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Background The leucocyte esterase (LE) strip test often is used to diagnose periprosthetic joint infection (PJI). In accordance with the manufacturer's directions, the LE strip test result is read 3 minutes after exposing it to joint fluid, but this has not been supported by robust research. Moreover, we have noted that the results of the LE strip test might change over time, and our previous studies have found that centrifugation causes the results of the LE strip test to degrade. Still, there is no evidence-based recommendation as to when to read the LE strip test to maximize diagnostic accuracy, in general, and the best reading times for the LE strip test before and after centrifugation need to be determined separately, in particular. Questions/purposes (1) What is the optimal timing for reading LE strip test results before centrifugation to diagnose PJI? (2) What is the optimal timing for reading LE strip test results after centrifugation to diagnose PJI? Methods This study was a prospective diagnostic trial. In all, 120 patients who were scheduled for revision arthroplasty and had signs of infection underwent joint aspiration in the outpatient operating room between July 2018 and July 2019 and were enrolled in this single-center study. For inclusion, patients must have had a diagnosis of PJI or nonPJI, valid synovial fluid samples, and must not have received antibiotics within 2 weeks before arthrocentesis. As such, 36 patients were excluded; 84 patients were included for analysis, and all 84 patients agreed to participate. The 2018 International Consensus Meeting Criteria (ICM 2018) was used for the classification of 49 patients with PJI (score ≥ 6) and 35 without PJI (score ≤ 2). The classification was used as the standard against which the different timings for reading LE strips were compared. All patients without PJI were followed for more than 1 year, during which they did not report the occurrence of PJI. All patients were graded against the diagnostic criteria regardless of their LE strip test results. In 83 patients, one drop of synovial fluid (50 μL) was applied to LE strips before and after centrifugation, and in one patient (without PJI), the sample was not centrifuged because the sample volume was less than 1.5 mL. The results of the strip test were read on an automated colorimeter. Starting from 1 minute after centrifugation, these strips were automatically read once every minute, 15 times (over a period of 16 minutes), and the results were independently recorded by two observers. Results were rated as negative, ±, 1+, and 2+ upon the machine reading. Grade 2+ (dark purple) was used as the threshold for a positive result. An investigator who was blinded to the study performed the statistics. Optimal timing for reading the LE strip before and after centrifugation was determined by using receiver operative characteristic (ROC) analysis. The specificity, sensitivity, and positive predictive and negative predictive values were calculated for key timepoints. Results Before centrifugation, the area under the curve was the highest when the results were read at 5 minutes (0.90 [95% CI 0.83 to 0.98]; sensitivity 0.88 [95% CI 0.75 to 0.95]; specificity 0.89 [95% CI 0.72 to 0.96]). After centrifugation, the area under the curve was the highest when the results were read at 10 minutes (0.92 [95% CI 0.86 to 0.98]; sensitivity 0.65 [95% CI 0.50 to 0.78]; specificity 0.97 [95% CI 0.83 to 1.00]). Conclusion The LE strip test results are affected by time and centrifugation. For samples without centrifugation, we found that 5 minutes after application was the best time to read LE strips. We cannot deny the use of centrifuges because this is an effective way to solve the sample-mingling problem at present. We recommend 10 minutes postapplication as the most appropriate time to read LE strips after centrifugation. Multicenter and large-sample size studies are warranted to further verify our conclusion. Level of evidence LevelII, diagnostic study.

Due to the increase of power transmission capacity, once an active power vacancy happens, power systems will face a serious frequency instability problem. With the development of communication technology in cyber physical power system (CPPS), demand response (DR) resources can take the initiative to reduce electricity utilization in order to tackle the system under-frequency challenge. This paper presented a frequency control model for CPPS considering DR strategy to rapidly forecast the effects of DR sources participating in frequency control. The model was verified through a case study as well.

