Curve Fitting Research Articles

Cumulative damage characteristics of tunnel initial support concrete under blasting load

Relying on the Beijing-Zhangjiakou high-speed railway Cao Mao Shan tunnel project, blasting vibration monitoring and sound wave testing experiments were carried out. The monitoring results show that the blasting vibration velocity corresponding to the initial support satisfies the Sadowski formula. The results of the sonic test show that with the increase of blasting times, the cumulative damage increases gradually, but the blasting damage increment shows a downward trend. In addition, as the blasting distance decreases, the blasting cumulative damage effect is significant. Through data analysis and curve fitting, the cumulative damage range Rcr and critical blasting vibration velocity PPVcr corresponding to blasting construction are obtained respectively. The numerical analysis results show that there is a good exponential function relationship between the cumulative damage range Rcr and the corresponding critical blasting vibration velocity PPVcr. The purpose of quantitative control of blasting damage can be achieved by setting the corresponding vibration velocity threshold.

High output stoma after surgery for rectal cancer - a risk factor for low anterior resection syndrome?

PurposeThe relationship between high-output stoma (HOS) and low anterior resection syndrome (LARS) was previously unclear. This study investigated the association between HOS and major LARS in rectal cancer patients with preventive stoma.MethodsWe conducted a retrospective analysis of 653 rectal cancer patients who underwent prophylactic ileostomy reversal after low anterior resection at the Fourth Hospital of Hebei Medical University between 2018 and 2021. Patients were categorized into HOS and non-HOS groups based on stoma output within 3 months before surgery. Major LARS was assessed using the LARS score. The association between HOS and major LARS was analyzed using multifactor logistic regression models, subgroup analyses, and smoothing curve fitting methods.ResultsAmong the 653 patients, 53 (8.1%) experienced HOS, and 81 (12.4%) developed major LARS after stoma closure. The HOS group exhibited a significantly higher risk of major LARS compared to the non-HOS group (P < 0.001). Multivariate logistic regression indicated that HOS was associated with a 210% increased risk of major LARS (OR: 3.10; 95% CI: 1.56, 6.14; P = 0.001). Subgroup analysis revealed that this association was more pronounced in older patients (age > 60), those without hypertension, with N0-N1 staging, a history of chemotherapy, and longer stoma closure intervals (Q3, Q4).ConclusionHOS is significantly associated with major LARS in rectal cancer patients, particularly in certain clinical subgroups. These findings suggest the need for careful management of HOS to potentially reduce LARS occurrence after stoma closure.

Triglyceride glucose-waist circumference as a useful predictor for diabetes mellitus: a secondary retrospective analysis utilizing a Japanese cohort study

Background and objectiveWhile the connection between the Triglyceride glucose-waist circumference (TyG-WC) index and the risk of diabetes remains understudied, this particular research delves into the potential predictive value of the TyG-WC index within a significant Japanese population.MethodsThis retrospective cohort study encompassed a comprehensive analysis of 15,413 Japanese adults, all of whom were diabetes-free at the outset of the study period from 2004 to 2015. Comprehensive medical records were obtained for all participants who underwent physical examinations. The study employed Cox proportional-hazards regression, smooth curve fitting, various sensitivity, and subgroup analyses to explore the association between TyG-WC and the development of diabetes. Furthermore, a Receiver Operating Characteristic (ROC) curve was created to detect the predictive capability of TyG-WC for diabetes risk.ResultsAfter a maximum of 13.0 years of follow-up, 358 people finally developed diabetes. Upon adjusting for covariates, the result showed TyG-WC was positively and independently associated with incident Diabetes Mellitus (DM) (Hazard Ratio (HR): 1.004, 95%C: 1.001–1.006). Furthermore, ROC curve analysis demonstrated that TyG-WC outperformed both the triglycerides-glucose index and triglyceride glucose-body mass index in predicting the onset of diabetes.ConclusionHigh levels of TyG-WC are autonomously linked to a heightened risk of diabetes in the Japanese demographic, indicating its potential as a dependable predictive indicator for diabetes mellitus in individuals at elevated risk.

Nonlinear association between depressive symptoms and homeostasis model assessment of insulin resistance: a cross-sectional analysis in the American population.

