Multivariate Linear Regression Equation Research Articles

The Impact of Flow Channel Structural Parameters on Both the Hydraulic Performance and Anticlogging Abilities of Variable Flow Emitters

Variable flow emitters are used in subsurface drip irrigation to address challenges in soil moisture transport. This study investigates the impact of flow channel structural parameters on the hydraulic performance and anticlogging ability of emitters using computational fluid dynamics (CFD) simulations and experimental tests. The results show that the realizable k–ε turbulence model can be used to simulate the flow field inside the variable flow emitter flow channel. The nRMSE between the measured (qm) and simulated (q) values of the flow rate is 11.23%, and the relative error between the measured (xm) and simulated (x) values of the flow index is 4.66%, which gives a high simulation accuracy. A polar analysis shows that the tooth angle (A) has the smallest effect on the effluent flow rate at 0.1 MPa (q0.1), x, and particle passage rate (η) of the variable flow emitter. Flow channel depth (D), tooth spacing (B), and tooth height (E) have a different order of precedence in the influence of the three indices, which are D > B > E > A, B > E > D > A and E > B > D > A, respectively. The value of η is positively correlated with the mean flow velocity (v) and the mean turbulent kinetic energy (k) in the flow channel, and η tends to increase and then decrease with the increase of x. The retention time of the particles in the flow channel is closely related to the magnitude of v and k. Three multivariate lin ear regression equations (R2 = 0.883–0.995) were constructed for q0.1, x, and η versus the flow channel structural parameters. The optimal design combination of channel structure parameters for different scenarios was determined using the scipy.optimize.minimize function in Python 3.8.0. The research results provide a reference for the optimal design of variable flow emitters.

Optimum Design of Cooling Structure for In-Wheel Motor Drive System

The high-efficient cooling structure is one of the key basic problems in the design of the highly integrated in-wheel motor (IWM) drive system. A 15 kW IWM drive system with the spiral cooling structure is taken as the research object in this article. First, the thermal characteristics under different conditions are analyzed based on the modeling and the heat source determination of the IWM drive system. Second, the highest temperature of insulation and permanent magnet and temperature difference of insulation are taken as optimization objectives. The inlet flow rate, the inlet and outlet diameters, the channel numbers, the channel height, and the channel ribs thickness of cooling structure are taken as optimization parameters to optimize based on the designed experiments, the multivariate linear regression equation and PSO method. Finally, the optimization results are verified by comparing the temperature field before and after optimization. The results show that the optimized structure can achieve better effect. The highest temperature of insulation, the highest temperature of permanent magnet and the temperature difference of insulation of IWM decreased by 9.27%, 9.52%, and 20.93%, respectively. This research work can provide some ideas and methods for the optimization design of cooling structure of IWM drive system.

Visualising the strength development of FICP-treated sand using impedance spectroscopy

Fungal Induced Calcium Carbonate Precipitation (FICP) is a novel method used in geotechnical engineering that enhances the engineering properties of sand by using the potential of fungal activity. This research is the first attempt to monitor the strength of FICP treated sand using embedded Piezoelectric (PZT) patch based Electromechanical Impedance (EMI) spectroscopy. In the past, the strength of such treated sand has been determined through the destructive methods like Unconfined Compressive Strength (UCS) test. In this study, the sand is mixed with the filamentous fungus Aspergillus Niger and the cementation solution (urea and \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\:{\ ext{C}\ ext{a}\ ext{C}\ ext{l}}_{2}$$\\end{document} in the ratio of 1:1) is injected after every 24 h. Results recorded from the cost-effective EVAL AD5933 chip indicate that the shifting of frequency impedance signals in each phase is in good alignment with UCS and calcium carbonate content (CCC). Following the 28-day treatment period, the treated sand achieves a maximum UCS of 3.93 MPa, accompanied by a CCC of 15.19%. In order to correlate EMI signals with treatment cycles, UCS, and CCC, various multi linear regression (MLR) equations for statistical metrics like root mean square deviation (RMSD), mean absolute percentage deviation (MAPD), and correlation coefficient deviation (CCD) are developed. Additionally, Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDX) analyses have been conducted to observe the success of the FICP process in the sand.

