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In order to improve the working characteristics of the scroll compressor, according to the scroll profile of the compressor, the energy efficiency ratio (EER) of the scroll compressor is taken as the objective function, and the number of scroll turns N and knots are determined based on the genetic annealing algorithm. The distance p, the height of the scroll body h, and the thickness of the scroll profile t are optimized. In the optimized solution set, three sets of optimized profile and initial profile are selected for theoretical calculation of thermodynamic characteristics and volume characteristics, and the specific influence of scroll compressor profile parameters on compressor characteristics is explored in detail, and compared with the unoptimized scroll. The initial parameters of the rotary compressor are compared with the theoretical performance. The results show that the pitch p has a significant effect on the energy efficiency ratio and discharge volume of the scroll compressor, and the number of scroll turns N has a significant effect on the characteristic of suction volume. Three kinds of optimized scroll profile parameters S2, S3, S4 are selected in the optimal solution set. Compared with the initial value S1, the working characteristics are improved. The energy efficiency ratio was increased by 38.10%, 42.58%, and 50.26%; the suction volume was increased by 66.1%, 82.3%, and 73.9%; the exhaust volume was increased by 21.1%, 29.6%, and 50%; the internal volume ratio was increased by 36.4%. 40.9%, 27.3%. It is proved that the use of genetic annealing algorithm achieves the purpose of improving the compressor's operating characteristics.

Background The interscalene brachial plexus block (ISB) is a commonly used nerve block technique for postoperative analgesia in patients undergoing shoulder arthroscopy surgery; however, it is associated with potentially serious complications. The use of suprascapular nerve block (SSNB) has been described as an alternative strategy with fewer reported side effects for shoulder arthroscopy. This review aimed to compare the impact of SSNB and ISB during shoulder arthroscopy surgery. Methods A meta-analysis was conducted to identify relevant randomized controlled trials involving SSNB and ISB during shoulder arthroscopy surgery. Web of Science, PubMed, Embase, Cochrane Controlled Trials Register, Cochrane Library, Highwire, CNKI, and Wanfang database were searched from 2010 through March 2021. Results We identified 1255 patients assessed in 17 randomized controlled trials. Compared with the ISB group, the SSNB group had higher VAS at rest in PACU (P = 0.003), 1 h after operation (P = 0.005), similar pain score 2 h (P = 0.39), 3-4 h (P = 0.32), 6-8 h after operation (P = 0.05), then lower VAS 12 h after operation (P = 0.00006), and again similar VAS 1 day (P = 0.62) and 2 days after operation (P = 0.70). As for the VAS with movement, the SSNB group had higher pain score in PACU (P = 0.03), similar VAS 4-6 h after operation (P = 0.25), then lower pain score 8-12 h after operation (P = 0.01) and again similar VAS 1 day after operation (P = 0.3) compared with the ISB group. No significant difference was found for oral morphine equivalents use at 24 h (P = 0.35), duration of PACU stay (P = 0.65), the rate of patient satisfaction (P = 0.14) as well as the rate of vomiting (P = 0.56), and local tenderness (P = 0.87). However, the SSNB group had lower rate of block-related complications such as Horner syndrome (P < 0.0001), numb (P = 0.002), dyspnea (P = 0.04), and hoarseness (P = 0.04). Conclusion Our high-level evidence established SSNB as an effective and safe analgesic technique and a clinically attractive alternative to interscalene block with the SSNB’S advantage of similar pain control, morphine use, and less nerve block-related complications during arthroscopic shoulder surgery, especially for severe chronic obstructive pulmonary disease, obstructive sleep apnea, and morbid obesity. Given our meta-analysis’s relevant possible biases, we required more adequately powered and better-designed RCT studies with long-term follow-up to reach a firmer conclusion.

SLM (selective laser melting) is an important additive manufacturing technology. Parts with complex structures can be produced by SLM, so surface cracks and other defects within SLM parts are difficult to be identified by traditional nondestructive testing techniques. In this paper, laser ultrasonic technology is proposed to identify the surface crack of SLM specimen. Because of the anisotropy and residual stress of the specimen, the time signal is strongly interfered with by noise, which makes the identification and location of the crack difficult. To solve this problem, the phase space was reconstructed from the time signal and analyzed by the local singular value decomposition method. According to the result of the experiment, this method can reveal the variation of the phase space and has a good effect on the identification and location of the surface crack whose depth is larger than 1 mm.