Depressive symptom, a pervasive mental health disorder, has garnered increasing attention due to its intricate interconnections with various physiological processes. One emerging avenue of investigation delves into the potential association between depressive symptom and Homeostasis Model Assessment of Insulin Resistance (HOMA-IR), a parameter reflecting insulin resistance. The intricate interplay between these two domains holds promising implications for understanding the multifaceted nature of depressive symptom and its impact on metabolic health. We used weighted multivariable logistic regression models with subgroup analysis to explore the relationship between depressive symptom and homeostasis model assessment of insulin resistance. Non-linear correlations were explored using fitted smoothing curves. Then, we constructed a two-piece linear regression model and performed a recursive algorithm to calculate the inflection point. The study included 20,282 participants in the United States. In the regression model adjusted for all confounding variables, the odds ratio (OR) for the correlation between depressive symptom and the Homeostasis Model Assessment of Insulin Resistance (HOMA-IR) was 1.01 (95% CI: 1.00, 1.01). However, a significant discrepancy between trend tests and regression analyses suggests a potential non-linear relationship between depressive symptom and the assessment of insulin resistance using the Homeostasis Model. Constrained cubic spline analysis confirmed this non-linear relationship, identifying an inflection point at 10.47. Before the inflection point, depressive symptom exhibited a significantly positive correlation with the assessment of insulin resistance using the Homeostasis Model. However, after the inflection point, a negative correlation was observed, though it did not reach statistical significance. We found a curve-like relationship between depressive symptom and homeostasis model assessment of insulin resistance.

Association of anxiety status and anxiety duration with constipation in adult Americans: a cross-sectional study using data from the NHANES 2007–2010

BackgroundConstipated patients may exhibit anxious behaviors, but the relationship between the two remains unclear. This population-based study aims to investigate the relationships of anxiety status and anxiety duration with constipation among U.S. adults.MethodsUsing data from the National Health and Nutrition Examination Survey (NHANES) database spanning from 2007 to 2010, a cross-sectional study included 8945 participants was performed to assess the relationships of anxiety status and anxiety duration with constipation. Participants’ characteristics were presented using mean or proportion. Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using multivariable logistic regression models. The analysis accounted for potential confounding factors, including gender, age, race/ethnicity, education level, marital status, PIR, BMI, smoking status, drinking status, chronic diseases, and dietary intake. Subgroup analyses were conducted to ensure the stability of the results. Smoothed curve fitting was applied to investigate both linear and nonlinear associations between anxiety duration and constipation risk. Threshold effects were assessed using two-piecewise linear regression models.ResultsOf the 8945 participants, 922 reported constipation, with a prevalence of 10.3%. After adjusting for confounding factors, individuals with anxiety status exhibited an increased risk of constipation (OR: 1.49, 95% CI: 1.28–1.73). Stratified analyses indicated that the association between anxiety status and constipation remained relatively stable across different stratification levels. Smoothed curve fitting and threshold effect analyses revealed a linear association between anxiety duration and constipation among adults aged 20–60, while a nonlinear inverted U-shaped relationship was observed in those aged 60 and older, with an inflection point at 10 days. The two variables correlated positively on the left side of the inflection point but not on the right.ConclusionThis study showed that a significant association between anxiety status and constipation among U.S. adults. Additionally, an age-dependent association between anxiety duration and constipation was observed, particularly among individuals aged 60 and older.

Association between a body shape index and bone mineral density in US adults based on NHANES data

The relationship between a body shape index (ABSI) and bone mineral density (BMD) remains uncertain, prompting further investigation. This study aims to elucidate the association between ABSI and BMD using data from the 2011–2018 National Health and Nutrition Examination Survey (NHANES), involving participants aged 20–60. ABSI was calculated using the formula: ABSI = 1000 × waist circumference (m)×weight (kg)−2/3×height (m)5/6. The analysis employed weighted multiple linear regression, smooth curve fitting, stratified analysis, and interaction tests to explore the relationship between ABSI and total BMD. The study included 10,291 participants, with a mean age of 39.11 ± 10.77 years, and 49.20% were women. The average ABSI was 80.21 ± 1.50. Total BMD, thoracic spine BMD, lumbar spine BMD, and pelvis BMD were measured, with mean values of 0.82 ± 0.11 g/cm², 1.03 ± 0.15 g/cm², and 1.24 ± 0.16 g/cm2, respectively. A negative correlation between ABSI and total BMD was observed. In the fully adjusted model, individuals in the highest ABSI quartile had total BMD levels 0.045 g/cm² lower than those in the lowest quartile. Interaction tests showed a consistent association between ABSI and total BMD across subgroups, with variations in sex and BMI. This analysis of NHANES data confirms a persistent negative association between ABSI and BMD, suggesting that ABSI could be useful in osteoporosis prevention and diagnosis.

