Thermal rectification is an exotic thermal transport phenomenon,an analog to electrical rectification,in which heat flux along one direction is larger than that in the other direction and is of significant interest in...Thermal rectification is an exotic thermal transport phenomenon,an analog to electrical rectification,in which heat flux along one direction is larger than that in the other direction and is of significant interest in electronic device applications.However,achieving high thermal rectification efficiency or rectification ratio is still a scientific challenge.In this work,we performed a systematic simulation of thermal rectification by considering both efforts of thermal conductivity asymmetry and geometrical asymmetry in a multi-segment thermal rectifier.It is found that the high asymmetry of thermal conductivity and the asymmetry of the geometric structure of multi-segment thermal rectifiers can significantly enhance the thermal rectification,and the combination of both thermal conductivity asymmetry and geometrical asymmetry can further improve thermal rectification efficiency.This work suggests a possible way for improving thermal rectification devices by asymmetry engineering.展开更多
This paper presents an enhanced version of the standard shooting method that enables problems with two unknown parameters to be solved.A novel approach is applied to the analysis of the natural vibrations of Euler-Ber...This paper presents an enhanced version of the standard shooting method that enables problems with two unknown parameters to be solved.A novel approach is applied to the analysis of the natural vibrations of Euler-Bernoulli beams.The proposed algorithm,named as two-parameter multiple shooting method,is a new powerful numerical tool for calculating the natural frequencies and modes of multi-segment prismatic and non-prismatic beams with different boundary conditions.The impact of the axial force and additional point masses is also taken into account.Due to the fact that the method is based directly on the fourth-order ordinary differential equation,the structures do not have to be divided into many small elements to obtain an accurate enough solution,even though the geometry is very complex.To verify the proposed method,three different examples are considered,i.e.,a three-segment non-prismatic beam,a prismatic column subject to non-uniformly distributed compressive loads,and a two-segment beam with an additional point mass.Numerical analyses are carried out with the software MATHEMATICA.The results are compared with the solutions computed by the commercial finite element program SOFiSTiK.Good agreement is achieved,which confirms the correctness and high effectiveness of the formulated algorithm.展开更多
A vortex domain wall's(VW) magnetic racetrack memory's high performance depends on VW structural stability,high speed, low power consumption and high storage density. In this study, these critical parameters w...A vortex domain wall's(VW) magnetic racetrack memory's high performance depends on VW structural stability,high speed, low power consumption and high storage density. In this study, these critical parameters were investigated in magnetic multi-segmented nanowires using micromagnetic simulation. Thus, an offset magnetic nanowire with a junction at the center was proposed for this purpose. This junction was implemented by shifting one portion of the magnetic nanowire horizontally in the x-direction(l) and vertically(d) in the y-direction. The VW structure became stable by manipulating magnetic properties, such as magnetic saturation(M_(4)) and magnetic anisotropy energy(K_(u)). In this case, increasing the values of M_(4) ≥ 800 kA/m keeps the VW structure stable during its dynamics and pinning and depinning in offset nanowires,which contributes to maintenance of the storage memory's lifetime for a longer period. It was also found that the VW moved with a speed of 500 m/s, which is desirable for VW racetrack memory devices. Moreover, it was revealed that the VW velocity could be controlled by adjusting the offset area dimensions(l and d), which helps to drive the VW by using low current densities and reducing the thermal-magnetic spin fluctuations. Further, the depinning current density of the VW(J_(d)) over the offset area increases as d increases and l decreases. In addition, magnetic properties, such as the M_(4) and K_(u),can affect the depinning process of the VW through the offset area. For high storage density, magnetic nanowires(multisegmented) with four junctions were designed. In total, six states were found with high VW stability, which means three bits per cell. Herein, we observed that the depinning current density(J_(d)) for moving the VW from one state to another was highly influenced by the offset area geometry(l and d) and the material's magnetic properties, such as the M_(4) and K_(u).展开更多
Background: Despite the conservative treatment of tibio-femoral osteoarthritis through realignment osteotomies, the rate of total knee replacements following an osteotomy is increasing. The aim of this study was to id...Background: Despite the conservative treatment of tibio-femoral osteoarthritis through realignment osteotomies, the rate of total knee replacements following an osteotomy is increasing. The aim of this study was to identify the factors associated with the progression of knee osteoarthritis after a medial closing-wedge distal femoral osteotomy. Methods: Hospital-based observational study on 20 patients who underwent a medial closing-wedge distal femoral osteotomy evaluating the progression of osteoarthritis using the Kellgren and Laurence classification. The Wilcoxon test was used to compare the variation in the progressive stage of the Kellgren and Laurence classification of knee osteoarthritis preoperatively and at the final follow up. Univariate analysis made it possible to determine the factors associated with progression. The final significance threshold for statistical tests was set at 5% (p Results: Overall, the mean follow-up of 46 months ± 6.6 months, with a mean age of 43 years (range: 27 - 69 years) and a female predominance (M: F = 3/7). The progression of tibiofemoral osteoarthritis following a medial closing-wedge distal femoral osteotomy is associated with valgus or varum malalignment been a moderate valgus (OR 6.2 [1.5 - 42.7] at 95% CI;p-value = 0.02), a correction of the mechanical deviation angle with a valgus alignment (OR 2.7 [0.9 - 8.3] at 95% CI), and loss of correction (OR 3.8 [1.3 - 11.6] at 95% CI;p -value) for the lateral compartment while varus alignment (OR 1.7 [0.9 - 8.3] 95% CI, p-value = 0.05) and with rupture of the lateral cortex (OR 2.8 [1.7 - 11.5] 95% CI, p-value = 0.02) were those of the medial compartment. Conclusion: Distal femur closing wedge osteotomy does not definitively interrupt the progression of valgus knee osteoarthritis. The factors associated with the progression of this pathology are modifiable. Taking them into account when performing this surgical technique could improve the osteotomy survival curve.展开更多
