Minimum Threshold Research Articles

Absolute and relative disparity mechanisms revealed by an equivalent noise analysis

The precision of stereopsis and vergence are ultimately limited by internal binocular disparity noise. Here we propose an equivalent noise model with both global and local internal disparity noises to provide a unified explanation of both absolute and relative disparity thresholds. To test this model, we developed a psychophysical procedure to measure the equivalent internal disparity noise by adding external disparity noise to random-Gabor-patch stereograms. We used the method of constant stimuli to measure the minimum and maximum disparity thresholds (Dmin and Dmax) for both absolute and relative disparity. Consistent with previous studies, we found that Dmin thresholds are substantially worse for absolute disparity than for relative disparity. We tested three relative disparity mechanisms: (1) the difference between the monocular separations of targets projecting to the two eyes; (2) the direct measurement of relative disparity; and (3) the difference of absolute disparities of targets. Computing the difference of absolute disparities when detecting relative disparity, Mechanism 3 cancels global noise, resulting in a much lower relative Dmin threshold, and provides a reasonable fit to the experimental data. We also found that the presence of as much as 2400 arcsec of external disparity noise does not appear to affect the Dmax threshold. This observation suggests that Dmax is implicated in a mechanism that disregards the disparity variance of individual items, relying instead on the average disparity across all items, supporting the depth model proposed in our previous study (Ding & Levi, 2021), which posits distinct mechanisms governing Dmin and Dmax thresholds.

Effect of moxibustion on colonic low-grade inflammatory response in rats with diarrhea-predominant irritable bowel syndrome based on mast cell degranulation.

To observe the effects of moxibustion on colonic mast cell degranulation and inflammatory factor expression in rats with diarrhea-predominant irritable bowel syndrome (IBS-D), and explore the potential mechanism of moxibustion in treating IBS-D. Forty-five rat pups born from 5 healthy SPF-grade pregnant SD rats, with 8 rats were randomly selected as the normal group. The remaining 37 rats were intervened with maternal separation, acetic acid enema, and chronic restraint stress to establish the IBS-D model. The successfully modeled 32 rats were then randomly assigned to a model group, a ketotifen group, a moxibustion group, and a moxibustion-medication group, with 8 rats in each group. The rats in the ketotifen group were intervened with intragastric administration of ketotifen solution (10 mL/kg); the rats in the moxibustion group were intervened with suspended moxibustion on bilateral "Tianshu" (ST 25) and "Shangjuxu" (ST 37); the rats in the moxibustion-medication group were intervened with suspended moxibustion combined with intragastric administration of ketotifen solution. All interventions were administered once daily for 7 consecutive days. The diarrhea rate and minimum volume threshold of abdominal withdrawal reflex (AWR) were calculated before and after modeling, as well as after intervention. After intervention, colonic tissue morphology was observed using HE staining; colonic mucosal ultrastructure was examined by scanning electron microscopy; colonic mast cell ultrastructure was observed using transmission electron microscopy; mast cell degranulation was assessed by toluidine blue staining; serum and colonic levels of histamine, interleukin (IL)-1β, IL-6, IL-1α, trypsin-like enzyme, and protease-activated receptor 2 (PAR-2) were measured by ELISA; the Western blot and real-time quantitative PCR were employed to evaluate the protein and mRNA expression of colonic IL-1β, IL-6, IL-1α, trypsin-like enzyme, and PAR-2; the immunofluorescence was used to detect the positive expression of histamine, IL-1β, IL-6, IL-1α, trypsin-like enzyme, and PAR-2 in the colonic tissue. Compared to the normal group, the rats in the model group exhibited extensive infiltration of inflammatory cells in colonic tissue, severe damage to the colonic mucosa, disordered arrangement of villi, reduced electron density, and a significant decrease in granule quantity within mast cells. The diarrhea rate and mast cell degranulation rate were increased (P<0.01), AWR minimum volume threshold was decreased (P<0.01); the serum and colonic levels of histamine, IL-1β, IL-6, IL-1α, trypsin-like enzyme, and PAR-2 were elevated (P<0.01); the positive expression of histamine, as well as protein, mRNA and positive expression of IL-1β, IL-6, IL-1α, trypsin-like enzyme, and PAR-2 in the colon were all elevated (P<0.01). Compared to the model group, the rats in the ketotifen group, the moxibustion group, and the moxibustion-medication group exhibited significantly reduced infiltration of inflammatory cells in colonic tissue, relatively intact colonic mucosa, orderly arranged villi, increased electron density, and an augmented number of mast cell granules; the diarrhea rate and mast cell degranulation rate were decreased (P<0.01), and AWR minimum volume threshold was increased (P<0.01); the serum and colonic levels of histamine, IL-1β, IL-6, IL-1α, trypsin-like enzyme, and PAR-2 were reduced (P<0.01); the positive expression of histamine, as well as protein, mRNA and positive expression of IL-1β, IL-6, IL-1α, trypsin-like enzyme, and PAR-2 in the colon were all decreased (P<0.01). Compared to the ketotifen group, the moxibustion group showed decreased serum levels of histamine, IL-6, and trypsin-like enzyme (P<0.01, P<0.05), as well as reduced colonic levels of IL-1β and IL-6 (P<0.01, P<0.05); the protein expression of colonic IL-1β, IL-1α, and PAR-2 was reduced (P<0.05), and the positive expression of colonic IL-1β and trypsin-like enzyme was reduced (P<0.01, P<0.05). Compared to both the ketotifen group and the moxibustion group, the moxibustion-medication group exhibited decreased diarrhea rate and mast cell degranulation rate (P<0.01), an increased AWR minimum volume threshold (P<0.01), reduced serum and colonic levels of histamine, IL-1β, IL-6, IL-1α, trypsin-like enzyme, and PAR-2 (P<0.01), decreased protein expression of colonic IL-1β, trypsin-like enzyme, and PAR-2 (P<0.01, P<0.05), reduced mRNA and positive expression of colonic IL-1β, IL-6, IL-1α, trypsin-like enzyme, and PAR-2 (P<0.01, P<0.05), and decreased positive expression of colonic histamine (P<0.01). Moxibustion on "Tianshu" (ST 25) and "Shangjuxu" (ST 37) might inhibit low-grade inflammatory reactions in the colon of IBS-D model rats. The mechanism may be related to the inhibition of histamine and trypsin-like enzyme secreted by mast cell, thereby reducing the expression of related inflammatory factors.