Rutting Caused by Grouser Wheel of Planetary Rover in Single-Wheel Testbed: LiDAR Topographic Scanning and Analysis

This paper presents datasets and analyses of 3D LiDAR scans capturing the rutting behavior of a rover wheel in a single-wheel terramechanics testbed. The data were acquired using a LiDAR sensor to record the terrain deformation caused by the wheel’s passage through a Toyoura sandbed, which mimics lunar regolith. Vertical loads of 25 N, 40 N, and 65 N were applied to study how rutting patterns change, focusing on rut amplitude, height, and inclination. This study emphasizes the extraction and processing of terrain profiles from noisy point cloud data, using methods like curve fitting and moving averages to capture the ruts’ geometric characteristics. A sine wave model, adjusted for translation, scaling, and inclination, was fitted to describe the wheel-induced wave-like patterns. It was found that the mean height of the terrain increases after the grouser wheel passes over it, forming ruts that slope downward, likely due to the transition from static to dynamic sinkage. Both the rut depth at the end of the wheel’s path and the incline increased with larger loads. These findings contribute to understanding wheel–terrain interactions and provide a reference for validating and calibrating models and simulations. The dataset from this study is made available to the scientific community.

Association between albumin changes and prognosis in older patients with acute myocardial infarction.

Acute myocardial infarction (AMI) is the leading cause of death in the world. Therefore, early identification of the prognosis of older patients with AMI are particularly urgent, and better to improve treatment. This study aimed to explore the association between albumin changes and prognosis in older patients with AMI. Outcomes included all-cause death during hospitalization, cardiac death, gastrointestinal hemorrhage, nonfatal myocardial infarction, acute heart failure, and severe arrhythmia. Multivariable-adjusted Cox regression analysis and curve fitting were used to assess the relationship between albumin changes and prognosis in patients with AMI. Our study included 288 older patients with AMI. A S-shaped association between the albumin changes and mortality of patients with AMI was found. For all-cause death, we found two inflection points were - 3.27 and 0.92 g/L. On the left side of -3.27 g/L, the OR was 0.41 (OR: 0.41, 95%CI: 0.32-0.64, p < 0.05). On the right side of 0.92 g/L, the OR was 0.58 (OR: 0.58, 95%CI: 0.34-0.86, p < 0.05). The OR was 2.12 between -3.27 and 0.92 g/L (OR: 2.12, 95%CI: 1.16-6.24, p < 0.05). For cardiac death, two inflection points were - 3.19 and 1.17 g/L. On the left side of -3.19 g/L, the OR was 0.45 (OR: 0.45, 95%CI: 0.28-0.79, p < 0.05). On the right side of 1.17 g/L, the OR was 0.63 (OR: 0.63, 95%CI: 0.38-0.86, p < 0.05). The OR was 4.53 between -3.19 and 1.17 g/L (OR: 4.53, 95%CI: 0.90-12.52, p > 0.05). After adjusting for all potential covariates, albumin changes were negatively associated with gastrointestinal hemorrhage (OR: 0.87; 95%CI: 0.81-0.94, p < 0.001). After adjusting for all potential covariates, albumin changes were negatively associated with acute heart failure (OR: 0.86; 95%CI: 0.75-0.99, p = 0.046). Out findings showed that a S-shaped association between the albumin changes and mortality of older AMI patients, with the inflection of roughly -3.27 g/L and 0.92/L. And changes in albumin levels are negatively correlated with gastrointestinal bleeding and acute heart failure. These findings were helpful for the clinical treatment.

The atherogenic index of plasma is associated with an increased risk of diabetes in non-obese adults: a cohort study.

