Threshold Research Articles

Psychometric properties of the Sinhala version of the Bandura’s exercise selfefficacy scale in women

Introduction: Engaging in regular exercise as part of a healthy lifestyle has shown an array of health benefits for many decades. Building confidence in maintaining an exercise routine is e ssential for success. To support individuals interested in exercise, the availability of appropriate measurement tools is vital. Bandura's Exercise Self-Efficacy Scale (ESE) is an 18-item brief measure that assesses confidence in exercising regularly and is a valuable tool for measuring exercise beliefs. Objectives: To translate and adapt the Banduras ESE scale into Sinhala language and examine its psychometric properties Methods: Data were collected from 225 women who were aged ≥ 18 years and had an interest in or a reason to watch their weight, in Panadura Medical Officer Health (MOH) Area, Sri Lanka. They were recruited using a purposive sampling method. Standard forward-backward translation was performed to translate the English version of ESE. The construct validity was tested using exploratory factor analysis. Reliability of the scale was determined by Cronbach’s alpha. Data were analysed using SPSS version 22.0. Results: Through exploratory factor analysis, 18-item ESE scale sho wed three factors with eigenvalues ranging from 1.392 to 9.409. The three-factor model explained 70.59% of total variance of the model. All the items in the scale were retained. The reliability of internal consistency, as assessed by Cronbach’s alpha, indicated interpersonal, competing and internal sub factors as 0.92, 0.91 and 0.89 respectively, which were above the thr eshold level of 0.7. Conclusions & Recommendations: The Sinhala translation of ESE is a reliable and valid scale to assess the level of self-efficacy for exercise among Sinhala-speaking adult women in Sri Lanka.

Effects of 24-week Polarized Training vs. Threshold Training in Obese Male Adults.

The combination of high volume of moderate-intensity continuous training with a low volume of high-intensity interval training improved body composition and physical capacities in individuals with obesity. However, polarized training (POL) has never been used in adult men with obesity. Thus, the purpose of this study was to investigate changes in body composition and physical capacities induced by a 24-week POL or threshold (THR) program in obese male adults. Twenty male patients (mean age 39.8±6.3 yrs; mean body mass index [BMI] 31.6±2.7 kg∙m-2) participated in this study (n: 10 POL, n: 10 THR). After 24-week, body mass (BM) and fat mass (FM) decreased by -3.20±3.10 kg (P<0.05) and -3.80±2.80 kg (P<0.05), respectively, similarly in both groups. Maximal oxygen uptake ( ̇VO2max) and ̇VO2 at respiratory compensation point (RCP) increased in the POL group (+8.5±12.2 and+9.0±17.0%, P<0.05) and in the THR group (+4.24±8.64 and+4.0±6.70%, P<0.05), as well ̇VO2 at gas exchange threshold (GET) increased similarly in both groups (+12.8±12.0%, P<0.05). POL and THR were equally effective in improving body composition and physical capacities in obese subjects. Future studies are needed to determine whether adherence to the training program can be improved by adding a running competition compared with a group without competition at the end of the training program.

Use of tritium in characterizing the leachate migration from a landfill – Central de tratamento de resíduos sólidos (CTRS) BR040 (Belo Horizonte, Minas Gerais, Brazil)