Background: Four factors determine the quality of an implantology kit: 1) Heat generated by the drills;2) Morphology of the osteotomy according to the diameter of the implant;3) Efficiency of collecting autologous bon...Background: Four factors determine the quality of an implantology kit: 1) Heat generated by the drills;2) Morphology of the osteotomy according to the diameter of the implant;3) Efficiency of collecting autologous bone;and 4) Osteotomy execution time. Materials and Methods: This article examines the heat produced by drills during osteotomy, focusing on the effect of the following factors: drilling technique;volume of autologous bone harvested;drilling time;implant primary stability;and the percentage of osseointegrated implants after primary healing. Discussion: The four factors mentioned above are analyzed based on the data obtained for sequential, biological, and One Drill milling techniques. Conclusions: 1) One Drill is the fastest technique for performing the osteotomy;2) All techniques stay within the biological temperature range of living bone, with the lowest increase in temperature achieved using One Drill with irrigation;3) The bone harvested showed no statistically significant differences between biological milling and the One Drill technique, both far superior to the sequential technique;and 4) There is no statistically significant difference in the number of osseointegrated implants among the three techniques analyzed.展开更多
BACKGROUND The preferred treatment for distal humeral intercondylar fractures is open reduction and internal fixation.While there is consensus about the posterior approach,several posterior approaches have been develo...BACKGROUND The preferred treatment for distal humeral intercondylar fractures is open reduction and internal fixation.While there is consensus about the posterior approach,several posterior approaches have been developed.It is debatable as to which approach is best.AIM To compare triceps reflecting anconeus pedicle(TRAP)and olecranon osteotomy approaches for internal fixation of distal humeral intercondylar fracture.METHODS In total,40 cases of Arbeitsgemeinschaft für Osteosynthesefragen/Association of the Study of Internal Fixation type C,closed,and Gustilo type I intercondylar humeral fractures were included.Patients ranged in age from 18 years to 70 years.The patients were randomized into two groups:TRAP group and olecranon osteotomy group,with 20 cases in each.All were followed up at 6 wk,3 months,6 months,and 12 months.Functional outcomes were measured in terms of flexion-extension arc,Disabilities of Arm,Shoulder and Hand score,and Mayo Elbow Performance Score.RESULTS The mean age was 43.2 years in the TRAP group and 37.5 years in the olecranon osteotomy group.The mean operative time and mean duration of hospital stay in the TRAP group were significantly higher than in the olecranon osteotomy group(119.5 vs 111.5 min and 9.85 vs 5.45 d,respectively).The mean arc of flexion-extension,Disabilities of Arm,Shoulder and Hand score,and Mayo Elbow Performance Score were comparable without any significant difference in the groups at the 12-month follow-up(107.0 vs 106.2,18.3 vs 15.7,and 84.2 vs 86.2,respectively).Ulnar paresthesia and superficial infections were comparable in both groups(2 cases vs 3 cases and 3 cases vs 2 cases,respectively).Hardware prominence was significantly higher in the olecranon osteotomy group,mostly due to tension band wiring.CONCLUSION Both approaches were equivalent,but there is a need for further study including higher numbers of subjects and longer study duration to prove the benefits of one approach over the other.展开更多
BACKGROUND Unicompartmental knee arthroplasty(UKA)and high tibial osteotomy(HTO)are well-established operative interventions in the treatment of knee osteoarthritis.However,which intervention is more beneficial to pat...BACKGROUND Unicompartmental knee arthroplasty(UKA)and high tibial osteotomy(HTO)are well-established operative interventions in the treatment of knee osteoarthritis.However,which intervention is more beneficial to patients with knee osteoarthritis remains unknown and a topic of much debate.Simultaneously,there is a paucity of research assessing the relationship between radiographic parameters of knee joint alignment and patient-reported clinical outcomes,preoperatively and following HTO or UKA.AIM To compare UKAs and HTOs as interventions for medial-compartment knee osteoarthritis:Examining differences in clinical outcome and investigating the relationship of joint alignment with respect to this.METHODS This longitudinal observational study assessed a total of 42 patients that had undergone UKA(n=23)and HTO(n=19)to treat medial compartment knee osteoarthritis.Patient-reported outcome measures(PROMs)were collected to evaluate clinical outcome.These included two disease-specific(Knee Injury and Osteoarthritis Outcome Score,Oxford Knee Score)and two generic(EQ-5D-5L,Short Form-12)PROMs.The radiographic parameters of knee alignment assessed were the:Hip-knee-ankle angle,mechanical axis deviation and angle of Mikulicz line.RESULTS Statistical analyses demonstrated significant(P<0.001),preoperative to postoperative,improvements in the PROM scores of both groups.There were,however,no significant inter-group differences in the postoperative PROM scores of the UKA and HTO group.Several significant correlations associated a more distolaterally angled Mikulicz line with worse knee function and overall health preoperatively(P<0.05).Postoperatively,two clusters of significant correlations were observed between the disease-specific PROM scores and knee joint alignment parameters(hip-knee-ankle angle,mechanical axis deviation)within the HTO group;yet no such associations were observed within the UKA group.CONCLUSION UKAs and HTOs are both efficacious operations that provide a comparable degree of clinical benefit to patients with medial compartment knee osteoarthritis.Clinical outcome has a limited association with radiographic parameters of knee joint alignment postoperatively;however,a more distolaterally angled Mikulicz line appears associated with worse knee function/health-related quality of life preoperatively.