Air cargo business booms as direct flights become a new growth point in Sino-Africa trade BEFoRE 2012, african airlines were seldom on the list of logistics partners of domestic large-scale enterprises. When a Kenya a...Air cargo business booms as direct flights become a new growth point in Sino-Africa trade BEFoRE 2012, african airlines were seldom on the list of logistics partners of domestic large-scale enterprises. When a Kenya airways Boeing 747 cargo plane touched down on chinese soil展开更多
This paper addresses an indefinite linear-quadratic mean field games for stochastic largepopulation system,where the individual diffusion coefficients may depend on both the state and the control of the agents.Moreove...This paper addresses an indefinite linear-quadratic mean field games for stochastic largepopulation system,where the individual diffusion coefficients may depend on both the state and the control of the agents.Moreover,the control weights in the cost functionals could be indefinite.The authors employ a direct approach to derive theε-Nash equilibrium strategy.First,the authors formally solve an N-player game problem within a vast but finite population setting.Subsequently,by introducing two Riccati equations,the authors decouple or reduce the high-dimensional systems to yield centralized strategies,which depend on the state of a specific player and the average state of the population.As the population size N goes infinity,the construction of decentralized strategies becomes feasible.Then,the authors demonstrate that these strategies constitute anε-Nash equilibrium.Finally,numerical examples are provided to demonstrate the effectiveness of the proposed strategies.展开更多
Loop transformations, such as loop interchange, reversal and skewing, have been unified under linear matrix transformations. A legal transformation matrix is usually generated based upon distance vectors or direction ...Loop transformations, such as loop interchange, reversal and skewing, have been unified under linear matrix transformations. A legal transformation matrix is usually generated based upon distance vectors or direction vectors. Unfortunately, for some nested loops, distance vectors may not be computable and direction vectors, on the other hand, may not contain useful information. We propose the use of linear equations or inequalities of distance vectors to approximate data dependence. This approach is advantageous since (1) many loops having no constant distance vectors have very simple equations of distance vectors; (2) these equations contain more information than direction vectors do, thus the cliance of exploiting potential parallelism is improved.In general, the equations or inequalities that approximate the data dependence of a given nested loop is not unique, hence classification is discussed for the purpose of loop transformation. Efficient algorithms are developed to generate all kinds of linear equations of distance vectors for a given nested loop. The issue of how to obtain a desired transformation matrix from those equations is also addressed.展开更多
BACKGROUND The direct anterior approach for total hip arthroplasty(DAA-THA)is increasing in popularity due to some advantages such as less surgical trauma,minimal dissection of soft tissues,shorter rehabilitation time...BACKGROUND The direct anterior approach for total hip arthroplasty(DAA-THA)is increasing in popularity due to some advantages such as less surgical trauma,minimal dissection of soft tissues,shorter rehabilitation times,faster return to daily activities,lower incidence of dislocation.On the other hand,the literature reports a high rate of intraoperative complications,with many different rates and complication types in the published papers.AIM To analyze our complications comparing results with the literature;to report measures that we have taken to reduce complications rate.METHODS All DAA-THA patients with one year minimum follow up who were operated at a single high-volume centre,between January 2010 and December 2019 were included in this retrospective study.All surgeries were performed using cementless short anatomical or straight stems and press fit cups.Patients’followup was performed,at 6 wk,3 mo,then annually post-surgery with clinical and radiological evaluation.Primary outcomes were stem revision for aseptic loosening and all-cause stem revision.Second outcome was intra-operative and post-operative complications identification.RESULTS A total of 394 patients underwent DDA-THA from January 2010 and December 2019,for a total of 412 hips;twelve patients lost to follow-up and one patient who died from causes not related to surgery were excluded from the study.The average age at the time of surgery was 61 years(range from 28 to 78 years).Mean follow-up time was 64.8 mo(range 12-120 mo).Seven stems were revised.One cortical perforation,one trochanteric and lateral cortical wall intraoperative fracture,one diaphyseal fracture,three clinically symptomatic early subsidence and one late aseptic loosening.We also observed 3 periprosthetic fractures B1 according to the Vancouver Classification.Other minor complications not requiring stem revision were 5 un-displaced fractures of the calcar region treated with preventive cerclage,one early infection,one case of late posterior dislocation,18 case of asymptomatic stem subsidence,6 cases of lateral cutaneous femoral nerve dysesthesia.CONCLUSION DAA is associated to good outcomes and lower incidence of dislocation.Complication rate can be reduced by mindful patient selection,thorough preoperative planning,sufficient learning curve and use of intraoperative imaging.展开更多
