This paper presents data, collected from video-recording, on the microscopic details of merging and weaving manoeuvres under congested traffic conditions. Based on these observations, a ...classification of the manoeuvres into free, forced and cooperative lane changes is proposed. A new lane change model is developed, incorporating explicit modelling of vehicle interactions using intelligent agent concepts. The model was implemented in the ARTEMiS traffic simulator, and several hypothetical test studies were conducted to demonstrate the capabilities of the new model. The results show that the model is able to reproduce the observed behaviour of individual vehicles in terms of speed, gap acceptance and conflict-resolution in all three types of lane change manoeuvres, and hence, it is able to simulate highly congested flow conditions in a realistic manner. The macroscopic results in terms of speed-flow relationship are close to the typical expected results. The model can simulate both freeways and signalised urban arterial networks.
This paper introduces Simulation of Intelligent TRAnsport Systems (SITRAS), a massive multi-agent simulation system in which driver-vehicle objects are modelled as autonomous agents. The simulation ...outputs can be used for the evaluation of Intelligent Transport Systems applications such as congestion and incident management, public transport priority and dynamic route guidance. The model concepts and specifications, and the first applications of the model in the area of incident modelling in urban arterial networks were described in previous publications. This paper presents the details of the lane changing and merging algorithms developed for the SITRAS model. These models incorporate procedures for ‘forced’ and ‘co-operative’ lane changing which are essential for lane changing under congested (and incident-affected) traffic conditions. The paper describes the algorithms and presents simulation examples to demonstrate the effects of the implemented models. The results indicate that only the forced and cooperative lane changing models can produce realistic flow-speed relationships during congested conditions.
In this experimental study, the authors evaluated the biomechanical properties of the femoral press-fit graft fixation technique in ACL reconstruction. 20 fresh frozen distal femurs, patellae and ...patellar ligaments were used from 10 cadaver specimens. Three bone-patellar tendon grafts of 10 mm width were prepared from each sample; altogether 60 bone-patellar tendon grafts were prepared for the experiment. Three 9 mm wide tunnels were drilled in each distal femur at different angles (0, 15, 30, 45, and 60 degrees). This means that 60 tunnels were drilled into the 20 femurs, 12 at each angle. The trapezoid bone blocks were impacted into the holes. The primary stability and stiffness of this press-fit fixation method were measured with a Zwick 020 computer-controlled testing device using maximum-failure tensile-strength tests. The ultimate tensile strength was the greatest at 45 degrees (534+/-20 N, range 507-554), with 118+/-10 N/mm (range 99-126) stiffness, followed by 485+/-35 N (range 416-510) with 122+/-13 N/mm (range 104-136) stiffness at 30 degrees, 353+/-18 N (range 320-371) with 113+/-13 N/mm (range 83-124) stiffness at 15 degrees, and 312+/-30 N (range 261-343) with 89+/-14 N/mm (ranged:68-103) stiffness at 0 degrees. In the cases of 0, 15, 30 and 45 degrees the bone blocks were pulled out of the drilled holes, but at 60 degrees rupture of the patellar tendon or breakage of the bone block occurred more frequently. It can be seen that the ultimate tensile strength increased with the angle between the loading direction and the bone block. When compared to data in the literature, these data showed similar and satisfying biomechanical properties of femoral press-fit fixation. Because of the known advantages of an implantation-free fixation technique, the femoral press-fit fixation technique can be a good alternative in ACL surgery. These results provide the basis for future studies involving the postoperative healing process of this femoral press-fit fixation technique in porcine knees.
The performance of the CMS Level-1 Trigger for supersymmetric events at an LHC luminosity of 2 x 1033 cm-2s-1 is reviewed. Energy and momentum trigger thresholds have been chosen to yield a maximum ...Level-1 output rate of 50 kHz, within a safety factor of three. The Level-1 trigger efficiencies for the majority of the channels studied are found to be greater than 90%, which provides a good basis for the High-Level Trigger, where more stringent conditions are applied. Reasons for occasional lower efficiencies are given.