Associations between fat taste sensitivity, nutritional intakes, body mass index and papillae density in healthy Algerian women: A cross-sectional study

Introduction: This study aimed to evaluate the link between nutritional intake, fat taste sensitivity, papillae density, and body mass index (BMI) in the Algerian women population. Methods: This work is a cross-sectional study; 140 women were recruited. Weight, height, and waist circumference were measured. Detection thresholds for oleic acid (OA) were determined according to three alternative forced choice method. Based on the cumulative distribution of minimum detection thresholds, participants were classified into hyposensitive ≥ 3 mM and hypersensitive &lt; 3 mM. Food intakes were recorded using 24-hour diaries on three different days. Fatty food consumption frequencies were studied using a frequency consumption survey. Papillae density was determined by tongue photography. Statistical analysis was performed with SPSS software version 25. Results: Our results indicated that 50 % of our population was overweight including 27 % of obesity. Average OA detection thresholds were greater in overweight and obese subjects compared to normal-weight subjects (p ˂ 0.001). A positive correlation was found between OA detection thresholds and BMI and waist circumference (p ˂ 0.001). Hyposensitive subjects consumed more energy and fat intake compared to hypersensitive subjects. Papillae density was inversely associated with BMI and OA detection thresholds. Conclusions: The study confirms the association between fat taste sensitivity and weight status in Algerian women. Overweight and/or obese participants were the least sensitive to OA compared to normal-weight participants. Hyposensitive subjects had higher intakes of energy and lipids compared to hypersensitive subjects. They also expressed a lower number of fungiform papillae. Overweight participants also had a lower number of fungiform papillae compared to normal-weight participants. A better understanding of the links between the detection of dietary lipids and energy/fat intakes in obese subjects may lead to new nutritional strategies to limit the risk of obesity.

Adaptive fuzzy-evidential classification based on association rule mining

As one of the most promising classification approaches, association classification (AC) integrates data classification and association discovery techniques for generating a compact set of classification association rules. Recently, the fuzzy set and evidence theories are successively applied into AC in order to improve the classification performance in terms of accuracy and interpretability. However, from the perspectives of applicability and universality, there still exists two important issues in the current AC framework. On one hand, several key parameters, such as the number of fused rules in classification and the minimum support threshold in association discovery, are difficult to be accurately predefined in practice. On the other hand, the fixed grid-based fuzzy partition is not benefit to adapt for those datasets with large number of features. In this paper, an association rule-based adaptive fuzzy-evidential classification framework (AR-AFEC) is developed for overcoming the above limitations. To do so, an optimal rule fusion strategy and a dynamic minimum support threshold setting scheme are proposed for adaptively learning the parameters during classification and association mining respectively. In addition, an entropy-based trapezoidal fuzzy partition technique is proposed to adaptively obtain the fuzzy sets defined on each continuous feature domain. Experiments on 26 benchmark datasets and a human activity recognition application demonstrate that the proposal can achieve better accuracy than some state-of-the-art rule-based classification approaches, using less rules with more general structure.

