Some studies in the formation of elastic tissue

Elastic tissue hyperplasia occurs normally in senile atrophic mammary tissue. It occurs also pathologically in mammary carcinomata, as a local reactive response Of the host's tissues to the tumour growth.It is suggested that a further study of these elastic changes in relation to the site of mammary carcinoma origin and in relation to other suspected precancerous conditions, would be of academical and practical value to our knowledge of the pathogenesis and pathology of mammary carcinoma

Sensing and real-time expert system for a masonry building robot

The construction industry is striving to eliminate dangerous and repetitive work, as well as increase quality and productivity in the various tasks. For this reason, there is growing interest in the use of automation and robotics. However, the requirements of robots for construction are different from those of industrial robots, due to the characteristics of the construction tasks and the relatively unstructured working environment. The main objective of this research is to investigate the enabling technology for a masonry tasking robot, utilising an experimental robot cell. To truly automate the masonry construction task, there is need to utilise the advancement in robotic technology, especially to deal with the unstructured environment. This view is in-line with this research, which attempts to solve part of the complex problems of automating the building task, by using forms of sensing and intelligence. Concentration on this is the main distinguishing difference between this work and the few other attempts at physical realisation and experimentation in masonry automation. In terms of research and development of masonry tasking machines and robots, there is much activity on an international scale. Concerning the provisions for machine intelligence in this, it appears that the work reported has the most advanced provisions for computer intelligence. This work is of general relevance to construction robots because imprecision, dynamic performance, unplanned events and cell component relocation are considered. The experimental robot cell, built at City University, is used in the research. Standard construction materials have been adopted with imprecise dimensions. Using a CAD/CAM facility, building project designs are translated into robot’s ‘theoretical task’. However, because the masonry material is unpredictable, this can not be directly implemented without real-time adjustments derived from sensing. Not withstanding, advantage is taken of pre-processing, with real-time accommodation of discrepancies, obstacle avoidance and un-planned events. In this, the robot cell performs intelligent processing using rule-based expert systems to carry out the masonry building tasks. Such a process contributes to the fundamental basis for the automation of all stages of building, from architectural planning through to execution of the construction work. A further complication is that the form of a move influences the dynamic response of the robot structure. Therefore, the structural dynamics response of the robot is taken into account in order to optimise performance. Rule based expert systems are investigated to enable a goal driven, intelligent planning approach to be implemented, that can provide an effective dynamic plan for the building task, as well as real-time adjustments to the automatically generated ‘theoretical task’. XXVI

20-year outcomes of anterior cruciate ligament reconstruction with hamstring tendon autograft: The catastrophic effect of age and posterior tibial slope

Background: No well-controlled studies have compared the long-term outcome of anterior cruciate ligament (ACL) reconstruction with hamstring tendon autograft between adolescents and adults. Increased posterior tibial slopes (PTSs) have been reported in the ACL-injured versus controls, but the effect of PTS on the outcome after reconstruction is relatively unexplored. Purpose: To compare the prospective longitudinal outcome of ‘‘isolated’’ ACL ruptures treated with anatomic endoscopic ACL reconstruction using hamstring tendon autograft over 20 years in adolescent and adult cohorts and to examine factors for repeat ACL injury. Study Design: Case-control study; Level of evidence, 3. Methods: A single-surgeon series of 200 consecutive patients undergoing isolated primary ACL reconstruction with hamstring tendon autograft were prospectively studied. Subjects were assessed preoperatively and at 2, 7, 15, and 20 years postoperatively. Outcomes included International Knee Documentation Committee (IKDC) Knee Evaluation, IKDC subjective scores, KT-1000 instrumented laxity testing, and radiological evaluation of degenerative change and medial tibial slope. Twenty-year outcomes were compared between those who underwent surgery at the age of 18 years or younger (adolescent group, n = 39) and those who underwent surgery when older than 18 years (adult group, n = 161). Results: At 20 years, 179 of 200 subjects were reviewed (89.5%). ACL graft rupture occurred in 37 subjects and contralateral ACL injury in 22 subjects. Of those with intact ACL grafts at 20 years, outcomes were not statistically different between adolescents and adults for the variables of IKDC subjective score (P = .29), return to preinjury activity level (P = .84), current activity level (P = .69), or degree of radiological degenerative change at 20 years (P = .51). The adolescent group had a higher proportion of grade 1 ligamentous laxity testing compared with the adult group (P = .003). Overall, ACL graft survival at 20 years was 86% for adults and 61% for adolescents (hazard ration, 3.3; P = .001). The hazard for ACL graft rupture was increased by 4.8 in adolescent males and 2.5 in adolescent females compared with adults. At 20 years, the ACL survival for adolescents with a PTS of ≥ 12° was 22%. The hazard for ACL graft rupture was increased by 11 in adolescents with a PTS of ≥ 12° (P = .001) compared with adults with a PTS \u3c 12°. Conclusion: Repeat ACL injury after isolated ACL reconstruction is common, occurring in 1 in 3 over 20 years. In the absence of further injury, isolated ACL reconstruction using this technique was associated with good long-term outcomes with respect to patient-reported outcomes and return to sports, regardless of age. However, mild ligament laxity and ACL graft rupture after ACL reconstruction are significantly more common in adolescents, especially adolescent males, compared with adults. PTS of 12° or more is the strongest predictor of repeat ACL injury, and its negative effect is most pronounced in adolescents