Nowadays, the power system is evolving into a complex cyber physical system with the closely merged physical system, information system, and communication network. It is critical to understand the connections between the power and cyber systems, and the potential impact of cyber vulnerability. In this study, a flexible hardware-in-the-loop (HIL) testbed is proposed for studying the cyber physical power system. By using the flexible interface, various co-simulation systems for different purposes are generated. Based on this testbed, three sample co-simulators are built as proofs. First, a HIL power and communication co-simulator with non-real-time synchronisation mechanism is introduced, and a case of false data injection attack on automation voltage control is studied. Then, a real-time power and communication HIL co-simulator is introduced, and a case considering the impact of communication bit error on the stability control system is simulated to demonstrate the performance of stability control equipment. Finally, another co-simulator for simulating the actual cyber-attack on the stability control system is introduced, and a case of a man-in-the-middle attack on the data link is simulated to demonstrate the impact of cyber-attack on the stability control system.

In order to maintain the dynamic stability of a Deep Ultra-Violet(DUV) lithographic projection objective,a kinematic supporting structure which is able to eliminate the effects of temperature change and external strain is designed.The lens surface deformation due to temperature variation and external strain is studied.Firstly,the theoretical formula for the compliance of a supporting seat is derived,then the radial compliance of the supporting seat is calculated by using the derived formula and is compared with the results of the whole supporting seat from a Finite Element Analysis(FEA) analysis.The lens surface profile variation due to temperature change and external strain is analyzed and the supporting structure is compared with a 3-point glue supporting structure.The calculated results indicate that the absolute difference between the radial compliance obtained from the derived formula and the FEA simulation is within 2.2%,RMS values of the optical surfaces are less than 0.36 nm with a 0.1 ℃ temperature rise,and the RMS values of the optical surfaces are less than 0.05 nm for a manufacturing tolerance is 5 μm.Compared with the 3-point glue suporting method,the kinematic supporting structure can eliminate the effect of temperature change and outside strain on the lens surface.

A novel mechanical anti-aliasing filtering fibre-optic hydrophone with a cylindrical Helmholtz resonator is constructed and tested. The experimental results show that the hydrophone has a function of low-pass filtering. The low frequency acoustic sensitivity is about −160 dB (1 rad/μPa), and the response curve has a resonance determined by the Helmholtz resonator. Theoretical and experimental results both show that the resonant frequency moves towards high frequency with the increasing orifice diameters. The sensitivity attenuation of high frequency is larger than 10 dB. This new fibre-optic hydrophone is a prototype device for a class of sensors used to eliminate the aliasing in future sonar systems.

A novel pseudo working-point control measurement scheme for the acoustic sensitivity of interferometric fiber-optic hydrophones is described and demonstrated. The measurement principle is introduced in detail. An experimental system, which interrogates an interferometric fiber-optic hydrophone with this method, is designed. The acoustic pressure phase sensitivity of the fiber-optic hydrophone is measured over the frequency range of 20-2500 Hz. The measured acoustic sensitivity is about -156.5 dB re 1 rad/μPa with a fluctuation lower than ±2 dB, which is in good agreement with the results obtained by the method of phase generated carrier. The experimental results testify the validity of this new method which has the advantages of no electric elements in the sensing head, the simplicity of signal processing, and wide working bandwidth.

STUDY DESIGN Controlled animal experiments. OBJECTIVE To test the dose and efficacy of teriparatide in a rat spinal fusion model. SUMMARY OF BACKGROUND DATA Teriparatide was shown to enhance spinal fusion in rats and rabbits previously, but the dose-dependent effect of teriparatide in spinal fusion in rats was not well characterized. METHODS A 0.5 × 0.5 cm trabecular bone graft was taken and implanted onto the L5 and L6 transverse processes of the same rat. Rats were randomly assigned into 3 groups: saline vehicle control (Vehicle), teriparatide 4 μg/kg per day (PTH4), and teriparatide 23 μg/kg per day (PTH23) subcutaneous injections for 4 weeks (5 d per wk). The L5-L6 spinal segments were harvested at week 4, and assessments included radiography, micro-computed tomography, manual palpation, and histomorphometry. L3 vertebra, femurs, and serum bone markers were examined. RESULTS The average radiographical score of L5-L6 fusion in Vehicle, PTH4, and PTH23 groups was 1.53, 2.87, and 4.11, respectively, with the PTH23 being significantly higher (P = 0.001 vs. Vehicle). The average micro-computed tomographic score of L5-L6 fusion in Vehicle, PTH4, and PTH23 groups was 1.53, 2.40, and 3.74, respectively (P = 0.001, PTH23 vs. Vehicle and PTH4). Manual palpation showed that fusion rate was 20%, 50%, and 67.7% in Vehicle, PTH4, and PTH23 groups, respectively. The bone mineralization apposition rate at the fusion site was significantly increased in a dose-dependent manner among the groups. Teriparatide significantly increased vertebral and femoral bone mineral density, bone mineral content, and trabecular area in a dose-dependent manner relative to Vehicle. No difference was found between the circulating Procollagen type I N-terminal propeptide and intact osteocalcin levels in the serum at 4 weeks after treatments. CONCLUSION Teriparatide at 23 μg/kg per day for 4 weeks showed anabolic skeletal effects and significantly enhanced spinal fusion rate in rats, whereas teriparatide at 4 μg/kg per day had also anabolic effects but did not significantly enhance spinal fusion rate. Higher doses of teriparatide may be needed to promote spinal fusion in short-term application.

