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Background Osteoarthritis (OA) is the most common form of arthritis, causing by multiple factors. It has long been a belief that arthritis pain is influenced by the weather. However, scientific studies have documented inconsistent results. To date, neither systematic review nor meta-analysis of existing findings has comprehensively considered their relations. The present study will critically appraise and synthesize the existing evidence from observational studies that examined the relationship between certain climate conditions and OA. Methods and design: This protocol will be conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocols (PRISMA-P) guidelines. There are no restrictions on the study date or publication status for searches in the Cochrane Library, EMBASE, Web of Science, PubMed, and other relative databases. All eligible observational studies will be included, with weather conditions as effect factors and OA symptom or imaging abnormality as outcomes. Two reviewers will be responsible for data extraction and analysis. Risk of bias and quality appraisal will be performed for the included studies using Newcastle-Ottawa Scale (NOS). Meta-analysis will be conducted using Rev Man V.5.3 with the associations between weather conditions and OA presented by odds ratios (ORs), relative risks (RRs), hazard ratios (HRs) and the 95% confidence intervals (CIs). Results This systematic review and meta-analysis will present the overall association between weather conditions and OA. The association of climate factors influencing OA incidence or progression would be further illustrated in subgroup analysis depending on whether that has been extensively described in the literature. Discussion This study will provide the analysis evidence on the effect of meteorological factors on OA. In an approach of dealing with weather conditions, the results will benefit the daily management of OA.

Full-scale discharge tests of transmission line–tower air gaps are costly and time-consuming, and they cannot exhaustively simulate all the gap configurations in practical engineering. In this paper, a machine learning model established by support vector machine is introduced to predict the switching impulse discharge voltages of the ultra-high-voltage (UHV) AC transmission line–tower air gaps. The three-dimensional finite element models of a UHV cup-type tower and a UHV compact transmission line were established for electric field calculation, and some features were extracted from the hypothetic discharge channel and the shortest path between the bundled conductor and the tower. These features under a given voltage were normalised and input to the SVM model, while the output is two binary values, respectively, representing gap withstanding or breakdown. Trained by experimental data of one type of the UHV transmission line–tower gaps, the SVM model is able to predict the discharge voltages of another gap type. The mean absolute percentage errors of the two engineering gap types, under different gap distances, are 8.31 and 4.86%, respectively, which are acceptable for engineering applications. The results provide a possible way to obtain the discharge voltages of complicated engineering gaps by mathematical calculations.

Air insulation strength relates closely to the electrostatic field distribution of the gap configuration. To achieve insulation prediction on the basis of electric field (EF) simulations, the spatial structure is characterized by a feature set including 38 parameters defined on a straight line between sphere electrodes. A support vector classifier (SVC) with particle swarm optimization (PSO) is used to establish a prediction model, whose input variables are those features. The EF nonuniform coefficient f of each sample gap is calculated and used for training sample selection according to the ranges off values. Trained by only 11-sample data, the PSO-optimized SVC model is employed to predict the power frequency breakdown voltages of 260-sphere gaps with a wide range of structure sizes. The predicted values coincide with the standard data given in IEC 60052 very well, with the same trend and minor relative errors. The MAPEs of the five predictions with different training sets are within 2.0%. The model is also effective to predict the breakdown voltages of Φ9.75-cm sphere-Φ6.5-cm sphere gaps, whose MAPEs are within 2.6%. The results demonstrate the effectiveness of the EF feature set and the generalization ability of the SVC model under the case of limited samples. This paper lays the foundation for estimating the dielectric strength of other air gaps with similar structures.

The hybrid high-voltage direct current (HVDC) breaker combines mechanical and power electronics switching that enables it to interrupt power flows within a few milliseconds. Mechanical switch is a key component of hybrid HVDC breaker and has a number of serially connected interrupter units which ideally would divide the voltage equally. The static voltage distribution characteristics and voltage sharing design of a multi-break mechanical switch were discussed in this study. A finite-element model was developed to study the static voltage distribution characteristics and capacitance parameters of multi-break mechanical switch (which actually consists of resistance and capacitance parameters under direct current) as a preliminary study. Comparisons were made under the simulation of vertical and U-shaped arrangement forms. The results indicate that the static voltage distribution of the high-voltage terminal is at least more than 65%, whereas the severe non-uniform voltage distribution can be well improved by means of the method proposed in this study.