BACKGROUND Branches of the lateral circumflex femoral artery(LCFA) stretch across the surgical field during a direct anterior total hip arthroplasty. It is an anatomical marker in direct anterior approach. As an impor...BACKGROUND Branches of the lateral circumflex femoral artery(LCFA) stretch across the surgical field during a direct anterior total hip arthroplasty. It is an anatomical marker in direct anterior approach. As an important vessel around the hip joint,this vessel was ligated in most situations. Although ligation of the vascular pedicle of the LCFA is a common, traditional procedure used to decrease bleeding, the ligation of the pedicle of the vessel is tedious and time-consuming.AIM To explore whether this ligation is truly necessary in a direct anterior approach to total hip arthroplasty.METHODS This single-center, single-surgeon, prospective study was performed to compare patients' bleeding undergoing ligation of the branches of the LCFA pedicle(group A) vs those treated with electrocautery from the branches of the LCFA(group B). In both groups, the pedicles were identified in the intermuscular plane between the tensor fasciae lata and the rectus femoris muscles. In group A, the pedicles were ligated with a silk ligature. In group B, the branches coming off the LCFA were controlled with electrocautery. We compared preoperative vs postoperative changes in blood hemoglobin levels, intraoperative blood loss,operative time, rates of transfusion, re-bleeding, and hematoma between the two groups.RESULTS The reduction of hemoglobin in group A was 20.9 ± 7.0, and in group B it was 21.2 ± 4.9. There was no statistically significant difference between the two groups(P > 0.05). The actual calculated blood loss in group A was 784 ± 125 mL,and in group B it was 722 ± 153 mL. There was a trend in group A having more blood loss(P = 0.078). The estimated blood loss in group A was 344 ± 88 mL, and in group B it was 346 ± 73 mL. There was no statistically significant difference between the two groups(P = 0.883). In addition, there were no significant differences in the rates of postoperative transfusion(10% vs 6.7%, P > 0.05),postoperative hematomas(6.7% vs 13.3%, P > 0.05), or re-bleeding(13.3% vs 20%,P > 0.05) between the two groups.CONCLUSION Ligation of the pedicle of the LCFA has no advantage in preventing or decreasing bleeding during or after a total hip arthroplasty using the direct anterior approach. Ligation of the pedicle of the vessel is a cumbersome, unnecessary procedure and can be replaced by electrocautery control of the branches off this artery that course through the surgical field.展开更多
BACKGROUND Dislocation rates after hemiarthroplasty reportedly vary from 1%to 17%.This serious complication is associated with increased morbidity and mortality rates.Approaches to this surgery are still debated,with ...BACKGROUND Dislocation rates after hemiarthroplasty reportedly vary from 1%to 17%.This serious complication is associated with increased morbidity and mortality rates.Approaches to this surgery are still debated,with no consensus regarding the superiority of any single approach.AIM To compare early postoperative complications after implementing the direct anterior and posterior approaches(PL)for hip hemiarthroplasty after femoral neck fractures.METHODS This is a comparative,retrospective,single-center cohort study conducted at a university hospital.Between March 2008 and December 2018,273 patients(a total of 280 hips)underwent bipolar hemiarthroplasties(n=280)for displaced femoral neck fractures using either the PL(n=171)or the minimally invasive direct anterior approach(DAA)(n=109).The choice of approach was related to the surgeons’practices;the implant types were similar and unrelated to the approach.Dislocation rates and other complications were reviewed after a minimum followup of 6 mo.RESULTS Both treatment groups had similarly aged patients(mean age:82 years),sex ratios,patient body mass indexes,and patient comorbidities.Surgical data(surgery delay time,operative time,and blood loss volume)did not differ significantly between the groups.The 30 d mortality rate was higher in the PL group(9.9%)than in the DAA group(3.7%),but the difference was not statistically significant(P=0.052).Among the one-month survivors,a significantly higher rate of dislocation was observed in the PL group(14/154;9.1%)than in the DAA group(0/105;0%)(P=0.002).Of the 14 patients with dislocation,8 underwent revision surgery for recurrent instability(posterior group),and one of them had 2 additional procedures due to a deep infection.The rate of other complications(e.g.,perioperative and early postoperative periprosthetic fractures and infection-related complications)did not differ significantly between the groups.CONCLUSION These findings suggest that the DAA to bipolar hemiarthroplasty for patients with femoral neck fractures is associated with a lower dislocation rate(<1%)than the PL.展开更多
In this paper, a direct probabilistic approach（DPA） is presented to formulate and solve moment equations for nonlinear systems excited by environmental loads that can be either a stationary or nonstationary random p...In this paper, a direct probabilistic approach（DPA） is presented to formulate and solve moment equations for nonlinear systems excited by environmental loads that can be either a stationary or nonstationary random process.The proposed method has the advantage of obtaining the response＇s moments directly from the initial conditions and statistical characteristics of the corresponding external excitations. First, the response＇s moment equations are directly derived based on a DPA, which is completely independent of the It？/filtering approach since no specific assumptions regarding the correlation structure of excitation are made.By solving them under Gaussian closure, the response＇s moments can be obtained. Subsequently, a multiscale algorithm for the numerical solution of moment equations is exploited to improve computational efficiency and avoid much wall-clock time. Finally, a comparison of the results with Monte Carlo（MC） simulation gives good agreement.Furthermore, the advantage of the multiscale algorithm in terms of efficiency is also demonstrated by an engineering example.展开更多
Through the direct parameter approach, a solution for spacecraft attitude tracking is presented. First of all, the spacecraft attitude tracking control model is built up by the error equation of the second-order nonli...Through the direct parameter approach, a solution for spacecraft attitude tracking is presented. First of all, the spacecraft attitude tracking control model is built up by the error equation of the second-order nonlinear quaternion-based attitude system. Based on the control model, a suitable controller is designed by the direct parameter approach. Compared with other control strategies, the direct parameter approach can offer all degrees of freedom for the controller to satisfy the requirements for system properties and turn the original nonlinear system into closed-loop linear system. Furthermore, this paper optimizes the controller according to the robustness, limitation of controller output and closed-loop eigenvalue sensitivity. Putting the controller into the original system, the state response of the closed-loop system and the output of controller are plotted in Matlab to verify the availability and robustness of the controller. Therefore, the controlled spacecraft can achieve the goal of tracking on the mobile target with the external disturbance torque.展开更多