展开更多
Through the analysis to the DDoS(distributed denial of service) attack, it will conclude that at different time segments, the arrive rate of normal SYN (Synchronization) package are similar, while the abnormal pac...Through the analysis to the DDoS(distributed denial of service) attack, it will conclude that at different time segments, the arrive rate of normal SYN (Synchronization) package are similar, while the abnormal packages are different with the normal ones. Toward this situation a DDoS defense algorithm based on multi-segment timeout technology is presented, more than one timeout segment are set to control the net flow. Experiment results show that in the case of little flow, multi-segment timeout has the ability dynamic defense, so the system performance is improved and the system has high response rate.展开更多
Complex product development will inevitably face the design planning of the multi-coupled activities, and overlapping these activities could potentially reduce product development time, but there is a risk of the addi...Complex product development will inevitably face the design planning of the multi-coupled activities, and overlapping these activities could potentially reduce product development time, but there is a risk of the additional cost. Although the downstream task information dependence to the upstream task is already considered in the current researches, but the design process overall iteration caused by the information interdependence between activities is hardly discussed; especially the impact on the design process' overall iteration from the valid information accumulation process. Secondly, most studies only focus on the single overlapping process of two activities, rarely take multi-segment and multi-ply overlapping process of multi coupled activities into account; especially the inherent link between product development time and cost which originates from the overlapping process of multi coupled activities. For the purpose of solving the above problems, as to the insufficiency of the accumulated valid information in overlapping process, the function of the valid information evolution (VIE) degree is constructed. Stochastic process theory is used to describe the design information exchange and the valid information accumulation in the overlapping segment, and then the planning models of the single overlapping segment are built. On these bases, by analyzing overlapping processes and overlapping features of multi-coupling activities, multi-segment and multi-ply overlapping planning models are built; by sorting overlapping processes and analyzing the construction of these planning models, two conclusions are obtained: (1) As to multi-segment and multi-ply overlapping of multi coupled activities, the total decrement of the task set development time is the sum of the time decrement caused by basic overlapping segments, and minus the sum of the time increment caused by multiple overlapping segments; (2) the total increment of development cost is the sum of the cost increment caused by all overlapping process. And then, based on overlapping degree analysis of these planning models, by the V1E degree function, the four lemmas theory proofs are represented, and two propositions are finally proved: (1) The multi-ply overlapping of the multi coupled activities will weaken the basic overlapping effect on the development cycle time reduction (2) Overlapping the multi coupled activities will decrease product development cycle, but increase product development cost. And there is trade-off between development time and cost. And so, two methods are given to slacken and eliminate multi-ply overlapping effects. At last, an example about a vehicle upper subsystem design illustrates the application of the proposed models; compared with a sequential execution pattern, the decreasing of development cycle (22%) and the increasing of development cost (3%) show the validity of the method in the example The proposed research not only lays a theoretical foundation for correctly planning complex product development process, but also provides specific and effective operation methods for overlapping multi coupled activities.展开更多
Developmental dysplasia of hip seriously affects the health of children,and pelvic osteotomy is an important part of surgical treatment.Improving the shape of the acetabulum,preventing or delaying the progression of o...Developmental dysplasia of hip seriously affects the health of children,and pelvic osteotomy is an important part of surgical treatment.Improving the shape of the acetabulum,preventing or delaying the progression of osteoarthritis is the ultimate goal of pelvic osteotomies.Re-directional osteotomies,reshaping osteotomies and salvage osteotomies are the three most common types of pelvic osteotomy.The influence of different pelvic osteotomy on acetabular morphology is different,and the acetabular morphology after osteotomy is closely related to the prognosis of the patients.But there lacks comparison of acetabular morphology between different pelvic osteotomies,on the basis of retrospective analysis and measurable imaging indicators,this study predicted the acetabular shape after developmental dysplasia of the hip pelvic osteotomy in order to help clinicians make reasonable and correct decisions and improve the planning and performance of pelvic osteotomy.展开更多
