Dostoevsky: A Man of Mission

Dr. H. E. S. Woldring spoke at Dordt College in commemoration of the 100th anniversary of Dostoevsky\u27s death. Although the speech published here is substantially as delivered, the editors, with Dr. Woldring\u27s permission, have edited it for the readers of Pro Rege

LARGE EDDY SIMULATION ANALYSIS OF FLUID JETS IN CROSS FLOW

This work has been carried out at the "Laboratoire de Modélisation et Simulation en mécanique des Fluides" of CEA during a stage of 6 months. The main subject of this work involves jets in cross flow, which are of fundamental industrial importance and play an important role in the validation of turbulence models. Two jet configurations are investigated with the TrioCFD code: • a tee junction of circular tubes where a hot jet discharges into a cold main flow. • a rectangular channel discharging a jet marked by a scalar into a main channel flow. The tee-junction configuration is very important for the phenomena of thermal fatigue. The OECD/NEA benchmark on the Vattenfall tee junction flow is analyzed. This test case is selected because, beside the experimental results, various calculations with several turbulence modeling approaches have been published. A Large Eddie Simulation (LES) modeling and calculation strategy is developed and validated on these data for jets in crossflow under thermal fatigue conditions. The rectangular jet configuration is important for basic physical understanding and modeling and has been analysed experimentally at CEA by previous studies. Such work was focused on the turbulent mixing between a rectangular channel flow with grid turbulence exiting a heated jet into a confined grid turbulent crossflow, with both kinematic and passive scalar high quality measurements in order to characterize its statistical properties (energy spectra, Reynolds stresses anisotropy and PdF). These experiments are analyzed for the first time with LES by applying the strategy developed for the first configuration. The turbulent inlet boundary conditions are well controlled in both experiment and calculation (grid turbulence). Structured and unstructured grids are used to predict the measured mean values and turbulent fluctuations (velocity and scalars) as well as the Reynolds stresses. The activities aimed also to test the capabilities of the TrioCFD code results through the inspection of their agreement with the experimental datas obtained for T-junctions mixing ducts for a preliminary analysis of TrioCFD performances and to get a balanced compliance of the code’s capabilities

Houdbaarheid van hout; het laat-Boreale dennenbos van Roderwolde als case study voor de conservering van hout

Veen ontstaat in meer of minder natte omstandigheden door de onvolledige afbraak (humificering) en opeenhoping (accumulatie) van plantenmateriaal. Tijdens de stapeling van organische materie worden ook microscopische en macroscopische resten zoals pollen, sporen van varens en schimmels, algen, bladresten, e.d. opgeslagen. Tot de meest in het oog springende plantenresten in veen behoort bewaard gebleven hout. Dit archief vormt een belangrijke bron van informatie met betrekking tot de vegetatie- en landschapsontwikkeling en de water- en voedselhuishouding ten tijde van de veenvorming. De conservering van hout vereist, ook vanwege de vaak grote afmetingen, speciale omstandigheden. De belangrijkste voorwaarden, nadat door veranderingen in de plaatselijke omstandigheden een einde is gekomen aan de boomgroei, zijn snelle afdekking en zuurstofloze omstandigheden

Motor learning outcomes of handrim wheelchair propulsion during active spinal cord injury rehabilitation in comparison with experienced wheelchair users

