On-line hydraulic state prediction for water distribution systems

World Environmental and Water Resources Congress 2009: Great Rivers Proceedings of World Environmental and Water Resources Congress 2009 May 17–21, 2009 Kansas City, MissouriThis paper describes and demonstrates a method for on‐line hydraulic state prediction in urban water networks. The proposed method uses a Predictor‐Corrector (PC) approach in which a statistical data‐driven algorithm is applied to estimate future water demands, while near real‐time field measurements are used to correct (i.e., calibrate) these predicted values on‐line. The calibration problem is solved using a modified Least Squares (LS) fit method. The objective function is the minimization of the least‐squares of the differences between predicted and measured hydraulic parameters (i.e., pressure and flow rates at several system locations), with the decision variables being the consumers' water demands. The a‐priori estimation (i.e., prediction) of the values of the decision variables, which improves through experience, facilitates a better convergence of the calibration model and provides adequate information on the system's hydraulic state for real time optimization. The proposed methodology is demonstrated on a prototypical municipal water distribution system

Dynamic alignment using external socket reaction moments in trans-tibial amputees

Background: Prosthetic alignment is used to optimize prosthetic functioning and comfort. Spatio-temporal and kinematic gait parameters are generally observed to guide this process. However, they have been shown to be influenced by compensations, which reduces their sensitivity to changes in alignment. Alternatively, the use of moments working at the base of the prosthetic socket, external socket reaction moments (ESRM), has been proposed to quantify prosthetic alignment. Research question: To investigate if a predetermined kinetic alignment criterion, 0Nm averaged over the stance phase, can be used to fine-tune prosthetic alignment. Methods: 10 transtibial amputees were included in this intervention study. Firstly, their prostheses were aligned using conventional alignment procedures. Kinetic parameters and Socket Comfort Score (SCS) were measured in this initial alignment (IA) condition. Subsequently, the coronal plane ESRM during gait was presented to the prosthetist in real time using a Gait Real-time Analysis Interactive Lab. The prosthetist iteratively adapted the prosthetic alignment towards a predetermined average ESRM during the stance phase of 0 Nm. At the Final Alignment (FA), kinetic parameters and SCS were measured again and a paired sample t-test was performed to compare ESRMs and SCSs between alignments. Results: A significant (p < 0.001) change was found in the absolute coronal plane ESRM (mean ± SD) from IA (|0.104| ± 0.058 Nm/kg) to FA (|0.012| ± 0.015 Nm/kg). In addition a significant (p < 0.001) change of the external coronal adduction knee moments was observed from IA (−0,127 ± 0.079 Nm/kg) to FA (−0.055 ± 0.089 Nm/kg), however this change was more variable among participants. On average, no significant (p = 0.37) change in the SCS was observed. Significance: While this study shows the potential of quantifying and guiding alignment with the assistance of kinetic criteria, it also suggests that a sole reliance on the ESRM as a single alignment criterion might be too simple

Posterior implant removal in patients with thoracolumbar spine fractures: long-term results

Purpose: Debate remains whether posterior implants after thoracolumbar spine fracture stabilization should be removed routinely or only in symptomatic cases. Implant related problems might be resolved or even prevented but removal includes secondary risks. The aim of this study was to evaluate safety, patient satisfaction and quality of life after implant removal. Methods: A retrospective cohort study was performed concerning 102 patients that underwent posterior implant removal after stabilization of a traumatic thoracolumbar fracture between 2003 and 2015. Patients were invited to fill in SF-36, EQ-5D and RMDQ questionnaires after implant removal. Additionally, questions concerning satisfaction were presented. Cobb angles before and after removal were measured and in- or decrease of symptoms was gathered from hospital charts. Results: Mean age at removal was 38 years and time from implant removal to questionnaire was approximately 7 years, 62 patients filled in the questionnaires. Complications were present in 8% and quality of life was reported as fairly good. Patients had less back pain related disability compared to chronic low back pain patients. After removal there was a kyphosis increase which did not correspond with worsened clinical outcome. Removal decreased most symptoms and even asymptomatic patients reported benefit in most cases. An increase of symptoms after removal was reported in 11% of patients. Conclusion: Implant removal is generally safe and provides high patient satisfaction. Overall, patients have a fairly good quality of life. Most symptomatic and asymptomatic patients report benefit from removal. However, low risks of complications and increase of symptoms have to be weighted for individual patients

Comment on “A variable rate coefficient chlorine decay model”

