Diversity maintenance using a population of repelling random-mutation hill climbers

A novel evolutionary algorithm, which can be viewed as an extension to the simple, yet effective, approach of the Random-Mutation Hill Climber (RMHC), is presented. The algorithm addresses the shortcomings of RMHC and its multi-individual parallel version through the introduction of a penalty term into the fitness function, which penalizes individuals in the population for being too similar, hence maintaining population diversity. The performance of the algorithm is evaluated on the deceptive trap and a set of SAT problems, comparing them to the Crowding EA. The results show that at a small cost of solution speed on simpler problems, the algorithm gains better capabilities of dealing with the issues of local maxima

Long-term outcome after anterior cervical discectomy without fusion

To retrospectively study the long-term outcome of patients after anterior cervical discectomy without fusion (ACD) compared to results published on the long-term outcome after ACD with fusion (ACDF). We reviewed the charts of all patients receiving ACD surgery between 1985 and 2000 to analyze the direct post-operative results as well as complications of the surgery. Moreover, 102 patients, randomly selected, were interviewed with the neck disability index to study possible persisting complaints up to 18 years after ACD surgery. A total of 551 Patients were identified. Two months post-operative follow up at the outpatient clinic revealed that 90.1% of patients were satisfied with the result of ACD surgery. At the time of the survey, this percentage had dropped to 67.6%. In addition, 20.6% and 11.8% had obtained moderate to severe complaints, respectively, in daily-life activities. Complaints were mainly localized in the neck region and occasionally provoked radiating pain in the arm. On the short term, ACD leads to a satisfied outcome. Over the longer term, patients report increasing complaints. The increase in complaints at the time of the survey may be the result of ongoing degenerative effects. Compared to published data on ACDF, there is no superiority of any fusion technique compared to ACD alone

The contribution of RCTs to quality management and their feasibility in practice

The randomized controlled trial (RCT) is generally accepted as the most reliable method of conducting clinical research. To obtain an unbiased evaluation of the effectiveness of spine surgery, patients should be randomly assigned to either new or standard treatment. The aim of the present article is to provide a short overview of the advantages and challenges of RCTs and to present a summary of the conclusions of the Cochrane Reviews in spine surgery and later published trials in order to evaluate their contribution to quality management and feasibility in practice. From the searches, 130 RCTs were included, 95 from Cochrane Reviews and systematic reviews, and 35 from additional search. No study comparing surgery with sham surgery was identified. The first RCT in spine surgery was published in 1974 and compared debridement and ambulatory treatment in tuberculosis of the spine. The contribution of RCTs in spinal surgery has markedly increased over the last 10 years, which indicates that RCTs are feasible in this field. The results demonstrate missing quality specifications. Despite the number of published trials there is conflicting or limited evidence to support various techniques of instrumentation. The only intervention that receives strong evidence is discectomy for faster relief in carefully selected patients due to lumbar disc prolapse with sciatica. For future trials, authors, referees, and editors are recommended to follow the CONSORT statement. RCTs provide evidence to support clinical opinions before implementation of new techniques, but the individual clinical experience is still important for the doctor who has to face the patient