Competitive Strategies and Performance of Kenya Airways Limited in Nairobi County, Kenya

Kenya Airways has experienced significant financial losses over a prolonged period, which has led to the requirement of a government bailout and the adoption of a restructuring initiative. Kenya Airways is a major player in the Kenyan aviation sector but has struggled to stay profitable compared to Ethiopian Airlines. Ethiopian Airlines has reported consistent profits for several years, in contrast. Kenya Airways is adopting competitive tactics to improve its performance, but there is a dearth of empirical research on the subject. The objective of this study was to analyse the impact of competitive strategies on the performance of Kenya Airways. The purpose of the study was to examine the impact of differentiation, cost leadership, focus, and innovation on the performance of Kenya Airways Limited. This study was anchored on the following theories: porter’s generic strategies model, dynamic capabilities, resource-based view, strategy-structure-performance, and balanced score card. This study employed a descriptive inquiry approach. The focus group for the study was comprised of a total of 180 staff members of Kenya Airways Limited. The sample size consisted of 124 employees, who were selected using a basic random sampling technique. A semi-structured questionnaire was used to collect primary data. This research assessed the accuracy of the research tool by utilizing the viewpoints of experts through a content validity method. Cronbach's alpha co-efficient was utilized to evaluate the dependability of the research instrument, and a minimum threshold of 0.7 was established. Data was analysed using descriptive statistics using means and standard deviations and inferential statistics. The study made use of correlation analysis and multiple regression analysis to deduce connections among different variables. Differentiation strategy had a positive and significant effect on performance of Kenya Airways of (β= 0.513, p &lt; 0.05). Cost leadership strategy had a positive and significant effect on performance of Kenya Airways of (β=0.458, p &lt; 0.05). Focus strategy had a positive and significant effect on performance of Kenya Airways of (β= 0.540, p &lt; 0.05). Innovation strategy had a positive and significant effect on performance of Kenya Airways of (β=0.651, p &lt; 0.05). The study concluded that differentiation strategy improves the performance of Kenya Airways. Cost leadership strategy helps to improve the performance of Kenya Airways Limited. Focus strategy enhances performance of Kenya Airways Limited and innovation strategy helps to improve performance of Kenya Airways Limited. The study recommended that the company should continue to offer unique features that sets it apart from other airlines. The company should operate efficiently in order to keep costs low.

Atlantic salmon Salmo salar do not prioritize digestion when energetic budgets are constrained by warming and hypoxia.

During summer, farmed Atlantic salmon (Salmo salar) can experience prolonged periods of warming and low aquatic oxygen levels due to climate change. This often results in a drop in feed intake; however, the physiological mechanism behind this behaviour is unclear. Digestion is a metabolically expensive process that can demand a high proportion of an animal's energy budget and might not be sustainable under future warming scenarios. We investigated the effects of elevated temperature and acute hypoxia on specific dynamic action (SDA; the energetic cost of digestion), and how much of the energy budget (i.e. aerobic scope, AS) was occupied by SDA in juvenile Atlantic salmon. AS was 9% lower in 21°C-acclimated fish compared to fish reared at their optimum temperature (15°C) and was reduced by ~50% by acute hypoxia (50% air saturation) at both temperatures. Furthermore, we observed an increase in peak oxygen uptakerate during digestion which occupied ~13% of the AS at 15°C and ~20% of AS at 21°C, and increased the total cost of digestion at 21°C. The minimum oxygen tolerance threshold in digesting fish was ~42% and ~53% at 15 and 21°C, respectively, and when digesting fish were exposed to acute hypoxia, gut transit was delayed. Thus, these stressors result in a greater proportion of the available energy budget being directed away from digestion. Moderate environmental hypoxia under both optimal and high temperatures severely impedes digestion and should be avoided to limit exacerbating temperature effects on fish growth.