Background Patients with knee osteoarthritis (KOA) often complain about clinical symptoms affected by weather-related factors. The purpose of the present study was to use cross-sectional analysis to determine whether weather sensitivity was associated with clinical symptoms, as well as structure abnormalities, in KOA patients.Methods Data from 80 participants were obtained from the Feng Hans Shi Effects on OA (FHS) study, an OA cohort study initiated in China in 2015. The weather sensitivity of each participant was determined by a self-reported questionnaire. The following measurements were used to assess clinical and biological outcomes: a visual analog scale (VAS) for pain; Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC); and blood levels of tumor necrosis factor α (TNF-α), interleukin 6 (IL-6), and interleukin 1(IL-1). Structural changes identified via magnetic resonance imaging (MRI) were also evaluated. Independent sample t-tests, chi-square tests, Fisher’s exact tests, Cochran-Armitage tests for linear trends, and binary linear regression were used to evaluate the clinical characteristics, biomarkers, WOMAC, and Whole-Organ Magnetic Resonance Imaging Score (WORMS) of weather-sensitive KOA patients and non-weather-sensitive KOA patients.Results Most of the KOA participants (57.5%) perceived the weather as affecting their knee-joint clinical symptoms. Through logistic regression analysis, the presence of weather sensitivity was found to increase the risk of KOA participants reporting higher levels of WOMAC pain scores [OR = 3.3 (95% CI: 1.1, 9.9), P > 0.032], functional scores [OR = 5.5 (95% CI: 1.8,16.8), P > 0.003], total scores [OR = 3.3 (95% CI: 1.1, 10.2), P = 0.034], WORMS cartilage scores [OR = 3.1 (95% CI: 1.1, 8.5), P < 0.027], and marrow abnormality scores [OR = 3.0 (95% CI: 1.1, 8.1), P > 0.029].Conclusions Weather-sensitive KOA patients were prone to show more serious clinical symptoms and structural abnormalities in their knee joints. Therefore, the existence of weather sensitivity may accelerate the progress of KOA.

With the construction of 200 kV flexible DC power grid, 200 kV DC circuit breakers have been demanded. The fast mechanical switch, which is an important component in the hybrid DC circuit breaker, usually adopts multi-break structure to meet the requirements of breaking time and effective opening stroke. For a 200 kV double-break fast mechanical switch, the voltage characteristics in the breaking process were analyzed firstly. Then, the distributed capacitances' parameters were calculated by the finite element method. Finally, the voltage-sharing components' parameters were simulated by using PSCAD/EMTDC. It is suggested that the voltage-sharing capacitors' value be selected from 260 pF to 300 pF, 200 Ω for the current limiting resistor, and 200 MΩ for the voltage-sharing resistor. The research can provide a reference for the voltage-sharing design of mechanical switches in non-arc hybrid DC circuit breakers.

Falls in late postmenopausal women with osteopenia usually cause fractures with severe consequences. This 36-month randomized, double-blind and placebo-controlled trial with a 10-year observational follow-up study aimed to investigate the long-term effect of herbal formula Bushen Yijing Fang (BSYJF) on fall risk in the late postmenopausal women with osteopenia. 140 late postmenopausal women (Femoral neck T-score, −2.5~−2 SD) were recruited and randomized to orally receive calcium carbonate 300 mg daily with either BSYJF or placebo for 36 months. The effect was further investigated for another 10-year follow-up. During the 36-month administration, there were 12 falls in BSYJF group and 28 falls in placebo group, respectively, indicating 64% lower risk of falls (RR 0.36 [95% CI, 0.18 to 0.71]; P = 0.004) in BSYJF group. During the 10-year follow-up, 36% lower fall risk (RR 0.64 [95% CI, 0.46 to 0.89]; P = 0.009) was observed in BSYJF group. No significant difference was found in safety profile between two groups. Thirty-six-month administration of BSYJF reduced fall risk with an increase in bone mass, and its latent effect on fall risk was continually observed in the 10-year follow-up in late postmenopausal women with osteopenia. This clinical trial was registered at Chinese clinical trial registry (ChiCTR-IOR-16008942).

