Statistical Analysis of Gait Maturation in Children Using Nonparametric Probability Density Function Modeling

Analysis of gait dynamics in children may help understand the development of neuromuscular control and maturation of locomotor function. This paper applied the nonparametric Parzen-window estimation method to establish the probability density function (PDF) models for the stride interval time series of 50 children (25 boys and 25 girls). Four statistical parameters, in terms of averaged stride interval (ASI), variation of stride interval (VSI), PDF skewness (SK), and PDF kurtosis (KU), were computed with the Parzen-window PDFs to study the maturation of stride interval in children. By analyzing the results of the children in three age groups (aged 3–5 years, 6–8 years, and 10–14 years), we summarize the key findings of the present study as follows. (1) The gait cycle duration, in terms of ASI, increases until 14 years of age. On the other hand, the gait variability, in terms of VSI, decreases rapidly until 8 years of age, and then continues to decrease at a slower rate. (2) The SK values of both the histograms and Parzen-window PDFs for all of the three age groups are positive, which indicates an imbalance in the stride interval distribution within an age group. However, such an imbalance would be meliorated when the children grow up. (3) The KU values of both the histograms and Parzen-window PDFs decrease with the body growth in children, which suggests that the musculoskeletal growth enables the children to modulate a gait cadence with ease. (4) The SK and KU results also demonstrate the superiority of the Parzen-window PDF estimation method to the Gaussian distribution modeling, for the study of gait maturation in children.This work was supported by the Fundamental Research Funds for the Central Universities of China (grant no. 2010121061), the Natural Science Foundation of Fujian (grant no. 2011J01371), and the National Natural Science Foundation of China (grant no. 81101115). N. Xiang was supported by Xiamen University Undergraduate Innovation Training Project (grant no. XDDC201210384072). Z. T. Zhong was supported by the Fundamental Research Funds for the Central Universities (grant no. CXB2011023). J. He was supported by the Xiamen University undergraduate student innovative experiment project (grant no. XDDC2011007). The authors acknowledge Hausdorff et al. for providing the data of gait experiments with public access via PhysioNet

Clinical efficacy of periodontal endoscopy-assisted subgingival scaling and root planning and its effect on psychology and quality of life in patients with periodontitis

Objective To investigate the clinical efficacy and effects of periodontal endoscope (PE)-assisted subgingival scaling and root planning (SRP) and traditional SRP on the psychological and quality of life of patients with periodontitis. Methods This study was reviewed and approved by the Ethics Committee, and informed consent was obtained from the patients. Patients with periodontitis who were treated in the Department of Periodontology, Nanjing Stomatological Hospital, Medical School of Nanjing University from April 2018 to December 2022 with residual periodontal pockets (PD ≥ 5 mm) 6 weeks after traditional SRP treatment were enrolled, and the residual periodontal pockets were further treated with PE-assisted SRP (PE+SRP). After 6 weeks of traditional SRP treatment and 3 months of PE+SRP treatment, clinical indicators, including plaque index (PLI), probing depth (PD), clinical attachment loss (CAL) and bleeding on probing (BOP), were measured, and periodontal tissue self-awareness scale scores, oral health impact profile-14 (OHIP-14) score and dental fear scale (DFS) score were collected. Moreover, visual analog scale (VAS) scores were collected after traditional SRP and PE-assisted SRP treatments. Results Twenty-three patients with periodontitis, including 832 sites of 486 affected teeth, were included in the clinical study. Three months after PE+SRP treatment, all clinical periodontal indicators, PLI (t = 9.254, P<0.001), PD (t = 50.724, P<0.001), CAL (t = 22.407, P<0.001) and BOP (t = 9.217, P<0.001), were significantly improved. Compared with traditional SRP (VAS: 2.48 ± 1.70), the pain caused by PE+SRP (VAS: 2.57±1.80) was not significantly different (t = 0,192, P = 0.850). There was no significant difference in the scores of the periodontal tissue self-awareness scale between the two groups (t = 1.485, P = 0.152). The OHIP-14 (SRP: 12.13±7.63; PE+SRP: 10.26 ± 5.25, t = -1.589, P = 0.126) and DFS (SRP: 40.70 ± 12.63; SRP+PE: 41.57 ± 12.61, t = 0.404, P = 0.690) scores were not significantly different. Conclusion All clinical periodontal indicators were significantly improved after PE-assisted SRP treatment of residual periodontal pockets, and compared with traditional SRP, PE-assisted SRP had no negative impact on the quality of life or psychological status of patients with periodontitis. Therefore, PE+SRP can be promoted in clinical practice