Landfills often become a source of environmental impact due to the percolation of the leachate (liquid resulting from the decomposition of buried waste), which can eventually disperse and contaminate the soil and water bodies. This study aimed to evaluate quantitatively and spatially the leachate plume from the former Belo Horizonte landfill in the Coqueiros and Taiobas watersheds by using tritium (3H) concentration in nineteen (19) sampling points: 14 groundwater, 4 surface water and 1 leachate. Among the methodologies applied to determine the 3H content in the leachate, pre-filtration proved to be the most effective due to the ease treating of the sample, as well as the identical results obtained compared to the traditional method. The 3H contents resulted in concentrations up to thirty times higher in the leachate (=96,19 to 111,87 TU) and ten times in groundwater (PM23/3 = 45,06 TU), compared to the calculated threshold (TS) of rainfall tritium (TS_3Hrain = 3,41 TU). Temporal series results indicate no trend and no influence of seasonality regarding the entry of pluvial tritium, leachate liquid level and wells water level. The 3H contour maps shows a transport of the mixture (water and leachate) towards the Coqueiros stream, with a higher concentration of leachate in wells closer to the landfill slope (PM13, PM14, PM15, and PM23) and in the southwest margin of the Coqueiros stream (PM17). In the furthest portion of the landfill, 3H levels are higher than the base threshold only at the deepest level of PM20 (=3,90 TU), possibly due to factors such as: i) denser character of the leachate compared to groundwater; ii) greater influence of recharge for regions further away from the landfill slope; and iii) the presence of the rock about 50 m from the surface. Based on the hydrogeological conceptual model, the transport of the leachate water mixture in the groundwater water compartment of the Coqueiros watershed basin seems to follow a piston or dispersion flow, with a small Peclet number (Pd = 0,05, as an example), as indicated by the high correlation coefficient values (R2 ≈ 0,85 to 0,99) from graphic interpolation. The mixture of water and leachate results in a transient time (tt) ≈ 30 years and linear velocity (Vl) ≈ 3–14 m/year in the interpolated sections. These indicate a coherent correlation with the mean hydraulic conductivity (K ≈ 29,34 m/year), as they result in effective porosity values between (Ne) ≈ 0.16 to 0.36, which corresponds to Ne range for unconsolidated sediments, similar to the wells lithotype profiles. Time series evaluation combined with lumped parameter approach suggest to be an interesting way to better understanding the HCM, and, therefore, to determine hydrodynamic parameters using tritium as a tracer.

Association between cognitive impairment and olfactory deficits in systemic lupus erythematosus without major neuropsychiatric syndromes.

The aim of the study was to investigate the utility of the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), evaluate cognitive deficits in systemic lupus erythematosus (SLE) patients and examine the relationship between cognitive and olfactory functions. 55 SLE patients and 50 healthy controls were administered by RBANS including five indexes: immediate memory (IMME), visuospatial/constructional (Vis/Con), language (LANG), attention (ATT), and delayed memory (DEME). Olfactory functions were evaluated by computerized testing including three stages of smell: threshold (THR), identification (ID), and memory (ME) of different odors. The disease activity and cumulative damage were assessed by the SLE Disease Activity Index 2000 (SLEDAI-2K) and the Systemic Lupus International Collaborating Clinics (SLICC)/American College of Rheumatology (ACR) Damage Index (SDI). SLE patients exhibited significant lower total RBANS scores, IMME, Vis/Con, ATT, and DEME index scores than healthy controls (p < 0.01 for all and p = 0.027 for attention). Reduced RBANS scores were associated with several organ involvement and autoantibodies. SLE patients with higher SLEDAI-2K scores or with accumulated damage (SDI≥1) showed decreased RBANS scores. All the olfactory scores in SLE patients were significantly decreased than controls (p = 0.001). Patients had higher proportion of anosmia (8.57% vs 0%) and hyposmia (28.58% vs 5.72%) than controls (χ2 = 10.533, p = 0.015). Multivariable regression analysis revealed that olfactory functions had a positive effect on RBANS index scores. Olfactory memory and total scores were significantly correlated with the DEME (r = 0.393, p = 0.021) and total scores (r = 0.429, p = 0.011). This study indicates that significantly cognitive and olfactory functions are impaired in SLE patients. The RBANS is a potentially useful instrument for evaluating neuropsychological status in SLE. Physicians are encouraged to perform routine screening in SLE patients to detect subtle cognitive dysfunction.

