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Core particle fueling, an essential task in the European demonstration fusion power plant EU-DEMO, relies on adequate pellet injection. However, pellets are fragile objects, and their delivery efficiency can hardly be assumed to be unity. Exploring kinetic control of the EU-DEMO1 scenario indicates that such missed-out pellets do cause a considerable problem for keeping a burning plasma. Missed-out pellets can cause a severe drop of plasma density that in turn results in a potential drastic loss of burn power. Efforts are under way at the ASDEX Upgrade (AUG) tokamak aiming to provide real-time monitoring of pellet arrival and announcement of missed-out cases to the control systems. To further optimize the controllers, system identification experiments have been performed to identify the dynamic response of the system to the actuators.

The flux fit method is used to self-consistently estimate the power deposition profile and heat transport profiles from temperature measurements originating from perturbative experiments with a modulated source. This Letter improves on this method by addressing the limitations and assumptions. The most crucial improvement is the additional freedom in the source deposition profile. Allowing for a variable central deposition location and height and including a skewness parameter produces deposition profiles more consistent with the measurement data, but still wider than equilibrium ray tracing in two different DIII-D discharges. Moreover, we show that the quality of the estimated deposition profile is key to the accuracy of diffusivity and convectivity estimates, but inversely, the estimated transport parameters hardly affect the quality of the power deposition estimate. Using this method, we show that the power deposition profile estimate is broadened with respect to ray-tracing by about 1.7–1.8 times in two DIII-D discharges.

The tokamak à configuration variable (TCV) continues to leverage its unique shaping capabilities, flexible heating systems and modern control system to address critical issues in preparation for ITER and a fusion power plant. For the 2019–20 campaign its configurational flexibility has been enhanced with the installation of removable divertor gas baffles, its diagnostic capabilities with an extensive set of upgrades and its heating systems with new dual frequency gyrotrons. The gas baffles reduce coupling between the divertor and the main chamber and allow for detailed investigations on the role of fuelling in general and, together with upgraded boundary diagnostics, test divertor and edge models in particular. The increased heating capabilities broaden the operational regime to include T e/T i ∼ 1 and have stimulated refocussing studies from L-mode to H-mode across a range of research topics. ITER baseline parameters were reached in type-I ELMy H-modes and alternative regimes with ‘small’ (or no) ELMs explored. Most prominently, negative triangularity was investigated in detail and confirmed as an attractive scenario with H-mode level core confinement but an L-mode edge. Emphasis was also placed on control, where an increased number of observers, actuators and control solutions became available and are now integrated into a generic control framework as will be needed in future devices. The quantity and quality of results of the 2019–20 TCV campaign are a testament to its successful integration within the European research effort alongside a vibrant domestic programme and international collaborations.

This work presents the use of a collisional-radiative model to infer plasma parameters from 2D emissivities of several deuterium Balmer lines. The emissivities were obtained by MANTIS, an absolutely calibrated, ten-camera imaging polychromator with < 5 m m spatial resolution, up to 800 Hz frame rate, viewing the lower divertor tangentially. Our analysis of those image frames generates 2D maps of plasma parameters such as electron density, temperature, neutral atomic density and the reaction rates for ionisation, recombination and charge exchange as a function of time. The analysis is compared and validated against a SOLPS-ITER simulation accounting for drifts. The results are compared against the simulation in 2D, radial and poloidal profiles to probe the numerous effects of particle transport in the scrape-off layer, in particular in the approach to detached divertor leg conditions. The inferred inner divertor leg radial profiles of the electron density and temperature were consistent with the SOLPS-ITER predictions. A significant transport of particles to the private flux region is found experimentally, that is not captured in the simulation. The simulation diverges from the experiment at the outer divertor target, where the plasma emission appears to be consistent with the emission driven by plasma–molecule interactions. Our analysis also shows prospects for aiding the power exhaust control efforts by potentially providing an optical tracking of the particle balance in the divertor.