A novel flat-flat resonator consisting of two crystals(Nd:YAG + Nd:YVO4) is established for power scaling in a diode-end-pumped solid-state laser. We systematically compare laser characteristics between multi-seg...A novel flat-flat resonator consisting of two crystals(Nd:YAG + Nd:YVO4) is established for power scaling in a diode-end-pumped solid-state laser. We systematically compare laser characteristics between multi-segmented(Nd:YAG + Nd:YVO4) and conventional composite(Nd:YAG + Nd:YAG) crystals to demonstrate the feasibility of spectral line matching for output power scale-up in end-pumped lasers. A maximum continuous-wave output power of 79.2 W is reported at 1064 nm, with Mx2= 4.82, My2= 5.48, and a pumping power of 136 W in the multi-segmented crystals(Nd:YAG + Nd:YVO4). Compared to conventional composite crystals(Nd:YAG + Nd:YAG), the optical-optical conversion efficiency of multi-segmented crystals(Nd:YAG + Nd:YVO4) from 808 nm to 1064 nm is enhanced from 30% to 58.8%,while the laser output sensitivity as affected by the diode-laser temperature is reduced from 55% to 9%.展开更多
Background: Hallux valgus deformity is one of the most common chronic and progressive foot deformities. Surgical correction of the deformity plays a central role in the treatment of symptomatic hallux valgus. However,...Background: Hallux valgus deformity is one of the most common chronic and progressive foot deformities. Surgical correction of the deformity plays a central role in the treatment of symptomatic hallux valgus. However, more than one hundred different surgical techniques have been described. Objective: To assess the radiological outcome of hallux valgus surgical correction using a scarf and akin osteotomies. Materials and methods: A cross-sectional hospital-based study was conducted on 25 adult patients (36 feet). Twenty-two females and two males with hallux valgus were treated with surgical correction using a scarf and akin osteotomies. All candidates were kept on regular postoperative, scheduled clinical follow-up programs for one year and assessed radiologically. Results: Twenty-five patients (36 feet) were included in this study. The hallux valgus angle significantly shifted to the normal range (less than 15°) after surgery, and the inter-metatarsal angle also improved to the normal range (less than 9°). Conclusion: Using scarf and akin osteotomies in treating moderate and severe hallux valgus deformity provides the satisfactory radiological outcomes in form of decreasing hallux valgus angle and inter-metatarsal angle.展开更多
BACKGROUND Although metaphyseal ulnar shortening osteotomy(MUSO)is safer for the treatment of ulnar impaction syndrome(UIS)than diaphyseal ulnar shortening osteotomy(DUSO),DUSO is widely used for UIS treatment.AIM To ...BACKGROUND Although metaphyseal ulnar shortening osteotomy(MUSO)is safer for the treatment of ulnar impaction syndrome(UIS)than diaphyseal ulnar shortening osteotomy(DUSO),DUSO is widely used for UIS treatment.AIM To evaluate the effectiveness of DUSO and MUSO for UIS treatment and determine the factors that should be considered when choosing surgical treatment for UIS.METHODS Articles comparing the effectiveness of DUSO and MUSO for UIS treatment were systematically retrieved from MEDLINE(Ovid),PubMed,EMBASE,and Cochrane Library.The demography,incidence of complications,secondary operation rate,postoperative DASH score,wrist pain on the visual analogue scale,and grip strength improvement were also evaluated.In addition,the correlation between the improvement of grip strength and the shortening of osteotomy length of ulna was analyzed.The outcome of the patient was discontinuous,and the odds ratio,risk ratio(RR),and 95%CI were calculated and analyzed via RevMan5.3 software.RESULTS Six studies,including 83 patients receiving MUSO(experimental group)and 112 patients receiving DUSO(control group),were included in the meta-analysis.The second operation rate was significantly higher after DUSO than after MUSO.The DASH scores were slightly lower in the MUSO group than in the DUSO group.The patients receiving MUSO had slightly better pain relief effect than patients receiving DUSO.However,the incidence of complications and improvement of grip strength were not significantly different between the two groups.CONCLUSION Although DUSO and MUSO provide similar effects for UIS,MUSO is associated with a lower secondary operation rate,slightly lower postoperative DASH scores and slightly better pain relief effect than DUSO,indicating that MUSO can effectively be used for UIS treatment.展开更多
BACKGROUND The treatment of late stages of Legg-Calvé-Perthes disease(LCPD)is controversial.Although the concept of femoral head containment is a well-established technique of treatment,its use remains debatable ...BACKGROUND The treatment of late stages of Legg-Calvé-Perthes disease(LCPD)is controversial.Although the concept of femoral head containment is a well-established technique of treatment,its use remains debatable in the late stages of the disease,as it does not improve symptoms in terms of limb length discrepancy and gait.AIM To assess the results of subtrochanteric valgus osteotomy in symptomatic patients with late-stage Perthes disease.METHODS From 2000 to 2007,36 symptomatic patients with late stage of Perthes disease were surgically treated with subtrochanteric valgus osteotomy and followed-up for 8 to 11 years using the IOWA score and range of motion(ROM)variables.The Mose classification was also assessed at the last follow-up to reflect possible remodeling.The patients were 8 years old or older at the time of surgery,in the post-fragmentation stage,and complaining of pain,limited ROM,Trendelenburg gait,and/or abductor weakness.RESULTS The preoperative IOWA score(average:53.3)markedly improved at the 1-year post follow-up period(average:85.41)and then slightly improved at the last follow-up(average:89.4)(P value<0.05).ROM improved,with internal rotation increased on average by 22°(from 10°preoperatively to 32°postoperatively)and abduction increased on average by 15.9°(from 25°preoperatively to 41°postoperatively).The mean Mose deviation of femoral heads was 4.1 mm at the end of the follow-up period.The tests used were the paired t-test and Pearson correlation test,where the level of significance was a P value less than 0.05.CONCLUSION Subtrochanteric valgus osteotomy can be a good option for symptomatic relief in patients with late-stage of LCPD.展开更多