AIM: To evaluate whether walking ability recovers early after bipolar hemiarthroplasty(BHA) using a direct anterior approach.METHODS: Between 2008 and 2010, 81 patients with femoral neck fracture underwent BHA using t...AIM: To evaluate whether walking ability recovers early after bipolar hemiarthroplasty(BHA) using a direct anterior approach.METHODS: Between 2008 and 2010, 81 patients with femoral neck fracture underwent BHA using the direct anterior approach(DAA) or the posterior approach(PA). The mean observation period was 36 mo. The age, sex, body mass index(BMI), time from admission to surgery, length of hospitalization, outcome after discharge, walking ability, duration of surgery, blood loss and complications were compared. RESULTS: There was no significant difference in the age, sex, BMI, time from admission to surgery, length of hospitalization, outcome after discharge, duration of surgery and blood loss between the two groups. Two weeks after the operation, assistance was not necessary for walking in the hospital in 65.0% of the patients in the DAA group and in 33.3% in the PA group(P < 0.05). As for complications, fracture of the femoral greater trochanter developed in 1 patient in the DAA group and calcar crack and dislocation in 1 patient each in the PA group.CONCLUSION: DAA is an approach more useful for BHA for femoral neck fracture in elderly patients than total hip arthroplasty in terms of the early acquisition of walking ability.展开更多
BACKGROUND Direct anterior approach(DAA)total hip arthroplasty(THA)in a supine position provides a unique opportunity to assess leg length discrepancy(LLD)intraoperatively with fluoroscopy.Reported fluoroscopic techni...BACKGROUND Direct anterior approach(DAA)total hip arthroplasty(THA)in a supine position provides a unique opportunity to assess leg length discrepancy(LLD)intraoperatively with fluoroscopy.Reported fluoroscopic techniques are useful but are generally complicated or costly.Despite the use of multiple techniques for leg length assessment,LLD continues to be a major post-operative source of patient dissatisfaction further emphasizing the importance of near-anatomic restoration.The utility of an alternative direct measurement of LLD on an intra-operative fluoroscopic pelvic image during DAA THA has not been reported.AIM To determine the reliability of a novel simple intra-operative measurement of LLD using a parallel line technique on a single fluoroscopic digital image of the pelvis.METHODS One hundred and seventy-one patients who underwent DAA THA were included for analysis.Intra-operative fluoroscopic and post-operative anterior-posterior radiographs were imported to TraumaCad and calibrated for LLD measurement.LLD was measured on each image using the right-left hip differences in lesser trochanter to pelvic reference line distances.Pelvic reference points included the teardrops and ischia.Fluoroscopic LLD was compared to the gold-standard measurement of LLD measured on a post-operative radiograph.RESULTS Mean absolute difference in teardrop referenced LLD between fluoroscopic and post-operative radiographs was 2.17 mm and based on the ischia mean absolute difference was 2.63 mm.Linear regression of fluoroscopic and post-operative radiograph LLD based on teardrop and ischia LLD found r2 values of 0.57 and 0.84,respectively.Mean absolute difference between fluoroscopic and postoperative x-ray LLD was within 5 mm in 95%of cases regardless of pelvic reference.CONCLUSION This study demonstrates that a single fluoroscopic view obtained during DAA THA for leg length assessment is clinically useful.展开更多
We read and discussed the study entitled“Complication rates after direct anterior vs posterior approach for Hip Hemiarthroplasty in elderly individuals with femoral neck fractures”with great interest.The authors hav...We read and discussed the study entitled“Complication rates after direct anterior vs posterior approach for Hip Hemiarthroplasty in elderly individuals with femoral neck fractures”with great interest.The authors have done justice to the topic of comparison of anterior and posterior surgical approaches for bipolar hemiarthroplasty which has been an everlasting debate in the existing literature.However,there are certain aspects of this study that need clarification from the authors.展开更多
The differences in complication rates between the direct anterior and posterior approaches for hemiarthroplasty in elderly patients with femoral neck fractures are not yet fully understood.Dislocation,a severe complic...The differences in complication rates between the direct anterior and posterior approaches for hemiarthroplasty in elderly patients with femoral neck fractures are not yet fully understood.Dislocation,a severe complication associated with increased mortality and often requiring additional surgery,may occur less frequently with the direct anterior approach compared to the posterior approach.Careful consideration of patient demographics is essential when planning the surgical approach.Future research in this area should focus on robust randomized controlled trials involving elderly patients recovering from femoral neck fractures.展开更多
Direct anterior approach (DAA) for total hip arthroplasty (THA) is a minimally invasive technique. In this approach, two assistants are necessary. We developed a retractor holding device called “Spider arm” to repla...Direct anterior approach (DAA) for total hip arthroplasty (THA) is a minimally invasive technique. In this approach, two assistants are necessary. We developed a retractor holding device called “Spider arm” to replace an assistant in the contra-lateral side. In this study, we investigated the usefulness of Spider arm in THA through direct anterior approach. 20 hips were operated without Spider arm and 21 hips were operated with Spider arm. The surgery time and the blood loss were compared. The cup position and leg length discrepancy were measured on radiography. There was no statistical significance between two groups in all parameters. No clinical complications were reported. With Spider arm, DAA-THA could be performed by two surgeons without deterioration of the surgery time and blood loss. The accuracy of cup position and leg length discrepancy was not affected. Spider arm can contribute to reducing the manpower in DAA-THA.展开更多