Purpose: To investigate changes in wheelchair propulsion technique and mechanical efficiency across first five weeks of active inpatient spinal cord injury rehabilitation and to compare the outcomes at discharge with experienced wheelchair users with spinal cord injury. Methods: Eight individuals with recent spinal cord injury performed six weekly submaximal exercise tests. The first and last measurement additionally contained a wheelchair circuit and peak graded exercise test. Fifteen experienced individuals performed all above-mentioned tests on one occasion. Results: Mechanical efficiency and propulsion technique did not change during the five weeks of inpatient rehabilitation. Peak power output during peak graded test and performance time on the wheelchair circuit improved between the first and the last week. No difference in propulsion technique, peak power output, and performance time was found between the persons with a recent injury and the experienced group. Mechanical efficiency was higher after the correction for the difference in relative power output in the experienced group. Conclusion: The group with a recent injury did not improve mechanical efficiency and propulsion technique over the period of active rehabilitation, despite significant improvements on the wheelchair circuit and in work capacity. The only significant difference between the groups was found in mechanical efficiency. Implications for rehabilitation The lack of time-dependent changes in mechanical efficiency and propulsion technique in the group with a recent spinal cord injury, combined with the lack of differences in technique, work capacity and on the wheelchair circuit between the groups, suggest that important adaptations of motor learning may happen even earlier in rehabilitation and emphasize that the group in active rehabilitation was relatively skilled. Standardized observational analyses of handrim wheelchair propulsion abilities during early spinal cord injury rehabilitation provide detailed understanding of wheelchair technique, skill as well as wheelchair propulsion capacity. Measurement of external power output is critical to interpretation of gross efficiency, propulsion technique, and capacity. Wheelchair quality and body weight - next to wheelchair fitness and skill - require careful consideration both in early rehabilitation as well as in the chronic phase of spinal cord injury

Low-intensity wheelchair training in inactive people with long-term spinal cord injury: A randomized controlled trial on fitness, wheelchair skill performance and physical activity levels

Objective: To investigate the effects of low-intensity wheelchair training on wheelchair-specific fitness, wheelchair skill performance and physical activity levels in inactive people with long-term spinal cord injury. Design: Randomized controlled trial. Participants: Inactive manual wheelchair users with spinal cord injury for at least 10 years (n = 29), allocated to exercise (n = 14) or no exercise. Methods: The 16-week training consisted of wheelchair treadmill-propulsion at 30-40% heart rate reserve or equivalent in terms of rate of perceived exertion, twice a week, for 30 min per session. Wheelchair-specific fitness was determined as the highest 5-s power output over 15-m overground wheelchair sprinting (P5-15m), isometric push-force, submaximal fitness and peak aerobic work capacity. Skill was determined as performance time, ability and strain scores over a wheelchair circuit. Activity was determined using a questionnaire and an odometer. Results: Significant training effects appeared only in P5-15m (exercise vs control: mean +2.0 W vs -0.7 W, p = 0.017, ru=0.65). Conclusion: The low-intensity wheelchair training appeared insufficient for substantial effects in the sample of inactive people with long-term spinal cord injury, presumably in part owing to a too-low exercise frequency. Effective yet feasible and sustainable training, as well as other physical activity programmes remain to be developed for inactive people with long-term spinal cord injury. Key words: activities of daily living; paraplegia; physical activity; physical fitness; spinal cord injuries; tetraplegia; rehabilitation; wheelchairs

Pollen-inferred regional vegetation patterns and demographic change in Southern Anatolia through the Holocene

Southern Anatolia is a highly significant area within the Mediterranean, particularly in terms of understanding how agriculture moved into Europe from neighbouring regions. This study uses pollen, palaeoclimate and archaeological evidence to investigate the relationships between demography and vegetation change, and to explore how the development of agriculture varied spatially. Data from 21 fossil pollen records have been transformed into forested, parkland and open vegetation types using cluster analysis. Patterns of change have been explored using non-metric multidimensional scaling (nMDS) and through analysis of indicator groups, such as an Anthropogenic Pollen Index, and Simpson’s Diversity. Settlement data, which indicate population densities, and summed radiocarbon dates for archaeological sites have been used as a proxy for demographic change. The pollen and archaeological records confirm that farming can be detected earlier in Anatolia in comparison with many other parts of the Mediterranean. Dynamics of change in grazing indicators and the OJCV (Olea, Juglans, Castanea and Vitis) index for cultivated trees appear to match cycles of population expansion and decline. Vegetation and land use change is also influenced by other factors, such as climate change. Investigating the early impacts of anthropogenic activities (e.g. woodcutting, animal herding, the use of fire and agriculture) is key to understanding how societies have modified the environment since the mid–late Holocene, despite the capacity of ecological systems to absorb recurrent disturbances. The results of this study suggest that shifting human population dynamics played an important role in shaping land cover in central and southern Anatolia