Low-level finite state control of knee joint in paraplegic standing

Low-level finite state (locked-unlocked) control is compared with open-loop stimulation of the knee extensor muscles in functional electrical stimulation (FES) induced paraplegic standing. The parameters were: duration of standing, relative torque loss in knee extensor muscles, knee angle stability, average stimulus output and average arm effort during standing. To investigate the impact of external mechanical conditions on controller performance, experiments were performed both under the condition of a freely moving ankle joint and of a mechanically stabilized ankle joint. Finite state control resulted in a 2.5 to 12 times increase of standing duration or in a 1.5 to 5 times decrease of relative torque loss in comparison with open-loop stimulation. Finite state control induced a limit cycle oscillation in the knee joint. Average maximum knee flexion was 6.2° without ankle bracing, and half that value with ankle bracing. Average arm support was 13.9 and 7.5% of the body weight without and with ankle bracing respectively

Location Choices of Migrant Nest-Leavers: Spatial Assimilation or Continued Segregation?

We examine ethnic differences in the ethnic composition of the destination neighbourhood upon leaving the parental home using administrative data for the entire birth cohort 1983 living in the Netherlands. The analysis provides little evidence of a clear intergenerational break in the location choices of young men and women from a non-western origin compared to their parents. The neighbourhood choice pattern of those who leave the parental home for independent and shared living arrangements does not differ markedly from that of their parents, while nest-leavers for union formation are more likely to move to neighbourhoods with a relatively small proportion of non-western inhabitants. A decomposition analysis indicates that an overwhelmingly large part of neighbourhood choice is explained by differences in background variables. Particularly, the origin neighbourhood type of nest-leavers seems to be a driving force underlying the choice of destination neighbourhood, given individual and parental socioeconomic characteristics.leaving home, spatial assimilation, migrants

Drift and Forbush decreases

Evidence is presented that the drift effect on the modulation of galactic cosmic rays can be seen on Forbush decreases observed by the Deep River and Hermanus neutron monitors

Teaching and Learning in Interdisciplinary Higher Education: A Systematic Review

Interdisciplinary higher education aims to develop boundary-crossing skills, such as interdisciplinary thinking. In the present review study, interdisciplinary thinking was defined as the capacity to integrate knowledge of two or more disciplines to produce a cognitive advancement in ways that would have been impossible or unlikely through single disciplinary means. It was considered as a complex cognitive skill that constituted of a number of subskills. The review was accomplished by means of a systematic search within four scientific literature databases followed by a critical analysis. The review showed that, to date, scientific research into teaching and learning in interdisciplinary higher education has remained limited and explorative. The research advanced the understanding of the necessary subskills of interdisciplinary thinking and typical conditions for enabling the development of interdisciplinary thinking. This understanding provides a platform from which the theory and practice of interdisciplinary higher education can move forwar

Designing colloidal ground state patterns using short-range isotropic interactions

DNA-coated colloids are a popular model system for self-assembly through tunable interactions. The DNA-encoded linkages between particles theoretically allow for very high specificity, but generally no directionality or long-range interactions. We introduce a two-dimensional lattice model for particles of many different types with short-range isotropic interactions that are pairwise specific. For this class of models, we address the fundamental question whether it is possible to reliably design the interactions so that the ground state is unique and corresponds to a given crystal structure. First, we determine lower limits for the interaction range between particles, depending on the complexity of the desired pattern and the underlying lattice. Then, we introduce a `recipe' for determining the pairwise interactions that exactly satisfies this minimum criterion, and we show that it is sufficient to uniquely determine the ground state for a large class of crystal structures. Finally, we verify these results using Monte Carlo simulations.Comment: 19 pages, 7 figure

Changes and Problems of Agricultural Development in Iran

There has been a big debate on the evolution of agricultural development (AD), the challenges and problems hindering AD in Iran since last decade. This study was implemented in the province of Esfahan and a number of 130 out of 212 agricultural experts from 13 different townships were selected as the target group. Totally 70 experts returned the completed questionnaires. The findings of the study revealed that most of the AD changes have been positive but in a very slow rate. Respondents unanimously claimed that the sustainability in agriculture and maintenance of agricultural lands are the most deteriorating issues during last ten years. With regard to AD problems, they stressed the lack of adequate fund allocated to the Ministry of Agriculture (MAJ) and lack of its power to control beneficiary dealers within the sector, unfair political influence, lack of international contacts and also untrustworthiness of agriculture for private investors as the most problematic obstacles for AD in Iran. They perceived that MAJ has not sufficiently addressed the problems so far, although, there are some promising movements. Experts believed that MAJ is not able to solve the majority of problems alone due to their extrinsic nature

Ethanol-water separation by pervaporation

The separation of ethanol-water mixtures is of great importance for the production of ethanol from biomass. Both ultrafiltration and pervaporation processes can be used for the continuous processing of fermentation and separation, The removal of ethanol from the ultrafiltration permeate can be accomplished by pervaporation. Separation of ethanol-water mixtures by the pervaporation process has been investigated. Results are presented for membranes which are preferentially permeable for ethanol and for others which are preferentially water permeable. Details on the preparation of several membrane types (homogeneous, asymmetric and composite) are given. A schematic process diagram is given in which the fermentation of sugars to ethanol is membrane-controlled

The Lazy Bootstrap. A Fast Resampling Method for Evaluating Latent Class Model Fit

The latent class model is a powerful unsupervised clustering algorithm for categorical data. Many statistics exist to test the fit of the latent class model. However, traditional methods to evaluate those fit statistics are not always useful. Asymptotic distributions are not always known, and empirical reference distributions can be very time consuming to obtain. In this paper we propose a fast resampling scheme with which any type of model fit can be assessed. We illustrate it here on the latent class model, but the methodology can be applied in any situation. The principle behind the lazy bootstrap method is to specify a statistic which captures the characteristics of the data that a model should capture correctly. If those characteristics in the observed data and in model-generated data are very different we can assume that the model could not have produced the observed data. With this method we achieve the flexibility of tests from the Bayesian framework, while only needing maximum likelihood estimates. We provide a step-wise algorithm with which the fit of a model can be assessed based on the characteristics we as researcher find important. In a Monte Carlo study we show that the method has very low type I errors, for all illustrated statistics. Power to reject a model depended largely on the type of statistic that was used and on sample size. We applied the method to an empirical data set on clinical subgroups with risk of Myocardial infarction and compared the results directly to the parametric bootstrap. The results of our method were highly similar to those obtained by the parametric bootstrap, while the required computations differed three orders of magnitude in favour of our method.Comment: This is an adaptation of chapter of a PhD dissertation available at https://pure.uvt.nl/portal/files/19030880/Kollenburg_Computer_13_11_2017.pd

Microtubule length distributions in the presence of protein-induced severing

Microtubules are highly regulated dynamic elements of the cytoskeleton of eukaryotic cells. One of the regulation mechanisms observed in living cells is the severing by the proteins katanin and spastin. We introduce a model for the dynamics of microtubules in the presence of randomly occurring severing events. Under the biologically motivated assumption that the newly created plus end undergoes a catastrophe, we investigate the steady state length distribution. We show that the presence of severing does not affect the number of microtubules, regardless of the distribution of severing events. In the special case in which the microtubules cannot recover from the depolymerizing state (no rescue events) we derive an analytical expression for the length distribution. In the general case we transform the problem into a single ODE that is solved numerically.Comment: 9 pages, 4 figure