The optical frequency comb has been widely used in precision measurement. In this study, a multi-peak fitting approach is first proposed to fit the two-photon transition spectrum which overlaps with the neighboring tr...The optical frequency comb has been widely used in precision measurement. In this study, a multi-peak fitting approach is first proposed to fit the two-photon transition spectrum which overlaps with the neighboring transition in Rb-87. The multi-peak fitting approach is used to eliminate the frequency shift affected by the neighboring transition. With locking the carrier envelope offset frequency at 1/4 repetition frequency, the transition frequency is measured to be 770569132739.9 +/- 5.8 kHz, which agrees well with the previous result recommended by Comite International des Poids et Mesures.展开更多
The observation and estimation of directional spectra of sea waves is one of the essential subjects of study of oceanic dynamics. On the basis of the irregular linear wave theory, estimation methods for i/UV, PUV and ...The observation and estimation of directional spectra of sea waves is one of the essential subjects of study of oceanic dynamics. On the basis of the irregular linear wave theory, estimation methods for i/UV, PUV and VV directional wave spectra are derived. By using ij and PUV data measured in-situ, directional wave spectra are estimated, meanwhile the virtues and defects of various spectra are comparied. This method provide a basis for the observations of sea waves.展开更多
Objective To discuss the approach and technique of the direct microsurgery of intracavemous sinus carotid artery aneurysms (ICCAAns). Methods All the 15 cases of ICCAAns underwent the direct microsurgery via the carot...Objective To discuss the approach and technique of the direct microsurgery of intracavemous sinus carotid artery aneurysms (ICCAAns). Methods All the 15 cases of ICCAAns underwent the direct microsurgery via the carotid artery-cavernous sinus space approach. Results Immediate carotid arteriography after the surgery showed that the aneurysms disappeared and the carotid artery could be showed clearly and normall. In a follow up period ranged frcm 1 months to 9 years,it was showed that,among 5 cases with 333,IV,V a,VI nerve paralysis before the surgery, three completely recovered,one recovered incompletely. All patients regained the capability of undertaking mormal cativities. None experienced rebleeding or neuroparalysis. Conclusion Direct microsurgery via this is approach is an ideal treatment of ICCAAns. 6 refs.展开更多
目的:比较直接前方入路与后外侧入路全髋关节置换术(THA)治疗股骨颈骨折患者的效果。方法:回顾性分析2022年1月至2025年1月该院收治的82例股骨颈骨折患者的临床资料,根据手术入路不同将其分为观察组和对照组各41例。观察组采用直接前方...目的:比较直接前方入路与后外侧入路全髋关节置换术(THA)治疗股骨颈骨折患者的效果。方法:回顾性分析2022年1月至2025年1月该院收治的82例股骨颈骨折患者的临床资料,根据手术入路不同将其分为观察组和对照组各41例。观察组采用直接前方入路THA治疗,对照组采用后外侧入路THA治疗,比较两组手术相关指标[切口长度、住院时间、术中出血量、术后72 h视觉模拟评分法(VAS)评分、术后引流量]水平,手术前后炎性指标[超敏C反应蛋白(hs-CRP)、白细胞介素-1β(IL-1β)、淀粉样蛋白A(SAA)]水平、术后髋关节功能[Charnley髋关节疗效量表(CHS)、Harris髋关节功能量表(HSS)]评分,以及并发症发生率。结果:两组手术时间比较,差异无统计学意义(P>0.05);研究组切口长度、住院时间均短于对照组,术中出血量、术后引流量均少于对照组,术后72 h VAS评分低于对照组,差异有统计学意义(P<0.05);术后3 d,两组hs-CRP、IL-1β、SAA水平均高于术前,但观察组低于对照组,差异有统计学意义(P<0.05);术后1个月,观察组CHS、HHS评分均高于对照组,差异有统计学意义(P<0.05);术后3、6个月,两组CHS、HHS评分均高于术后1个月,但组间比较,差异均无统计学意义(P>0.05);两组并发症发生率比较,差异无统计学意义(P>0.05)。结论:直接前方入路THA治疗股骨颈骨折患者可缩短切口长度和住院时间,减少术中出血量和术后引流量,降低疼痛评分和炎性指标水平,以及提高髋关节功能评分的效果优于后外侧入路THA治疗。展开更多
The direct anterior approach to the hip has been suggested to have several advantages compared to previously popular approaches through its use of an intra-muscular and intra-nervous interval betweenthe tensor fasciae...The direct anterior approach to the hip has been suggested to have several advantages compared to previously popular approaches through its use of an intra-muscular and intra-nervous interval betweenthe tensor fasciae latae and sartorius muscles. Recent increased interest in tissue-sparing and minimallyinvasive arthroplasty has given rise to a sharp increase in the utilization of direct anterior total hip arthroplasty. A number of variations of the procedure have been described and several authors have published their experiences and feedback to successfully accomplishing this procedure. Additionally, improved understanding of relevant soft tissue constraints and anatomic variants has provided improved margin of safety for patients. The procedure may be performed using speciallydesigned instruments and a fracture table, however many authors have also described equally efficacious performance using a regular table and standard arthroplasty tools. The capacity to utilize fluoroscopy intraoperatively for component positioning is a valuable asset to the approach and can be of particular benefit for surgeons gaining familiarity. Proper management of patient and limb positioning are vital to reducing risk of intra-operative complications. An understanding of its limitations and challenges are also critical to safe employment. This review summarizes the key features of the direct anterior approach for total hip arthroplasty as an aid to improving the understanding of this important and effective method for modern hip replacement surgeons.展开更多
Direct anterior total hip arthroplasty has become increasingly more popular among arthroplasty surgeons,in large part due to the use of an intramuscular interval and desire to reduce soft tissue damage.Several studies...Direct anterior total hip arthroplasty has become increasingly more popular among arthroplasty surgeons,in large part due to the use of an intramuscular interval and desire to reduce soft tissue damage.Several studies have now been published comparing the anterior intramuscular to other commonly used approaches,and many studies have published complication rates on large series of patients.Review of comparative studies indicates direct anterior hips tend towards shorter hospital stays and high rates of patients discharged to home.Although some studies show evidence of early benefit in functional outcomes,there is no strong evidence that the anterior approach provides any long term functional improvements compared to other approaches.Additionally,evidence to support reduced damage to soft tissue may not translate to certain clinical significance.Rates of intra-operative femur fracture,operative time and blood loss rates are notably higher for those developing familiarity with this approach.However,when surgeons have performed a modest number of procedures,the complication rates tend to markedly decrease in most studies to levels comparable to other approaches.Accuracy of component positioning also favors the anterior approach in some studies.This review summarizes the available literature comparing the direct anterior to other approaches for total hip arthroplasty and provides a comprehensive summary of common complications.展开更多