We commend Jonkergouw et al. (1) for adopting the goal of\ud developing a chlorine decay model that is practical for “...day-to-day water distribution network modelling purposes and chlorine dosing optimisation studies” in the sense that the model coefficients are independent of loading conditions\ud (initial and rechlorination doses)

Identifying candidates for arthroscopic primary repair of the anterior cruciate ligament: A case-control study

Introduction: There has been a recent resurgence of interest in arthroscopic primary repair of proximal anterior cruciate ligament (ACL) tears. Patient selection is critical but not much is currently known on what predicts the possibility of repair. Goal of this study was therefore to assess predictive factors for the possibility of arthroscopic primary ACL repair. Methods: In this retrospective case–control study, all patients undergoing ACL surgery in a ten-year interval were included. Patients were treated with primary repair if there was a proximal tear and good tissue quality, or otherwise underwent ACL reconstruction. Collected data were age, gender, BMI, injury-to-surgery delay, injury mechanism and concomitant injuries. Receiver operating characteristic curves were used to find cutoff values, and all significant dependent variables were used in multivariate logistic analysis to assess independent predictors for the possibility of primary repair. Results: Three hundred sixty-one patients were included, of which in 158 patients (44%) primary repair was possible. Multivariate analysis (R2 = 0.340, p 35 years (Odds ratio [OR] 4.2, 95% CI 2.4–7.5,p < 0.001), surgery within 28 days (OR 3.3, 95% CI 1.9–5.7, p < 0.001), and BMI < 26 (OR 1.9, 95% CI 1.1–3.3,p = 0.029) were predictive for the possibility of primary repair, and lateral meniscus injury presence decreased the likelihood of repair (OR 0.5, 95% CI 0.3–0.8, p = 0.008). Conclusion: In this large cohort study, it was noted that 44% of patients had repairable ACL tears. Primary repair was more likely to be possible in older patients, patients with lower BMI and when surgery was performed within four weeks of injury

Identifying candidates for arthroscopic primary repair of the anterior cruciate ligament: A case-control study

Introduction: There has been a recent resurgence of interest in arthroscopic primary repair of proximal anterior cruciate ligament (ACL) tears. Patient selection is critical but not much is currently known on what predicts the possibility of repair. Goal of this study was therefore to assess predictive factors for the possibility of arthroscopic primary ACL repair. Methods: In this retrospective case–control study, all patients undergoing ACL surgery in a ten-year interval were included. Patients were treated with primary repair if there was a proximal tear and good tissue quality, or otherwise underwent ACL reconstruction. Collected data were age, gender, BMI, injury-to-surgery delay, injury mechanism and concomitant injuries. Receiver operating characteristic curves were used to find cutoff values, and all significant dependent variables were used in multivariate logistic analysis to assess independent predictors for the possibility of primary repair. Results: Three hundred sixty-one patients were included, of which in 158 patients (44%) primary repair was possible. Multivariate analysis (R2 = 0.340, p 35 years (Odds ratio [OR] 4.2, 95% CI 2.4–7.5,p < 0.001), surgery within 28 days (OR 3.3, 95% CI 1.9–5.7, p < 0.001), and BMI < 26 (OR 1.9, 95% CI 1.1–3.3,p = 0.029) were predictive for the possibility of primary repair, and lateral meniscus injury presence decreased the likelihood of repair (OR 0.5, 95% CI 0.3–0.8, p = 0.008). Conclusion: In this large cohort study, it was noted that 44% of patients had repairable ACL tears. Primary repair was more likely to be possible in older patients, patients with lower BMI and when surgery was performed within four weeks of injury

Outcome in patient-specific PEEK cranioplasty: A two-center cohort study of 40 implants

The best material choice for cranioplasty following craniectomy remains a subject to discussion. Complication rates after cranioplasty tend to be high. Computer-assisted 3-dimensional modelling of polyetheretherketone (PEEK) was recently introduced for cranial reconstruction. The aim of this study was to evaluate patient- and surgery-related characteristics and risk factors that predispose patients to cranioplasty complications. This retrospective study included a total of 40 cranial PEEK implants in 38 patients, performed at two reference centers in the Netherlands from 2011 to 2014. Complications were registered and patient- and surgery-related data were carefully analysed. The overall complication rate of PEEK cranioplasty was 28%. Complications included infection (13 %), postoperative haematoma (10 %), cerebrospinal fluid leak (2.5 %) and wound-related problems (2.5 %). All postoperative infections required removal of the implant. Nonetheless removed implants could be successfully re-used after re-sterilization. Although overall complication rates after PEEK cranioplasty remain high, outcomes are satisfactory, as our results compare favourably to recent literature reports on cranial vault reconstructio