Experimental Study on Proportion Optimization of Rock-like Materials Based on Genetic Algorithm Inversion.

It is very important to clarify the optimization method of the rock-like material ratio for accurately characterizing mechanical properties similar to the original rock. In order to explore the optimal ratio of rock-like materials in gneissic granite, the water-paste ratio, iron powder content and coarse sand content were selected as the influencing factors of the ratio. An orthogonal test design and sensitivity analysis of variance were used to obtain the significant influencing factors of the ratio factors on seven macroscopic mechanical parameters, including compressive strength σc, tensile strength σt, shear strength τf, elastic modulus E, Poisson's ratio ν, internal friction angle φ and cohesion c. A multivariate linear regression equation was constructed to obtain the quantitative relationship between the significant ratio factors and the macroscopic mechanical parameters. Finally, a rock-like material ratio optimization program based on genetic algorithm inversion was written. The results show that the water-paste ratio had extremely significant effects on σc, σt, τf, E, ν and c. The iron powder content had a highly significant effect on σc, σt, τf and c, and it had a significant effect on ν and φ. Coarse sand content had a significant effect on σc, E and c. The multiple linear regression model has good reliability after testing, which can provide theoretical support for predicting the macroscopic mechanical parameters of rock-like materials to a certain extent. After testing, the ratio optimization program works well. When the water-paste ratio is 0.5325, the iron powder content is 3.975% and the coarse sand content is 15.967%, it is the optimal ratio of rock-like materials.

Wooden furniture design based on physiological-psychological measurement technology and Kansei engineering: Taking Ming-style chair as an example

Psychological and physiological cognitive measurements were combined with Kansei engineering theory to study the shape of the traditional Chinese official-hat chair, a kind of Ming-style chairs, while investigating people’s perceptual cognitive process. This work employed focus groups to obtain 5 groups of representative words and 22 typical samples for evaluation experiments. After data preprocessing, principal component analysis (PCA) was used to extract three main components: “Concise-Ornate”, “Soft-Strong”, and “Elegant-Vulgar”. In terms of component weight calculation, the analytic hierarchy process (AHP) was initially used to calculate the subjective cognitive weight of different components, and then eye-tracking technology was used to assist in calculating the physiological cognitive weight. Finally, combining the subjective and objective weights, the weights of the components were determined as: backrest (41.02%) > stretcher (18.29%) > handrail (11.64%) > top rail (11.14%) > outside stick (8.64%) > inside stick (5.32%) > foot rail (3.95%). The four main components—backrest, stretcher, handrail, and top rail—along with perceptual image evaluations, were selected to establish a multivariate linear regression equation, thereby constructing a mathematical mapping relationship between perceptual image and main design elements. This provides theoretical support for designers in creating different perceptual images.

Effects of artificial intelligence learning environments on engineers’ intercultural communication competence: mediating role of learning adaptability

ABSTRACT The purpose of this study is to investigate the impact of artificial intelligence learning environments on the intercultural communication competence of engineers. Engineering students at Chinese higher education institutions were invited to participate, and 990 students (510 males and 480 females) from different school types, majors, and grades completed an online survey. After analyses with multivariate linear regression and structural equation modelling, the results show that different dimensions of AI learning environments – including personalized learning, use of technology, and cooperation and interaction – have significant positive impacts on engineers’ intercultural communication competence and learning adaptability. At the same time, learning adaptability plays a mediating role between AI learning environments and intercultural communication competence. This study suggests that AI learning environments may have the potential to (i) enhance engineers’ intercultural communication competence and learning adaptability, an (ii) indirectly improve engineers’ intercultural communication competence through enhancements in their learning adaptability.

Assessment of dental age estimation using dentinal translucency in ground sections of single rooted teeth: a digital image analysis.