BACKGROUND The direct anterior approach(DAA) for total hip arthroplasty(THA) is a less invasive and muscle-sparing approach that seems to improve early function and patient satisfaction. Several studies, however, have...BACKGROUND The direct anterior approach(DAA) for total hip arthroplasty(THA) is a less invasive and muscle-sparing approach that seems to improve early function and patient satisfaction. Several studies, however, have reported high complication and revision rates due to the technical difficulties related to the femoral preparation.AIM To evaluate the usefulness and safety of a new stem equipped with a morphometric design and a size-specific medial curvature in DAA for THA.METHODS This retrospective study was based on 130 patients that underwent mini-invasive DAA procedures for THA using the Accolade Ⅱ stem. A total of 144 procedures were included in the assessment, which was based on postoperative complications, survival rates, functional parameters, and patient related outcomes.RESULTS Overall complications were recorded in 6 procedures(4.2%). There were no complications related to the stem implantation and no intraoperative fractures. Only one patient was revised for deep infection. On radiographs, biomechanical hip reconstruction was satisfactory and no stem showed any subsidence greater than 2 mm. Full osseointegration based on Engh scores was seen in all of the implanted stems. Median Harris hip score at final follow-up was 99 points(range 44-100 points), which resulted excellent in 91.3% of patients. The median values of the osteaorthritis outcome score ranged from 87.5 to 95.CONCLUSION The mid-term positive outcomes and low complication rate in our consecutive series of patients support the safety and suitability of this new stem design in DAA for THA.展开更多
文摘Air cargo business booms as direct flights become a new growth point in Sino-Africa trade BEFoRE 2012, african airlines were seldom on the list of logistics partners of domestic large-scale enterprises. When a Kenya airways Boeing 747 cargo plane touched down on chinese soil
基金supported by National Key R&D Program of China under Grant No.2022YFA1006104the National Natural Science Foundations of China under Grant Nos.12471419 and 12271304Shandong Provincial Natural Science Foundations under Grant Nos.ZR2024ZD35 and ZR2022JQ01。
文摘This paper addresses an indefinite linear-quadratic mean field games for stochastic largepopulation system,where the individual diffusion coefficients may depend on both the state and the control of the agents.Moreover,the control weights in the cost functionals could be indefinite.The authors employ a direct approach to derive theε-Nash equilibrium strategy.First,the authors formally solve an N-player game problem within a vast but finite population setting.Subsequently,by introducing two Riccati equations,the authors decouple or reduce the high-dimensional systems to yield centralized strategies,which depend on the state of a specific player and the average state of the population.As the population size N goes infinity,the construction of decentralized strategies becomes feasible.Then,the authors demonstrate that these strategies constitute anε-Nash equilibrium.Finally,numerical examples are provided to demonstrate the effectiveness of the proposed strategies.
文摘Loop transformations, such as loop interchange, reversal and skewing, have been unified under linear matrix transformations. A legal transformation matrix is usually generated based upon distance vectors or direction vectors. Unfortunately, for some nested loops, distance vectors may not be computable and direction vectors, on the other hand, may not contain useful information. We propose the use of linear equations or inequalities of distance vectors to approximate data dependence. This approach is advantageous since (1) many loops having no constant distance vectors have very simple equations of distance vectors; (2) these equations contain more information than direction vectors do, thus the cliance of exploiting potential parallelism is improved.In general, the equations or inequalities that approximate the data dependence of a given nested loop is not unique, hence classification is discussed for the purpose of loop transformation. Efficient algorithms are developed to generate all kinds of linear equations of distance vectors for a given nested loop. The issue of how to obtain a desired transformation matrix from those equations is also addressed.
文摘BACKGROUND The direct anterior approach for total hip arthroplasty(DAA-THA)is increasing in popularity due to some advantages such as less surgical trauma,minimal dissection of soft tissues,shorter rehabilitation times,faster return to daily activities,lower incidence of dislocation.On the other hand,the literature reports a high rate of intraoperative complications,with many different rates and complication types in the published papers.AIM To analyze our complications comparing results with the literature;to report measures that we have taken to reduce complications rate.METHODS All DAA-THA patients with one year minimum follow up who were operated at a single high-volume centre,between January 2010 and December 2019 were included in this retrospective study.All surgeries were performed using cementless short anatomical or straight stems and press fit cups.Patients’followup was performed,at 6 wk,3 mo,then annually post-surgery with clinical and radiological evaluation.Primary outcomes were stem revision for aseptic loosening and all-cause stem revision.Second outcome was intra-operative and post-operative complications identification.RESULTS A total of 394 patients underwent DDA-THA from January 2010 and December 2019,for a total of 412 hips;twelve patients lost to follow-up and one patient who died from causes not related to surgery were excluded from the study.The average age at the time of surgery was 61 years(range from 28 to 78 years).Mean follow-up time was 64.8 mo(range 12-120 mo).Seven stems were revised.One cortical perforation,one trochanteric and lateral cortical wall intraoperative fracture,one diaphyseal fracture,three clinically symptomatic early subsidence and one late aseptic loosening.We also observed 3 periprosthetic fractures B1 according to the Vancouver Classification.Other minor complications not requiring stem revision were 5 un-displaced fractures of the calcar region treated with preventive cerclage,one early infection,one case of late posterior dislocation,18 case of asymptomatic stem subsidence,6 cases of lateral cutaneous femoral nerve dysesthesia.CONCLUSION DAA is associated to good outcomes and lower incidence of dislocation.Complication rate can be reduced by mindful patient selection,thorough preoperative planning,sufficient learning curve and use of intraoperative imaging.