The in situ pyrolysis of metal–organic-frameworks (MOFs) is an effective strategy to prepare magnetic metal nanoparticle (NP) doped porous carbon materials. These composite materials have shown great potential as high performance electromagnetic wave (EMW) absorption materials. So far, the precise control of composite composition and structure has remained a major challenge in constructing highly porous composites with uniformly distributed NPs. In this work, we report a facile route to synthesize tuneable Co NPs embedded in porous nitrogen-doped carbon (Co/NC) nanorods through the direct thermolysis of the bimetal–organic framework (CoZn–ZIF) precursor. By adjusting the proportion of Co2+ in the MOF precursor, the content and distribution of Co NPs in the composite absorber change accordingly. When the molar ratio between Co2+ and Zn2+ is 3 : 1, the carbonized composites exhibit the largest external surface area and the best EMW absorption performance. With a filler mass loading of merely 15 wt%, the minimum reflection loss (RLmin) reaches −52.3 dB at 10.1 GHz with a thin layer thickness of 2.5 mm. The largest effective absorption bandwidth (EAB) of 5.0 GHz (11.1–16.1 GHz) is achieved in a 2.0 mm thick sample. The qualified bandwidth can be up to 14.5 GHz (3.5–18.0 GHz) with the integrated thickness from 1.0 mm to 5.5 mm. The enhanced conductive/magnetic losses, strong interfacial/dipolar/defect polarization, hierarchical pore structure and the geometric effect endow the Co/NC absorber with improved impedance matching and enhanced attenuation of EMW. This work provides a good direction for the future study of MOF-derived lightweight and efficient EMW absorbing materials.

BackgroundDuring the posterior approach, it has been shown that a significant reduction in dislocation rate can be achieved with the repair of the posterior soft tissue. However, no consensus exists about the best way to perform this repair. This review aimed to compare the transosseous with transmuscular repair of the posterior soft tissue in total hip arthroplasty (THA).MethodsWe conducted a meta-analysis to identify studies involving transosseous versus transmuscular repair of the posterior soft tissue in THA in electronic databases, including Web of Science, Embase, PubMed, Cochrane Controlled Trials Register, Cochrane Library, Highwire, CBM, CNKI, VIP, Wanfang database, up to July 2020. Finally, we identified 1417 patients (1481 hips) assessed in seven studies.ResultsCompared with transmuscular repair, transosseous repair resulted in less incidence of dislocation (P= 0.003), less blood loss during operation (P< 0.00001) and lower VAS score within 3 months (P= 0.02). There were no significant differences in terms of trochanteric fracture rate (P= 0.56), Harris hip score at 3 months (P= 0.35) and 6 months (P= 0.89), VAS score within 6 months (P= 0.53), and operation time (P= 0.70) between two groups.ConclusionThe lower dislocation rate, less blood loss, and lower VAS scores after operation supported transosseous repair's superiority to transmuscular repair. Besides, no additional medical cost and operating time were associated with transosseous repair compared with transmuscular repair. Hence, we recommend that transosseous repair be chosen first by orthopedists when performing reconstruction of the posterior soft tissue in THA via a posterolateral approach. Given the relevant possible biases in our meta-analysis, we required more adequately powered and better-designed RCT studies with long-term follow-up to reach a firmer conclusion.