Human dentition is unique to individuals and helps in identification of individuals in forensic odontology. This study proposes to study the manually ground sections of single rooted teeth using digital methods for dental age estimation. To assess the dentinal translucency from the scanned digital images of manually ground section of teeth using commercially available image edition software. Corroborating the root dentinal translucency length and region of interest (ROI) of translucency zone in pixels (as a marker of dental age) with the chronological age of the subject, as stratified by different age groups. Twenty single-rooted extracted teeth from 20 patients each from 6 groups divided as per age. Manual sectioning of the teeth followed by scanning the sections was done. Root area in pixels and ROI of translucency zone were measured. From the observed values, translucency length percentage (TLP) and percentage of ROI in pixels (TPP) was calculated and tabulated. Pearson's correlation coefficients were obtained for age with TLP and TPP. Positive correlation existed between age and TLP and also between age and TPP. With the obtained data, multilinear regression equations for specific age groups based on 10-year intervals were derived. By a step-down analysis method, age was estimated with an average error of around ±7.9 years. This study gives a novel method for age-estimation that can be applied in real-time forensic sciences.

Inter-well Connectivity Mapping System Based on Production Dynamic Data

In the process of oilfield development, interwell connectivity is an important index for reservoir evaluation, but after most of the oilfields enter into the medium-high water content development stage, the evaluation of interwell connectivity becomes the key to improve the efficiency of injection and recovery development. In order to solve the problems of time-consuming and costly of the traditional dynamic connectivity research methods, a water-driven injection and recovery inter-well connectivity calculation model was established through the study of Liu76-60 well group. In the process of the study, the inter-well model was established by processing the data of the well group, and the inter-well connectivity between injection and extraction wells was calculated on the basis of this model, and the calculated results were verified by multivariate linear regression equations. The final results show that the model established in the study is more accurate in evaluating the inter-well connectivity, and the comparison can be confirmed to be consistent with the results of the production dynamics, so the model can be used to evaluate the inter-well connectivity, which has a positive effect on the effective improvement of the efficiency of injection and recovery development in the reservoir.

Crystal chemistry and molar volume of potassic-chloro-hastingsite

Abstract. Several geological processes such as crustal and mantle metasomatism, high-grade metamorphism, and the formation of ore deposits involve the exchange of halogens, especially chlorine, between silicate minerals and fluids. It is well established that the presence of octahedral iron is vital to the process of Cl incorporation into amphiboles. However, other compositional controls on Cl incorporation, such as the effect of TAl, ANa, AK, and A-site occupancy are not as well constrained. This study reports on the compositional and structural relationships amongst a suite of 25 synthetic calcium amphiboles with a diverse range of Cl contents (0–1.68 atoms per formula unit (apfu)). Most amphiboles were synthesized along the potassic-hastingsite–potassic-chloro-hastingsite join (KCa2(Fe4Fe3+)(Al2Si6)O22(OH,Cl)2). Additional work involved substitution of Na for K, variable Al content, and substitution of Mg for Fe2+ in the bulk composition to explore these compositional effects on Cl incorporation. The relationship between pressure and the Cl content of amphiboles was also explored over the pressure range 0.3–2.0 GPa. Otherwise, synthesis conditions were 700 °C and 0.3 GPa with fO2 near Ni–NiO. Iron (II) chloride was used as the source of Cl. Some experiments used variably concentrated FeCl2 brines (0–100 molal), while others were nominally anhydrous, containing only the water absorbed by the hygroscopic FeCl2. All amphiboles were characterized by Rietveld refinements of powder X-ray diffraction patterns, electron microprobe analysis, and Mössbauer spectroscopy, the latter to determine Fe3+ fraction. This study finds a positive relationship between pressure and the Cl content of the amphibole. Both Fe2+ and Fe3+ are positively correlated with Cl among amphiboles with variable Fe#, but the correlation is poor to nonexistent for Mg-free amphiboles. Results indicate that the substitution of CFe2+,3+ for CMg and CFe2+,3+ for CAl facilitate Cl incorporation, with the former having a larger effect. The A-site occupancy is positively correlated with Cl in all amphiboles except those synthesized in dilute FeCl2 brines (≤ 6 m), which are negatively correlated. No correlation is observed between the Cl content of the amphibole and either the species of A cation (K vs. Na) or TAl. The composition vs. unit cell parameter data were analyzed using multivariate linear regression to better understand the process of Cl incorporation and to predict the molar volume of endmember chloro-amphiboles. The regression indicates an expansion of 0.181 Å (0.99 %) and 0.048 Å (0.90 %) along the b and c edges respectively, a reduction in β by 0.76° (0.72 %), and a contraction of 0.060 Å (0.59 %) along a when fully substituting Cl for OH in potassic-hastingsite. The multivariate linear regression equations allow the prediction of molar volumes for select endmember chloro-amphiboles, such as potassic-chloro-hastingsite = 964.63 ± 1.29 Å3 or 290.5 ± 0.4 cm3 mol−1.

