Onderzoekingen over de warmtedoorgang in een vertikale pijpverdamper

The influences were investigated of various operating parameters on beat transmission, i.e. the evaporative capacity, in a single vertical evaporator tube, fed with pure water.With natural circulation, temperature level and difference had a pronounced influence, especially at lower values of these parameters (e.g. boiling temperature 40°C, temperature difference 15°C). The heat transmission coefficient k increased for increasing temperature level as well as for increasing temperature difference.The influence of the apparent liquid level was very important and was more pronounced for lower temperature levels and smaller differences. For each set of operating temperatures an apparent liquid level existed, for which k was maximum. The apparent liquid level had a very big influence on circulation rate. Forced circulation induced higher values of k only if the forced circulation rate was much higher than the natural one. Because natural circulation was slow for low temperatures and small differences forced circulation was found to be advantageous in these conditions.With forced circulation the influence of temperature difference on k was small and sometimes reversed. Due to decreased viscosity, k was higher at higher temperatures. The most important influence on k was exerted by forced circulation rate.With flash evaporation k was generally slightly smaller than with forced circulation, except at high circulation rates, where k became equal for both systems.</p

Theoretical spectroscopy of astaxanthin in crustacyanin proteins: absorption, circular dichroism, and nuclear magnetic resonance

Solid state NMR/Biophysical Organic Chemistr

A new neuropsychological instrument measuring effects of age and drugs on fitness to drive: development, reliability, and validity of MedDrive

Background: Current guidelines underline the limitations of existing instruments to assess fitness to drive and the poor adaptability of batteries of neuropsychological tests in primary care settings. Aims: To provide a free, reliable, transparent computer based instrument capable of detecting effects of age or drugs on visual processing and cognitive functions. Methods: Relying on systematic reviews of neuropsychological tests and driving performances, we conceived four new computed tasks measuring: visual processing (Task1), movement attention shift (Task2), executive response, alerting and orientation gain (Task3), and spatial memory (Task4). We then planned five studies to test MedDrive's reliability and validity. Study-1 defined instructions and learning functions collecting data from 105 senior drivers attending an automobile club course. Study-2 assessed concurrent validity for detecting minor cognitive impairment (MCI) against useful field of view (UFOV) on 120 new senior drivers. Study-3 collected data from 200 healthy drivers aged 20-90 to model age related normal cognitive decline. Study-4 measured MedDrive's reliability having 21 healthy volunteers repeat tests five times. Study-5 tested MedDrive's responsiveness to alcohol in a randomised, double-blinded, placebo, crossover, dose-response validation trial including 20 young healthy volunteers. Results: Instructions were well understood and accepted by all senior drivers. Measures of visual processing (Task1) showed better performances than the UFOV in detecting MCI (ROC 0.770 vs. 0.620; p=0.048). MedDrive was capable of explaining 43.4% of changes occurring with natural cognitive decline. In young healthy drivers, learning effects became negligible from the third session onwards for all tasks except for dual tasking (ICC=0.769). All measures except alerting and orientation gain were affected by blood alcohol concentrations. Finally, MedDrive was able to explain 29.3% of potential causes of swerving on the driving simulator. Discussion and conclusions: MedDrive reveals improved performances compared to existing computed neuropsychological tasks. It shows promising results both for clinical and research purposes

The influence of alcohol (0.5‰) on the control and manoeuvring level of driving behaviour, finding measures to assess driving impairment:A simulator study

Objective: The influence of psychoactive substances on driving performance and traffic safety has been extensively studied. Research on the influence of alcohol at the control level of behaviour (i.e. automated processes) has been well established and has shown that the ability to operate a vehicle decreases with rising alcohol levels. However, results one level higher at the manoeuvring level (i.e. conscious processes), are inconsistent. The current study aimed to replicate findings on the influence of alcohol on the control level of behaviour and investigate effects on the manoeuvring level in order to find suitable measures to assess driving impairment. Method: The study was double-blind, placebo-controlled with a counterbalanced treatment order and a two-way crossover design. Thirty participants performed tasks in a driving simulator under the influence of alcohol (0.5‰) and a placebo. In the driving tasks the control level of behaviour (swerving, average speed, and speed variation) was investigated, as well as the manoeuvring level of behaviour (distance to other traffic during an overtaking manoeuvre, reaction time to a traffic light turning amber, and response to a suddenly merging car). Results: As expected, alcohol affected the control level of behaviour negatively. Participants swerved more and showed more speed variation after alcohol intake. The manoeuvring level of driving behaviour was also affected by alcohol. The distance to other drivers during an overtaking manoeuvre was smaller under the influence of alcohol. Results on reaction time were however less straightforward. Reaction time increased significantly under the influence of alcohol when reacting to a traffic light but not in reaction to a car unexpectedly merging into traffic. When analysing behaviour in reaction to these different events in more detail it became clear that they were responded to in varying manners, making it difficult to find an average impairment measure. Conclusions: The deteriorating effect of alcohol at the control level of driving behaviour was replicated, confirming the suitability of the standard deviation of lateral position and the variation in speed as measures of impairment. At the manoeuvring level, the kept distance to the leading car during an overtaking manoeuvre appeared to be a suitable measure to assess impairment as well as reaction time to a traffic light. The current study also confirms the difficulties in evaluating complex driving behaviour and the need for more research on this subject

Driving performance and neurocognitive skills of long-term users of sedating antidepressants

Objective: To assess driving performance and neurocognitive skills of long‐term users of sedating antidepressants, in comparison to healthy controls. Methods: Thirty‐eight long‐term (>6 months) users of amitriptyline (n = 13) and mirtazapine (n = 25) were compared to 65 healthy controls. Driving performance was assessed using a 1‐h standardised highway driving test in actual traffic, with road‐tracking error (standard deviation of lateral position [SDLP]) being the primary measure. Secondary measures included neurocognitive tasks related to driving. Performance differences between groups were compared to those of blood alcohol concentrations of 0.5 mg/ml to determine clinical relevance. Results: Compared to controls, mean increase in SDLP of all antidepressant users was not significant, nor clinically relevant (+0.75 cm, 95% CI: - 0.83 cm; +2.33 cm). However, users treated less than 3 years (n = 20) did show a significant and clinically relevant increase in SDLP (+2.05 cm). No significant effects were observed on neurocognitive tasks for any user group, although large individual differences were present. Most results from neurocognitive tests were inconclusive, while a few parameters confirmed non‐inferiority for users treated longer than 3 years. Conclusion: The impairing effects of antidepressant treatment on driving performance and neurocognition mitigate over time following long‐term use of 3 years