文摘BACKGROUND Branches of the lateral circumflex femoral artery(LCFA) stretch across the surgical field during a direct anterior total hip arthroplasty. It is an anatomical marker in direct anterior approach. As an important vessel around the hip joint,this vessel was ligated in most situations. Although ligation of the vascular pedicle of the LCFA is a common, traditional procedure used to decrease bleeding, the ligation of the pedicle of the vessel is tedious and time-consuming.AIM To explore whether this ligation is truly necessary in a direct anterior approach to total hip arthroplasty.METHODS This single-center, single-surgeon, prospective study was performed to compare patients' bleeding undergoing ligation of the branches of the LCFA pedicle(group A) vs those treated with electrocautery from the branches of the LCFA(group B). In both groups, the pedicles were identified in the intermuscular plane between the tensor fasciae lata and the rectus femoris muscles. In group A, the pedicles were ligated with a silk ligature. In group B, the branches coming off the LCFA were controlled with electrocautery. We compared preoperative vs postoperative changes in blood hemoglobin levels, intraoperative blood loss,operative time, rates of transfusion, re-bleeding, and hematoma between the two groups.RESULTS The reduction of hemoglobin in group A was 20.9 ± 7.0, and in group B it was 21.2 ± 4.9. There was no statistically significant difference between the two groups(P > 0.05). The actual calculated blood loss in group A was 784 ± 125 mL,and in group B it was 722 ± 153 mL. There was a trend in group A having more blood loss(P = 0.078). The estimated blood loss in group A was 344 ± 88 mL, and in group B it was 346 ± 73 mL. There was no statistically significant difference between the two groups(P = 0.883). In addition, there were no significant differences in the rates of postoperative transfusion(10% vs 6.7%, P > 0.05),postoperative hematomas(6.7% vs 13.3%, P > 0.05), or re-bleeding(13.3% vs 20%,P > 0.05) between the two groups.CONCLUSION Ligation of the pedicle of the LCFA has no advantage in preventing or decreasing bleeding during or after a total hip arthroplasty using the direct anterior approach. Ligation of the pedicle of the vessel is a cumbersome, unnecessary procedure and can be replaced by electrocautery control of the branches off this artery that course through the surgical field.
基金This study was reviewed and approved by the Ethics Committee of the HUB-Hospital Erasme.
文摘BACKGROUND Dislocation rates after hemiarthroplasty reportedly vary from 1%to 17%.This serious complication is associated with increased morbidity and mortality rates.Approaches to this surgery are still debated,with no consensus regarding the superiority of any single approach.AIM To compare early postoperative complications after implementing the direct anterior and posterior approaches(PL)for hip hemiarthroplasty after femoral neck fractures.METHODS This is a comparative,retrospective,single-center cohort study conducted at a university hospital.Between March 2008 and December 2018,273 patients(a total of 280 hips)underwent bipolar hemiarthroplasties(n=280)for displaced femoral neck fractures using either the PL(n=171)or the minimally invasive direct anterior approach(DAA)(n=109).The choice of approach was related to the surgeons’practices;the implant types were similar and unrelated to the approach.Dislocation rates and other complications were reviewed after a minimum followup of 6 mo.RESULTS Both treatment groups had similarly aged patients(mean age:82 years),sex ratios,patient body mass indexes,and patient comorbidities.Surgical data(surgery delay time,operative time,and blood loss volume)did not differ significantly between the groups.The 30 d mortality rate was higher in the PL group(9.9%)than in the DAA group(3.7%),but the difference was not statistically significant(P=0.052).Among the one-month survivors,a significantly higher rate of dislocation was observed in the PL group(14/154;9.1%)than in the DAA group(0/105;0%)(P=0.002).Of the 14 patients with dislocation,8 underwent revision surgery for recurrent instability(posterior group),and one of them had 2 additional procedures due to a deep infection.The rate of other complications(e.g.,perioperative and early postoperative periprosthetic fractures and infection-related complications)did not differ significantly between the groups.CONCLUSION These findings suggest that the DAA to bipolar hemiarthroplasty for patients with femoral neck fractures is associated with a lower dislocation rate(<1%)than the PL.
基金supported by the Defense Industrial Technology Development Program (Grant JCKY2013601B)the "111" Project (Grant B07009)the National Natural Science Foundation of China (Grants 11372025, 11432002)
文摘In this paper, a direct probabilistic approach（DPA） is presented to formulate and solve moment equations for nonlinear systems excited by environmental loads that can be either a stationary or nonstationary random process.The proposed method has the advantage of obtaining the response＇s moments directly from the initial conditions and statistical characteristics of the corresponding external excitations. First, the response＇s moment equations are directly derived based on a DPA, which is completely independent of the It？/filtering approach since no specific assumptions regarding the correlation structure of excitation are made.By solving them under Gaussian closure, the response＇s moments can be obtained. Subsequently, a multiscale algorithm for the numerical solution of moment equations is exploited to improve computational efficiency and avoid much wall-clock time. Finally, a comparison of the results with Monte Carlo（MC） simulation gives good agreement.Furthermore, the advantage of the multiscale algorithm in terms of efficiency is also demonstrated by an engineering example.
基金supported by National Natural Science Foundation of China(No.61321062)
文摘Through the direct parameter approach, a solution for spacecraft attitude tracking is presented. First of all, the spacecraft attitude tracking control model is built up by the error equation of the second-order nonlinear quaternion-based attitude system. Based on the control model, a suitable controller is designed by the direct parameter approach. Compared with other control strategies, the direct parameter approach can offer all degrees of freedom for the controller to satisfy the requirements for system properties and turn the original nonlinear system into closed-loop linear system. Furthermore, this paper optimizes the controller according to the robustness, limitation of controller output and closed-loop eigenvalue sensitivity. Putting the controller into the original system, the state response of the closed-loop system and the output of controller are plotted in Matlab to verify the availability and robustness of the controller. Therefore, the controlled spacecraft can achieve the goal of tracking on the mobile target with the external disturbance torque.