This study aims to investigate the relationship between the atherogenic index of plasma (AIP) and diabetes risk in Chinese non-obese adults. This is important because the incidence of diabetes is significant in non-obese populations, and evidence regarding this association is limited. We conducted a retrospective cohort study with 82,977 Chinese non-obese adults. We used Cox proportional hazards regression to assess the relationship between baseline AIP levels and diabetes incidence. We also employed cubic spline functions and smooth curve fitting to investigate potential nonlinear relationships. Sensitivity and subgroup analyses were conducted to validate our findings. The median follow-up duration for these participants was 3.10 years, during which 1,041 subjects (1.25%) were diagnosed with diabetes. Adjusted analyses demonstrated a strong positive association between AIP and the risk of diabetes onset (HR 2.07; 95% CI: 1.63-2.63; p < 0.001). The risk of diabetes increased with higher AIP quartiles, especially between the highest (Q4) and lowest (Q1) quartiles (adjusted HR 1.55; 95% CI: 1.27-1.89). We also identified a nonlinear relationship between AIP and diabetes risk. Sensitivity and subgroup analyses confirmed these findings. Furthermore, E-value analysis indicated that the results were robust against unmeasured confounding variables. Our findings highlight a positive, nonlinear association between AIP and diabetes risk in Chinese non-obese adults. Lowering triglycerides (TG) or increasing high-density lipoprotein cholesterol (HDL-C) levels may help reduce this risk.

Association between base excess and mortality in septic older adults.

Septic older adults represent a vulnerable population with high mortality rates. Base excess (BE), an indicator of acid-base status, may serve as a prognostic marker in sepsis. This study aimed to investigate the association between BE and mortality in septic older adults. A retrospective analysis included septic older adults (age ≥ 65 years) from the Medical Information Mart for Intensive Care (MIMIC)-IV database. The primary outcome was 30-day mortality. Multivariate Cox regression models and Kaplan-Meier analysis were used to assess the association between BE and 30-day mortality. A two-segment linear regression model with smooth curve fitting was employed to examine threshold effects of BE on clinical outcomes. The study comprised 7379 participants, with a 21.8% 30-day mortality rate and an 18.6% in-hospital mortality rate. A nonlinear, U-shaped relationship (P < 0.001) was observed between BE and 30-day mortality in septic older adults, indicating increased risk with higher or lower BE levels. Various BE groups showed different hazard ratios for mortality: 2.7 (2.26-3.22), 1.86 (1.65-2.09), 1.41 (1.19-1.67), and 1.9 (1.4-2.58), respectively, compared with the reference group (-3 mEq/L ≤ BE < 3 mEq/L). The inflection point was calculated as 0.5 mEq/L. Our findings suggest a U-shaped relationship between BE and mortality in septic older adults, emphasizing the importance of monitoring acid-base status in sepsis management for this population. Geriatr Gerontol Int 2025; ••: ••-••.

Associations between oxidation balance score and abdominal aortic calcification, and the mediating role of glycohemoglobin: a nationally representative cross-sectional study from NHANES.

Abdominal aortic calcification (AAC) is prevalent among middle-aged and elderly populations, elevating the risk of cardiovascular and cerebrovascular events. Leveraging data from the National Health and Nutrition Examination Survey (NHANES), we conducted a nationally representative cross-sectional study. Our aim was to evaluate whether subjective interventions could influence AAC scores by modifying the antioxidant/pro-oxidant status of individuals and to investigate the role of glycohemoglobin in this relationship. The study analyzed data from 1,600 U.S. adults. The study used oxidation balance score (OBS) as an exposure variable derived from 16 dietary and 4 lifestyle factors, as well as glycohemoglobin obtained from blood tests. The main outcome measure was AAC, which was evaluated by dual-energy X-ray absorption and quantified by Kauppila scoring system. The mean (SD) age of the 1,600 patients was 56.53 (10.90) years, with a female predominance (50.22%). According to weighted linear regressions not adjusted for covariates, the AAC scores were lower in the third and fourth quartile groups of OBS than in the first quartile group of OBS (Q3: coefficients [coef], -0.92 [95% CI, -1.64 to-0.20], p = 0.017; Q4: coefficients [coef], -0.97 [95% CI, -1.86 ~ -0.08; p < 0.035]). According to the weighted linear regression subgroup analyses, there were no significant OBS-AAC correlations among males (p > 0.05), but there were significant correlations among females (p < 0.05). Smooth fitting curves showed a more significant trend of change in the negative correlation between OBS and AAC scores in postmenopausal women than in premenopausal women. In further mediation analyses, glycohemoglobin was identified as a mediator of the relationship between the oxidative balance score and AAC. This study revealed a significant negative correlation between OBS and AAC scores, particularly in postmenopausal women. The negative correlation between OBS and AAC is partly mediated by glycohemoglobin.