Contains fulltext : 232443.pdf (Publisher’s version ) (Closed access) BACKGROUND: In the Netherlands, access to direct-acting antivirals (DAAs) against hepatitis C virus (HCV) has been unrestricted for chronic infection since 2015. We evaluated whether the nationwide incidence of HCV infections in individuals with HIV has changed since 2015. METHODS: In this retrospective cohort study, data from the ATHENA cohort of people with HIV aged 18 years or older attending any of the 24 HIV treatment centres in the Netherlands between 2000 and 2019 were assessed. We used parametric proportional hazards models with a piecewise exponential survival function to model HCV primary infection and reinfection incidence per 1000 person-years. FINDINGS: Of the 23 590 individuals without previous HCV infection, 1269 cases of HCV primary infection were documented (incidence 5·2 per 1000 person-years [95% CI 5·0-5·5]). The highest incidence was observed in men who have sex with men (MSM; 7·7 per 1000 person-years [7·3-8·2]) and was lower in people who inject drugs (PWID; 1·7 per 1000 person-years [0·7-4·1]) and other key populations (1·0 per 1000 person-years [0·8-1·2]). In MSM, incidence increased in 2007 to 14·3 per 1000 person-years and fluctuated between 8·7 and 13·0 per 1000 person-years from 2008 to 2015. In 2016, incidence declined to 6·1 cases per 1000 person-years and remained steady between 4·1 and 4·9 per 1000 person-years from 2017 to 2019. Of the 1866 individuals with a previous HCV infection, 274 reinfections were documented (incidence 26·9 per 1000 person-years [95% CI 23·9-30·3]). The highest incidence rate was observed in MSM (38·5 per 1000 person-years [33·9-43·7]) and was lower in PWID (10·9 per 1000 person-years [3·5-33·8]) and other key populations (8·9 per 1000 person-years [6·3-12·5]). In MSM, reinfection incidence fluctuated between 38·0 and 88·9 per 1000 person-years from 2006 to 2015, reaching 55·6 per 1000 person-years in 2015. In 2016, reinfection incidence declined to 41·4 per 1000 person-years, followed by further decreases to 24·4 per 1000 person-years in 2017 and 11·4 per 1000 person-years in 2019. INTERPRETATION: The sharp decline in HCV incidence in MSM with HIV shortly after restrictions on DAAs were lifted suggests a treatment-as-prevention effect. HCV incidence was already low in PWID and other groups before unrestricted access. Ongoing HCV transmission is occurring in MSM, as illustrated by a declining but high rate of reinfection, stressing the need for additional preventive measures. FUNDING: Dutch Ministry of Health, Welfare, and Sport.

Mismatch repair (MMR) testing is recommended in the Netherlands for all patients under 70 years of age with newly diagnosed colorectal cancer (CRC) in order to identify Lynch syndrome. T1 CRC can be removed by local excision or oncological surgical resection. We evaluated the frequency of MMR testing in pT1 lesions within the Dutch CRC screening cohort. pT1 CRC diagnosed within the Dutch population-based screening program from 2016-2018 were identified by the Dutch pathology registry (PALGA). Pathology reports were evaluated, including registration of MMR testing (by immunohistochemistry and/or microsatellite instability PCR). Frequency of MMR testing was compared between pT1 tumors that were treated by local (endoscopic or transanal) excision and oncological surgical resections. A total of 3.692 pT1 CRCs were diagnosed (median age 63 years, 61.4% males). MMR testing was performed in 83% and uptake increased over time (71% in 2016 to 92% in 2018, p0.01). MMR testing was significantly more often performed in younger patients and in academic hospitals. When pT1 CRC was treated by oncological surgical resection (n=1.132), MMR testing was performed in 89% of cases and was known prior to oncological resection in 51% of cases. MMR testing occurred significantly less often in case of local excision (80% of n=2.560) compared to oncological surgical resection (p0.01). MMR testing was performed in 83% of T1 CRCs and uptake increased over time. MMR testing was more frequently performed in pT1 CRC resected by oncological surgical resection compared with local excision.