Early-life cumulative exposure to excess bodyweight and midlife cognitive function: longitudinal analysis in three British birth cohorts

Excess bodyweight (BMI >25 kg/m2) in midlife (age 40-65 years) has been linked to future cognitive decline and an increased risk of dementia. Whether chronic exposure to excess bodyweight in the early decades of life (<40 years) is associated with compromised cognitive function by midlife, however, remains unclear. This study therefore aimed to test potential bidirectional direct and indirect pathways linking cumulative exposure to excess bodyweight and cognitive function in the early decades of life. In this longitudinal analysis, harmonised measures of BMI and cognitive function were available in 19 742 participants aged 47-53 years recruited to the 1946 National Survey of Health and Development (n=2131), the 1958 National Child Development Study (n=9385), and the 1970 British Cohort Study (n=8226). Individual BMI trajectories spanning three decades from age 10-40 years were created for each participant and excess bodyweight duration, BMI change between ages, and cumulative excess bodyweight exposure were calculated. Harmonised measures of verbal and non-verbal ability, mathematical ability, and reading ability were used to create a latent factor for childhood cognitive function, and immediate and delayed recall, animal naming, and letter-search speed tests were used for midlife cognitive function. Multivariable linear regression and structural equation models (SEM) were used to test for potential bidirectional relationships between cognition and excess bodyweight in both individual cohorts and pooled datasets while accounting for other potential early-life confounders. Increases in BMI during adolescence and greater cumulative exposure to excess bodyweight across early life were associated with lower midlife cognitive function in all cohorts (eg, pooled difference in cognitive function per 10 years excess bodyweight duration -0·10; 95% CI -0·12 to -0·08; p<0·001). Further adjustment for childhood cognitive function attenuated many of these associations towards the null (eg, pooled difference in cognitive function per 10 years excess bodyweight duration -0·04; 95% CI -0·06 to -0·02; p=0·001), however, with any remaining associations then fully attenuating once further adjusted for other early-life factors (eg, pooled difference in cognitive function per 10 years excess bodyweight duration 0, -0·03 to 0·01; p=0·38). In the reverse direction, low childhood cognition was associated with greater cumulative exposure to excess bodyweight over the next four decades, although much of this relationship was found to probably be explained via other potentially modifiable upstream early-life factors such as childhood disadvantage. SEM in all cohorts suggested the presence of modest direct and indirect pathways connecting earlier cognitive function to later excess bodyweight, but scarce evidence for an effect of early-life excess bodyweight on cognitive function by midlife. The association between cumulative exposure to excess bodyweight in early life and lower cognitive function in midlife is probably confounded by a persistently lower cognitive function from childhood. Initiatives to improve early-life factors such as childhood disadvantage and education, however, might exert dual but independent benefits on both of these factors before old age. Alzheimer's Research UK, Diabetes Research and Wellness Foundation, Diabetes UK, British Heart Foundation, and Medical Research Council.