Increased nonstationarity of stormflow threshold behaviors in a forested watershed due to abrupt earthquake disturbance

Abstract. Extreme earthquake disturbances to the vegetation of local and regional landscapes could swiftly impair the former hydrologic function, significantly increasing the challenge of predicting threshold behaviors of rainfall–runoff processes as well as the hydrologic system's complexity over time. It is still unclear how alternating catchment hydrologic behaviors under an ongoing large earthquake disruption are mediated by long-term interactions between landslides and vegetation evolution. In a well-known watershed affected by the Wenchuan earthquake, the nonlinear hydrologic behavior is examined using two thresholds with intervening linear segments. A lower rising threshold (THr) value (210.48 mm) observed in post-earthquake local landslide regions exhibited a faster stormflow response rate than that in undisturbed forest and grassland–shrubland regions, easily triggering huge flash-flood disasters. Additionally, an integrated response metric pair (integrated watershed average generation threshold THg−IWA and rising threshold THr−IWA) with areas of disparate land use, ecology, and physiography was proposed and efficiently applied to identify emergent catchment hydrologic behaviors. The interannual variation in the two integrated hydrologic thresholds before and following the earthquake was assessed to detect the temporal nonstationarity in hydrologic extremes and nonlinear runoff response. The year 2011 was an important turning point along the hydrologic disturbance–recovery timescale following the earthquake, as post-earthquake landslide evolution reached a state of extreme heterogeneity in space. At that time, the THr−IWA value decreased by ∼ 9 mm compared with the pre-earthquake level. This is closely related to the fast expansion of landslides, leading to a larger extension of variable source area from the channel to neighboring hillslopes, and faster subsurface stormflow, contributing to flash floods. Finally, we present a conceptual model interpreting how the short- and long-term interactions between earthquake-induced landslides and vegetation affect flood hydrographs at event timescale that generated an increased nonstationary hydrologic behavior. This study expands our current knowledge of threshold-based hydrologic and nonstationary stormflow behaviors in response to abrupt earthquake disturbance for the prediction of future flood regimes.

Analysis of Artifactual Components Rejection Threshold towards Enhanced Characterization of Neural Activity in Post-Stroke Survivor.

Research advancement has spurred the usage of electroencephalography (EEG)-based neural oscillatory rhythms as a biomarker to complement clinical rehabilitation strategies for the recovery of motor functions in stroke survivors. However, the inevitable contamination of EEG signals with artifacts from various sources limits its utilization and effectiveness. Thus, the integration of Independent Component Analysis (ICA) and Independent Component Label (ICLabel) has been widely employed to separate neural activity from artifacts. A crucial step in the ICLabel preprocessing pipeline is the artifactual ICs rejection threshold (TH) parameter, which determines the overall signal's quality. For instance, selecting a high TH will cause many ICs to be rejected, thereby leading to signal over-cleaning, and choosing a low TH may result in under-cleaning of the signal. Toward determining the optimal TH parameter, this study investigates the effect of six different TH groups (NO-TH and TH1-TH6) on EEG signals recorded from post-stroke patients who performed four distinct motor imagery (MI) tasks including wrist and grasping movements. Utilizing the EEG-beta band signal at the brain's sensorimotor cortex, the performance of the TH groups was evaluated using three notable EEG quantifiers. Overall, the obtained result shows that the considered THs will significantly alter neural oscillatory patterns. Comparing the performance of the TH-groups, TH-3 with a confidence level of 60% showed consistently stronger signal desynchronization and lateralization. The correlation result shows that most of the electrode pairs with high correlation values are replicable across all the MI tasks. It also revealed that brain activity correlates linearly with distance, and a strong correlation between electrode pairs is independent of the different brain cortices. The study outcome may facilitate adequate therapeutic intervention for stroke rehab.Clinical Relevance: This study indicated that optimal selection of the ICLabel artifactual rejection threshold is essential for EEG enhancement for adequate signal characterization. Thus, a TH-values with a confidence level between 50% - 70% would be suggested for artifactual ICs rejection in MI-EEG.

Unraveling the mystery of isocaloric endurance training - Influence of exercise modality, biological sex, and physical fitness

