fragmented olive orchards that covered an area of 3200 ha and located in the Middle Dalmatia, Croatia. The aqua regia Cu concentration was determined by ICP-OES; and basic soil properties (pH, carbonates, SOC, and particle size distribution), by standard analytical procedures. The mean value of Cu concentration of 68.4 mg kg–1 was more than twice as high as the mean values of the naturally occurring concentration of Cu in the Terra rossa soil. High mean value and a wide range of copper in the soil (33.8–250 mg kg–1) are due to the long-lasting application of Cu-based fungicides related to the fact that the olive growing area and vines overlap. The Cu contamination risk assessment in olive orchards was calculated by comparing the detected concentrations of Cu with the soil quality standards prescribed by the Finnish Decree and Croatian Ordinance and using the threshold value of the regional background data on Cu concentration in Terra rossa soil. According to the Finnish Decree, in 7.5% of cases, Cu concentration in soils exceeded the threshold limit of 100 mg kg–1, which indicates the need for further assessment of the potential contamination of the area. In 7.5% of cases, Cu exceeded the critical limit of 150 mg kg–1 that presents an ecological risk. By applying the Croatian Ordinance, in 10% of cases, the concentration of Cu exceeded the maximum admissible concentration of 120 mg kg–1, so that the soil can be considered contaminated and unsuitable for agriculture. The regional threshold value for the background concentration of Cu in the Terra rossa soil amounted to 55 mg kg–1, and its use in 47.5% of cases indicates the need for further assessment of the potential contamination in the area. The presented results showed significant differences between national soil guideline values (SGVs) and the regional threshold value for Cu and confirmed the fact that there is no general and accurate reference method for soil contamination assessment that can be applied at all sites. The use of threshold values derived for a particular soil type that dominates in a given area would be more reliable than the national soil quality standards. Research has pointed to the problem of soil contamination with Cu under olive orchards and has highlighted the need for studying the given issue in the areas, where olives share space with vines, and in particular, where mixed or consociate cropping system is present. [ABSTRACT FROM AUTHOR]

[Objective] In this paper, the Dosage-Response Relationship of Simulated Acid Rain (SAR) on plants was investigated and fitting analysis method was used to analyze the toxicity threshold of SAR stress on plants. The study could provide a theoretical basis for screening plants suitable in acid rain area. [ Method ] This study investigated the sensitivity of plant species to SAR based on the modeled Dosage-Re sponse Relationship on the total chlorophyll content (Chi) of 26 types of plant species, subjected to 50 days exposure to SAR. Model fitting allowed quantitative evaluation of the Dosage-Response Relationship and an accurate estimation of the EClO, termed as the pH of the SAR re sulting in a Chi 10% lower than the reference value to obtain the toxicity threshold of the Chi of these 26 plants under SAR stress. [Result] The response of Chi in leaves of different plants to SAR was significantly different. These Dosage-Response Relationships were promotion type, non-affection type, low promotion-high inhibition type and inhibition type. Based on the fitting calculation of the Dosage-Response Relationship, the toxicity threshold of the Chi of 26 plants affected by SAR stress was obtained. [ Conclusion] ( i ) The Chi of plant leaves could effectively characterize the Dosage-Response Relationship of SAR on plants. ( ii ) The effect of SAR on the Chi of plant leaves had a dual effect of promotion and inhibition, which meaned that the toxic effect of acid rain coexists with the effect of fenilization. ( iii) Threshold value of Viburnum odoratissimum Ker-Gaw!., Musa basjoo Sieb. & Zucc. and Gnetum montanum Markgr. was pH< 2. 0. The cultivation of these plants could effectively protect the urban environment and maintain the ecological balance in acid rain area of Southwest China. [ABSTRACT FROM AUTHOR]

In this paper, we extend the state equations for the stock of unskilled and skilled workers by introducing internal training and study the dynamics of the number of skilled workers at the firm level. A threshold (R0) is defined, which can be used to judge whether skilled workers continue to exist. However, R0 is difficult to explicitly calculate because of its abstract form in infinite‐dimensional spaces. Therefore, a numerical approximation method to calculate R0 is provided. The factors affecting R0 are discussed through numerical examples. Based on the calculation results, we provide some suggestions for hiring/firing and training strategies in firms. [ABSTRACT FROM AUTHOR]

A fault is an error that has effects on system behaviour. A software metric is a value that represents the degree to which software processes work properly and where faults are more probable to occur. In this research, we study the effects of removing redundancy and log transformation based on threshold values for identifying faults-prone classes of software. The study also contains a comparison of the metric values of an original dataset with those after removing redundancy and log transformation. E-learning and system dataset were taken as case studies. The fault ratio ranged from 1%-31% and 0%-10% for the original dataset and 1%-10% and 0%-4% after removing redundancy and log transformation, respectively. These results impacted directly the number of classes detected, which ranged between 1-20 and 1-7 for the original dataset and 1-7 and 0-3) after removing redundancy and log transformation. The Skewness of the dataset was deceased after applying the proposed model. The classified faulty classes need more attention in the next versions in order to reduce the ratio of faults or to do refactoring to increase the quality and performance of the current version of the software. [ABSTRACT FROM AUTHOR]

In this paper, we study a more general diffusive spatially dependent vaccination model for infectious disease. In our diffusive vaccination model, we consider both therapeutic impact and nonlinear incidence rate. Also, in this model, the number of compartments of susceptible, vaccinated and infectious individuals are considered to be functions of both time and location, where the set of locations (equivalently, spatial habitats) is a subset of R n with a smooth boundary. Both local and global stability of the model are studied. Our study shows that if the threshold level R 0 ≤ 1 , the disease-free equilibrium E 0 is globally asymptotically stable. On the other hand, if R 0 > 1 then there exists a unique stable disease equilibrium E ∗ . The existence of solutions of the model and uniform persistence results are studied. Finally, using finite difference scheme, we present a number of numerical examples to verify our analytical results. Our results indicate that the global dynamics of the model are completely determined by the threshold value R 0 . [ABSTRACT FROM AUTHOR]