Validity of Using the Load-Velocity Relationship to Estimate 1 Repetition Maximum in the Back Squat Exercise: A Systematic Review and Meta-Analysis.

LeMense, AT, Malone, GT, Kinderman, MA, Fedewa, MV, and Winchester, LJ. Validity of using the load-velocity relationship to estimate 1 repetition maximum in the back squat exercise: a systematic review and meta-analysis. J Strength Cond Res 38(3): 612-619, 2024-The one repetition maximum (1RM) test is commonly used to assess muscular strength. However, 1RM testing can be time consuming, physically taxing, and may be difficult to perform in athletics team settings with practice and competition schedules. Alternatively, 1RM can be estimated from bar or movement velocity at submaximal loads using the minimum velocity threshold (MVT) method based on the load-velocity relationship. Despite its potential utility, this method's validity has yielded inconsistent results. The purpose of this systematic review and meta-analysis was to assess the validity of estimated 1RM from bar velocity in the back squat exercise. A systematic search of 3 electronic databases was conducted using combinations of the following keywords: "velocity-based training," "load-velocity profiling," "mean velocity," "mean propulsive velocity," "peak velocity," "maximal strength," "1RM," "estimation," "prediction," "back squat," and "regression." The search identified 372 unique articles, with 4 studies included in the final analysis. Significance was defined as a p level less than 0.05. A total of 27 effects from 71 subjects between the ages of 17-25 years were analyzed; 85.2% of effects were obtained from male subjects. Measured 1RMs ranged from 86.5 to 153.1 kg, whereas estimated 1RMs ranged from 88.6 to 171.6 kg. Using a 3-level random effects model, 1RM back squat was overestimated when derived from bar velocity using the MVT method (effect sizes [ES] = 0.5304, 95% CI: 0.1878-0.8730, p = 0.0038). The MVT method is not a viable option for estimating 1RM in the free weight back squat. Strength and conditioning professionals should exercise caution when estimating 1RM from the load-velocity relationship.

Investigating the influence of perforated façade skins on indoor illuminance level: a case study

ABSTRACT Building shading systems is crucial to both avoid indoor overheating during summer and control daylight inflow. This is particularly relevant in exposed glazed façade during summer, where the risk of excessive solar radiation and light entering the building is elevated. The study proposes the use of Dialux software to support the design of sun-shading devices with the two-fold objective of reducing the risk of glare along the façade side and avoiding a dark effect on the opposite side. The procedure is based on a multiple-design approach that simulates the effect of diverse shading panel configurations on indoor illuminance distribution. Then the procedure is implemented on a residential case study in Bologna (Italy) resulted in having a limited depth and thus a high risk of excessive illuminance. The results demonstrate that Dialux is sensitive to changes in the openness factor and geometry of the panel. The multiple simulations allowed the optimal illuminance level of around 300 lux for more than 70% of the case study room surface while containing the area exceeding the optimal level under 1000 lux to less than 20% and to avoid reaching the minimum threshold of 100 lux through a shading system with Openness Factor ranging between 11 and 15%. The workflow can serve not only as a tool for addressing and verifying the design choices but as a design support means itself. Due to its structure and easiness of inputting data and modelling stage, the methodology has a high replicability potential.

A two-dimensional perspective of the rotational evolution of rapidly rotating intermediate-mass stars

Context. Recently, the first successful attempt at computing stellar structure and evolution models in two dimensions was presented with models that include centrifugal deformation and self-consistently compute the velocity field. Aims. The aim of the present study is to explore the rotational evolution of two-dimensional models of stars rotating at a significant fraction of their critical angular velocity. From the predictions of these models, we aim to improve our understanding of the formation of single Be stars. Methods. Using the ESTER code, which solves the stellar structure of a rotating star in two dimensions with time evolution, we computed evolution tracks of stars of between 4 and 10 M⊙ for initial rotation rates ranging between 60 and 90% of the critical rotation rate. Furthermore, we compute models for both a Galactic metallicity and an SMC metallicity. Results. A minimum initial rotation rate at the start of the main sequence is needed to spin up the star to critical rotation within its main sequence lifetime. This threshold depends on the stellar mass, and increases with increasing mass. The models do not predict any stars above 8 M⊙ to reach (near-)critical rotation during the main sequence. Furthermore, we find the minimum threshold of initial angular velocity is lower for SMC metallicity than for Galactic metallicity, which is in agreement with the increased fraction of observed Be stars in lower metallicity environments. The strong difference in the rotational evolution between different masses is not predicted by any one-dimensional stellar evolution models. Conclusions. Our self-consistent two-dimensional stellar evolution models provide further insight into the rotational evolution of intermediate-mass stars, and our predictions are consistent with observations of velocity distributions and the fraction of Be stars amongst B-type stars. We find that stars with a mass above 8 M⊙ do not increase their fraction of critical rotation during the main sequence. As a fraction of stars above 8 M⊙ have been observed to display the Be phenomenon, other processes or formation channels must be at play, or, alternatively, critical rotation is not required for the Be phenomenon above this mass.