BackgroundA sedentary lifestyle with low energy expenditure (EE) is associated with chronic diseases and mortality. Barriers such as “lack of time” or “lack of motivation” are common reasons why physical exercise is neglected in the general population. To optimize EE in the time available, time-efficient but also enjoyable types of exercise are required. We therefore used an isocaloric approach to systematically investigate the effects of six different endurance exercise modalities on metabolic, mechanical, cardiorespiratory, and subjective variables in relation to biological sex and physical fitness. MethodsOut of 104, 92 healthy participants (21 recreationally trained and 18 trained females, 25 recreationally trained and 28 trained males) were subjected to physiological exercise testing to determine the exercise intensities for six exercise modalities, i.e., three different high-intensity interval training (HIIT) protocols (5 × 4 min, 15 × 1 min, 30 × 30 sec intervals), threshold (THR), speed endurance production (SEP), and low-intensity continuous endurance training (LIT). One of three HIIT sessions served as the reference for the subsequent isocaloric exercise modalities which were completed in randomized order. Metabolic and mechanical variables, i.e., EE during exercise, time to isocaloric EE (Tiso), relative and absolute fat contribution, post-exercise oxygen consumption (EPOC), mechanical energy, as well as cardiorespiratory and subjective variables, i.e., heart rate, oxygen uptake response, rating of perceived exertion, and enjoyment were assessed. Data were analyzed using a 6 × 2 × 2 repeated-measures ANOVA. ResultsAll three versions of HIIT and THR achieved the same EE during exercise for the same training duration. We found that LIT had a 1.6-fold (p < 0.001) and SEP a 1.3-fold (p < 0.001) longer Tiso compared to HIIT with no effects of biological sex (p = 0.42, pη2 = 0.01) or physical fitness (p = 0.09, pη2 = 0.04). There was a main effect of exercise modality on EPOC (p < 0.001, pη2 = 0.76) with highest values for HIIT 30 × 30 (p = 0.032) and lowest for LIT (p < 0.001). The highest relative and absolute amounts of fatty acids were measured during LIT (p < 0.001), and the lowest values were obtained during HIIT modalities. HIIT 30 × 30 was the most enjoyable version of HIIT (p = 0.007), while THR was the least enjoyable exercise modality (p = 0.008). ConclusionHIIT modalities are time-saving and enjoyable, regardless of sex and physical fitness. The results illustrate the relationship between exercise modality and metabolic, physiological, and subjective responses, and are thus of great interest to healthy individuals seeking time-saving and enjoyable exercise options.

Development of a quasi-humanoid phantom to perform dosimetric and radiobiological measurements for out-of-field doses from external beam radiation therapy.

Our understanding of low dose, out‐of‐field radiation and their radiobiological effects are limited, in part due to the rapid technological advances in external beam radiotherapy, especially for non‐coplanar and dynamic techniques. Reliable comparisons of out‐of‐field doses produced by advanced radiotherapy techniques are difficult due to the limitations of commercially available phantoms. There is a clear need for a functional phantom to accurately measure the dosimetric and radiobiological characteristics of out‐of‐field doses, which would in turn allow clinicians and medical physicists to optimize treatment parameters. We designed, manufactured, and tested the performance of a quasi‐humanoid (Q‐H) adult phantom. To test the physics parameters, we used computed tomography (CT) scans of assembled Q‐H phantom. Static open field and dynamic techniques were measured both in‐ and out‐of‐field with ionization chambers and radiochromic films for two configurations (full solid and with water‐filled containers). In the areas simulating soft tissues, lung, and bones, median Hounsfield units and densities were, respectively: 129.8, ‐738.7, 920.8 HU and 1.110, 0.215, 1.669 g/cm3. Comparison of the measured to treatment planning systems (TPS) in‐field dose values for the sample volumetric arc therapy (VMAT) (6 MV flattening filter‐free (FFF)) plan, 96.4% of analyzed points passed the gamma evaluation criteria (L2%/2 mm, threshold (TH) 10%) and less than 1.50% for point dose verification. In the two phantom configurations: full poly(methyl) methacrylate (PMMA) and with water container, the off‐axis median doses for open field, relative to the central axis of the beam (CAX) were similar, respectively: 0.900% versus 0.907% (15 cm distance to CAX); 0.096% versus 0.120% (35 cm); 0.018% versus 0.018% (52 cm); 0.009% versus 0.008% (74 cm). For VMAT 6 MV FFF, doses relative the CAX were, respectively: 0.667% (15 cm), 0.062% (35 cm), 0.019% (52 cm), 0.016% (74 cm). The Q‐H phantom meets the International Commission on Radiation Units and Measurements (ICRU) and American Association of Physicists in Medicine (AAPM) recommended phantom criteria, providing medical physicists with a reliable, comprehensive system to perform dose calculation and measurements and to assess the impact on radiobiological response and on the risk of secondary tumor induction.