Instantaneous Electricity Peak Load Forecasting Using Optimization and Machine Learning

Accurate instantaneous electricity peak load prediction is crucial for efficient capacity planning and cost-effective electricity network establishment. This paper aims to enhance the accuracy of instantaneous peak load forecasting by employing models incorporating various optimization and machine learning (ML) methods. This study examines the impact of independent inputs on peak load estimation through various combinations and subsets using multilinear regression (MLR) equations. This research utilizes input data from 1980 to 2020, including import and export data, population, and gross domestic product (GDP), to forecast the instantaneous electricity peak load as the output value. The effectiveness of these techniques is evaluated based on error metrics, including mean absolute error (MAE), mean square error (MSE), mean absolute percentage error (MAPE), root mean square error (RMSE), and R2. The comparison extends to popular optimization methods, such as particle swarm optimization (PSO), and the newest method in the field, including dandelion optimizer (DO) and gold rush optimizer (GRO). This comparison is made against conventional machine learning methods, such as support vector regression (SVR) and artificial neural network (ANN), in terms of their prediction accuracy. The findings indicate that the ANN and GRO approaches produce the least statistical errors. Furthermore, the correlation matrix indicates a robust positive linear correlation between GDP and instantaneous peak load. The proposed model demonstrates strong predictive capabilities for estimating peak load, with ANN and GRO performing exceptionally well compared to other methods.

Study on serum uric acid concentration and serum uric acid/creatinine ratio in patients with type 2 diabetes

Objectives: 1. Determination of serum uric acid concentration and serum uric acid/creatinine ratio in patients with type 2 diabetes. 2. Find out correlations between serum uric acid, serum uric acid/creatinine ratio and some clinical and paraclinical characteristics in patients with type 2 diabetes. Materials and methods: 141 patients with type 2 diabetes, at the Examination Department of Khanh Hoa Provincial General Hospital from April 2022 to June 2023; method: cross-sectional descriptive study, data processing using SPSS 18.0 software. Results: men account for 56%, women account for 44%. The average age was 55.3 ± 9.7 year. The average time to detect diabetes is 9.4 ± 6.6 year. The rate of hypertension is 42.6%. The obesity rate is 26.2%. Average waist circumference: 81.06 ± 8.9 cm. Good fasting blood glucose control accounts for 39.0%, good HbA1c control accounts for 36.9%. The average GFR is: 83.42 ± 22.81 (ml/min/1.73m2), GFR reduction accounts for 11.3%, CKD accounts for 43.9%. The average serum UA concentration was: 345.87 ± 98.57 mmol/l, the average serum UA/Cre value was: 4.23 ± 1.3, with 23.4% increased serum UA. There is a negative correlation between UA and GFR, r = - 0.409. UA concentration in the group with CKD was higher than the group without CKD, p &lt; 0.05. There is an association between UA according to CKD stage, p &lt; 0.001. There is a relationship between UA/Cre according to CKD stage, p &lt; 0.0001. There is a statistically significant relationship (p &lt; 0.001) between UA concentration and urinary ACR level. Multivariable linear regression equation: GFR = 118.122 + 5.449*UA/Cre – 0.674*Age - 3.563*Urea - 0.014*ACR, with R2 = 64.1%, B = 5.449, p &lt; 0.001. ROC curve analysis: Serum UA value: AUC = 0.767, p &lt; 0.001, PI: 433.5, Se: 56.3%, Sp: 87.2%). Serum UA/Cre value: AUC = 0.131, p &lt; 0.05. Conclusions: Serum UA/Cre ratio has prognostic value for CKD in patients with type 2 diabetes (R2 = 64.1%, B = 5.449). Serum UA concentration is valuable in predicting the occurrence of CKD in patients with type 2 diabetes (AUC = 0.767, cut-off point is 434 (µmol/l), with Se: 56.3% and Sp: 87.2%. Key words: diabetes, serum uric acid, serum uric acid/ creatinine ratio.