In contemporary magnetic confinement devices, the density distribution is sensed with interferometers and actuated with feedback controlled gas injection and open-loop pellet injection. This is at variance with the density control for ITER and DEMO, that will depend mainly on pellet injection as an actuator in feed-back control. This paper presents recent developments in state estimation and control of the electron density profile for ITER using relevant sensors and actuators. As a first step, Thomson scattering is included in an existing dynamic state observer. Second, model predictive control is developed as a strategy to regulate the density profile while avoiding limits associated with the total density (Greenwald limit) or gradients in the density distribution (e.g. neoclassical impurity transport). Simulations show that high quality density profile estimation can be achieved with Thomson Scattering and that the controller is capable of regulating the distribution as desired.

Plasma density is one of the key quantities that need to be controlled in real-time as it scales directly with fusion power and, if left uncontrolled, density limits can be reached leading to a disruption. On ASDEX Upgrade (AUG), the real-time measurements are the line-integrated density, measured by the interferometers, and the average density derived from the bremsstrahlung measured by spectroscopy. For control, these measurements are used to reconstruct the radial density profile using an extended Kalman filter (EKF). However, in discharges where ion cyclotron resonance heating (ICRH) is used, the measurements from the interferometers are corrupted and the reconstructed density is false. In this paper, the existing EKF implementation is improved, implemented and experimentally verified on AUG. The new EKF includes a new particle transport model in the prediction model RAPDENS as well as a new representation of ionization and recombination. Furthermore, an algorithm was introduced that is capable of detecting the corrupt diagnostics; this algorithm is based on the rate of change of the innovation residual. The changes to the RAPDENS observer resulted in better density reconstruction in ICRH discharges where corrupt measurement occur. The new version has been implemented on the real-time control system at AUG and functions properly in ICRH discharges.

In magnetic confinement thermonuclear fusion the exhaust of heat and particles from the core remains a major challenge. Heat and particles leaving the core are transported via open magnetic field lines to a region of the reactor wall, called the divertor. Unabated, the heat and particle fluxes may become intolerable and damage the divertor. Controlled ‘plasma detachment’, a regime characterized by both a large reduction in plasma pressure and temperature at the divertor target, is required to reduce fluxes onto the divertor. Here we report a systematic approach towards achieving this critical need through feedback control of impurity emission front locations and its experimental demonstration. Our approach comprises a combination of real-time plasma diagnostic utilization, dynamic characterization of the plasma in proximity to the divertor, and efficient, reliable offline feedback controller design., The exhaust of heat and particles is an important challenge in future nuclear fusion devices. Here the authors report the use of carbon emission as indicator for plasma detachment in a tokamak and its real-time feedback control.

Systematic extraction of locally valid dynamic models from experiments is necessary for controller design and the validation of high fidelity models. This paper describes the extraction of a dynamic model in the form of a transfer function, giving the dynamic response of the CIII (465.0 nm) emission front position to deuterium gas puffing in the TCV divertor during flattop, relevant for heat exhaust control. The model is extracted using frequency response data from both SOLPS-ITER simulations and perturbative experiments. We use the steady-state solutions of the model SOLPS-ITER to obtain an additional data point at the zero frequency, as the identifiable frequency range by perturbative experiments is lower bounded by discharge time. We specifically approach the problem from a control engineering point of view, aiming to develop control-oriented models for the systematic design of impurity emission front controllers. We find a transfer function structure based on a diffusive process to best describe the obtained frequency response data. The resulting transfer function model accurately reproduces the local dynamic response measured during experiments, so it can be used to assess new controllers offline for similar discharge scenarios.

In this paper we present a novel algorithm to extract the optical plasma boundary and radiation front for detached divertor plasmas. We show that reliable detection of the divertor leg and radiation front is possible using lightweight image processing tools. Using a non-tomographic approach, the detected divertor leg and radiation front can be mapped to the poloidal plane. This approach is fast and accurate enough for real-time control purposes, allowing in particular real-time plasma shape and detachment control, and post-shot detachment physics and dynamics analysis.

Transient electron temperature measurements of a step power experiment at W7-AS are reassessed by direct comparison of the up- and downward responses of the electron temperature. The analysis shows that the response at some distance to the center behaves linearly and the model predicted responses based on a power-dependent diffusion coefficient that vary from the measured step responses.

