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In this paper, we evaluate the application of Bayesian Optimization (BO) to discrete event simulation (DES) models. In a first step, we create a simple model, for which we know the optimal set of parameter values in advance. We implement the model in SimPy, a framework for DES written in Python. We then interpret the simulation model as a black box function subject to optimization. We show that it is possible to find the optimal set of parameter values using the open source library GPyOpt. To enhance our evaluation, we create a second and more complex model. To better handle the complexity of the model, and to add a visual component, we build the second model in Simio, a commercial off-the-shelf simulation modeling tool. To apply BO to a model in Simio, we use the Simio API to write an extension for optimization plug-ins. This extension encapsulates the logic of the BO algorithm, which we deployed as a web service in the cloud.
The fact that simulation models are black box functions with regard to their behavior and the influence of their input parameters makes them an apparent candidate for Bayesian Optimization (BO). Simulation models are multivariable and stochastic, and their behavior is to a large extent unpredictable. In particular, we do not know for sure which input parameters to adjust to maximize (or minimize) the model’s outcome. In addition, the complex models can take a substantial amount of time to run.
Bayesian Optimization is a sequential and self-learning algorithm to optimize black box functions similar to as we find them in simulation models: they contain a set of parameters for which we want to identify the optimal set, they are expensive to evaluate, and they exhibit stochastic noise. BO has proven to efficiently optimize black box functions from varius disciplines. Among those, and most notably, it is successfully applied in machine learning algorithms to optimize hyperparameters.
Events are intangible services and services marketing thus plays a considerable role within event management education. The marketing mix with its “4 Ps” (product, price, promotion, place) is an essential element of many event management curricula. Most educational institutions also reflect the development (and related discussions) towards the existence of “7 Ps” – adding personnel, physical facilities and process management (Meffert/ Bruhn 2009) – or even “8 Ps” – adding physical environment, purchasing process, packaging and participation(Burke/ Resnick 2000) – within the service marketing domain.
Artificial intelligence will change our lives permanently - both at work and in our private lives. But how does machine learning actually work? The authors explore this question in their English-language textbook. They teach the necessary basics for the use of support vector machines, for example, through linear programming, the Lagrange multiplier, kernels and the SMO algorithm. They also cover neural networks, evolutionary algorithms, and Bayesian networks. Definitions are highlighted in the book and assignments invite readers to think along. The textbook is aimed at students of computer science, engineering and natural sciences, especially in the fields of robotics, artificial intelligence, and mathematics.
Objective
To identify assessment tools used to evaluate patients with temporomandibular disorders (TMD) considered to be clinically most useful by a panel of international experts in TMD physical therapy (PT).
Methods
A Delphi survey method administered to a panel of international experts in TMD PT was conducted over three rounds from October 2017 to June 2018. The initial contact was made by email. Participation was voluntary. An e-survey, according to the Checklist for Reporting Results of Internet E-Surveys (CHERRIES), was posted using SurveyMonkey for each round. Percentages of responses were analysed for each question from each round of the Delphi survey administrations.
Results
Twenty-three experts (completion rate: 23/25) completed all three rounds of the survey for three clinical test categories: 1) questionnaires, 2) pain screening tools and 3) physical examination tests. The following was the consensus-based decision regarding the identification of the clinically most useful assessments. (1) Four of 9 questionnaires were identified: Jaw Functional Limitation (JFL-8), Mandibular Function Impairment Questionnaire (MFIQ), Tampa Scale for Kinesiophobia for Temporomandibular disorders (TSK/TMD) and the neck disability index (NDI). (2) Three of 8 identified pain screening tests: visual analog scale (VAS), numeric pain rating scale (NRS) and pain during mandibular movements. (3) Eight of 18 identified physical examination tests: physiological temporomandibular joint (TMJ) movements, trigger point (TrP) palpation of the masticatory muscles, TrP palpation away from the masticatory system, accessory movements, articular palpation, noise detection during movement, manual screening of the cervical spine and the Neck Flexor Muscle Endurance Test.
Conclusion
After three rounds in this Delphi survey, the results of the most used assessment tools by TMD PT experts were established. They proved to be founded on test construct, test psychometric properties (reliability/validity) and expert preference for test clusters. A concordance with the screening tools of the diagnostic criteria of TMD consortium was noted. Findings may be used to guide policymaking purposes and future diagnostic research.
The Brief Symptom Inventory (BSI)-18 is a widely-used tool to assess changes in general distress in patients despite an ongoing debate about its factorial structure and lack of evidence for longitudinal measurement invariance (LMI). We investigated BSI-18 scores from 1,081 patients from an outpatient clinic collected after the 2nd, 6th, 10th, 18th, and 26th therapy session. Confirmatory factor analysis (CFA) was used to compare models comprising one, three, and four latent dimensions that were proposed in the literature. LMI was investigated using a series of model comparisons, based on chi-square tests, effect sizes, and changes in comparative fit index (CFI). Psychological distress diminished over the course of therapy. A four-factor structure (depression, somatic symptoms, generalized anxiety, and panic) showed the best fit to the data at all measurement occasions. The series of model comparisons showed that constraining parameters to be equal across time resulted in very small decreases in model fit that did not exceed the cutoff for the assumption of measurement in variance. Our results show that the BSI-18 is best conceptualized as a four-dimensional tool that exhibits strict longitudinal measurement invariance. Clinicians and applied researchers do not have to be concerned about the interpretation of mean differences over time.
