1,742 research outputs found
Potential of Stewardly Technology: Norms for the Industrial Enterprise
In the last sentence of the last full paragraph on page 24, an error appears which, in effect, reverses the intended meaning of that sentence. The second occurrence of the words no longer should be deleted so that the sentence reads as follows:
In fact, Goudzwaard says, this process is so far along that some workers no longer find the dehumanizing work situation as miserable, and regard remaining responsibilities as undesirable burdens
Why so serious?:game-based learning in health profession education: state of the art and future directions
If you look around carefully, you see a lot of use of game elements that aim to motivate people towards a certain behaviour. From smileys on posts that aim to lower your driving speed, to earning stars in language learning apps. Game-based learning is the use of game elements to make learning more attractive and to encourage people to continue their learning. This is logical right? The longer you learn, the better the outcome. Or not? This doctoral thesis examines the effects of using game-based learning in medical education. Why and when should it be applied? We have investigated whether it is advisable to develop a game suitable for everyone. We discovered that there are 5 different game personas (player types): competitors, socializers, social achievers, explorers and trolls. Everyone has their own preferences when it comes to social interactions and achieving goals within a game. From this we were able to develop a taxonomy, which has been tested at almost all medical universities in the Netherlands. It shows that medical students are mainly socially oriented players. While most game based learnings are not at all. This doctoral research can offer perspective in current developments, gives direction where it could go, but also has a critical note on the use of game-based learning that is should not be applied too much
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Long-term alterations in the corticotropin-releasing hormone system : effects on emotional function and attention
Depression is one of the most common medical conditions worldwide. The most frequently observed neuroendocrine symptom among depressives is an enhanced secretion of the stress hormone cortisol. It has been hypothesised that corticotropin-releasing hormone (CRH) hypersecretion is, at least in part, responsible for these elevated cortisol levels. In addition, increased CRH levels in the CSF indicate that the hyperactivity of the CRH system is not limited to an augmented release of CRH into the portal vein, which indirectly enhances cortisol release, but possibly also in the brain. Therefore, it is possible that some of the symptoms, such as increased anxiety, altered endocrinological responses to 5-HT1A receptor challenge and reduced attentional performance observed in depression are due to a hyperactive central CRH system. In this work, the role of CRH on these phenomena was investigated in mice. In order to assess anxiety-related behaviour, a range of anxiety tests, based on different principles, were employed. Investigation of differences between four mouse strains and effects of long-term treatment with the selective serotonin reuptake inhibitor citalopram on anxiety-related behaviour revealed that the outcome of one test does not necessarily predict the outcome of another test based on different principles, suggesting that different aspects of anxiety can be taxed. Along similar lines, life-long overproduction of CRH increases anxiety-related behaviour in some paradigms, but not in all. Therefore, one might speculate that chronic CRH excess may increase some, but not all, aspects of anxiety. Treatment of CRH overexpressors revealed that chronic treatment with citalopram increased anxiety-related behaviour in wildtype mice, but induced opposite effects in CRH overexpressing mice, i.e., the effects of antidepressants depended on baseline performance. Citalopram has beneficial effects in both patients suffering from anxiety disorders as well as depressive patients. These findings open the possibility that the beneficial effects of citalopram in depressed patients may at least in part depend on the activity of the CRH system seen in these patients, and that the elevation of CRH activity may be the cause of the occurrence of increased anxiety in this illness. Furthermore, the results obtained with citalopram suggest important interactions between CRH and serotonin (5-HT). Related to this, a lack of increased HPA-axis activation after a 5-HT1A receptor challenge was demonstrated, a phenomenon also reported in depressed patients. This contrasts an unaltered hypothermic response after such pharmacological challenge in CRH transgenic mice, which has also been reported in depressed patients. Finally, the role of CRH in attentional processes, which are also impaired in depressed patients, were investigated. Lack of CRH did not affect visuospatial attention. In addition, lack of CRH receptor 2 or acute blockade of CRH receptor 1 did not affect attentional processes. Life-long loss of CRH receptor 1 resulted in a mild impairment. However, closer examination of performance of these animals suggest that this may not be a pure attentional deficit and opens the possibility that other factors contributed to these effects. In contrast, overproduction of CRH induced a more clear-cut impairment in visuospatial attention. Moreover, altered responsiveness to cholinergic drugs on visuospatial attentional performance observed in these mice point towards an interaction of the CRH system and the cholinergic neurotransmitter system in the modulation of these processes. Taken together, overproduction of CRH increases some aspects of anxiety-related behaviour, blocks 5-HT1A receptor mediated HPA-axis activation, and disrupts visuospatial attention, all symptoms that occur in depression. Therefore, inhibiting CRH activity may be a potential target for treatment of depression