文摘AIM: To evaluate whether walking ability recovers early after bipolar hemiarthroplasty(BHA) using a direct anterior approach.METHODS: Between 2008 and 2010, 81 patients with femoral neck fracture underwent BHA using the direct anterior approach(DAA) or the posterior approach(PA). The mean observation period was 36 mo. The age, sex, body mass index(BMI), time from admission to surgery, length of hospitalization, outcome after discharge, walking ability, duration of surgery, blood loss and complications were compared. RESULTS: There was no significant difference in the age, sex, BMI, time from admission to surgery, length of hospitalization, outcome after discharge, duration of surgery and blood loss between the two groups. Two weeks after the operation, assistance was not necessary for walking in the hospital in 65.0% of the patients in the DAA group and in 33.3% in the PA group(P < 0.05). As for complications, fracture of the femoral greater trochanter developed in 1 patient in the DAA group and calcar crack and dislocation in 1 patient each in the PA group.CONCLUSION: DAA is an approach more useful for BHA for femoral neck fracture in elderly patients than total hip arthroplasty in terms of the early acquisition of walking ability.
文摘BACKGROUND Direct anterior approach(DAA)total hip arthroplasty(THA)in a supine position provides a unique opportunity to assess leg length discrepancy(LLD)intraoperatively with fluoroscopy.Reported fluoroscopic techniques are useful but are generally complicated or costly.Despite the use of multiple techniques for leg length assessment,LLD continues to be a major post-operative source of patient dissatisfaction further emphasizing the importance of near-anatomic restoration.The utility of an alternative direct measurement of LLD on an intra-operative fluoroscopic pelvic image during DAA THA has not been reported.AIM To determine the reliability of a novel simple intra-operative measurement of LLD using a parallel line technique on a single fluoroscopic digital image of the pelvis.METHODS One hundred and seventy-one patients who underwent DAA THA were included for analysis.Intra-operative fluoroscopic and post-operative anterior-posterior radiographs were imported to TraumaCad and calibrated for LLD measurement.LLD was measured on each image using the right-left hip differences in lesser trochanter to pelvic reference line distances.Pelvic reference points included the teardrops and ischia.Fluoroscopic LLD was compared to the gold-standard measurement of LLD measured on a post-operative radiograph.RESULTS Mean absolute difference in teardrop referenced LLD between fluoroscopic and post-operative radiographs was 2.17 mm and based on the ischia mean absolute difference was 2.63 mm.Linear regression of fluoroscopic and post-operative radiograph LLD based on teardrop and ischia LLD found r2 values of 0.57 and 0.84,respectively.Mean absolute difference between fluoroscopic and postoperative x-ray LLD was within 5 mm in 95%of cases regardless of pelvic reference.CONCLUSION This study demonstrates that a single fluoroscopic view obtained during DAA THA for leg length assessment is clinically useful.
文摘We read and discussed the study entitled“Complication rates after direct anterior vs posterior approach for Hip Hemiarthroplasty in elderly individuals with femoral neck fractures”with great interest.The authors have done justice to the topic of comparison of anterior and posterior surgical approaches for bipolar hemiarthroplasty which has been an everlasting debate in the existing literature.However,there are certain aspects of this study that need clarification from the authors.
文摘The differences in complication rates between the direct anterior and posterior approaches for hemiarthroplasty in elderly patients with femoral neck fractures are not yet fully understood.Dislocation,a severe complication associated with increased mortality and often requiring additional surgery,may occur less frequently with the direct anterior approach compared to the posterior approach.Careful consideration of patient demographics is essential when planning the surgical approach.Future research in this area should focus on robust randomized controlled trials involving elderly patients recovering from femoral neck fractures.
文摘Direct anterior approach (DAA) for total hip arthroplasty (THA) is a minimally invasive technique. In this approach, two assistants are necessary. We developed a retractor holding device called “Spider arm” to replace an assistant in the contra-lateral side. In this study, we investigated the usefulness of Spider arm in THA through direct anterior approach. 20 hips were operated without Spider arm and 21 hips were operated with Spider arm. The surgery time and the blood loss were compared. The cup position and leg length discrepancy were measured on radiography. There was no statistical significance between two groups in all parameters. No clinical complications were reported. With Spider arm, DAA-THA could be performed by two surgeons without deterioration of the surgery time and blood loss. The accuracy of cup position and leg length discrepancy was not affected. Spider arm can contribute to reducing the manpower in DAA-THA.
基金Supported by the National Natural Science Foundation of China under Grant Nos 91336103,10934010 and 61078026
文摘The optical frequency comb has been widely used in precision measurement. In this study, a multi-peak fitting approach is first proposed to fit the two-photon transition spectrum which overlaps with the neighboring transition in Rb-87. The multi-peak fitting approach is used to eliminate the frequency shift affected by the neighboring transition. With locking the carrier envelope offset frequency at 1/4 repetition frequency, the transition frequency is measured to be 770569132739.9 +/- 5.8 kHz, which agrees well with the previous result recommended by Comite International des Poids et Mesures.
文摘The observation and estimation of directional spectra of sea waves is one of the essential subjects of study of oceanic dynamics. On the basis of the irregular linear wave theory, estimation methods for i/UV, PUV and VV directional wave spectra are derived. By using ij and PUV data measured in-situ, directional wave spectra are estimated, meanwhile the virtues and defects of various spectra are comparied. This method provide a basis for the observations of sea waves.