Background The infrapatellar fat pad (IPFP) or Hoffa’s fat pad is often resected during total knee arthroplasty in order to improve visibility. However, the management of the IPFP during total knee arthroplasty (TKA) is the subject of an ongoing debate that has no clear consensus. The purpose of this review was to appraise if resection of the IPFP affects clinical outcomes. Methods We conducted a meta-analysis to identify relevant randomized controlled trials involving infrapatellar fat pad resection and infrapatellar fat pad preservation during total knee arthroplasty in electronic databases, including Web of Science, Embase, PubMed, Cochrane Controlled Trials Register, Cochrane Library, Highwire, CBM, CNKI, VIP, and Wanfang database, up to March 2020. Results Nine randomized controlled trials, involving 783 TKAs (722 patients), were included in the systematic review. Outcome measures included patellar tendon length (PTL), Insall-Salvati ratio (ISR), rate of anterior knee pain, Knee Society Scores (KSS), and knee range of motion. The meta-analysis identified a trend toward the shortening of the patellar tendon with IPFP resection at 6 months (P = 0.0001) and 1 year (P = 0.001). We found no statistical difference in ISR (P = 0.87), rate of anterior knee pain within 6 months (p = 0.45) and 1 year (p = 0.38), KSS at 1 year (p = 0.77), and knee range of motion within 6 months (p = 0.61) and 1 year (0.46). Conclusion Based on the available level I evidence, we were unable to conclude that one surgical technique of IPFP can definitively be considered superior over the other. More adequately powered and better-designed randomized controlled trial (RCT) studies with long-term follow-up are required to produce evidence-based guidelines regarding IPFP resection.

Reflective learning is a fundamental part of human learning and development and has attracted attention from management scholars as well as practitioners. In this study, we build on trait activation theory and investigate how proactive personality and team task support jointly influence employee reflective learning. Using a questionnaire survey, we collected data at two-time points from 154 participants nested in 37 teams in five organizations in the UK. The results from multilevel analyses showed that proactive personality had a positive effect on reflective learning up to a certain point. Over and above this inflection point, this positive effect ceased to further increase. In addition, the nonlinear effect of proactive personality on reflective learning was much stronger when team task support was weak than when it was strong. The finding regarding the nonlinear relationship extends our understanding of the effect of proactive personality. The cross-level moderating effect of team task support suggests a complementary perspective to appreciate the interactions between proactive personality and its relevant situational characteristics. Practitioners can use these findings to design effective intervention plans and facilitate employee reflective learning in specific settings and in workplace learning in general.

According to the main combat style of the future unmanned boat group, the main threats of the unmanned boat group are pointed out. Then, aiming at the air strike characteristics of small air-ship missile and the defensive equipment of the unmanned boat group, the calculation model of aerial threat fan is proposed. Based on the thread fan, under the aerial threat fan for formation modes: ring configuration, equidistant configuration and linear configuration, The model of unmanned boat group air defense zone allocation is put forward. Furthermore, a method of target allocation based on air defense zone is given. Finally, based on the traditional threat of small airborne missiles carried by helicopters and the performance of electronic warfare weapons carried on boats, aiming at the three typical unmanned formations proposed in this paper, simulation verification is performed according to the distribution method proposed in this paper. The effectiveness of the ship group defense formation configuration and firepower allocation method are verified by the simulation results.

Manganese doped aluminum nitride (AlN:Mn) nanowires were fabricated by direct nitridation of Al and Mn mixed powders. The as-synthesized AlN:Mn nanowires were characterized by X-ray diffraction, Raman, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, scanning and transmission electron microscopy. The measurements reveal the successful incorporation of Mn2+ ions into AlN nanowires. The magnetic and optical properties of the AlN:Mn nanowires were studied using vibrating sample magnetometer and photoluminescence spectroscopy. The AlN:Mn nanowires exhibit room temperature ferromagnetic behavior and a red emission band centered at 597 nm corresponding to the 4T1(4G)-6A1(6S) transition of Mn2+. The abnormal thermal quenching behavior and long afterglow feature are investigated through the temperature dependent emission and the afterglow spectrum. The thermoluminescence curve shows that AlN: Mn nanowires have a wide trap distribution, which leads to the abnormal thermal quenching behavior and persistent luminescence. Multifunctional AlN:Mn nanowires with magnetic and luminescence properties are expected to be used in spintronic and optoelectronic nanodevices.