BACKGROUND The ExeterTM Universal cemented femoral component is widely used for total hip replacement surgery.Although there have been few reports of femoral component fracture,removal of a broken femoral stem can be ...BACKGROUND The ExeterTM Universal cemented femoral component is widely used for total hip replacement surgery.Although there have been few reports of femoral component fracture,removal of a broken femoral stem can be a challenging procedure.CASE SUMMARY A 54-year-old man with a Dorr A femur sustained a refracture of a primary ExeterTM stem,two years after receiving a revision using a cement-within-cement technique(CWC)through an extended trochanteric osteotomy(ETO).The technical problems related to the CWC technique and the ETO played a major role in the stem fatigue refracture.We performed revision surgery and removed the distal cement using a cortical femoral window technique,followed by reimplantation with an uncemented,modular,distally-fixed uncemented stem.The patient experienced an uneventful postoperative recovery.CONCLUSION Re-fracture of a modern femoral ExeterTM stem is a rare event,but technical complications related to revision surgery can lead to this outcome.The cortical window osteotomy technique can facilitate the removal of a broken stem and cement,allowing for prosthetic reimplantation under direct vision and avoiding ETO-related complications.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.12274355)Xiamen University Malaysia Research Fund(Grant Nos.XMUMRF/2022C9/IORI/003 and XMUMRF/2022-C10/IORI/004)。
文摘Thermal rectification is an exotic thermal transport phenomenon,an analog to electrical rectification,in which heat flux along one direction is larger than that in the other direction and is of significant interest in electronic device applications.However,achieving high thermal rectification efficiency or rectification ratio is still a scientific challenge.In this work,we performed a systematic simulation of thermal rectification by considering both efforts of thermal conductivity asymmetry and geometrical asymmetry in a multi-segment thermal rectifier.It is found that the high asymmetry of thermal conductivity and the asymmetry of the geometric structure of multi-segment thermal rectifiers can significantly enhance the thermal rectification,and the combination of both thermal conductivity asymmetry and geometrical asymmetry can further improve thermal rectification efficiency.This work suggests a possible way for improving thermal rectification devices by asymmetry engineering.
文摘This paper presents an enhanced version of the standard shooting method that enables problems with two unknown parameters to be solved.A novel approach is applied to the analysis of the natural vibrations of Euler-Bernoulli beams.The proposed algorithm,named as two-parameter multiple shooting method,is a new powerful numerical tool for calculating the natural frequencies and modes of multi-segment prismatic and non-prismatic beams with different boundary conditions.The impact of the axial force and additional point masses is also taken into account.Due to the fact that the method is based directly on the fourth-order ordinary differential equation,the structures do not have to be divided into many small elements to obtain an accurate enough solution,even though the geometry is very complex.To verify the proposed method,three different examples are considered,i.e.,a three-segment non-prismatic beam,a prismatic column subject to non-uniformly distributed compressive loads,and a two-segment beam with an additional point mass.Numerical analyses are carried out with the software MATHEMATICA.The results are compared with the solutions computed by the commercial finite element program SOFiSTiK.Good agreement is achieved,which confirms the correctness and high effectiveness of the formulated algorithm.
文摘A vortex domain wall's(VW) magnetic racetrack memory's high performance depends on VW structural stability,high speed, low power consumption and high storage density. In this study, these critical parameters were investigated in magnetic multi-segmented nanowires using micromagnetic simulation. Thus, an offset magnetic nanowire with a junction at the center was proposed for this purpose. This junction was implemented by shifting one portion of the magnetic nanowire horizontally in the x-direction(l) and vertically(d) in the y-direction. The VW structure became stable by manipulating magnetic properties, such as magnetic saturation(M_(4)) and magnetic anisotropy energy(K_(u)). In this case, increasing the values of M_(4) ≥ 800 kA/m keeps the VW structure stable during its dynamics and pinning and depinning in offset nanowires,which contributes to maintenance of the storage memory's lifetime for a longer period. It was also found that the VW moved with a speed of 500 m/s, which is desirable for VW racetrack memory devices. Moreover, it was revealed that the VW velocity could be controlled by adjusting the offset area dimensions(l and d), which helps to drive the VW by using low current densities and reducing the thermal-magnetic spin fluctuations. Further, the depinning current density of the VW(J_(d)) over the offset area increases as d increases and l decreases. In addition, magnetic properties, such as the M_(4) and K_(u),can affect the depinning process of the VW through the offset area. For high storage density, magnetic nanowires(multisegmented) with four junctions were designed. In total, six states were found with high VW stability, which means three bits per cell. Herein, we observed that the depinning current density(J_(d)) for moving the VW from one state to another was highly influenced by the offset area geometry(l and d) and the material's magnetic properties, such as the M_(4) and K_(u).
