Towards a socially adaptive digital playground

We are working towards a socially adaptive digital playground for children. To this end, we are looking into nonverbal synchrony and other social signals as a measure of social behaviour and into ways to alter game dynamics to trigger and inhibit certain social behaviours. Our first results indicate that we can indeed influence social behaviours in a digital playground by changing game dynamics. Furthermore, our first results show that we will be able to sense some of these social behaviours using only computer vision techniques. I propose an iterative method for working towards a socially adaptive digital playground

Interaction of antithrombin III with surface-immobilized albumin-heparin conjugates

The interaction between antithrombin III (ATIII) and albumin-heparin conjugates covalently coupled onto carboxylated polystyrene beads either in buffer containing albumin or in plasma was studied using 14C-labeled ATIII. Binding isotherms of ATIII were modeled using a summation of two Langmuir equations. These equations describe the binding of ATIII to two different sets of binding sites, one with a high, the other with a low affinity for ATIII. The average binding constants for the binding of ATIII to these sites are 9 × 106 L/mol and 0.3 × 106 L/mol, respectively. The binding of ATIII to surface binding sites with a high affinity for ATIII was correlated with the presence of specific ATIII binding sites in the immobilized heparin. Binding of ATIII from albumin solutions to binding sites with a low affinity for ATIII was dominated by nonspecific binding of ATIII to the immobilized heparin. A third small fraction of the surface bound ATIII is probably adsorbed to sites on the surface not covered with heparin. In the case of the binding of ATIII to the heparinized surface from plasma solutions, a fraction of initially adsorbed ATIII was desorbed by other plasma proteins. This desorption in combination with direct competition between ATIII and other plasma proteins resulted in lower ATIII surface concentrations using plasma as compared to the ATIII surface concentrations obtained using albumin solutions. The binding of ATIII to nonspecific binding sites was almost completely inhibited in the presence of plasma proteins. The amount of ATIII bound to immobilized heparin via specific ATIII binding sites was 30% lower in plasma solutions as compared to the specific binding of ATIII using albumin solutions. It is concluded that the accessibility of immobilized heparin for ATIII in plasma decreases by binding of heparin-binding proteins onto the immobilized heparin and/or by adsorption of other plasma proteins on the heparinized surface

Spatially structured genetic variation in a broadcast spawning bivalve: quantitative vs. molecular traits

Understanding the origin, maintenance and significance of phenotypic variation is one of the central issues in evolutionary biology. An ongoing discussion focuses on the relative roles of isolation and selection as being at the heart of genetically based spatial variation. We address this issue in a representative of a taxon group in which isolation is unlikely: a marine broadcast spawning invertebrate. During the free-swimming larval phase, dispersal is potentially very large. For such taxa, small-scale population genetic structuring in neutral molecular markers tends to be limited, conform expectations. Small-scale differentiation of selective traits is expected to be hindered by the putatively high gene flow. We determined the geographical distribution of molecular markers and of variation in a shell shape measure, globosity, for the bivalve Macoma balthica (L.) in the western Dutch Wadden Sea and adjacent North Sea in three subsequent years, and found that shells of this clam are more globose in the Wadden Sea. By rearing clams in a common garden in the laboratory starting from the gamete phase, we show that the ecotypes are genetically different; heritability is estimated at 23%. The proportion of total genetic variation that is between sites is much larger for the morphological additive genetic variation (QST = 0.416) than for allozyme (FST = 0.000–0.022) and mitochondrial DNA cytochrome-c-oxidase-1 sequence variation (ΦST = 0.017). Divergent selection must be involved and intraspecific spatial genetic differentiation in marine broadcast spawners is apparently not constrained by low levels of isolation.