Reconciling conflicting clinical studies of ANTIOXIDANT SUPPLEMENTATION AS HIV THERAPY: A MATHEMATICAL APPROACH
Small highly reactive molecules called reactive oxygen species (ROS) play a crucial role in cell signalling and infection control. However, high levels of ROS can cause significant damage to cell structure and function. Studies have shown that infection with the human immunodeficiency virus (HIV) results in increased ROS concentrations, which can in turn lead to faster progression of HIV infection, and cause CD4+ T-cell apoptosis. To counteract these effects, clinical studies have explored the possibility of raising antioxidant levels, with mixed results. In this thesis, a mathematical model is used to explore this potential therapy, both analytically and numerically. For the numerical work, we use clinical data from both HIV-negative and HIV-positive injection drug users (IDUs) to estimate model parameters; these groups have lower baseline concentrations of antioxidants than non-IDU controls. Our model suggests that increases in CD4+ T cell concentrations can result from moderate levels of daily antioxidant supplementation, while excessive supplementation has the potential to cause periods of immunosuppression. We discuss implications for HIV therapy in IDUs and other populations which may have low baseline concentrations of antioxidants
Evaporation and absorption of inkjet printed droplets with surfactants
Inkjet printing involves several key challenges. An important aspect is the flow dynamics after deposition of an ink droplet onto a substrate. The drop will evaporate and -- if the substrate is porous -- absorb at the same time. Typically, this process also involves additional components like surfactants. Surfactants are molecules that adsorb onto interfaces, thereby reducing the local surface tension, which has significant ramifications for the droplet dynamics. The reduced interfacial tension can result in rich behavior, including circulatory flow patterns and accelerated absorption dynamics. It is therefore of no surprise that there are still many open questions regarding the mechanisms of surfactants in sessile droplets. In this thesis an attempt is made to answer some of these questions in a satisfactory way.In order to gain insight into the dynamics of surfactant-laden droplets, a numerical model is employed. This model is based on lubrication theory, meaning that the assumption is made that the contact radius of the droplet has a significantly larger magnitude that the height. By making this assumption it becomes possible to describe the droplet evolution only in terms of a height profile, making lubrication theory an efficient and transparent modeling technique. With this model as a basis, several extensions are introduced of which the surfactant transport is the most prominent one. This transport is governed by several convection-diffusion-adsorption equations both at the interfaces and in the bulk of the fluid. Furthermore, absorption into the porous medium is modeled with Darcy's law and the evaporation field is calculated using an analytical solution.First, the contact line dynamics of an evaporating droplet with insoluble surfactants are examined using two different methods: a precursor film model and a slip model. For pure droplets these models are shown to perform comparably with respect to literature data, but when surfactants are involved the precursor film model results in several problems, because it does not inherently distinguish between the droplet and the film. Therefore, surfactants can freely flow in and out of the precursor film, which is an issue that requires to be solved before this model can be used in the current context. The slip model, on the other hand, reveals that even if there is no explicit pinning force present, surfactants can still keep the contact line fixed. This is caused by the reduction in space on the interface during evaporation, which increases the surfactant concentration and decreases the surface tension accordingly. The result is a lower equilibrium contact angle, which slows down the contact line retraction as if actually pinning it.Furthermore, the various regimes of the fluid flow in evaporating droplets with soluble surfactants are mapped. It is shown that with the inclusion of surfactants typically one out of two flow patterns exists: a circulatory flow, where there is the combination of an outward capillary flow in the bulk of the droplet and an inward Marangoni flow close to the interface (called the `Marangoni regime'), and a purely outward flow, where there is only a capillary flow towards the contact line, while the flow at the interface nearly halts due to Marangoni effects (called the `coffee-ring regime'). Surfactant properties that are found to typically promote the Marangoni regime over the coffee ring regime are fast sorption kinetics and high solubility, while for the droplet conditions fast evaporation is a promoting factor. Also, the absorption of droplets in porous media is modeled and the effects of surfactants on this process are analyzed. It is found that for pure droplets with both pinned and moving contact lines the penetration depth, being the deepest point where fluid has absorbed, evolves in a similar manner. However, for a