文摘Objective To discuss the approach and technique of the direct microsurgery of intracavemous sinus carotid artery aneurysms (ICCAAns). Methods All the 15 cases of ICCAAns underwent the direct microsurgery via the carotid artery-cavernous sinus space approach. Results Immediate carotid arteriography after the surgery showed that the aneurysms disappeared and the carotid artery could be showed clearly and normall. In a follow up period ranged frcm 1 months to 9 years,it was showed that,among 5 cases with 333,IV,V a,VI nerve paralysis before the surgery, three completely recovered,one recovered incompletely. All patients regained the capability of undertaking mormal cativities. None experienced rebleeding or neuroparalysis. Conclusion Direct microsurgery via this is approach is an ideal treatment of ICCAAns. 6 refs.
文摘目的:比较直接前方入路与后外侧入路全髋关节置换术(THA)治疗股骨颈骨折患者的效果。方法:回顾性分析2022年1月至2025年1月该院收治的82例股骨颈骨折患者的临床资料,根据手术入路不同将其分为观察组和对照组各41例。观察组采用直接前方入路THA治疗,对照组采用后外侧入路THA治疗,比较两组手术相关指标[切口长度、住院时间、术中出血量、术后72 h视觉模拟评分法(VAS)评分、术后引流量]水平,手术前后炎性指标[超敏C反应蛋白(hs-CRP)、白细胞介素-1β(IL-1β)、淀粉样蛋白A(SAA)]水平、术后髋关节功能[Charnley髋关节疗效量表(CHS)、Harris髋关节功能量表(HSS)]评分,以及并发症发生率。结果:两组手术时间比较,差异无统计学意义(P>0.05);研究组切口长度、住院时间均短于对照组,术中出血量、术后引流量均少于对照组,术后72 h VAS评分低于对照组,差异有统计学意义(P<0.05);术后3 d,两组hs-CRP、IL-1β、SAA水平均高于术前,但观察组低于对照组,差异有统计学意义(P<0.05);术后1个月,观察组CHS、HHS评分均高于对照组,差异有统计学意义(P<0.05);术后3、6个月,两组CHS、HHS评分均高于术后1个月,但组间比较,差异均无统计学意义(P>0.05);两组并发症发生率比较,差异无统计学意义(P>0.05)。结论:直接前方入路THA治疗股骨颈骨折患者可缩短切口长度和住院时间,减少术中出血量和术后引流量,降低疼痛评分和炎性指标水平,以及提高髋关节功能评分的效果优于后外侧入路THA治疗。
文摘The direct anterior approach to the hip has been suggested to have several advantages compared to previously popular approaches through its use of an intra-muscular and intra-nervous interval betweenthe tensor fasciae latae and sartorius muscles. Recent increased interest in tissue-sparing and minimallyinvasive arthroplasty has given rise to a sharp increase in the utilization of direct anterior total hip arthroplasty. A number of variations of the procedure have been described and several authors have published their experiences and feedback to successfully accomplishing this procedure. Additionally, improved understanding of relevant soft tissue constraints and anatomic variants has provided improved margin of safety for patients. The procedure may be performed using speciallydesigned instruments and a fracture table, however many authors have also described equally efficacious performance using a regular table and standard arthroplasty tools. The capacity to utilize fluoroscopy intraoperatively for component positioning is a valuable asset to the approach and can be of particular benefit for surgeons gaining familiarity. Proper management of patient and limb positioning are vital to reducing risk of intra-operative complications. An understanding of its limitations and challenges are also critical to safe employment. This review summarizes the key features of the direct anterior approach for total hip arthroplasty as an aid to improving the understanding of this important and effective method for modern hip replacement surgeons.
文摘Direct anterior total hip arthroplasty has become increasingly more popular among arthroplasty surgeons,in large part due to the use of an intramuscular interval and desire to reduce soft tissue damage.Several studies have now been published comparing the anterior intramuscular to other commonly used approaches,and many studies have published complication rates on large series of patients.Review of comparative studies indicates direct anterior hips tend towards shorter hospital stays and high rates of patients discharged to home.Although some studies show evidence of early benefit in functional outcomes,there is no strong evidence that the anterior approach provides any long term functional improvements compared to other approaches.Additionally,evidence to support reduced damage to soft tissue may not translate to certain clinical significance.Rates of intra-operative femur fracture,operative time and blood loss rates are notably higher for those developing familiarity with this approach.However,when surgeons have performed a modest number of procedures,the complication rates tend to markedly decrease in most studies to levels comparable to other approaches.Accuracy of component positioning also favors the anterior approach in some studies.This review summarizes the available literature comparing the direct anterior to other approaches for total hip arthroplasty and provides a comprehensive summary of common complications.
文摘BACKGROUND The direct anterior approach(DAA) for total hip arthroplasty(THA) is a less invasive and muscle-sparing approach that seems to improve early function and patient satisfaction. Several studies, however, have reported high complication and revision rates due to the technical difficulties related to the femoral preparation.AIM To evaluate the usefulness and safety of a new stem equipped with a morphometric design and a size-specific medial curvature in DAA for THA.METHODS This retrospective study was based on 130 patients that underwent mini-invasive DAA procedures for THA using the Accolade Ⅱ stem. A total of 144 procedures were included in the assessment, which was based on postoperative complications, survival rates, functional parameters, and patient related outcomes.RESULTS Overall complications were recorded in 6 procedures(4.2%). There were no complications related to the stem implantation and no intraoperative fractures. Only one patient was revised for deep infection. On radiographs, biomechanical hip reconstruction was satisfactory and no stem showed any subsidence greater than 2 mm. Full osseointegration based on Engh scores was seen in all of the implanted stems. Median Harris hip score at final follow-up was 99 points(range 44-100 points), which resulted excellent in 91.3% of patients. The median values of the osteaorthritis outcome score ranged from 87.5 to 95.CONCLUSION The mid-term positive outcomes and low complication rate in our consecutive series of patients support the safety and suitability of this new stem design in DAA for THA.