The Impact of the Employee’s Personal Characteristics on the Abuse of Sickness Absence: Empirical Evidence From Poland

Abstract Objective The tendency to abuse sickness absence is a complex problem conditioned by many factors, that can be divided, depending on the level of impact, into three groups: micro (related to personal characteristics), meso (related to the work environment), and macro (related to the broader environment). The subject of interest in the article is the first level (micro). The aim is to evaluate the impact of various personal factors on the declared abuse of sickness leave in Poland. Research Design &amp; Methods The data was gathered using the CAWI survey. The research sample consisted of 1067 respondents (full-time employees). Statistical analysis incorporated multivariable linear regression and structural equation modelling. Findings Some personal characteristics have a significant impact on the declared abuse of sick leave. These factors are: gender, age, number of children, place of living, marital status, and subjective health. We found no impact of education and financial status. Implications &amp; Recommendations Although abusing sick leave is a serious economic and organisational problem, its causes still remain relatively poorly recognised. Personal characteristics determine the propensity to abuse sick leave, and they need to be taken into account under the process of managing absence behaviours. Contribution &amp; Value Added The added value of the study is drawing attention to the new personal factors which were not previously identified as a determinant of abuse of sick leave. These are: the number of children, place of living, and marital status.

The Sailing Boat Price Study Based on Principal Component Regression Analysis

This paper conducts research on the pricing of second-hand sailboats under certain assumptions. Initially, a substantial amount of potentially relevant indicators and data related to sailboat pricing were collected from the internet. The Pearson correlation coefficient was used to investigate the correlation between these indicators and to filter them. Due to the distinctive characteristics of sailboats, they were categorized into monohull sailboats and catamarans for separate analysis. Subsequently, the processed data were used for price prediction using a BP neural network, yielding preliminary results. To obtain an explicit method for calculating sailboat prices, this paper employed principal component analysis to calculate the pricing objective function for both types of sailboats. This led to the derivation of two multivariate linear regression equations, which were subjected to significance testing. The results indicate that the objective functions obtained in this paper can serve as references for pricing second-hand sailboats.

Multivariate Analysis and Optimization of the Relationship between Soil Nutrients and Berry Quality of Vitis vinifera cv. Cabernet Franc Vineyards in the Eastern Foothills of the Helan Mountains, China

The aim of this study is to explore the relationship between soil nutrients and berry quality for the wine grape Vitis vinifera cv. Cabernet Franc in the eastern foothills of the Helan Mountains, and subsequently to optimize soil nutrient conditions for optimal berry quality, thus providing guidance for vineyard soil management. Based on the basic data on soil nutrients and berry quality indicators, a partial least squares regression method was used to screen for major soil nutrient factors affecting the grape quality index. Then, the selected soil nutrient factors were taken as independent variables and the corresponding grape quality indicators were taken as dependent variables and a multilinear regression equation was formulated by the method of multivariate linear regression. Finally, the optimal solution for fruit quality and soil nutrients was solved using linear programming equations. The results showed that there was a lack of total nitrogen, organic matter, nitrate nitrogen, ammonium nitrogen, and available phosphorus in the soil nutrients, and an alkaline soil. There is a significant positive correlation between some soil nutrient indices, and there is also a multivariate linearity problem. Among all berry quality indices, titratable acid, tannin, and anthocyanin were negatively correlated with eleven and ten soil indices, respectively, while other berry quality indices were positively correlated with most soil nutrient indices. The optimal parameters for grape quality were determined using the method of linear programming equations, and the corresponding soil nutrient indicators content were defined.

Employees’ professional situation and the abuse of sick leave absence in Poland

The propensity to abuse sickness leave is a complex issue conditioned by various individual and contextual factors. The aim of the article is to assess the effect of various work-related factors on the abuse of sick leave in Poland. Three categories of sick leave abuse were distinguished: compulsion, escape and recreation. The data were gathered using the CAWI survey. Statistical analyzes incorporated multivariable linear regression and structural equation modelling. The research sample consisted of 1067 respondents (full-time employees). Some work-related factors have a significant impact on the abuse of sick leave. These factors are: (1) motivational working conditions, (2) social working conditions, (3) qualifications and (4) form of ownership. The main conclusion is that the assessment of specific aspects of working conditions has a different impact on the declared abuse of sickness absence. A high assessment of the 'social’ (interpersonal) aspect is associated with a low tendency to engage in unethical behavior, whereas a high assessment of the 'motivational’ aspect is associated with a high tendency in this respect. Moreover, it was found that a low tendency to abuse is also expressed by people who highly assess their professional qualifications. Finally, abuses are committed relatively often by public administration employees.