BACKGROUND Due to its long intracranial course, the abducens nerve is vulnerable in case of acceleration injury of the head. In rare cases, this may lead to posttraumatic paralysis of this cranial nerve. CASE DESCRIPTION A 4-year-old girl visited the emergency department after sustaining a head trauma. Neurological examination revealed no focal abnormalities at first. Three days later, she experienced diplopia, the consequence of isolated abducens nerve paralysis. CT and MRI brain imaging revealed no abnormalities. We treated her with an eye patch for a short time. At examination after 1 year, she was no longer experiencing any symptoms and the paralysis had almost completely disappeared. CONCLUSION Isolated paralysis of the abducens nerve may occur until up to 6 days after a trauma, without any visible intracranial abnormalities revealed by imaging. Even though only few children with this condition have been described, prognosis seems to be favourable and symptoms disappear in the majority of patients. Frequent follow-up by the ophthalmologist and the orthoptist is recommended, possibly with symptomatic treatment of the diplopia.

The Magnum-PSI facility is unique in its ability to produce and even exceed the heat and particle fluxes expected in the divertor of a fusion reactor, combined with good access to the plasma-material interaction region for diagnostics and relatively easy sample manipulation. In addition, it is possible to study the effects of transient heat loads on a plasma-facing surface, similar to those expected during so called Edge Localized Modes. By virtue of a newly installed superconducting magnet, Magnum-PSI can now maintain these conditions for hours on end for truly long term tests of candidate plasma facing materials. The electron density and temperature in the plasma beam center as a function of different magnetic fields up to 1.6 T, gas flow and source current are determined: particle fluxes greater than 10 25 m −2 s −1 and heat fluxes of up to 50 MW m −2 are obtained. Linear regression and artificial neural network analysis have been used to gain insight in the general behavior of plasma conditions as a function of these machine settings. The plasma conditions during transient plasma heat loading have also been determined. These capabilities are now being exploited to reach fluence of up to 10 30 particles m −2 at ITER-relevant conditions, equivalent to a significant fraction of the divertor service lifetime for the first time.

The heat flux is one of the key parameter used to quantify and understand transport in fusion devices. In this paper, a new method is introduced to calculate the heat flux including its confidence with high accuracy based on perturbed measurements such as the electron temperature. The new method is based on ideal filtering to optimally reduce the noise contributions on the measurements and piece-wise polynomial approximations to calculate the time derivative. Both methods are necessary to arrive at a heat flux and effective diffusion coefficient with high accuracy. The new methodology is applied to a measurement example using electron cyclotron resonance heating block-wave modulation at the Large Helical Device showing the merit of the newly developed methodology.

The key to success in developing a wearable dialysis device is a technique to safely and efficiently regenerate and reuse a small volume of dialysate in a closed-loop system. In a hemodialysis model in goats, we explored whether urea removal by electro-oxidation (EO) could be effectively and safely applied in vivo. A miniature dialysis device was built, containing 1 or 2 “EO units,” each with 10 graphite electrodes, with a cumulative electrode surface of 585 cm2per unit. The units also contained poly(styrene-divinylbenzene) sulfonate beads, FeOOH beads, and activated carbon for respective potassium, phosphate, and chlorine removal. Urea, potassium, and phosphate were infused to create “uremic” conditions. Urea removal was dependent on total electrode surface area [removal of 8 mmol/h (SD 1) and 16 mmol/h (SD 2) and clearance of 12 ml/min (SD 1) and 20 ml/min (SD 3) with 1 and 2 EO units, respectively] and plasma urea concentration but not on flow rate. Extrapolating urea removal with 2 EO units to 24 h would suffice to remove daily urea production, but for intermittent dialysis, additional units would be required. EO had practically no effects on potassium and phosphate removal or electrolyte balance. However, slight ammonium releasewas observed, and some chlorine release at higher dialysate flow rates. Minor effects on acid-base balance were observed, possibly partly due to infusion of chloride. Mild hemolysis occurred, which seemed related to urea infusion. In conclusion, clinically relevant urea removal was achieved in vivo by electro-oxidation. Efficacy and safety testing in a large-animal model with uremia is now indicated.

