Experimental evaluation of confidence interval procedures in sequential steady-state simulation

Sequential analysis of simulation output is generally accepted as the most efficient way for securing representativeness of samples of collected observations. In this scenario a simulation experiment is stopped when the relative precision of estimates, defined as the relative width of confidence intervals at an assumed confidence level, reaches the required level. This paper deals with the statistical correctness of the methods proposed for estimating confidence intervals for mean values in sequential steady-state stochastic simulation. We formulate basic rules that should be followed in proper experimental analysis of coverage of different steadystate interval estimators. Our main argument is that such analysis should be done sequentially. The numerical results of our preliminary coverage analysis of the method of Spectral Analysis (SA/HW) and Nonoverlapping Batch Means are presented, and compared with those obtained by traditional, non-sequential approaches

Microprocessor based system for the development of control and protection of HVDC convertors.

This project investigates aspects of microprocessor based control and protection schemes for high voltage direct current convertors. To enable this investigation to be carried out, a multiple microprocessor HVDC development system has been assembled. This provides the necessary hardware resources, as well as providing the software development facilities necessary for the implementation of real time control and protection tasks. In order to assess and optimise the performance of the various control and protection systems, considerable interactive monitoring facilities are provided as part of the HVDC development system's software. The development system is used to implement real time control of a small scale convertor model. It is also used to implement a new form of convertor fault detection, which is in turn used as the basis for an implementation of convertor fault development control techniques for the first time on an operating convertor. The operation of the fault development control scheme is examined in some detail, and results are presented showing its operation over a wide variety of fault types and system conditions

The Relationship between Disc Degeneration and Morphologic Changes in the Intervertebral Foramen of the Cervical Spine: A Cadaveric MRI and CT Study

A cadaveric study was performed to investigate the relationship between disc degeneration and morphological changes in the intervertebral foramen of cervical spine, including the effect on the nerve root. Seven fresh frozen human cadavers were dissected from C1 to T1, preserving the ligaments, capsules, intervertebral disc and the neural structures. The specimens were scanned with MRI and then scanned through CT scan in the upright position. Direct mid-sagittal and 45 degree oblique images were obtained to measure the dimension of the intervertebral disc height, foraminal height, width, area and segmental angles. Disc degeneration was inversely correlated with disc height. There was a significant correlation between disc degeneration and foraminal width (p<0.005) and foraminal area (p<0.05), but not with foraminal height. Disc height was correlated with foraminal width but not with height. The segmental angles were decreased more in advanced degenerated discs. There was a correlation between nerve root compression and decreased foraminal width and area (p<0.005). This information and critical dimensions of the intervertebral foramen for nerve root compression should help in the diagnosis of foraminal stenosis of the cervical spine in patients presenting with cervical spondylosis and radiculopathy

An important Norwegian contribution to the study of the bursae of the upper and lower extremities

We present a critical analysis of the monograph of A.S.D. Synnestvedt (1869) “En anatomisk beskrivelse af de paa over- og underestremiteterne forekommende Bursae mucosae”. The analysis was completed using anatomical information from the historically oldest publications dealing with the bursae of the extremities: Albinus (1734), Monro (1788), Rosenmüller (1799). We are of the opinion that Synnestvedt's publication is important, not only historically but also as a source of information for recent medical practitioners. Synnestvedt's monograph has a wealth of literary citations, unambiguous opinions of seasoned anatomists regarding the structure and function of the synovial membrane, and detailed descriptions of dissections he performed on fetal and adult cadavers. The information in this publication may enhance the diagnosis of bursopathies and enthesopathies of the extremities

Acromioclavicular joint reconstruction with coracoacromial ligament transfer using the docking technique

<p>Abstract</p> <p>Background</p> <p>Symptomatic Acromioclavicular (AC) dislocations have historically been surgically treated with Coracoclavicular (CC) ligament reconstruction with transfer of the Coracoacromial (CA) ligament. Tensioning the CA ligament is the key to success.</p> <p>Methods</p> <p>Seventeen patients with chronic, symptomatic Type III AC joint or acute Type IV and V injuries were treated surgically. The distal clavicle was resected and stabilized with CC ligament reconstruction using the CA ligament. The CA ligament was passed into the medullary canal and tensioned, using a modified 'docking' technique. Average follow-up was 29 months (range 12–57).</p> <p>Results</p> <p>Postoperative ASES and pain significantly improved in all patients (p = 0.001). Radiographically, 16 (94%) maintained reduction, and only 1 (6%) had a recurrent dislocation when he returned to karate 3 months postoperatively. His ultimate clinical outcome was excellent.</p> <p>Conclusion</p> <p>The docking procedure allows for tensioning of the transferred CA ligament and healing of the ligament in an intramedullary bone tunnel. Excellent clinical results were achieved, decreasing the risk of recurrent distal clavicle instability.</p

Covid-19 triage in the emergency department 2.0: how analytics and AI transform a human-made algorithm for the prediction of clinical pathways

The Covid-19 pandemic has pushed many hospitals to their capacity limits. Therefore, a triage of patients has been discussed controversially primarily through an ethical perspective. The term triage contains many aspects such as urgency of treatment, severity of the disease and pre-existing conditions, access to critical care, or the classification of patients regarding subsequent clinical pathways starting from the emergency department. The determination of the pathways is important not only for patient care, but also for capacity planning in hospitals. We examine the performance of a human-made triage algorithm for clinical pathways which is considered a guideline for emergency departments in Germany based on a large multicenter dataset with over 4,000 European Covid-19 patients from the LEOSS registry. We find an accuracy of 28 percent and approximately 15 percent sensitivity for the ward class. The results serve as a benchmark for our extensions including an additional category of palliative care as a new label, analytics, AI, XAI, and interactive techniques. We find significant potential of analytics and AI in Covid-19 triage regarding accuracy, sensitivity, and other performance metrics whilst our interactive human-AI algorithm shows superior performance with approximately 73 percent accuracy and up to 76 percent sensitivity. The results are independent of the data preparation process regarding the imputation of missing values or grouping of comorbidities. In addition, we find that the consideration of an additional label palliative care does not improve the results

Symptomatic asymmetry in the first six months of life: differential diagnosis

Asymmetry in infancy is a clinical condition with a wide variation in appearances (shape, posture, and movement), etiology, localization, and severity. The prevalence of an asymmetric positional preference is 12% of all newborns during the first six months of life. The asymmetry is either idiopathic or symptomatic. Pediatricians and physiotherapists have to distinguish symptomatic asymmetry (SA) from idiopathic asymmetry (IA) when examining young infants with a positional preference to determine the prognosis and the intervention strategy. The majority of cases will be idiopathic, but the initial presentation of a positional preference might be a symptom of a more serious underlying disorder. The purpose of this review is to synthesize the current information on the incidence of SA, as well as the possible causes and the accompanying signs that differentiate SA from IA. This review presents an overview of the nine most prevalent disorders in infants in their first six months of life leading to SA. We have discovered that the literature does not provide a comprehensive analysis of the incidence, characteristics, signs, and symptoms of SA. Knowledge of the presented clues is important in the clinical decision making with regard to young infants with asymmetry. We recommend to design a valid and useful screening instrument