Determination of the air void content of asphalt concrete mixtures using artificial intelligence techniques to segment micro-CT images

ABSTRACT X-ray micro-computed tomography (micro-CT) is an advanced technique able to provide a comprehensive examination of the volumetric characteristics of asphalt mixtures. A key step for the air void (AV) quantification using micro-CT images is the segmentation, which is a stage of the digital image processing. The most common segmentation technique, the manual threshold (TH) selection, depends significantly on the operator skills, image homogeneity, and material complexity. These factors that can limit the reproducibility of the TH procedure. Machine learning and deep learning recently appeared as promising alternatives to solve this challenge. In this paper, images of an asphalt concrete (AC) specimen were acquired in a modern high-resolution micro-CT scanner to determine its AV content using four different segmentation tools, i.e. TH, watershed, machine learning, and deep learning. All methods presented similar results for the total AV content. The advantages and limitations of using each technique were discussed in terms of computational effort, user-friendliness, and accuracy of the results. Machine learning and deep learning were identified as powerful tools for AC segmentation, being accurate and easy to adjust, however taking longer data processing times.

Energy efficient virtual machine migration approach with SLA conservation in cloud computing

In the age of online workload explosion, cloud users are increasing exponentialy. Therefore, large scale data centers are required in cloud environment that leads to high energy consumption. Hence, optimal resource utilization is essential to improve energy efficiency of cloud data center. Although, most of the existing literature focuses on virtual machine (VM) consolidation for increasing energy efficiency at the cost of service level agreement degradation. In order to improve the existing approaches, load aware three-gear THReshold (LATHR) as well as modified best fit decreasing (MBFD) algorithm is proposed for minimizing total energy consumption while improving the quality of service in terms of SLA. It offers promising results under dynamic workload and variable number of VMs (1–290) allocated on individual host. The outcomes of the proposed work are measured in terms of SLA, energy consumption, instruction energy ratio (IER) and the number of migrations against the varied numbers of VMs. From experimental results it has been concluded that the proposed technique reduced the SLA violations (55%, 26% and 39%) and energy consumption (17%, 12% and 6%) as compared to median absolute deviation (MAD), inter quartile range (IQR) and double threshold (THR) overload detection policies, respectively.

A protocol for absolute dose verification of SBRT/SRS treatment plans using Gafchromic™ EBT-XD films.

To provide a practical protocol for absolute dose verification of stereotactic body radiotherapy (SBRT) and stereotactic radiosurgery (SRS) treatment plans, based on our clinical experience. It aims to be a concise summary of the main aspects to be considered when establishing an accurate film dosimetry system. Procedures for film calibration and conversion to dose are described for a dosimetry system composed of Gafchromic™ EBT-XD films and a flatbed document scanner. Factors that affect the film-scanner response are also reviewed and accounted for. The accuracy of the proposed methodology was assessed by taking a set of strips irradiated to known doses and its applicability is illustrated for ten SBRT/SRS treatment plans. The film response was converted to dose using red and triple channel dosimetry. The agreement between the planned and measured dose distributions was evaluated using global gamma analysis with criteria of 3%/2mm 10% threshold (TH), 2%/2mm 10% TH, and 2%/2mm 20% TH. The differences between the expected and determined doses from the strips analysis were 0.9±0.6% for the red channel and 1.1±0.7% for the triple channel method. Regarding the SBRT/SRS plans verification, the mean gamma passing rates were 99.5±1.0% vs 99.6±1.0% (3%/2mm 10% TH), 96.9±3.5% vs 99.1±1.3% (2%/2mm 10% TH) and 98.4±1.8% vs 98.8±1.5% (2%/2mm 20% TH) for red and triple channel dosimetry, respectively. The proposed protocol allows for accurate absolute dose verification of SBRT/SRS treatment plans, applying both single and triple channel methods. It may work as a guide for users that intend to implement a film dosimetry system.