The hybrid high voltage direct current (HVDC) breaker is a key equipment of the DC grid. The high speed mechanical switch is a key component of the hybrid HVDC breaker and has a number of serially connected switch units. The serially connected units should divide the voltage uniformly. The static voltage distributions and distributed capacitances of a 500 kV hybrid HVDC breaker mechanical switch are studied in this paper. A three dimensional finite element model, considering the actual dimension parameters of six 110 kV high speed mechanical units in serially vertical arrangement, is established to study the static voltage distribution characteristics and capacitance parameters of a 500 kV multi-break high-speed mechanical switch, with six 110 kV high speed mechanical switches in serially vertical arrangement. The calculated results indicate that, under vertical arrangement, from the point of capacitive voltage distribution, the static voltage distributions of the six mechanical switch units are non-uniform, and the high voltage unit is more than 75% of the whole voltage.

Objective. The aim of this study is to systematically evaluate the evidence whether traditional Chinese herbal patches (TCHPs) for osteoarthritis (OA) are effective and safe and analyze their medication patterns.Methods. A systematic literature search was performed using all the possible Medical Subject Headings (MeSH) and keywords from January 1979 to July 2013. Both randomized controlled trials (RCTs) and observational studies were included. Estimated effects were analyzed using mean difference (MD) or relative risk (RR) with 95% confidence intervals (CI) and meta-analysis.Results. 86 kinds of TCHPs were identified. RCTs and controlled clinical trials (CCTs) which were mostly of low quality favored TCHPs for local pain and dysfunction relief. TCHPs, compared with diclofenac ointment, had significant effects on global effectiveness rate (RR = 0.50; 95% CI (0.29, 0.87)). Components of formulae were mainly based on the compounds “Xiao Huo Luo Dan” (Minor collateral-freeing pill) and “Du Huo Ji Sheng Tang” (Angelicae PubescentisandLoranthidecoction). Ten kinds of adverse events (AEs), mainly consisting of itching and/or local skin rashes, were identified after 3-4 weeks of follow-up.Conclusions. TCHPs have certain evidence in improving global effectiveness rate for OA; however, more rigorous studies are warranted to support their use.

Background: Knee osteoarthritis (KOA) is the most common form of arthritis, leading to pain disability in seniors and increased health care utilization. Acupotomy has been widely used to treat KOA. But its efficiency has not been scientifically and methodically evaluated. The aim of this study is to evaluate the efficacy and safety of acupotomy for the treatment of patients with KOA. Methods: Relevant studies will be searched from the databases of PubMed, EMBASE, Cochrane Library, China Knowledge Resource Integrated Database, Weipu Database for Chinese Technical Periodicals, SinoMed, and Wanfang Database from their inception to June 10, 2019. Two researchers will independently select studies, collect data, and assess the methodology quality by the Cochrane risk of bias tool. Results: The systematic review will provide high-quality evidence to assess the efficacy and safety of acupotomy for KOA by pain, stiffness, and dysfunction of knee joint, and quality of life, as well as adverse events. Conclusion: The systematic review will provide evidence to assess the effectiveness and safety of acupotomy therapy for KOA patients. PROSPERO registration number: PROSPERO CRD42019132082

Objective. To assess the short-term efficacy and safety of two kinds of Traditional Chinese herbal patches, Fufang Nanxing Zhitong Gao (FNZG) and Shangshi Jietong Gao (SJG), for painful knee osteoarthritis (OA).Methods. Patients were randomly enrolled in a double-blind, placebo-controlled study to receive FNZG (n=60), SJG (n=60), or placebo patch (n=30) for 7 days. Outcome measures included visual analogue scale (VAS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and Traditional Chinese Medicine Syndrome Questionnaire (TCMSQ) subscale.Results. Although there was no significant difference among, three groups in short-term pain management, patients receiving FNZG got significant improvement in symptom of fear of coldness as compared with placebo patch (P=0.029). The most common local adverse events of rash, itching, erythema, and slightly damaged skin were observed in 7% of participants.Conclusions. FNZG may be a useful treatment for symptom of knee OA and merits long-term study in broader populations.