Introduction To determine whether foveal light and dark adaptation are affected in glaucoma. Methods Case-control study with 23 glaucoma patients and 51 controls. Light and dark adaptation were measured twice. After 10 minutes pre-adaptation to 0.0032 cd/m2, the background luminance increased stepwise to 320 (5 log unit step) or 10,000 cd/m2 (6.5 log unit step) for 10 minutes, then it decreased back to 0.0032 cd/m2 for 30 minutes. Foveal contrast sensitivity [CS]) as a function of time was determined using a 1.15 degree increment. Time resolution of the experiments was 30 seconds. Multiple linear regression was used to analyse the effect of glaucoma on the CS plateau and adaptation time (time to reach the plateau minus 3 dB); analyses were adjusted for age and gender. Results After light adaptation to 320 and 10,000 cd/m2, glaucoma patients had a 0.22 (P

In this paper, techniques for optimal input design are used to optimize the waveforms of perturbative experiments in modern fusion devices. The main focus of this paper is to find the modulation frequency for which the accuracy of the estimated diffusion coefficient is maximal. Mathematically, this problem can be formulated as an optimization problem in which the Fisher information matrix is maximized. First, this optimization problem is solved for a simplified diffusion model, while assuming a slab geometry and a semi-infinite domain. Later, the optimization is repeated under more general conditions such as a cylindrical geometry, finite domain, and simultaneous estimation of multiple transport coefficients. Based on the results of these optimizations, guidelines are offered to select the modulation frequency and to determine the optimality of the corresponding experiment. © 2018 EURATOM

Old and recent experiments show that there is a direct response to the heating power of transport observed in modulated ECH experiments both in tokamaks and stellarators. This is most apparent for modulated experiments in the Large Helical Device (LHD) and in Wendelstein 7 advanced stellarator (W7-AS). In this paper we show that: (1) this power dependence can be reproduced by linear models and as such hysteresis (in flux) has no relationship to hysteresis as defined in the literature; (2) observations of 'hysteresis' (in flux) and a direct response to power can be perfectly reproduced by introducing an error in the estimated deposition profile as long as the errors redistribute the heat over a large radius; (3) non-local models depending directly on the heating power can also explain the experimentally observed Lissajous curves (hysteresis); (4) how non-locality and deposition errors can be recognized in experiments and how they affect estimates of transport coefficients; (5) from a linear perturbation transport experiment, it is not possible to discern deposition errors from non-local fast transport components (mathematically equivalent). However, when studied over different operating points non-linear-non-local transport models can be derived which should be distinguishable from errors in the deposition profile. To show all this, transport needs to be analyzed by separating the transport in a slow (diffusive) time-scale and a fast (heating/non-local) time-scale, which can only be done in the presence of perturbations.

The development of the plasma diagnostic and control (D&C) system for a future tokamak demonstration fusion reactor (DEMO) is facing unprecedented challenges. The DEMO D&C system has to operate with very high reliability, since any loss of plasma control may result in machine damage. On the same time, high accuracy of the D&C system is needed in order to allow for plasma operation near operational limits, where the fusion power is maximized. The implementation and performance of diagnostic components is however limited by space restrictions (optimization of the tritium breeding rate; integrity of the first wall and divertor against loads), and by adverse effects acting on the front-end components (neutron and gamma radiation, heat loads, erosion and deposition). Finally, the capabilities of the available actuators (poloidal field coils, external heating and fueling) are limited as well. As part of the European DEMO conceptual design studies, the development of the D&C system has recently been launched [1]. A preliminary suite of candidate diagnostics for DEMO have been selected, aiming to cover all the main plasma control quantities with some redundancy, and choosing types and locations for diagnostic front-end components such that long-term durability with minimum need for maintenance can be expected under typical loads (e.g. neutron radiation, particle fluxes and fluencies). Specifically, only robust metallic or ceramics diagnostic components shall be used inside the vacuum vessel, while the more sensitive components shall be located at more remote (protected) positions. This initial plasma diagnostic suite comprises microwave diagnostics, magnetic coil based and Hall sensors, passive spectroscopy and radiation power measurements, divertor thermo-current measurement, infrared interferometry/polarimetry and neutron-gamma measurements. In the first R&D phase the possibilities and conditions for integration of diagnostic sightlines and front-end components into the machine have been investigated, and an understanding of the required number of channels and components has been obtained. The conditions for controllability of the DEMO plasma are being analyzed by numerical simulations. To this purpose, the transport modelling code ASTRA, coupled to a radiation module, has been connected to the Simulink simulation framework, and the performance properties of diagnostics and actuators are being added [2]. Similarly, the existing CREATE equilibrium code is being amended to include limitations of diagnostics and actuators, such that the controllability e.g. of fast VDEs can be simulated under DEMO relevant settings. Furthermore, predictive control oriented models such as RAPTOR are being further developed as an alternative approach to analyze the controllability of DEMO. The common goal is to arrive at numerical simulations which closely mimic the control of the DEMO plasma such that the controllability based on the available diagnostics and actuators can be demonstrated quantitatively. Based on these R&D results, an initial version of the DEMO diagnostic and control concept has been elaborated and will be presented in this paper.