Non-targeted metabolomics analyses by mass spectrometry to explore metabolic stress after six training weeks in high level swimmers.

ABSTRACT The objective was to compare the metabolic responses of high-level national swimmers to threshold or polarised training. 22 swimmers (n = 12 males and 10 females) participated in a 28-week cross-over intervention study consisting of 2 × 6 period weeks of training. Swimmers were assigned randomly to either training group for the first period: polarised (POL) (81% in energetic zone 1: blood lactate [La]b ≤ 2 mmol.L−1; 4% in zone 2: 2 mmol.L−1 <[La]b ≤ 4 mmol.L−1; 15% in zone 3: [La]b > 4 mmol.L−1) or threshold (THR) (65%/25%/10%). Before and after each training period, urine samples were collected for non-targeted metabolomics analysis. Mixed model analysis was performed on metabolomics data including fatigue class factors and/or training and/or interaction. Ion intensities of 6-keto-decanoylcarnitine (+31%), pregnanediol-3-glucuronide (+81%), P-cresol sulphate (+18%) were higher in the threshold group (P < 0.05) indicating higher glycogenic depletion and inflammation without alteration of the neuroendocrine stress axis. 4-phenylbutanic acid sulphate was 200% higher in less fatigued swimmers (P < 0.01) linking the anti-inflammatory activity at the cell membrane level to the subjective perception of fatigue. This research suggests the importance of replenishing glycogen stores and reducing inflammation during high thresholds training loads.

Growth threshold-effect on renewable energy consumption in major oil-producing countries in sub-Saharan Africa: a dynamic panel threshold regression estimation

Purpose This study aims to explore the relationship between the growth threshold effect on renewable energy consumption (REC) in the major oil-producing countries in sub-Saharan Africa (SSA) over the period 1990–2018. Design/methodology/approach This article used a dynamic panel threshold regression model introduced by Hansen (1996, 1999 and 2000) threshold (TR) models. The procedure is achieved using 5,000 bootstrapping replications and the grid search to obtain the asymptotic distribution and p-values. For the long-run relationship among our variables, the author followed the process in Pesaran et al. (1999) pooled mean group (PMG) for heterogeneous panels. Furthermore, for the robustness of our empirical results due to the sensitivity of the results to outliers, the author used the approach by Cook (1979) distance measure. The author applied quantile (QR) regression to explore the distribution of dependent variables following Bassett and Koenker (1982) and Koenker and Bassett (1978) approaches. Findings The results from the threshold effect test and threshold regression revealed a significant single threshold effect of growth level on REC. Furthermore, the result from the PMG estimation showed the growth of the variable, energy intensity, consumer prices and CO2 emissions play a significant role in REC in major oil-producing countries in SSA. The growth threshold estimation results indicated one significant threshold value of 1.013% at one period lagged of real growth. The outlier’s sensitivity detention greatly influenced our empirical results. Originality/value The article filled the literature gap by applying a combined measure that is robustness to detect outliers in the data, which none of the studies in the literature addresses hitherto. Further, the article extends the quantile regression to growth – REC literature.

A clustering based ensemble of weighted kernelized extreme learning machine for class imbalance learning