Previous studies have revealed changed functional connectivity patterns between brain areas in chess players using resting-state functional magnetic resonance imaging (rs-fMRI). However, how to exactly characterize the voxel-wise whole brain functional connectivity pattern changes in chess players remains unclear, which could provide more convincing evidence for establishing the relationship between long-term chess practice and brain function changes. In this study, we employed newly developed whole brain functional connectivity pattern homogeneity (FcHo) method to identify the voxel-wise changes of functional connectivity patterns in 28 chess master players and 27 healthy novices. Seed-based functional connectivity analysis was used to identify the alteration of corresponding functional couplings. FcHo analysis revealed significantly increased whole brain functional connectivity pattern similarity in anterior cingulate cortex (ACC), anterior middle temporal gyrus (aMTG), primary visual cortex (V1), and decreased FcHo in thalamus and precentral gyrus in chess players. Resting-state functional connectivity analyses identified chess players showed decreased functional connections between V1 and precentral gyrus. Besides, a linear support vector machine (SVM) based classification achieved an accuracy of 85.45%, a sensitivity of 85.71% and a specificity of 85.19% to differentiate chess players from novices by leave-one-out cross-validation. Finally, correlation analyses revealed that the mean FcHo values of thalamus were significantly negatively correlated with the training time. Our findings provide new evidences for the important roles of ACC, aMTG, V1, thalamus and precentral gyrus in chess players and indicate that long-term professional chess training may enhance the semantic and episodic processing, efficiency of visual-motor transformation, and cognitive ability.

As a method of non-traditional machining, EDM plays an important role in advanced manufacturing technology. The EDM process involves multi-physics coupling effects such as electromagnetics, thermal and fluid. It has the characteristics of instantaneity, randomness and complexity, which brings difficulties to the study of discharge process. In this paper, a multi-physics coupling model of the EDM discharge process is established based on magnetohydrodynamics, the discharge process is simulated transiently. Results show that the plasma channel is formed within 0.1μs, the highest current density and temperature are in the centre of the plasma channel, and gradually decrease along the radial direction with the increase of the radius, and there is little change along the axial direction; The electric field intensity between tools gradually stabilizes after the plasma channel is formed; The velocity of dielectric between tools takes the centre of the plasma channel as the axis of symmetry, in the form of a symmetrical vortex, with the direction from tool to workpiece, and the maximum velocity is at the centre of the tools.

In order to improve the efficiency of the EDM power supply in processing difficult-to-process materials such as particle-reinforced metal matrix composites, the article proposed an ejecting-explosion EDM method, designed the signal generator module. The principle is to introduce a pulse current with a larger peak value in the traditional pulse power supply, and the two circuits cooperate with each other and process in order to increase the explosive force and discharge energy during discharge. Under the action of explosive force, they are removed together with the metal matrix in a solid form, thereby improving the processing efficiency. According to the high and low voltage composite structure, a controllable step processing waveform is proposed, and a signal generator module is designed.

Dog bites are a health risk in a number of workplaces such as the delivery, veterinary and dog rescue sectors. This study aimed to explore how workers negotiate the risk of dog bites in daily interactions with dogs and the role of procedures in workplace safety. Participants who encounter dogs at work were recruited using snowball sampling. Ethnographic methods (interviews, focus group discussions, participant-observations) were used for data collection. All data were coded qualitatively into themes. Six themes describing dog bite risk management were identified: ‘Surveillance of dogs’, ‘Communicating risk, ‘Actions taken to manage perceived risk’, ‘Reporting bites and near-misses’, ‘Investigating bites and near-misses’, and, ‘Learning and teaching safety’. While the procedures described dog bite risk as objective, when interacting with dogs, participants drew on experiential knowledge and subjective judgment of risk. There was a discrepancy between risks that the procedures aimed to guard against and the risk participants were experiencing in the course of work. This often led to disregarding procedures. Paradoxically, procedures generated risks to individual wellbeing and sometimes employment, by contributing to blaming employees for bites. Dog bite prevention could be improved by clarifying definitions of bites, involving at risk staff in procedure development, and avoiding blaming the victim for the incident.