ObjectiveThis study aimed to develop a practice guideline for a structured and consensus-based approach to relieve symptoms of pneumonia in patients with dementia in nursing homes. MethodsA five-round Delphi study involving a panel consisting of 24 experts was conducted. An initial version of the practice guideline was developed with leading representatives of Dutch University Medical Centers with a department for elderly care medicine, based on existing guidelines for palliative care. The experts evaluated the initial version, after which we identified topics that reflected the main divergences. The experts rated their agreement with statements that addressed the main divergences on a 5-point Likert scale. Consensus was determined according to pre-defined criteria. The practice guideline was then revised according to the final decisions made by the project group and the representatives. ResultsThe response rate for the expert panel was 67%. Main divergences included the applicability of guidelines for palliative care to patients with dementia and pneumonia in long-term care and the appropriateness of specific pharmacological treatment of dyspnea and coughing. Moderate consensus was reached for 80% of the statements. Major revisions included adding pharmacological treatment for coughing and recommending opioid rotation in the case of opioid-induced delirium. Two areas of divergent opinion remained: the usefulness of oxygen administration and treatment of rattling breath. The project group made the final decision in these areas. ConclusionsWe developed a mostly consensus-based practice guideline for patients with dementia and pneumonia and mapped controversial issues for future investigation. Copyright (c) 2014 John Wiley & Sons, Ltd.

BACKGROUND & AIMS: Real-time differentiation of diminutive polyps (1-5 mm) during endoscopy could replace histopathology analysis. According to guidelines, implementation of optical diagnosis into routine practice would require it to identify rectosigmoid neoplastic lesions with a negative predictive value (NPV) of more than 90%, using histologic findings as a reference, and agreement with histology-based surveillance intervals for more than 90% of cases.METHODS: We performed a prospective study with 39 endoscopists accredited to perform colonoscopies on participants with positive results from fecal immunochemical tests in the Bowel Cancer Screening Program at 13 centers in the Netherlands. Endoscopists were trained in optical diagnosis using a validated module (Workgroup serrAted polypS and Polyposis). After meeting predefined performance thresholds in the training program, the endoscopists started a 1-year program (continuation phase) in which they performed narrow band imaging analyses during colonoscopies of participants in the screening program and predicted histological findings with confidence levels. The endoscopists were randomly assigned to groups that received feedback or no feedback on the accuracy of their predictions. Primary outcome measures were endoscopists' abilities to identify rectosigmoid neoplastic lesions (using histology as a reference) with NPVs of 90% or more, and selecting surveillance intervals that agreed with those determined by histology for at least 90% of cases.RESULTS: Of 39 endoscopists initially trained, 27 (69%) completed the training program. During the continuation phase, these 27 endoscopists performed 3144 colonoscopies in which 4504 diminutive polyps were removed. The endoscopists identified neoplastic lesions with a pooled NPV of 90.8% (95% confidence interval 88.6-92.6); their proposed surveillance intervals agreed with those determined by histologic analysis for 95.4% of cases (95% confidence interval 94.0-96.6). Findings did not differ between the group that did vs did not receive feedback. Sixteen endoscopists (59%) identified rectosigmoid neoplastic lesions with NPVs greater than 90% and selected surveillance intervals in agreement with those determined from histology for more than 90% of patients.CONCLUSIONS: In a prospective study following a validated training module, we found that a selected group of endoscopists identified rectosigmoid neoplastic lesions with pooled NPVs greater than 90% and accurately selected surveillance intervals for more than 90% of patients over the course of 1 year. Providing regular interim feedback on the accuracy of neoplastic lesion prediction and surveillance interval selection did not lead to differences in those endpoints. Monitoring is suggested, as individual performance varied. ClinicalTrials.gov no: NCT02516748; Netherland Trial Register: NTR4635.