The hypoxic ventilatory response and hypoxic burden are predictors of the magnitude of ventilatory long-term facilitation in humans.

Mild intermittent hypoxia initiates progressive augmentation (PA) and ventilatory long-term facilitation (vLTF) in humans. The magnitude of these forms of plasticity might be influenced by anthropometric and physiological variables, as well as protocol elements. However, the impact of many of these variables on the magnitude of respiratory plasticity has not been established in humans. A meta-analysis was completed using anthropometric and physiological variables obtained from 124 participants that completed one of three intermittent hypoxia protocols. Simple correlations between the aggregate variables and the magnitude of PA and vLTF standardized to baseline was completed. Thereafter, the variables correlated to PA or vLTF were input into a multilinear regression equation. Baseline measures of the hypoxic ventilatory response was the sole predictor of PA (R=0.370, P=0.012). Similarly, this variable along with the hypoxic burden predicted the magnitude of vLTF (R=0.546, P<0.006 for both variables). In addition, the magnitude of PA was strongly correlated to vLTF (R=0.617, P<0.001). Anthropometric measures do not predict the magnitude of PA and vLTF in humans. Alternatively, the hypoxic ventilatory response was the sole predictor of PA, and in combination with the hypoxic burden, predicted the magnitude of vLTF. These influences should be considered in the design of mild intermittent hypoxia protocol studies in humans. Moreover, the strong correlation between PA and vLTF suggests that a common mechanistic pathway may have a role in the initiation of these forms of plasticity. KEY POINTS: Mild intermittent hypoxia initiates progressive augmentation (PA) and ventilatory long-term facilitation (vLTF) in humans. Many of the anthropometric and physiological variables that could impact the magnitude of these forms of plasticity are unknown. Anthropometric and physiological variables were measured from a total of 124 participants that completed one of three distinct intermittent hypoxia protocols. The variables correlated to PA or vLTF were input into a multilinear regression analysis. The hypoxic ventilatory response was the sole predictor of PA, while this variable in addition to the average hypoxic burden predicted the magnitude of vLTF. A strong correlation between PA and vLTF was also revealed. These influences should be considered in the design of mild intermittent hypoxia protocol studies in humans. Moreover, the strong correlation between PA and vLTF suggests that a common mechanistic pathway may have a role in the initiation of these forms of plasticity.

Magnetic Resonance Imaging Of Calvarial Diploe Thickness for Sex And Age Estimation of A Sample Of Egyptian Population