Hyperelastic constitutive modeling of healthy and enzymatically mediated degraded articular cartilage.

This research demonstrates a systematic curve fitting approach for acquiring parametric values of hyperelastic constitutive models for both healthy and enzymatically mediated degenerated cartilage to facilitate finite element modeling of cartilage. Several widely used phenomenological hyperelastic constitutive models were tested to adequately capture the changes in cartilage mechanics that vary with the differential/unequal abundance of matrix metalloproteinases (MMPs). Trauma and physiological conditions result in an increased production of collagenases (MMP-1) and gelatinases (MMP-9), which impacts the load-bearing ability of cartilage by significantly deteriorating its extracellular matrix (ECM). The material parameters in the constitutive equation of each hyperelastic model are significant for developing a comprehensive computational interpretation of MMP mediated degenerated cartilage. Stress-strain responses obtained from indentation test were fitted with selected Ogden, polynomial, reduced polynomial, and van der Waals hyperelastic constitutive models by optimizing their adjustable parameters (material constants). The goodness of fit of the 2nd order reduced polynomial and van der Waals model exhibited the closest data fitting with the experimental stress-strain distributions of healthy and degraded articular cartilage. The coefficient of the shear modulus for the 2nd order reduced polynomial decreased gradually by 21.9% to 80.1% with more enzymatic degradation of collagen fibril due to the relative abundance of MMP-1 (collagenases), and 28.5% to 69.2% for the van der Waals model. Our findings showed that the major materials coefficients of the models were reduced in the degenerated cartilages, and the reduction varied differentially with the relative abundance of MMPs-1 and 9, correlating the severity of degeneration. This work advances the understanding of cartilage mechanics and offers insights into the impact of biochemical (enzymatic) effects on cartilage degradation.

Inverse association of triglyceride-glucose and triglyceride/HDL-c indexes with serum 25(OH) vitamin D levels in US adults.

The triglyceride-glucose index (TyG) and the triglyceride to high-density lipoprotein ratio (TG/HDL-c) are novel indicators for assessing insulin resistance (IR) in epidemiological studies. This study aimed to evaluate the association between 25-hydroxy-vitamin D [25(OH)D] levels and these two indicators in the adult population of the United States. 14,380 participants aged 20 years and older were included from the National Health and Nutrition Examination Survey (NHANES). Multivariable linear regression models were used to analyze the association between 25(OH)D and TyG, as well as TG/HDL-c. Smooth fitting curves were employed to identify potential non-linear relationships between 25(OH)D, TyG, and TG/HDL-c. The findings revealed a negative association between 25(OH)D and TyG, with the effect being more pronounced in males and individuals with diabetes (p < 0.01). Similarly, 25(OH)D was negatively associated with TG/HDL-c, with a stronger impact observed in males compared to females. The study population was divided into four quartiles based on 25(OH)D concentration, and TyG and TG/HDL-c levels in Q3 and Q4 were lower than those in Q1. Furthermore, a non-linear relationship was observed between 25(OH)D and TyG, with an inflection point at 19.352 ng/mL. A non-linear relationship was also found between TG/HDL-c and 25(OH)D, with an inflection point at 37.211 ng/mL. 25(OH)D is an independent factor significantly associated with TyG and TG/HDL-c indexes. This negative association may be related to the role of 25(OH)D in insulin resistance.

The nonlinear association between body roundness index and infertility in married women

Infertility is increasingly linked to obesity, especially visceral fat accumulation. The Body Roundness Index (BRI) provides a precise quantification of body and visceral fat but its implications for infertility risks and diagnostic value are yet to be fully determined. This study analyzed data from 1,305 married women aged 20–45 years, drawn from the National Health and Nutrition Examination Survey (NHANES). Logistic regression was utilized to examine the relationship between BRI and infertility, incorporating univariate and multivariate regression analyses, smooth curve fittings, and subgroup analyses. Additionally, Receiver Operating Characteristic (ROC) analysis assessed the predictive capability of BRI for infertility. An increase in one unit of BRI correlated with a 13% higher prevalence of infertility after adjusting for covariates (OR = 1.13; 95% CI: 1.05, 1.21). Women with higher BRI exhibited greater infertility odds compared to the reference group (OR: 2.20, 95% CI: 1.42, 3.42). Smooth curve fitting analysis revealed a positive, nonlinear relationship, with an inflection point observed at a BRI value of 7.95. Subgroup analyses upheld the robustness of this association across varied demographic segments. ROC curves indicated significant diagnostic potential of BRI in younger women, whereas its predictive relevance diminished in those over 35, akin to other obesity markers. This study is the first to rigorously affirm a strong link between increased BRI and the higher prevalence of infertility among married women aged 20–45. To optimize fertility, maintaining a healthy weight and waist circumference is recommended. The integration of BRI into clinical practice could assist in early intervention for women at risk of infertility. However, further research is required to identify effective predictive markers for infertility in women aged 36–45.