This paper presents an optimized algorithm for estimating static and dynamic gait parameters. We use a marker- and contact-less motion capture system that identifies 20 joints of a person walking along a corridor.
Based on the proposed gait cycle detection basic metrics as walking frequency, step/stride length, and support phases are estimated automatically. Applying a rigid body model, we are capable to calculate static and dynamic gait stability metrics. We conclude with initial results of a clinical study evaluating orthopaedic technical support.
Background
Against the background of a steadily increasing degree of digitalization in health care, a professional information management (IM) is required to successfully plan, implement, and evaluate information technology (IT). At its core, IM has to ensure a high quality of health data and health information systems to support patient care.
Objectives
The goal of the present study was to define what constitutes professional IM as a construct as well as to propose a reliable and valid measurement instrument.
Methods
To develop and validate the construct of professionalism of information management (PIM) and itsmeasurement, a stepwise approach followed an established procedure from information systems and behavioral research. The procedure included an analysis of the pertaining literature and expert rounds on the construct and the
instrument, two consecutive and comprehensive surveys at the national and international level, exploratory and confirmatory factor analyses as well as reliability and validity testing.
Results
Professionalism of information management was developed as a construct consisting of the three dimensions of strategic, tactical, and operational IMas well as of the regularity and cyclical phases of IM procedures as the two elements of professionalism.
The PIM instrument operationalized the construct providing items that incorporated IM procedures along the three dimensions and cyclical phases. These procedures had to be evaluated against their degree of regularity in the instrument. The instrument proved to be reliable and valid in two consecutive measurement phases
and across three countries.
Conclusion
It can be concluded that professionalism of information management is a meaningful construct that can be operationalized in a scientifically rigorous manner. Both science and practice can benefit from these developments in terms of improved self-assessment, benchmarking capabilities, and eventually, obtaining a better understanding of health IT maturity.
Injection of slurry or digestate below maize seeds is a relatively new technique developed to improve nitrogen use efficiency. However, this practice has the major drawback of increasing nitrous oxide (N2O) emissions. The application of a nitrification inhibitor (NI) is an effective method to reduce these emissions. To evaluate the effect of the NI 3,4‐dimethypyrazole phosphate (DMPP) on N2O emissions and the stabilization of ammonium, a two‐factorial soil‐column experiment was conducted. PVC pipes (20 cm diameter and 30 cm length) were used as incubation vessels for the soil‐columns. The trial consisted of four treatments in a randomized block design with four replications: slurry injection, slurry injection + DMPP, digestate injection, and digestate injection + DMPP. During the 47‐day incubation period, N2O fluxes were measured twice a week and cumulated by linear interpolation of the gas‐fluxes of consecutive measurement dates. After completion of the gas flux measurement, concentration of ammonium and nitrate within the soil‐columns was determined. DMPP delayed the conversion of ammonium within the manure injection zone significantly. This effect was considerably more pronounced in treatment digestate + NI than in treatment slurry + NI. Regarding the cumulated N2O emissions, no difference between slurry and digestate treatments was determined. DMPP reduced the release of N2O significantly. Transferring the results into practice, the use of DMPP is a promising way to reduce greenhouse gas emissions and nitrate leaching, following the injection of slurry or digestate.
Background/Aim
This study aimed to establish the somatosensory profile of patients with lumbar radiculopathy at pre-and post-microdiscectomy and to explore any association between pre-surgical quantitative sensory test (QST) parameters and post-surgical clinical outcomes.
Methods
A standardized QST protocol was performed in 53 patients (mean age 38 ± 11 years, 26 females) with unilateral L5/S1 radiculopathy in the main pain area (MPA), affected dermatome and contralateral mirror sites and in age- and gender-,and body site-matched healthy controls. Repeat measures at 3 months included QST, the Oswestry Disability Index (ODI) and numerous other clinical measures; at 12 months, only clinical measures were repeated. A change <30% on the ODI was defined as ‘no clinically meaningful improvement’.
Results
Patients showed a significant loss of function in their symptomatic leg both in the dermatome (thermal, mechanical, vibration detection p < .002), and MPA (thermal, mechanical, vibration detection, mechanical pain threshold, mechanical pain sensitivity p < .041) and increased cold sensitivity in the MPA (p < .001). Pre-surgical altered QST parameters improved significantly post-surgery in the dermatome (p < .018) in the symptomatic leg and in the MPA (p < .010), except for thermal detection thresholds and cold sensitivity. Clinical outcomes improved at 3 and 12 months (p < .001). Seven patients demonstrated <30% change on the ODI at 12 months. Baseline loss of function in mechanical detection in the MPA was associated with <30% change on the ODI at 12 months (OR 2.63, 95% CI 1.09–6.37, p = .032).
Conclusion
Microdiscectomy resulted in improvements in affected somatosensory parameters and clinical outcomes. Pre-surgical mechanical detection thresholds may be predictive of clinical outcome.
Significance
This study documented quantitative sensory testing (QST) profiles in patients with lumbar radiculopathy in their main pain area (MPA) and dermatome pre- and post-microdiscectomy and explored associations between QST parameters and clinical outcome. Lumbar radiculopathy was associated with loss of function in modalities mediated by large and small sensory fibres. Microdiscectomy resulted in significant improvements in loss of function and clinical outcomes in 85% of our cohort. Pre-surgical mechanical detection thresholds in the MPA may be predictive of clinical outcome.