Background: Magnetic resonance imaging (MRI) is a mainstay radiological technique that is becoming more desirable in forensic identification for its non-invasive, non-ionizing and highly precise nature. Objectives: This study aimed to investigate whether sex and age could be estimated based on Calvarial Diploe Thickness (CDT) using MRI in a sample of the Egyptian population. Methods: The study was conducted on cranial MRI images of 306 adult Egyptians. For sex and age estimation, seven CDT measurements were assessed on 256 cranial MRI images of known sex and age. A binary logistic regression equation was developed for sex prediction. Multivariate linear regression analyses were performed to generate age prediction equations; equation (1), gender was included, while equation (2) was irrespective of gender. All regression equations were tested on 50 cranial MRI images. Results: The results revealed a significant binary logistical regression model for sex prediction of r2 0.442 and classification accuracy 71.6%. The Receiver Operating Characteristic (ROC) curve showed an area under the curve (AUC) 0.816, sensitivity 76.6 %, and specificity of 70.5%. Testing the equation showed accuracy for identifying males (78.2 %), accuracy for identifying females (70.4 %), and overall accuracy (74 %). Regarding age estimation, Pearson correlation showed no statistically significant correlation between age and all CDT measurements. Age prediction multivariate linear regression models (sex-stratified/sex-pooled) were statistically insignificant, with very low adjusted r2 and high standard error of estimate. Testing the multivariate linear regression equations showed Mean Absolute deviation (MAD) between the chronological age and predicted age of 9.09254 years and Mean Absolute Percentage Error (MAPE) of 28.458% for the multivariate linear regression equation (1) and MAD of 8.94469 years; and MAPE of 27.9829% for the multivariate linear regression equation (2). Conclusion: We concluded that the studied CDT measurements could be included as a new candidate in MRI-based sex estimation for Egyptians while are unfavorable for estimating age. Our results provide preliminary results for assessing a new approach for estimating sex and age for Egyptians. Applying such parameters on a greater sector of Egyptians for both sex and age estimation is highly recommended.

Visual impairment and retinal and brain neurodegeneration: A population-based study.

Visual impairment and retinal neurodegeneration are intrinsically connected and both have been associated with cognitive impairment and brain atrophy, but the underlying mechanisms remain unclear. To investigate whether transneuronal degeneration is implicated, we systematically assessed the relation between visual function and retinal, visual pathway, hippocampal and brain degeneration. We analyzed baseline data from 3316 eligible Rhineland Study participants with visual acuity (VA), optical coherence tomography (OCT), and magnetic resonance imaging (MRI) data available. Regional volumes, cortical volume, and fractional anisotropy (FA) were derived from T1-weighted and diffusion-weighted 3 T MRI scans. Statistical analyses were performed using multivariable linear regression and structural equation modeling. VA and ganglion cell layer (GCL) thinning were both associated with global brain atrophy (SD effect size [95% CI] -0.090 [-0.118 to -0.062] and 0.066 [0.053-0.080], respectively), and hippocampal atrophy (-0.029 [-0.055 to -0.003] and 0.114 [0.087-0.141], respectively). The effect of VA on whole brain and hippocampal volume was partly mediated by retinal neurodegeneration. Similarly, the effect of retinal neurodegeneration on brain and hippocampal atrophy was mediated through intermediate visual tracts, accounting for 5.2%-23.9% of the effect. Visual impairment and retinal neurodegeneration were robustly associated with worse brain atrophy, FA, and hippocampal atrophy, partly mediated through disintegration of intermediate visual tracts. Our findings support the use of OCT-derived retinal measures as markers of neurodegeneration, and indicate that both general and transneuronal neurodegeneration along the visual pathway, partly reflecting visual impairment, account for the association between retinal neurodegeneration and brain atrophy.

Knowledge, attitudes, and practices of parents toward sexuality education for primary school children in China.

This cross-sectional study provides insight into the perceptions of Chinese parents of primary school children with respect to sexuality education. A sample of 19,745 parents was surveyed using an online questionnaire in Beijing, Tianjin, and Hebei, China. SPSS version 23.0 was used for data analysis. In this study, nearly 90% of parents had positive attitudes toward the sexuality education of children in primary schools. However, Chinese parents had limited knowledge of sexuality education. More than 60% of parents were unaware of the sexuality questions that children may encounter at different ages and did not have any accurate information on child sexual abuse prevention education. Although ~ 70% of parents (both fathers and mothers) reported that they had used television and Internet resources to talk with their children about sexuality and 63% reported that they had read books with their children about sexuality, < 30% reported using appropriate terminology with their children on sexuality education and only 40% reported talking to their children about sexuality comfortably. The multivariate linear regression equation showed some factors associated with the practices of parents in sexuality education, including parental knowledge, attitudes, their experience in receiving sex education in childhood, and their educational level. The findings from this study suggest that it is important to develop culturally relevant training programs for parents of primary schools in Chinese society. The implications and limitations of these findings are discussed.