Most of the classification problems in real word suffer from the problem of class skewness. Various methods are required to handle the classification of problems having class skewness. Several methods have been proposed for this purpose which includes some ensemble methods. Most of such ensemble methods targets on creating balanced sub-problems like UnderBagging based kernelized Extreme Learning Machine (UBKELM), UnderBagging based Reduced Kernel Extreme Learning Machine (UBRKELM), Random Undersampling Boost (RUSBoost), EasyEnsemble and BalanceCascade. This work suggests that apart from class skewness, there are many other factors like class overlapping, length of decision boundary and the number of probability distributions present in the problem which are responsible for performance degradation of a classifier. This work proposes an ensemble method which decomposes a complex imbalanced problem into simpler sub-problems, solves these sub-problems using cost sensitive classifiers and then combines the results of each classifier using voting methods. A classification problem can have mixture distribution, the complexity of the problem increases with increase in the number of probability distributions present in it. The proposed problem decomposition method try to create less complex sub-problems by decreasing the number of distributions present in the sub-problems than the original problem. The proposed method uses a clustering evaluation algorithm to find the optimal number of sub-problems. For decomposing an imbalanced classification problem into sub-problems this work uses fuzzy clustering algorithm (FCM) which is a soft clustering algorithm, i.e. the overlapping between the sub-problems depends on the selected value of threshold (TH) parameter in the FCM algorithm. The sub-problems created in this work may or may not be balanced, so Weighted Kernelized Extreme Learning Machine (WKELM) is used to create the classifiers for these sub-problems. The final prediction of the ensemble of these classifiers is determined using soft voting and majority voting. The proposed method is evaluated on 38 benchmark binary class imbalanced datasets downloaded from KEEL dataset repository. The obtained results show that the proposed method outperforms other state of the art methods of imbalance classification. The Wilcoxon signed rank test is performed to show the significant improvement in results.

Effect of sand burial on the subcritical water repellency of a dominant moss crust in a revegetated area of the Tengger Desert, Northern China

Abstract Sand burial is a ubiquitous disturbance that influences the ecological and hydrological properties of moss crusts in many sandy desert areas. There is little available information regarding the effect of sand burial on the water repellency (WR) of moss crusts in desert areas. Therefore, this study evaluated the effects of sand burial (sand depths of 0 (control), 0.5, 1, 2, 4 and 10 mm) followed by three simulated precipitation regimes (through applying 4 and 6 mm, 2 and 3 mm, and 1 and 1.5 mm of distilled water at 8-day intervals in spring and autumn, respectively) on the WR of a widespread moss crust dominated by Bryum argenteum Hedw. in a revegetated area of the Tengger Desert, China. The results showed moss crust WR remained subcritical during the whole experiment, and that it considerably decreased immediately after sand burial, even though the values of WR were significantly higher in autumn than those in spring under the same treatment (p &lt; 0.05). Furthermore, the depth threshold (TD) values for sand burials that reduced WR to zero were 1 and 2 mm in spring and autumn, respectively. After a recovery period of nearly one-season (72 days), the WR of the moss crust significantly increased (p &lt; 0.05). In addition, sand burial had two separate effects on moss crust WR. Specifically, shallower sand burial (burial depth less than 0.5 mm) increased moss crust WR, whereas deeper sand burial (burial depth exceeds 0.5 mm) decreased it. The TD values also significantly increased to 2 and 4 mm in spring and autumn, respectively. These findings about the effects of sand burial on moss crust WR provide additional information that can be used to better understand the influence of sand burial on moss crust colonization and maintenance in arid sand-burial-stressed ecosystems, and to help explain why there are some contrasting viewpoints on biocrust WR.

Assessment of toxicity of metals in river sediments for human supply: Distribution, evaluation of pollution and sources identification

Ten surface sediments collected from Joanes River, Bahia, Brazil in rainy and drought periods in 2019 were evaluated according to the enrichment factor (EF), potential ecological risk index (RI), potential contamination index (PCI), pollution load index (PLI), and index of geoaccumulation (Igeo). Initially the dry sediment was subjected to granulometric analysis and determination of the concentration of organic matter. Then, the samples were digested in HNO3 and analyzed by Inductively Coupled Plasma Optical Emission Spectrometry (ICP OES) to determine the metals cadmium (Cd), copper (Cu), chromium (Cr), nickel (Ni), lead (Pb) and zinc (Zn). Zn and Cu were classified in that order as the most contaminated elements in most sediment. Comparison of the total metal concentrations with the threshold (TELs) and probable (PELs) effect levels in sediment quality guidelines suggested a more worrisome situation for Zn (648.83–1415.90 μg g−1; PELZn = 315 μg g−1), of which concentrations were occasionally associated with adverse biological effects in four sediments, followed by Cu in five sediments during dry and rainy periods; while adverse effects were rarely associated with Cd, Cr, Ni, and Pb. In another evaluation, Cd, Cu, Cr, and Zn could be considered the most dangerous in the entire river, as they were classified in the high levels of contamination by the PCI, associated with serious adverse effects in most samples. In an assessment regarding the ecological risks in the study environment, the sediment samples remained below the limit established by the risk index (IR). The Zn presented moderately severe enrichment (6.78–11.83) in all the collection stations in the dry and rainy periods, followed by the Cd that presented moderate enrichment (2.23–4.17), whose values exceeded almost 1000 times the background at one site. Through the PCA it was possible to evidence the existing correlation between metals, organic matter, and silt and clay fraction. The results obtained in the PCA represented more than 80% of the variance between the data. The environmental risk assessment revealed a significant increase in the risk associated with metals during the rainy season. This is probably due to the greater supply of organic matter from the leaching of the margins.