文摘Background: Despite the conservative treatment of tibio-femoral osteoarthritis through realignment osteotomies, the rate of total knee replacements following an osteotomy is increasing. The aim of this study was to identify the factors associated with the progression of knee osteoarthritis after a medial closing-wedge distal femoral osteotomy. Methods: Hospital-based observational study on 20 patients who underwent a medial closing-wedge distal femoral osteotomy evaluating the progression of osteoarthritis using the Kellgren and Laurence classification. The Wilcoxon test was used to compare the variation in the progressive stage of the Kellgren and Laurence classification of knee osteoarthritis preoperatively and at the final follow up. Univariate analysis made it possible to determine the factors associated with progression. The final significance threshold for statistical tests was set at 5% (p Results: Overall, the mean follow-up of 46 months ± 6.6 months, with a mean age of 43 years (range: 27 - 69 years) and a female predominance (M: F = 3/7). The progression of tibiofemoral osteoarthritis following a medial closing-wedge distal femoral osteotomy is associated with valgus or varum malalignment been a moderate valgus (OR 6.2 [1.5 - 42.7] at 95% CI;p-value = 0.02), a correction of the mechanical deviation angle with a valgus alignment (OR 2.7 [0.9 - 8.3] at 95% CI), and loss of correction (OR 3.8 [1.3 - 11.6] at 95% CI;p -value) for the lateral compartment while varus alignment (OR 1.7 [0.9 - 8.3] 95% CI, p-value = 0.05) and with rupture of the lateral cortex (OR 2.8 [1.7 - 11.5] 95% CI, p-value = 0.02) were those of the medial compartment. Conclusion: Distal femur closing wedge osteotomy does not definitively interrupt the progression of valgus knee osteoarthritis. The factors associated with the progression of this pathology are modifiable. Taking them into account when performing this surgical technique could improve the osteotomy survival curve.
文摘Background: Four factors determine the quality of an implantology kit: 1) Heat generated by the drills;2) Morphology of the osteotomy according to the diameter of the implant;3) Efficiency of collecting autologous bone;and 4) Osteotomy execution time. Materials and Methods: This article examines the heat produced by drills during osteotomy, focusing on the effect of the following factors: drilling technique;volume of autologous bone harvested;drilling time;implant primary stability;and the percentage of osseointegrated implants after primary healing. Discussion: The four factors mentioned above are analyzed based on the data obtained for sequential, biological, and One Drill milling techniques. Conclusions: 1) One Drill is the fastest technique for performing the osteotomy;2) All techniques stay within the biological temperature range of living bone, with the lowest increase in temperature achieved using One Drill with irrigation;3) The bone harvested showed no statistically significant differences between biological milling and the One Drill technique, both far superior to the sequential technique;and 4) There is no statistically significant difference in the number of osseointegrated implants among the three techniques analyzed.
文摘BACKGROUND The preferred treatment for distal humeral intercondylar fractures is open reduction and internal fixation.While there is consensus about the posterior approach,several posterior approaches have been developed.It is debatable as to which approach is best.AIM To compare triceps reflecting anconeus pedicle(TRAP)and olecranon osteotomy approaches for internal fixation of distal humeral intercondylar fracture.METHODS In total,40 cases of Arbeitsgemeinschaft für Osteosynthesefragen/Association of the Study of Internal Fixation type C,closed,and Gustilo type I intercondylar humeral fractures were included.Patients ranged in age from 18 years to 70 years.The patients were randomized into two groups:TRAP group and olecranon osteotomy group,with 20 cases in each.All were followed up at 6 wk,3 months,6 months,and 12 months.Functional outcomes were measured in terms of flexion-extension arc,Disabilities of Arm,Shoulder and Hand score,and Mayo Elbow Performance Score.RESULTS The mean age was 43.2 years in the TRAP group and 37.5 years in the olecranon osteotomy group.The mean operative time and mean duration of hospital stay in the TRAP group were significantly higher than in the olecranon osteotomy group(119.5 vs 111.5 min and 9.85 vs 5.45 d,respectively).The mean arc of flexion-extension,Disabilities of Arm,Shoulder and Hand score,and Mayo Elbow Performance Score were comparable without any significant difference in the groups at the 12-month follow-up(107.0 vs 106.2,18.3 vs 15.7,and 84.2 vs 86.2,respectively).Ulnar paresthesia and superficial infections were comparable in both groups(2 cases vs 3 cases and 3 cases vs 2 cases,respectively).Hardware prominence was significantly higher in the olecranon osteotomy group,mostly due to tension band wiring.CONCLUSION Both approaches were equivalent,but there is a need for further study including higher numbers of subjects and longer study duration to prove the benefits of one approach over the other.
文摘BACKGROUND Unicompartmental knee arthroplasty(UKA)and high tibial osteotomy(HTO)are well-established operative interventions in the treatment of knee osteoarthritis.However,which intervention is more beneficial to patients with knee osteoarthritis remains unknown and a topic of much debate.Simultaneously,there is a paucity of research assessing the relationship between radiographic parameters of knee joint alignment and patient-reported clinical outcomes,preoperatively and following HTO or UKA.AIM To compare UKAs and HTOs as interventions for medial-compartment knee osteoarthritis:Examining differences in clinical outcome and investigating the relationship of joint alignment with respect to this.METHODS This longitudinal observational study assessed a total of 42 patients that had undergone UKA(n=23)and HTO(n=19)to treat medial compartment knee osteoarthritis.Patient-reported outcome measures(PROMs)were collected to evaluate clinical outcome.These included two disease-specific(Knee Injury and Osteoarthritis Outcome Score,Oxford Knee Score)and two generic(EQ-5D-5L,Short Form-12)PROMs.The radiographic parameters of knee alignment assessed were the:Hip-knee-ankle angle,mechanical axis deviation and angle of Mikulicz line.RESULTS Statistical analyses demonstrated significant(P<0.001),preoperative to postoperative,improvements in the PROM scores of both groups.There were,however,no significant inter-group differences in the postoperative PROM scores of the UKA and HTO group.Several significant correlations associated a more distolaterally angled Mikulicz line with worse knee function and overall health preoperatively(P<0.05).Postoperatively,two clusters of significant correlations were observed between the disease-specific PROM scores and knee joint alignment parameters(hip-knee-ankle angle,mechanical axis deviation)within the HTO group;yet no such associations were observed within the UKA group.CONCLUSION UKAs and HTOs are both efficacious operations that provide a comparable degree of clinical benefit to patients with medial compartment knee osteoarthritis.Clinical outcome has a limited association with radiographic parameters of knee joint alignment postoperatively;however,a more distolaterally angled Mikulicz line appears associated with worse knee function/health-related quality of life preoperatively.