Dog bites affect the health and wellbeing of the victims and impact the organisations whose employees are injured. However, bites in the course of work or measures used by the employers to remedy them have not been previously explored. This study used the Health and Safety Executive’s database (Reporting of Injuries, Diseases and Dangerous Occurrences Regulation) to understand: (1) The occupational and demographic characteristics of bite victims; (2) Circumstances in which they were bitten; and (3) The remedial actions listed by the employers. Between April 2011- March 2018, 1812 dog bites were reported; middle-age men were most often bitten demographic. Dog bites occurred in two distinct scenarios. Firstly, entering or leaving a private property, typically whilst delivering mail with a dog owner often present and the victim usually not interacting with or aware of the dog before the bite. In the second scenario, the victim was usually a female, dog professional, familiar with the dog and interacting with them before the bite. The remedial actions used by the employers focused on reducing the risk by acting pre- or during the bite event (e.g. euthanizing the offending dog, restricting dog access to employees or providing protective equipment). Post-event counter-measures were rare, but included counselling to the victims. Risk was addressed primarily through administrative measures (e.g. policies), which commonly targeted changing individuals’ behaviour, which may limit effectiveness of prevention. Drawing on injury prevention models we suggest novel ways of preventing bites, e.g. equipment re-design and addressing social norms.

Sliding window method is widely used to study the functional connectivity dynamics in brain networks. A key issue of this method is how to choose the window length and number of clusters across different window length. Here, we introduced a universal method to determine the optimal window length and number of clusters and applied it to study the dynamic functional network connectivity (FNC) in major depressive disorder (MDD). Specifically, we first extracted the resting-state networks (RSNs) in 27 medication-free MDD patients and 54 healthy controls using group independent component analysis (ICA), and constructed the dynamic FNC patterns for each subject in the window range of 10-80 repetition times (TRs) using sliding window method. Then, litekmeans algorithm was utilized to cluster the FNC patterns corresponding to each window length into 2-20 clusters. The optimal number of clusters was determined by voting method and the optimal window length was determined by identifying the most representative window length. Finally, 8 recurring FNC patterns regarded as FNC states were captured for further analyzing the dynamic attributes. Our results revealed that MDD patients showed increased mean dwell time and fraction of time spent in state #5, and the mean dwell time is correlated with depression symptom load. Additionally, compared with healthy controls, MDD patients had significantly reduced FNC within FPN in state #7. Our study reported a new approach to determine the optimal window length and number of clusters, which may facilitate the future study of the functional dynamics. These findings about MDD using dynamic FNC analyses provide new evidence to better understand the neuropathology of MDD.

Background: Spine surgeons in particular face the most hostile liability environment among the surgical specialties. Systemic studies related to spine surgery litigation in China is absent. The aim of this study was to analyze the characteristics of medical malpractice litigation involving spine surgery in Beijing for the past 6 years.Methods: Two online legal databases, Wusong and Weike, were queried for court verdicts involving spine surgery from Jan 2013 to Dec 2018 in Beijing. For all included cases, data pertaining to defendants, plaintiffs, case outcomes, allegations, and verdicts were abstracted, and descriptive analyses were performed. Results: A total of 186 legal cases were examined, 122 cases were excluded due to irrelevance or insufficient information. Of the 64 cases included in this investigation, 40.6% of them were male. The mean age of the plaintiffs was 53.2 ± 18.6 years. The most common complaint addressed in this study is dissatisfaction with consent (53.1%, n=34), followed by additional surgery required (40.2%, n=26), unsatisfactory outcome to surgery (17.6%, n=11), postoperative paralysis (15.6%, n=10) and postoperative infection (15.6%, n=10). The most common primary disease among all the cases is lumbar spinal stenosis (28.1%, n=18), followed by spinal tumor (18.8%, n=12), cervical spondylosis (17.2%, n=11), vertebral fracture (14.1%, n=9), deformity (12.5%, n=8) and others (9.3%, n=6). Spine surgeons successfully defended themselves in 13 cases (20.3%), which resulted in no indemnity payment. The rest 51 cases (79.7%) were closed with an average verdict payout of 155,562 Yuan, which was significant lower than the average compensation claimed by the plaintiff (783,172 Yuan) (p < 0.05). Conclusions: Identifying the most common reasons for litigation and summarizing their characteristics may help decrease litigation rate and improve the patient experience. Further investigations with larger sample size and more complete database are needed.