Body Mass Index mediates the relationship between estimated glucose disposal rate and gallstones

This study examined the relationship between gallstones and estimated glucose disposal rate (eGDR) in people in the United States and the possible mediating function of body mass index (BMI). Data came from the National Health and Nutrition Examination Survey (NHANES), conducted between 2017 and March 2020. Logistic regression, subgroup analysis, smoothed curve fitting, and causal mediation studies were among the statistical techniques used to examine the participant data. There were 595 subjects with a gallstone diagnosis out of 5,656 total. A significant negative association between eGDR and gallstones was observed by fully adjusted multivariate logistic regression analysis with an OR of 0.90 and a 95% confidence interval (CI) of (0.83, 0.98). The mediation analysis indicated that BMI accounted for 58.58% of the relationship between eGDR and the occurrence of gallstones. This study identified a substantial non-linear negative relationship between the occurrence of gallstones and eGDR levels, with BMI acting as a mediating factor. A fresh viewpoint on gallstone therapy and prevention is offered by these findings.

The clinical application and anatomical analysis of proximal peroneal artery perforator in free fibula flap based on CTA

BackgroundThe vascularized free fibular flap is increasingly recognized as the standard technique for the repair of complex soft tissue and hard tissue defects in oral and maxillofacial surgery. Conventionally, the vascular supply to the skin island is derived from the distal perforators of the peroneal artery. However, complications may arise if these distal perforators are either absent or damaged during surgical procedures, highlighting the necessity to employ the proximal peroneal perforators as an alternative. This study aims to investigate the anatomical characteristics—including the presence, distribution, and origin—of proximal peroneal perforators through computed tomography angiography (CTA) prior to surgical intervention. A secondary objective is to confirm their viability when distal perforators are unavailable or when dual-skin paddles are needed.MethodsA comprehensive review was conducted involving 50 patients who underwent CTA examinations. Three-dimensional reconstruction of DICOM data was utilized to document the presence, quantity, location, and variations of proximal perforators. Relative positions of the origin points were measured, and the distances from these points to the fibula were calculated. Additionally, 11 studies were included in which a proximal perforator was successfully used to prepare a free fibula chimeric myocutaneous flap for the reconstruction of maxillofacial defects.ResultsAmong the 100 lower limbs evaluated, a successful identification rate of 98% for proximal perforators was achieved via CTA. Of those identified, 70% were found to originate from the fibular artery, 22% branched concurrently with it, and 8% emerged prior to the point of emergence of the fibular artery. Analysis through curve fitting indicated that the origin points of proximal perforators were predominantly located approximately 13.17 mm below the origin of the fibular artery, with their endpoints projecting about 123.9 mm below the fibular head.ConclusionsThe high prevalence of proximal peroneal perforators identified in this population, along with their relatively stable anatomical positions, suggests their significant surgical potential. In scenarios where the distal peroneal perforator is absent or suffers intraoperative injury, the proximal peroneal perforator can serve as a reliable alternative for preparing a free fibula osteal flap combined with a proximal peroneal perforator skin paddle.

Associations between systemic immune-inflammatory index and visceral adipose tissue area: results of a national survey.

Global health issues related to obesity are growing. Visceral adipose tissue (VAT) significantly contributes to complications associated with obesity. Reducing adipose tissue accumulation can improves inflammation. However, it is still unknown how the systemic immune-inflammation index (SII) and VAT area are related. With the help of multivariate linear regression and smooth curve fitting, the relationship between SII and VAT area was explored with data from the 2013 and 2014 National Health and Nutrition Examination Survey (NHANES). Analyzing subgroups and testing for interaction were used to investigate whether the relationship was accurate across demographics. From 20 to 59 years of age, 3,290 individuals were observed to have a positive correlation between SII and VAT area. In accordance with the fully adjusted model, the VAT area increased by 9.34 cm2 for every unit increase in log SII [β = 9.34, 95% CI (4.02, 14.67)]. In the highest quartile of SII, the VAT area was 5.46 cm2 [β = 5.46, 95% CI (2.21, 8.71)] higher than that in the lowest quartile. Additionally, the population that was overweight or obese showed a stronger positive correlation. SII has a positive correlation with VAT area in US adults. SII may be valuable in clinical applications to evaluate the severity of VAT area.