基金Supported by the Natural Science Foundation ofHebei Province (F2004000133)
文摘Through the analysis to the DDoS(distributed denial of service) attack, it will conclude that at different time segments, the arrive rate of normal SYN (Synchronization) package are similar, while the abnormal packages are different with the normal ones. Toward this situation a DDoS defense algorithm based on multi-segment timeout technology is presented, more than one timeout segment are set to control the net flow. Experiment results show that in the case of little flow, multi-segment timeout has the ability dynamic defense, so the system performance is improved and the system has high response rate.
基金sponsored by Jiangsu Provincial Colleges and Universities Natural Science Foundation of China (Grant No.08KJD410001)Humanities and Social Sciences Planning Fund of Ministry of Education of China (Grant No. 12YJAZH151)Humanities and Social Sciences Youth Fund of Ministry of Education of China (Grant No. 12YJCZH209)
文摘Complex product development will inevitably face the design planning of the multi-coupled activities, and overlapping these activities could potentially reduce product development time, but there is a risk of the additional cost. Although the downstream task information dependence to the upstream task is already considered in the current researches, but the design process overall iteration caused by the information interdependence between activities is hardly discussed; especially the impact on the design process' overall iteration from the valid information accumulation process. Secondly, most studies only focus on the single overlapping process of two activities, rarely take multi-segment and multi-ply overlapping process of multi coupled activities into account; especially the inherent link between product development time and cost which originates from the overlapping process of multi coupled activities. For the purpose of solving the above problems, as to the insufficiency of the accumulated valid information in overlapping process, the function of the valid information evolution (VIE) degree is constructed. Stochastic process theory is used to describe the design information exchange and the valid information accumulation in the overlapping segment, and then the planning models of the single overlapping segment are built. On these bases, by analyzing overlapping processes and overlapping features of multi-coupling activities, multi-segment and multi-ply overlapping planning models are built; by sorting overlapping processes and analyzing the construction of these planning models, two conclusions are obtained: (1) As to multi-segment and multi-ply overlapping of multi coupled activities, the total decrement of the task set development time is the sum of the time decrement caused by basic overlapping segments, and minus the sum of the time increment caused by multiple overlapping segments; (2) the total increment of development cost is the sum of the cost increment caused by all overlapping process. And then, based on overlapping degree analysis of these planning models, by the V1E degree function, the four lemmas theory proofs are represented, and two propositions are finally proved: (1) The multi-ply overlapping of the multi coupled activities will weaken the basic overlapping effect on the development cycle time reduction (2) Overlapping the multi coupled activities will decrease product development cycle, but increase product development cost. And there is trade-off between development time and cost. And so, two methods are given to slacken and eliminate multi-ply overlapping effects. At last, an example about a vehicle upper subsystem design illustrates the application of the proposed models; compared with a sequential execution pattern, the decreasing of development cycle (22%) and the increasing of development cost (3%) show the validity of the method in the example The proposed research not only lays a theoretical foundation for correctly planning complex product development process, but also provides specific and effective operation methods for overlapping multi coupled activities.
基金Supported by Scientific Research Project of Hunan Education Department,No.21A0054.
文摘Developmental dysplasia of hip seriously affects the health of children,and pelvic osteotomy is an important part of surgical treatment.Improving the shape of the acetabulum,preventing or delaying the progression of osteoarthritis is the ultimate goal of pelvic osteotomies.Re-directional osteotomies,reshaping osteotomies and salvage osteotomies are the three most common types of pelvic osteotomy.The influence of different pelvic osteotomy on acetabular morphology is different,and the acetabular morphology after osteotomy is closely related to the prognosis of the patients.But there lacks comparison of acetabular morphology between different pelvic osteotomies,on the basis of retrospective analysis and measurable imaging indicators,this study predicted the acetabular shape after developmental dysplasia of the hip pelvic osteotomy in order to help clinicians make reasonable and correct decisions and improve the planning and performance of pelvic osteotomy.
基金Project supported by the National Defense Pre-Research Foundation of China(Grant No.9140A020105)
文摘A novel flat-flat resonator consisting of two crystals(Nd:YAG + Nd:YVO4) is established for power scaling in a diode-end-pumped solid-state laser. We systematically compare laser characteristics between multi-segmented(Nd:YAG + Nd:YVO4) and conventional composite(Nd:YAG + Nd:YAG) crystals to demonstrate the feasibility of spectral line matching for output power scale-up in end-pumped lasers. A maximum continuous-wave output power of 79.2 W is reported at 1064 nm, with Mx2= 4.82, My2= 5.48, and a pumping power of 136 W in the multi-segmented crystals(Nd:YAG + Nd:YVO4). Compared to conventional composite crystals(Nd:YAG + Nd:YAG), the optical-optical conversion efficiency of multi-segmented crystals(Nd:YAG + Nd:YVO4) from 808 nm to 1064 nm is enhanced from 30% to 58.8%,while the laser output sensitivity as affected by the diode-laser temperature is reduced from 55% to 9%.