Can redistribution of vaccine improve global welfare? Lessons from COVID-19.

The disparity in the distribution of COVID-19 vaccine has been recorded with more than 70% vaccination rate for high-income countries as compared to less than 40% for low-income countries. The low affordability of vaccines for the majority of low-income group invites the need for redistribution of vaccines. The disproportionate donation of vaccines across the globe motivates us to explore the incentive for the high-income group to redistribute. An exploratory analysis of cross-country COVID-19 vaccination distribution data shows that the countries which have received vaccines as donation has also contributed to vaccine wastage. This paper intends to provide a theoretical background for this counterintuitive observation using welfare analysis. We find that the market mechanism leads to a negative impact on global welfare due to redistribution. Only an invention with a defined redistribution mechanism may ensure an increase in global welfare. It is found that a critical value of redistribution mechanism reinforced by a minimum threshold level of income is essential to enhance welfare. The reduced form from the theoretical predictions is empirically validated with cross-country data on COVID-19 vaccination for all countries. As identified in theory, the internal support variables like political stability, government effectiveness, and health expenditure at the country level will impact global welfare. Therefore, when global cooperation is essential during a health crisis like COVID-19, improved internal coordination and intentions cannot be ignored.

Electrochromic Glazing and Evaluation of Visual and Non-Visual Effects of Daylight: Simulation Studies for Brasilia – Brazil

The employment of electrochromic glazing can be a solution to balance circadian lighting and avoid glare. This can be achieved by controlling daylight entering the room and may be useful within the context of highly glazed facades in buildings in hot climates. Nevertheless, the use of this technology is rarely discussed in this context. In this regard, the aim of this study is to investigate the electrochromic glazing for the lighting conditions, including visual and non-visual effects within the luminous context of Brasilia, Brazil. The method consisted of computer simulations of a representative highly glazed non-residential room with the comparison of electrochromic glazing and conventional clear glass. Climate Studio was used to evaluate the visual effects of light for the entire year, and ALFA for the evaluation of melanopic daylight illuminance, vertical illuminance, and melanopic daylight efficacy ratio (mel-DER) in four days, including two solstices and two equinoxes encompassing the beginning of the four seasons. Results for the electrochromic glazing showed a better balance between a minimum threshold of 250 lux of mel-EDI without exceeding 1,500 lux of vertical illuminance in comparison with the clear glass. This was achieved in 33.33% of the hours for the north, against 27.78% of the hours for the east, 29.17% for the west, and 24.72% for the south. For the clear glass, this balance was achieved in only 9.17% of the hours for north, 10.28% for east, 12.22% for west, and 15% for south. Regarding the spectrum, higher results of melanopic daylight efficacy ratio were observed for the clear glass over the four simulated days. The main conclusion was that the electrochromic glazing was capable of providing a better balance between visual and non-visual requirements and can be a suitable solution for highly glazed facades in Brasilia. Nevertheless, particularly for the north orientation, the supply of circadian lighting can be jeopardized when the electrochromic glazing remained at the dark state.

Conventional in vitro fertilisation rather than intracytoplasmic sperm injection when only one oocyte is retrieved: Time to overcome irrational fears.