We present our technique for surgically treating Tossy III acromioclavicular joint dislocation, discuss the indications for various procedures, and evaluate our postoperative results. We operated on ...17 patients suffering from chronic acromioclavicular instability after such dislocation using a modified Weaver-Dunn procedure, in which there is no lateral clavicular end resection, the coracoacromial ligament graft is sutured to the inferior part of the clavicle by transosseal sutures, and a Bosworth coracoclavicular screw is used to protect the graft postoperatively for 8 weeks. After a mean of 37 months we evaluated shoulder function by the Constant score and the subjective and radiological results. Mean Constant score was 91.9% (74-100%); it was 80-90% in 5 patients and above 90% in 11. One patient had screw loosing after the operation and suffered partial loss of reduction and discomfort during shoulder loading. All patients but one returned to work, and all but one have returned to their preoperative activity at the same level. Subjectively, there were 11 excellent and 6 good results. Compared to the contralateral uninjured side, radiography showed anatomical reposition in the vertical plane in 9 cases, slight loss of reduction in 6 (difference in the distance between the inferior border of the acromion and the clavicle is 2-4 mm), and partial loss of reduction in 2 (4-8 mm). We recommend the modified Weaver-Dunn procedure for surgical treatment of chronic, Tossy grade III acromioclavicular joint dislocations as it provides good functional and subjective results. Our modification is indicated mainly for young patients because posttraumatic arthrosis occurs more frequently in elderly patients, making clavicular end resection necessary.
Background
The security of the graft fixation is an important factor of anterior cruciate ligament reconstruction, especially in the early postoperative period.
Hypothesis
The femoral press-fit ...fixation technique is a safe, alternative technique for the fixation of the bone-patellar tendon-bone graft.
Study Design
Case series; Level of evidence, 4.
Methods
Between January 1, 1998, and June 30, 2002, 285 patients, with a mean age of 29.1 years, underwent operation and observation in our department. All patients had arthroscopic anterior cruciate ligament reconstruction using bone-patellar tendon-bone graft with femoral press-fit and tibial interference screw fixation. The mean follow-up period was 35.8 months (range, 24-77 months). During each patient's evaluation, a physical examination, a subjective evaluation, the International Knee Documentation Committee and Lysholm scores, KT-1000 arthrometer testing, and radiological evaluation were performed. The paired Student t test or X2 test was used for statistical analysis.
Results
According to the International Knee Documentation Committee score, 241 patients (85%) had good (46 normal and 195 nearly normal) results, whereas 39 patients had abnormal and 5 patients had severely abnormal overall results. The preoperative mean Lysholm score was 63.5 ± 12.7 points. At the final examination, the mean value was 93.5 ± 7.8 points (P <. 01). One hundred ninety-seven athletes could return to their previous sports activity level, whereas 13 patients gave up their sports career. The KT-1000 arthrometer results showed a side-to-side difference of 1.91 ± 2.1 mm at the maximum manual strength tests.
Conclusion
The femoral press-fit fixation is an alternative fixation method for the bone-patellar tendon-bone graft and provides good stability for the anterior cruciate ligament reconstruction. The use of press-fit fixation technique avoids most interference screw or other hardware-induced complications at the femoral side.
Recurrent anterior shoulder instability and the restoration of sports ability after surgery are common problems, especially among professional athletes. The purpose of this study was to evaluate the ...rate, level and time of returning to sports activity activity after Bankart procedure in anterior shoulder instability in high level athletes. From 1992-1994 61 patients suffering from recurrent anterior shoulder instability were operated on open Bankart procedure, 44 out of 61 were professional athletes. There were 7 handball, 7 basketball, 6 football, 2 waterpolo and 1 baseball player and 4 wrestlers, 2 weight-lifters, 2 boxers, 3 bicyclists, 2 motorists, 2 swimmers, 2 sailors, 2 kayakers and 2 skiers. The mean duration of instability was 19.1 months (3-72) before operation. 29 patients had posttraumatic recurrent anterior dislocation and 15 patients had posttraumatic anterior subluxations. The average number of redislocations was 4.4, ranging from 2 to 11. At the follow-up examination the patients were tested clinically for instability using the special score created by Walch and Duplay and the Constant functional score. We measured the strength of the rotator cuff by Kintrex isokinetic device from the 10th postoperative week. 35 out of 44 professional athletes could be followed-up. The average follow-up period was 14.2 months, from 6 to 31. 88% of the patients were able to return to sports participation, 66% on the previous level and 22% on a lower level. 12% of the patients finished their professional sports career. The mean rehabilitation period was 5.8 months, the average period of full restoration of sports ability was 9.3 months. Similar results were documented with the Constant score and the Walch-Duplay test (88% excellent or good, 12% fair). The main reason for the inability to continue sports activity was some pain during extreme abduction and external rotation of the arm and recurrent sensations of subluxation (3 cases). Based on the results of the follow-up examinations an early diagnosis is paramount followed by timely surgical intervention to restore anatomical integrity in proven cases of shoulder instability in professional athletes. The open Bankart procedure is preferred giving excellent functional results and providing good chances for the athletes to return to their previous sports level.
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