文摘Background: Hallux valgus deformity is one of the most common chronic and progressive foot deformities. Surgical correction of the deformity plays a central role in the treatment of symptomatic hallux valgus. However, more than one hundred different surgical techniques have been described. Objective: To assess the radiological outcome of hallux valgus surgical correction using a scarf and akin osteotomies. Materials and methods: A cross-sectional hospital-based study was conducted on 25 adult patients (36 feet). Twenty-two females and two males with hallux valgus were treated with surgical correction using a scarf and akin osteotomies. All candidates were kept on regular postoperative, scheduled clinical follow-up programs for one year and assessed radiologically. Results: Twenty-five patients (36 feet) were included in this study. The hallux valgus angle significantly shifted to the normal range (less than 15°) after surgery, and the inter-metatarsal angle also improved to the normal range (less than 9°). Conclusion: Using scarf and akin osteotomies in treating moderate and severe hallux valgus deformity provides the satisfactory radiological outcomes in form of decreasing hallux valgus angle and inter-metatarsal angle.
文摘BACKGROUND Although metaphyseal ulnar shortening osteotomy(MUSO)is safer for the treatment of ulnar impaction syndrome(UIS)than diaphyseal ulnar shortening osteotomy(DUSO),DUSO is widely used for UIS treatment.AIM To evaluate the effectiveness of DUSO and MUSO for UIS treatment and determine the factors that should be considered when choosing surgical treatment for UIS.METHODS Articles comparing the effectiveness of DUSO and MUSO for UIS treatment were systematically retrieved from MEDLINE(Ovid),PubMed,EMBASE,and Cochrane Library.The demography,incidence of complications,secondary operation rate,postoperative DASH score,wrist pain on the visual analogue scale,and grip strength improvement were also evaluated.In addition,the correlation between the improvement of grip strength and the shortening of osteotomy length of ulna was analyzed.The outcome of the patient was discontinuous,and the odds ratio,risk ratio(RR),and 95%CI were calculated and analyzed via RevMan5.3 software.RESULTS Six studies,including 83 patients receiving MUSO(experimental group)and 112 patients receiving DUSO(control group),were included in the meta-analysis.The second operation rate was significantly higher after DUSO than after MUSO.The DASH scores were slightly lower in the MUSO group than in the DUSO group.The patients receiving MUSO had slightly better pain relief effect than patients receiving DUSO.However,the incidence of complications and improvement of grip strength were not significantly different between the two groups.CONCLUSION Although DUSO and MUSO provide similar effects for UIS,MUSO is associated with a lower secondary operation rate,slightly lower postoperative DASH scores and slightly better pain relief effect than DUSO,indicating that MUSO can effectively be used for UIS treatment.
文摘BACKGROUND The treatment of late stages of Legg-Calvé-Perthes disease(LCPD)is controversial.Although the concept of femoral head containment is a well-established technique of treatment,its use remains debatable in the late stages of the disease,as it does not improve symptoms in terms of limb length discrepancy and gait.AIM To assess the results of subtrochanteric valgus osteotomy in symptomatic patients with late-stage Perthes disease.METHODS From 2000 to 2007,36 symptomatic patients with late stage of Perthes disease were surgically treated with subtrochanteric valgus osteotomy and followed-up for 8 to 11 years using the IOWA score and range of motion(ROM)variables.The Mose classification was also assessed at the last follow-up to reflect possible remodeling.The patients were 8 years old or older at the time of surgery,in the post-fragmentation stage,and complaining of pain,limited ROM,Trendelenburg gait,and/or abductor weakness.RESULTS The preoperative IOWA score(average:53.3)markedly improved at the 1-year post follow-up period(average:85.41)and then slightly improved at the last follow-up(average:89.4)(P value<0.05).ROM improved,with internal rotation increased on average by 22°(from 10°preoperatively to 32°postoperatively)and abduction increased on average by 15.9°(from 25°preoperatively to 41°postoperatively).The mean Mose deviation of femoral heads was 4.1 mm at the end of the follow-up period.The tests used were the paired t-test and Pearson correlation test,where the level of significance was a P value less than 0.05.CONCLUSION Subtrochanteric valgus osteotomy can be a good option for symptomatic relief in patients with late-stage of LCPD.
文摘BACKGROUND The ExeterTM Universal cemented femoral component is widely used for total hip replacement surgery.Although there have been few reports of femoral component fracture,removal of a broken femoral stem can be a challenging procedure.CASE SUMMARY A 54-year-old man with a Dorr A femur sustained a refracture of a primary ExeterTM stem,two years after receiving a revision using a cement-within-cement technique(CWC)through an extended trochanteric osteotomy(ETO).The technical problems related to the CWC technique and the ETO played a major role in the stem fatigue refracture.We performed revision surgery and removed the distal cement using a cortical femoral window technique,followed by reimplantation with an uncemented,modular,distally-fixed uncemented stem.The patient experienced an uneventful postoperative recovery.CONCLUSION Re-fracture of a modern femoral ExeterTM stem is a rare event,but technical complications related to revision surgery can lead to this outcome.The cortical window osteotomy technique can facilitate the removal of a broken stem and cement,allowing for prosthetic reimplantation under direct vision and avoiding ETO-related complications.