The use of intracytoplasmic sperm injection (ICSI) currently extends beyond male factor infertility, notably replacing conventional in vitro fertilisation (IVF) in scenarios like limited oocyte availability, where it is used as a precaution against complete fertilisation failure. While existing studies on the use of conventional IVF in such situations provide some reassurance, the available evidence is somewhat insufficient and ICSI is commonly used. To evaluate whether conventional IVF can be a feasible option when only one oocyte is retrieved. A retrospective study was performed to evaluate the fertilisation rate with conventional IVF in women retrieving only one oocyte and whose partner had normal semen. The study aimed at evaluating whether the fertilisation rate was aligned with the threshold indicated by recognized IVF laboratory performance indicators (Vienna Consensus). Clinical pregnancy and live birth rates were secondary outcomes. Out of 304 cycles with a single oocyte inseminated with conventional IVF, 209 achieved normal fertilisation and 82 did not. Thirteen had no mature oocytes. The fertilisation rate was 69% (95% CI: 63-74%) and increased to 72% (95% CI: 66-77%) when immature oocytes were excluded. The fertilisation rate surpassed the minimum competency threshold of the Vienna Consensus (60%), even if below the benchmark value (75%). Clinical pregnancy and live birth rates per oocyte retrieval were 10% and 8%, respectively. Univariate and multivariate analyses failed to identify any predictive factor of fertilisation. Conventional IVF with one oocyte met Vienna Consensus standards even if it fell short of higher benchmarks.

Effects of moxibustion on visceral hypersensitivity and colonic inflammatory response in mice with chronic ulcerative colitis.

To observe the effects of moxibustion at "Zusanli" (ST36) on the expression levels of tumor necrosis factor (TNF)-α, TNF receptor 1 (TNF-R1), p38 mitogen-activated protein kinase (P38 MAPK), and transient receptor potential vanilloid 1 (TRPV1) in the colon tissue of mice with chronic ulcerative colitis (UC), so as to explore the underlying mechanisms of moxibustion in improving visceral hypersensitivity in chronic UC. Male C57BL/6J mice were randomly divided into normal group, normal with moxibustion (NM) group, model group, and model with moxibustion (MM) group, with 10 mice in each group. The chronic UC model was established by drinking 2.5% dextran sodium sulfate for 3 cycles. Mice in the NM and MM groups received moxibustion at ST36 for 20 min, 5 days per week with a 2-day break, for a total of 4 weeks. The disease activity index (DAI) score of each group was evaluated before and after treatment. The minimum volume threshold of abdominal wall retraction reflex (AWR) was measured to observe the intestinal sensitivity of mice. The colon length was measured. The pathological changes of colon tissue were observed by HE staining. The expression of mucin in colon goblet cells was detected by periodate Scheff staining. The intestinal fibrosis was observed by Masson staining. The number of trypsin-positive cells (i.e., mast cell) and the expression level of TNF-α in colon tissue were detected by immunofluorescence staining. The expression levels of TNF-R1, P38 MAPK and TRPV1 in colon tissue were detected by immunohistochemistry. Compared with the normal group after treatment, the model group showed increased DAI score (P<0.001), decreased AWR minimum volume threshold (P<0.01), shortened colon length (P<0.001), significant inflammatory infiltration in the colon tissue, reduced mucin secretion (P<0.01), increased collagen fiber deposition (P<0.001), and elevated expression levels of TNF-α, TNF-R1, P38 MAPK, and TRPV1 (P<0.001, P<0.01, P<0.05). Compared with the model group, the MM group showed decreased DAI score (P<0.01), increased AWR minimum volume threshold (P<0.001), elongated colon length (P<0.001), reduced inflammatory cell infiltration, improved integrity of mucosal glandular structure, enhanced mucin secretion (P<0.01), decreased collagen fiber deposition (P<0.001), decreased number of mast cells in the colon tissue (P<0.001), and decreased expression levels of TNF-α, TNF-R1, P38 MAPK, and TRPV1 (P<0.001, P<0.01, P<0.05). There were no significant differences in the above index between the NM group and the normal group. Moxibustion can reduce visceral hypersensitivity, alleviate inflammatory infiltration and fibrotic damage in the colon tissue of mice with chronic UC. These effects may be associated with the down-regulation of TNF-α, TNF-R1, P38 MAPK, and TRPV1 expression in colon.

Fully discrete model of kinetic ion-induced electron emission from metal surfaces

Ion-induced electron emission (IIEE) is an important process whereby ions impinging on a material surface lead to net emission of electrons into the vacuum. While relevant for multiple applications, IIEE is a critical process of electric thruster (ET) operation and testing for space propulsion, and, as such, it must be carefully quantified for safe and reliable ET performance. IIEE is a complex physical phenomenon, which involves a number of ion-material and ion-electron processes, and is a complex function of ion mass, energy, and angle, as well as host material properties, such as mass and electronic structure. In this paper, we develop a discrete model of kinetic IIEE to gain a more accurate picture of the electric thruster chamber and facility material degradation processes. The model is based on three main developments: (i) the use of modern electronic and nuclear stopping databases, (ii) the use of the stopping and range of ions in matter to track all ion and recoil trajectories inside the target material, and (iii) the use of a scattering Monte Carlo approach to track the trajectories of all mobilized electrons from the point of first energy transfer until full thermalization or escape. This represents a substantial advantage in terms of physical accuracy over existing semi-analytical models commonly used to calculate kinetic IIEE. We apply the model to Ar, Kr, and Xe irradiation of W and Fe surfaces and calculate excitation spectra as a function of ion depth, energy, and angle of incidence. We also obtain minimum threshold ion energies for net nonzero yield for each ion species in both Fe and W and calculate full IIEE yields as a function of ion energy and incidence angle. Our results can be used to assess the effect of kinetic electron emission in models of full ET facility testing and operation.