PROBABILISTIC FATIGUE LIFE PREDICTION APPROACH FOR MULTI-SITE DAMAGE COMPONENTS

Fatigue is a phenomenon of high uncertainty,especially for components with multiple damage sites.The fatigue life（ either mean value or probability distribution of the random variable） of a complex component with multiple damage sites is not equal to that of a simple component with only one damage site.A multi-site damage component is a series system with many weak links（ damage sites） in probability sense.A probabilistic fatigue life prediction model for multi-site damage component is presented based on a systematic thought,as well as the order statistics and extreme statistics concept.Such developed model can naturally reflect the effect of the dependence among different damage sites.Experimental result and the example on multi-site damage component fatigue life prediction shows that the fatigue life of a multi-site damage component is much lower than that of a single site damage component

Simulation Analysis and Experimental Study of the Strength of Aluminum Alloy Suspension Structure

High-speed trains have a large amount of ancillary equipment, which is suspended from the underside of the train by means of a suspension structure. Due to the large mass of the ancillary equipment, the suspension structure is subjected to various loads during train operation and there is a risk of fatigue failure. In this paper, the stress distribution at the suspension point and the lo-cation of the maximum stress point under load are investigated in detail based on actual test loads at the suspension point and finite element simulation analysis. In order to further investigate the fracture failure of the suspension points, experimental studies were carried out. Firstly, static strength tests were carried out to obtain the load–displacement curves of the structural members and to determine the fracture strength of the structure based on the displacement sensors, and secondly, fatigue tests at different stress levels were carried out to obtain the load–life curves of the structural members and to investigate the probabilistic load–life curves at different reliability levels. The test results show that the structural component has a high fracture strength of 65kN, while the conditional fatigue strength is relatively low, corresponding to a load level of 12.5kN at a median life of 106 cycles. The above research work provides the necessary basis for the design, optimization and reliability assessment of the suspension structures of high-speed trains

Fabrication and Mechanical Properties of SiCw(p)/SiC-Si Composites by Liquid Si Infiltration using Pyrolysed Rice Husks and SiC Powders as Precursors

Dense silicon carbide (SiC) matrix composites with SiC whiskers and particles as reinforcement were prepared by infiltrating molten Si at 1550 °C into porous preforms composed of pyrolysed rice husks (RHs) and extra added SiC powder in different ratios. The Vickers hardness of the composites showed an increase from 18.6 to 21.3 GPa when the amount of SiC added in the preforms was 20% (w/w), and then decreased to 17.3 GPa with the increase of SiC added in the preforms up to 80% (w/w). The values of flexural strength of the composites initially decreased when 20% (w/w) SiC was added in the preform and then increased to 587 MPa when the SiC concentration reached 80% (w/w). The refinement of SiC particle sizes and the improvement of the microstructure in particle distribution of the composites due to the addition of external SiC played an effective role in improving the mechanical properties of the composites

Functional properties of glutelin from Camellia oleifera seed cake: Improvement by alkali-assisted phosphorylation through changes in protein structure

To explore the effect and its mechanism of alkali-assisted phosphorylation on the functional properties of Camellia Oleifera seeds cake glutelin (CSCG), CSCG was treated with different concentration of sodium trimetaphosphate (STMP, 1.0, 2.0, 3.0, 4.0, and 5%, w/v) in different pH environment (3.0, 5.0, 7.0, 9.0, and 11.0). The results showed that alkali assist improved the phosphorylation degree of CSCG, and the optimum pH value is 9.0. FT-IR and XPS confirmed the successful modification of phosphate groups on CSCG through covalent interaction. Alkali-assisted phosphorylation decreased the particle size and increased electronegativity of CSCG, as well as changed in its surface hydrophobicity, crystallinity, and intrinsic fluorescence. All these changes of protein structure triggered by alkali-assisted phosphorylation led to the improvement of water solubility, water/oil absorption capacity, emulsifying ability, foamability, and in vitro digestibility of CSCG. This work could provide a theoretical basis for industrial production of CSCG with excellent functional properties

An improved sensor for the magnetic susceptibility imaging technique for detecting impurities in non-ferromagnetic materials

International audienceA cantilever-based sensor of magnetic force is a potential tool for magnetic susceptibility imaging in bulky materials. To solve the limitations of the previously reported sensors, in this study, a Hall device is employed to measure the magnetic field variation caused by the displacement of sensing magnet attached to the free end of the cantilever. The improved sensor has the smaller size and the higher lateral resolution and the adopted permanent magnet can be attached onto the cantilever’s free end to improve its sensitivity to the magnetic susceptibility. Based on the improved sensor configuration, two types of sensors are presented and their performances are experimentally investigated. Type-1 sensor with the cylindrical sensing magnet with a diameter of 5 mm is capable of detecting a cubic impurity (with a side length of 1 mm) of 304 stainless steel or aluminum with a depth of 1 mm in a photosensitive resin block. Type-2 sensor employs a sensing magnet with a diameter of 1.2 mm and possesses higher lateral resolution than Type-1 sensor. The estimated sensitivity of Type-2 sensor is about one third of that of Type-1 sensor. Although the impurity of aluminum and even resin cannot be distinguished from the air background in the magnetic susceptibility imaging results obtained by Type-2 sensor, the cubic impurity of 304 stainless steel can be successfully detected by Type-2 sensor