Vanwege de invoering van de Basiskwalificatie Onderwijs (BKO) staat onderwijs opnieuw in de belangstelling. Dat is terecht. De bij universitaire loopbanen gangbare eenzijdige nadruk op onderzoek heeft te lang geduurd. De noodzakelijke competenties voor een goed docent binnen de context van probleemgestuurd onderwijs (PGO) worden in deze opinierende bijdrage geschetst. Een docent is een vakdidacticus die communiceert, coordineert en innoveert; deze vier dimensies voor een PGO-leeromgeving komen in dit artikel aan bod. (Berkel HJM van. Wat maakt een PGO-docent tot een goede docent? Tijdschrift voor Medisch Onderwijs 2009;28(4):167–174.)

A previous study compared socio-demographic characteristics, health problem characteristics, and primary process data between a database sample of patients referred to physical therapy (PT) versus a sample of patients referred for specific manual physical therapy (MPT) diagnosis and management. This study did not differentiate between patients based on affected body region or diagnosis. The present study is a secondary analysis of these data for patients with non-specific low-back pain (LBP). Statistical analysis indicated that the MPT patient sample was significantly (P

Background and study aims In selected patients with chronic pancreatitis in whom conventional plastic stenting fails and in whom surgery is contraindicated or declined, insertion of a biliary self-expanding metal stent (SEMS) may be a valuable treatment option. Patients and methods Between 1994 and 1999, 13 patients with chronic pancreatitis received SEMS for benign biliary strictures (four women and nine men; mean age 56). The indications for SEMS placement were: contraindication to surgery (n = 10), presumed inoperable pancreatic carcinoma (n = 1), concomitant unresectable lung cancer (n = 1), and declined surgery (n = 1). The success of treatment was defined as adequate biliary drainage due to SEMS therapy. Results The mean follow-up period was 50 months (range 6 days - 86 months). Nine patients (69 %) were successfully treated with SEMS therapy: a patent first SEMS (n = 5); a patent second SEMS inserted through the first SEMS (n = 3); and one patent SEMS after balloon cleaning. SEMS treatment was not successful in four patients (due to stent migration in one case and occlusion in three ). The mean patency period of the SEMS was 60 months (95 % CI, 43 months - 77 months). At 33 months, the probability of adequate biliary drainage with SEMS therapy was 75 %. Conclusions SEMS therapy was safe and provided successful and prolonged biliary drainage in a selected group of patients with benign biliary strictures due to chronic pancreatitis in whom surgical intervention was not possible or desirable.

In this paper, the estimation of the thermal diffusivity from perturbative experiments in fusion plasmas is discussed. The measurements used to estimate the thermal diffusivity suffer from stochastic noise. Accurate estimation of the thermal diffusivity should take this into account. It will be shown that formulas found in the literature often result in a thermal diffusivity that has a bias (a difference between the estimated value and the actual value that remains even if more measurements are added) or have an unnecessarily large uncertainty. This will be shown by modeling a plasma using only diffusion as heat transport mechanism and measurement noise based on ASDEX Upgrade measurements. The Fourier coefficients of a temperature perturbation will exhibit noise from the circular complex normal distribution (CCND). Based on Fourier coefficients distributed according to a CCND, it is shown that the resulting probability density function of the thermal diffusivity is an inverse non-central chi-squared distribution. The thermal diffusivity that is found by sampling this distribution will always be biased, and averaging of multiple estimated diffusivities will not necessarily improve the estimation. Confidence bounds are constructed to illustrate the uncertainty in the diffusivity using several formulas that are equivalent in the noiseless case. Finally, a different method of averaging, that reduces the uncertainty significantly, is suggested. The methodology is also extended to the case where damping is included, and it is explained how to include the cylindrical geometry.