Deep learning model to predict visual field in central 10° from optical coherence tomography measurement in glaucoma

Background/AimTo train and validate the prediction performance of the deep learning (DL) model to predict visual field (VF) in central 10° from spectral domain optical coherence tomography (SD-OCT).MethodsThis multicentre, cross-sectional...

High Spatial Resolution Digital Positron Emission Tomography Images With Dedicated Source-to-background Algorithm for Radiotherapy Planning.

To evaluate the utility of high spatial resolution digital positron emission tomography images with the source-to-background ratio (SBR) algorithm for gross tumour volume (GTV) delineation. The bowl and spheres (10-37 mm) were filled with fluoro-2-deoxy-D-glucose to achieve 4-16 times background radioactivity. The images were reconstructed using three isotropic voxel sizes. The SBR and percentage threshold (TH) to SUVmax were calculated. The plots between SBR and TH were fitted using a regression equation. The contoured volumes (CVs) of the spheres were calculated by applying TH. TH was 38.6+75.0/SBR for 4 mm voxel size; 39.6+37.0/SBR for 2 mm; and 38.8+35.2/SBR for 1 mm. The mean relative errors between CV and true volume for 4, 2, and 1 mm voxel sizes were 15%, 7%, and 7%, respectively. The present technique is useful for GTV delineation with reduced contouring error.

Relay selection schemes in threshold DF cooperative systems with wireless power transfer

In this work, a dual-hop cooperative wireless energy harvesting system, in which there are a Source-Destination (S−D) pair and several relay candidates is considered. all relay candidates adopt threshold decode-and-forward (DF) relaying scheme to decide whether to aid S−D pair information transmission or not. We assumed that these relay candidates and S are all equipped with single receiving antenna while D is equipped multiple receiving antenna and adopts generalized selection combining scheme to achieve receiving diversity gain. We also consider that relay candidates and S can harvest energy from D with finite energy storage capacity under time switching scheme. Three kinds of best relay selection (RS) schemes based threshold (TH) DF relay scheme, that is, the TH optimal source-relay link, the TH optimal relay-destination link, and the TH optimal source-relay-destination link, are proposed and studied. Closed-form analytical expressions for the outage probability over the three proposed RS schemes are derived and verified by Monte-Carol simulations.

Automatic Selection Method of Urban Road Network Considering Structural Characteristics

Abstract. Road network is one of the key elements of map, and its selection effect directly determines the quality of map generalization. In the process of automatic road network selection under a large scale, it is not only necessary to consider the connectivity and integrity of the road itself, but also necessary to take account of the network characteristics and density characteristics of the road network as a whole. However, most of the existing methods cannot take into account the coordination and maintenance of the above-mentioned features, which leads to the result that the spatial distribution characteristics are easily destroyed after the selection. So an automatic selection method of road network considering structural characteristics is proposed in this paper. Firstly, road stroke connection is generated based on road semantics, geometry and topology features, and the end arc, end stroke and end mesh is identified as the objects to be removed in the selection process. Then, road stroke connection is divided into four categories according to the association characteristics of road stroke connection, and the importance of each stroke is evaluated by length, connectivity and betweenness centrality. Finally, the importance threshold (TS) of road stroke connection and the mesh density threshold (TN) are set, and the stroke connection with the least importance is gradually removed to realize the automatic selection of road network. The reliability and superiority of this method are verified by the road topographic map (1 : 10000) test of a region in Jiangsu Province.