Unilateral versus bilateral upper limb training after stroke

Beek, P.J. [Promotor]Kwakkel, G. [Promotor]Peper, C.E. [Copromotor

On seed physiology, biomechanics and plant phenology in Eragrostis tef

• Key words: Teff (Eragrostis tef (Zuccagni) Trotter), germination, temperature, model, leaf appearance, phyllochron, development rate, lodging, biomechanics, safety factor, flowering, heading, day length, photoperiod. • Background Teff (Eragrostis tef (Zuccagni) Trotter) is a C4 annual grass species (Poaceae) originating from Ethiopia. Teff cultivation in the Netherlands is thought to be economically feasible because teff grains and flour do not contain gluten and are rich in iron. These two characteristics make teff a desirable ingredient in health products, particularly for celiac disease patients. At the start of this project Dutch teff yields were modest (1.0 - 1.5 Mg•ha-1). The sowing and harvest dates were (too) late in the season and the crop was sensitive to lodging. Here, lodging is defined as the permanent displacement of shoots from their vertical due to root or shoot failure. • The objective of this research is to detail some processes that underlie the sensitivity to lodging and the late harvest. Therefore we studied seed germination, lodging resistance, day length response, pace of leaf appearance. • Germination of teff can be described by assuming a normally distributed rate of germination within the seed population. Minimal and maximal temperatures required for germination depend on water availability (water potential). Conversely, the minimal required water potential for germination depends on temperature. • Lodging was inevitable for teff grown on a Dutch sandy soil. We identified that not only the shoots of teff are prone to lodging, but that the roots are also a major factor in the lodging process. Furthermore, water adhering to the shoots alone, without wind action, could induce lodging in the studied cultivars. • Flowering in teff is significantly delayed by exposure to long days. Teff is therefore a short day plant; not only panicle initiation, but also development and outgrowth of the panicle were influenced by photoperiod. • Phyllochron, defined as the time required between the appearance of two successive teff leaves, increased abruptly for the last few leaves on the main stem of teff. After re-evaluation of literature data this abrupt increase in phyllochron seemed to be also present in both wheat and rice. The delay is most likely independent of temperature, but might be related to the moment of panicle initiation. • In conclusion, the study on teff identified clear targets for breeding towards a high-yielding cultivar in the Netherlands. </p

Achievement goal adoption: the interplay between strategic task framing and regulatory focus

In the present study, I investigate whether employees' achievement goal adoption (mastery goal on skill development versus performance goal on outperforming others) can be predicted based on the regulatory fit or misfit between the means required by strategic task framing (eagerness versus vigilance) and individuals' regulatory focus (promotion focus on gains versus prevention focus on non-losses). Specifically, I argue that mastery goals will be more strongly pursued for tasks framed in a fitting, relative to misfitting way, mainly as a result of the autonomous feeling one experiences when executing a task with a preferred strategy. In contrast, performance goals are expected to be pursued in case of tasks that are framed in a misfitting, relative to fitting way, mainly due to the externally controlled feeling one perceives when executing a task with an assigned strategy that would not be one's preferred strategy. These expectations are tested in an experiment in which I measured individuals' (N = 186) regulatory focus, after which they engaged in an eager-framed or vigilant-framed task, in relation to which their achievement goals were assessed (prior to the task). Results indicated the existence of a fitting effect, since prevention focus is positively related to mastery goals when tasks required vigilance, but negatively when tasks required eagerness. In addition, prevention focus was found to be positively related to performance goals when tasks required eagerness, and negatively when tasks required vigilance. However, no significant findings occurred for promotion focus. These findings provide initial support for the notion that managers can predict and influence employees' achievement goal adoption

Crossing the Great Divide: Rewritings of the U.S.-Mexican Encounter in Walter Abish and Richard Rodríguez

In a 1978 essay on the relationship between Mexico and the United States, Octavio Paz suggested that the two countries were separated by a perhaps insuperable divide. Yet two recent works—Richard Rodríguez\u27s collection of essays Days of Obligation: An Argument with My Mexican Father (1992) and Walter Abish\u27s novel Eclipse Fever (1993)—offer evidence of a changing outlook on the U.S.-Mexican encounter. Abish and Rodríguez build upon the storehouse of images of the irreconcilable differences between the two nations. However, insofar as they play with and question these images, they draw attention to the unstable, fluctuating nature of the U.S.-Mexican encounter in the late twentieth century. Abish focuses on the prevailing inequality in the relationship between the U.S. and Mexico, and reflects on the distinctive traits of the national character of each of the two countries. Yet a variety of narrative strategies serve to block any reading of Eclipse Fever in terms of sharply differentiated group identities. Rodríguez repeatedly evokes commonplace contrasts between the two nations. Yet his reading both of a variety of cultural phenomena, and of his own trajectory as an individual, suggests a complex interweaving of the cultures of Mexico and the United States