The purpose of this study is to analyze the pelvic strain behavior after iliac tumor type I resection. Six adult cadaveric specimens were tested. The iliac subtotal resection models were established according to Ennecking's type I resection. The surficial strains of the defect pelvis and the intact pelvis were measured using 6 strain gauges attached to the key regions of pelvis including the site of lateral sacral mass, iliac arcuate line and the superior ramus of pubis. Axial loading from the proximal lumbar was applied by MTS load cell in the gradient of 0 N to 500 N in the double feet standing state. Much change of the strains was found of the pelvis after type I resection. Compared with the intact pelvis, the remarkable change of strain values was found on both side of the superior ramus of pubis, compressive strain altering to tensile strain. In addition, the average strain values on the normal sites of lateral sacral mass (-554.5plusmn251.2 muepsiv ) and iliac arcuate line(-1105.5plusmn352.7 muepsiv) under vertical load of 500 N were enlarged, which were 2.86 times and 3.77 time as much as the those in the corresponding sites of the intact pelvis. The differences of strain values on this two sites between the defect pelvis and the intact pelvis were statistically significant (p

The purpose of this study is to analyze the pelvic stability after type I resection of iliac tumor. Six adult cadaveric specimens were tested. The iliac subtotal resection models were established according to Ennecking' s type I resection. Markers were affixed to the key regions of the pelves. Axial loading from proximal lumbar was applied by MTS load cell in the gradient from ON to 500 N in the double feet standing state. Images in front view were obtained using CCD (charge coupled device). Based on Image J software, displacements of SI (the first sacral vertebrae) of the resected pelves and the intact pelves were calculated respectively using digital marker tracing method with center-of-mass algorithm. Serious instabilities were found in the resected pelves. The rotational movements SI around the normal side femoral head of the resected pelvis were found. The average vertical displacement of SI of the resected pelvis was 6.951plusmn3.384 mm under vertical load of 500 Newton, which were 8.34 times compared with the intact pelvis. The average rotational angle of SI around the normal side femoral head of the resected pelvis was 4.055 plusmn 1.843deg, which were 12.5 times compared with the intact pelvis. Biomechanical model of type I resection of iliac tumor was established. Essential pelvic reconstruction must be introduced because of the serious instability of the pelvis after tumor resection. Digital marker tracing method with center-of-mass algorithm based on Image J software has good perspective for application in biomechanical research, which is a simple method with high precision.

A technique is described to eliminate polarization-induced fading in fiber-optic interferometers with two or three polarizers. Modeling and simulation show that two polarizers should be angularly spaced by 90 degrees to alleviate polarization-induced fading. A test system is set up with two 6.5 km fiber coils to link the data. A bistate polarization diversity receiver is tested for reducing polarization-induced fading. The signal is demodulated using a digital phase-generated carrier and the system demonstrates self-noise up to 7.7 microrad/square root Hz (at 1 kHz).

Just as we know, in the local power system, the network is always open, so, many existing methods for bad data identification (BDI) can't work well. We present a new method of time series analysis for bad data measurements identification. In this method, a local system is divided into several small areas. For each area, we form two data series, one is formed by the hourly load data of this area, the other is the 168th order difference of the above series; for each of the series, we build three AR (autoregression) models using various methods. With these six models, we can identify the bad data of real-power measurements of lines which are connected to this small area. This method has been tested in a real local system, the results shows that it can satisfy a real-time application. >