The airport access gap in Latin America and the Caribbean

We estimate the investment gap in the provision of adequate levels of access to airports in Latin America and the Caribbean. Based on georeferenced data for population centers and existing airport locations, we estimate the region requires USD 10 billion in investments to close the gap for 23 million people living in localities of more than 100,000 inhabitants who currently lack sufficient access to airports offering adequate service standards within reasonable travel times. The gap is equivalent to approximately 18% of total investment in transport in Latin America in 2019, but is quite sensitive to variations in the criteria chosen to define access in terms of maximum access time and minimum population center size thresholds.

Impact of natural resource rents on well-being in sub-Saharan Africa: The role of human capital

This study contributes to the resource curse literature in diverse means. First, using a non-monetary welfare measure, the study investigates the validity of the resource curse hypothesis in sub-Saharan Africa (SSA). Secondly, the paper examines the impact of natural resource rents on human welfare through the human capital channel and finally investigates the minimum human capital score to avert the resource curse in SSA. The empirical analysis conducted using the system Generalized Method of Moment (GMM) econometric approach on a panel of 32 SSA countries spanning the period 2004–2019, demonstrates that resource rents have a dumping effect on human progress. However, investing in human capital may avert the negative repercussions emanating from the natural resource-welfare link. Further, the study revealed the minimum threshold level for human capital score and tertiary school enrollment rate as 2.40 units and 23.21 %, respectively, necessary to avert the prosperity curse. To increase human prosperity, policymakers are recommended to increase investment in education in order to increase tertiary school enrollment above the estimated threshold and institute policies that will increase the average years the productive unit spent in schooling.

Predicting recreational water quality and public health safety in urban estuaries using Bayesian Networks

To support the reactivation of urban rivers and estuaries for bathing while ensuring public safety, it is critical to have access to real-time information on microbial water quality and associated health risks. Predictive modelling can provide this information, though challenges concerning the optimal size of training data, model transferability, and communication of uncertainty still need attention. Further, urban estuaries undergo distinctive hydrological variations requiring tailored modelling approaches. This study assessed the use of Bayesian Networks (BNs) for the prediction of enterococci exceedances and extrapolation of health risks at planned bathing sites in an urban estuary in Sydney, Australia. The transferability of network structures between sites was assessed. Models were validated using a novel application of the k-fold walk-forward validation procedure and further tested using independent compliance and event-based sampling datasets. Learning curves indicated the model's sensitivity reached a minimum performance threshold of 0.8 once training data included ≥ 400 observations. It was demonstrated that Semi-Naïve BN structures can be transferred while maintaining stable predictive performance. In all sites, salinity and solar exposure had the greatest influence on Posterior Probability Distributions (PPDs), when combined with antecedent rainfall. The BNs provided a novel and transparent framework to quantify and visualise enterococci, stormwater impact, health risks, and associated uncertainty under varying environmental conditions. This study has advanced the application of BNs in predicting recreational water quality and providing decision support in urban estuarine settings, proposed for bathing, where uncertainty is high.

Simulating net ecosystem exchange under seasonal snow cover at an Arctic tundra site