Control Synthesis for Hypersonic Vehicle Flight Testing with Input–Output-Sampled Nonlinearities

The flight testing of hypersonic vehicles is challenging due to the nonlinear, uncertain, and possibly unstable dynamics of these vehicles. This paper presents a control synthesis method for a hypersonic vehicle with the purpose of guaranteeing robust stability during flight testing when accurate analytic vehicle models are unavailable. Conventional model-based approaches typically rely on curve fitting of numerical simulation and test data, which can introduce inaccuracies. Our proposed approach assumes knowledge of the linear form of the ordinary differential equation and uses quadratic constraints to bound sampled data that accounts for the nonlinear and uncertain portion of the model for controller synthesis by iteratively solving convex semidefinite programs. A numerical example demonstrating the effectiveness of the proposed method is performed before applying the technique to a nonlinear hypersonic vehicle found in the literature. Using the synthesized stabilizing controller, we demonstrate that the vehicle states remain within a certified bound given a known harmonic excitation when initiated from a quantified set of allowable initial conditions. Based on these simulation results, our proposed control synthesis method shows promise in ensuring robustness when performing hypersonic vehicle flight testing.

Global path planning on uneven terrain at construction sites for robots based on an improved A* Algorithm

With the increasing application of construction robots on construction sites, autonomous path planning in unstructured and uneven construction sites has become an urgent challenge. Current path planning approaches face several issues, including prolonged computation times, low efficiency, and redundant nodes, often resulting in impractical paths for robots. Addressing these concerns, this study introduces a global path planning method based on an enhanced A* algorithm to ensure safe and robust navigation of construction robots in such challenging environments. The Improved A* algorithm initially incorporates a bidirectional alternating search strategy to expedite computational speed. Subsequently, it employs path node filtering to mitigate issues associated with bidirectional search and reduce the number of critical nodes, thereby enhancing search efficiency. Furthermore, the introduction of slope constraints decreases the robot's climbing and tilting angles, augmenting the safety of the planned paths. Finally, the paths are smoothed using Bézier curve fitting, facilitating better motion control for the robots. The efficacy of the improved algorithm was validated through experiments on elevation maps with varying terrain and obstacle densities. Simulation results indicate that, compared to the traditional A* algorithm, the Improved A* algorithm reduced computation time by 71.05% to 82.90% and the number of critical nodes by 51.94% to 70.53%, while only increasing the path length by 14.6% to 37.84%. Additionally, there was a significant reduction in climbing and tilting angles, and the paths have become smoother. Therefore, this method not only improves efficiency while generating safe and reliable paths in unstructured and uneven construction sites, but also enables robots to adapt to complex environments, and promotes automation and intelligent construction processes.

Non-high-density to high-density lipoprotein cholesterol ratio and its association with infertility in U.S. women: a cross-sectional study.

To investigate the relationship between Non-High-Density Lipoprotein Cholesterol to High-Density Lipoprotein Cholesterol Ratio (NHHR) and infertility in US female adults aged 20 to 45. Our research team utilized data from the 2013-2018 National Health and Nutrition Examination Survey (NHANES) to conduct a cross-sectional study. Multivariable logistic regression was conducted to examine the association between NHHR and infertility, with trend tests providing additional insight into this relationship. Further, smoothed curve fitting was applied for a more detailed exploration. To ensure the robustness of our results, we conducted subgroup and sensitivity analyses. Between 2013 and 2018, our study included 2,947 participants, with 342(11.6%) self-reported infertility. A positive association was found between NHHR and infertility (OR=1.17,95%CI:1.07-1.27). Compared with the first trimester, the third trimester of NHHR was associated with an OR of 1.79(95% CI: 1.31-2.44) in model 3. The results of subgroup analyses revealed that the association between NHHR and infertility was nearly consistent. NHHR demonstrated a positive correlation with infertility among U.S. female adults. Further investigation is needed to explore their association better and the underlying mechanisms.