moving contact line case the absorption process is much slower than for a pinned case, because the contact area shrinks over time. This also results in the wetted region having a more pointed shape after absorption in the moving contact line case. It is shown that surfactants can accelerate the absorption process, but only if the adsorption kinetics are not too fast compared to the absorption time scale. Otherwise, all surfactant adsorbs onto the pore walls before reaching the wetting front.Lastly, a start is made with developing a model that describes particle transport during evaporation, both for small and large concentrations. For small concentrations, the colloidal dynamics can be described by a `tracer particle model', where the particles are considered to be massless and passive. For the tracer particle model it is shown that the lubrication model does not describe the velocity field in the contact line region accurately. If a circulatory flow is present, particles still accumulate at the contact line as if there is only a capillary flow. Possible solutions to this issue lie in the introduction of correction terms that are otherwise neglected in lubrication theory or to use an altogether different model that fully incorporates the Navier-Stokes equation for viscous flows. At higher concentrations, the particle dynamics can be described by a `two-phase model', where the particles are considered as a distinct phase that affects the fluid dynamics. It is found that any two-phase particle model for evaporating droplets requires to take into account the maximum packing density of particles, since this concentration is already reached in the initial stages of the drying process. By introducing several ad-hoc corrections when the maximum packing density is reached, it is shown that reasonable results can be obtained. However, in order to make the model viable it also needs to take into account the underlying physics, which can possibly be achieved by modeling the transition from a Stokes regime flow to a Darcy regime flow at high particle fractions
Voorsorteren op gezinsleven?:Al vóór de komst van kinderen van voltijd naar deeltijd
Vrouwen hebben net als mannen meestal betaald werk, maar ze werken wel veel vaker dan mannen in deeltijd. Het doel van dit onderzoek is om na te gaan in hoeverre vrouwen als anticipatie op het eventueel krijgen van kinderen al minder gaan werken. Daartoe werden mannen en vrouwen die tussen 2006 en 2008 het mbo, hbo of wo verlieten met een diploma, tot negen jaar na hun afstuderen gevolgd op de arbeidsmarkt . Uit de analyse bleek dat vrouwen een jaar na uitstroom uit het onderwijs al significant vaker in deeltijd werkten dan mannen. Ook stapten vrouwen die voltijds werkten vaker dan mannen over naar een deeltijdbaan. Daarnaast bleek dat werkende, kinderloze vrouwen met een partner vaker een deeltijdbaan hadden dan vergelijkbare vrouwen die niet samenwoonden. Bij mannen was dat juist omgekeerd: mannen die samenwoonden zonder kinderen gingen minder vaak van een voltijdbaan naar een deeltijdbaan dan alleenstaande mannen
The performance of different classification criteria sets for spondyloarthritis in the worldwide ASAS-COMOSPA study
Background: In this study, we sought to compare the performance of spondyloarthritis (SpA) classification criteria sets in an international SpA cohort with patients included from five continents around the world.
Methods: Data from the (ASAS) COMOrbidities in SPondyloArthritis (ASAS-COMOSPA) study were used. ASAS-COMOSPA is a multinational, cross-sectional study with consecutive patients diagnosed with SpA by rheumatologists worldwide. Patients were classified according to the European Spondyloarthropathy Study Group (ESSG), modified European Spondyloarthropathy Study Group (mESSG), Amor, modified Amor, Assessment of SpondyloArthritis international Society (ASAS) axial Spondyloarthritis (axSpA), ASAS peripheral spondyloarthritis (pSpA) and ClASsification criteria for Psoriatic Arthritis (CASPAR) criteria. Overlap between the classification criteria sets was assessed for patients with and without back pain. Furthermore, patients fulfilling different arms of the ASAS axSpA criteria (imaging arm, clinical arm, both arms) were compared on the presence of SpA features.
Results: A total of 3942 patients (5 continents, 26 countries) were included. The mean age was 43.6 years, 65.0% were male, 56.2% were human leucocyte antigen B27-positive and 64.4% had radiographic sacroiliitis (based on modified New York criteria). Of the patients, 85.5% were classified by the ASAS SpA criteria (87.7% ASAS axSpA, 12.3% ASAS pSpA). Fulfilment of the Amor, ESSG and CASPAR criteria was present in 83.3%, 88.4% and 21.6% of patients, respectively. Of the patients with back pain (n = 3227), most were classified by all three of Amor, ESSG and ASAS axSpA criteria (71.4%). Patients fulfilling the imaging arm and the clinical arm of the ASAS axSpA criteria had similar presentations of SpA features. In patients without back pain, overlap between classification criteria sets was seen, although to a lesser extent.
Conclusions: Most patients with a clinical diagnosis of axial SpA in the worldwide ASAS-COMOSPA study fulfil several classification criteria sets, and a substantial overlap between different criteria sets is seen, which suggests a high level of credibility of the criteria. Large inter-regional differences in the fulfilment of classification criteria were not found. Patients fulfilling the clinical arm were remarkably similar to patients fulfilling the imaging arm with respect to the presence of most SpA features
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