Abstract. Estimates of winter (snow-covered non-growing season) CO2 fluxes across the Arctic region vary by a factor of 3.5, with considerable variation between measured and simulated fluxes. Measurements of snow properties, soil temperatures, and net ecosystem exchange (NEE) at Trail Valley Creek, NWT, Canada, allowed for the evaluation of simulated winter NEE in a tundra environment with the Community Land Model (CLM5.0). Default CLM5.0 parameterisations did not adequately simulate winter NEE in this tundra environment, with near-zero NEE (&lt; 0.01 gCm-2d-1) simulated between November and mid-May. In contrast, measured NEE was broadly positive (indicating net CO2 release) from snow-cover onset until late April. Changes to the parameterisation of snow thermal conductivity, required to correct for a cold soil temperature bias, reduced the duration for which no NEE was simulated. Parameter sensitivity analysis revealed the critical role of the minimum soil moisture threshold of decomposition (Ψmin) in regulating winter soil respiration. The default value of this parameter (Ψmin) was too high, preventing simulation of soil respiration for the vast majority of the snow-covered season. In addition, the default rate of change of soil respiration with temperature (Q10) was too low, further contributing to poor model performance during winter. As Ψmin and Q10 had opposing effects on the magnitude of simulated winter soil respiration, larger negative values of Ψmin and larger positive values of Q10 are required to simulate wintertime NEE more adequately.

Spectral information content of Compton scattering events in silicon photon counting detectors.

Silicon (Si) is a possible sensor material for photon counting detectors (PCDs). A major drawback of Si is that roughly two-thirds of x-ray interactions in the diagnostic energy range are Compton scattering. Because Compton scattering is an energy-insensitive process, it is commonly assumed that Compton events retain little spectral information. To quantify how much information can be recovered from Compton scattering events in models of Si PCDs. We built a simplified model of Si interactions including two interaction mechanisms: photoelectric effect and Compton scattering. We considered three different binning options that represent strategies for handling Compton events: in Compton censoring, all events under 38keV (the maximum energy possible from Compton scattering for a 120keV incident photon) were discarded; in Compton counting, all events between 1 and 38keV were placed into a single bin; in Compton binning, all events were placed into energy bins of uniform width. These were compared to the ideal detector, which always recorded the correct energy (i.e., 100% photoelectric effect). Every photon was assumed to interact once and only once with Si, and the energy bin width was 5keV. In the primary analysis, the Si detector was irradiated with a 120kV spectrum filtered by 30cm of water, with 99.5% of the arriving spectrum above 38keV so that there was good separation between photoelectric effect and Compton scattering, and the figures of merit were the Cramér-Rao lower bound (CRLB) of the variance of iodine and water basis material decomposition images, as well as the CRLB of virtual monoenergetic images (i.e., linear combinations of material images) that maximize iodine CNR or water CNR. We also constructed a local linear estimator that attains the CRLB. In secondary analyses, we applied other sources of spectral distortion: (1) a nonzero minimum energy threshold; (2) coarser, 10keV energy bins; and (3) a model of charge sharing. With our chosen spectrum, 67% of the interactions were Compton scattering. Consistent with this, the material decomposition variance for the Compton censoring model, averaged over both basis materials, was 258% greater than the ideal detector. If Compton events carried no spectral information, the Compton counting model would show similar variance. Instead, its basis material variance was 103% greater than the ideal detector, implying that Compton counts indeed carry significant spectral information. The Compton binning model had a basis material variance 60% greater than the ideal detector. The Compton binning model was not affected by a 5keV minimum energy threshold, but the variance increased from 60% to 107% when charge sharing was included and to 78% with coarser energy bins. For optimized CNR images, the average variance was 149%, 12%, and 10% higher than the ideal detector for the Compton censoring, counting, and binning models, reinforcing the hypothesis that Compton counts are useful for detection tasks and that precise energy assignments are not necessary. Substantial spectral information remains after Compton scattering events in silicon PCDs.

T2FM: A novel hashtable based type-2 fuzzy frequent itemsets mining

Association rule mining (ARM) is an important research issue in the field of data mining that aims to find relations among different items in binary databases. The conventional ARM algorithms consider the frequency of the items in binary databases, which is not sufficient for real time applications. In this paper, a novel hash table based Type-2 fuzzy mining algorithm (T2FM) with an efficient pruning strategy is presented for discovering multiple fuzzy frequent itemsets from quantitative databases. The algorithm employs a hash table based structure for efficient storage and retrieval of item/itemset which reduces the search efficiency to O(1) or constant time. Previously, type-2 based Apriori and FP-growth based fuzzy frequent itemsets mining were proposed, which required large amounts of computation and a greater number of candidate generation and processing. Meanwhile, the proposed approach reduces a huge amount of computation by finding the common keys before the actual intersection operation takes place. An efficient pruning strategy is proposed to avoid unpromising candidates in order to speed up the computations. Several experiments are carried out to verify the efficiency of the approach in terms of runtime and memory for different minimum support threshold and the results show that the designed approach provides better performance compared to the state-of-the-art algorithms.