How to Mix Molecules with Mathematics

In this paper we develop two methods to calculate thermodynamic properties of mixtures. Starting point are the basic assumptions that also form the basis for the COSMO-RS model. In this approach, the individual molecules are represented by their geometrical shape with an electrical charge density on their surfaces. Next, the surface is split up into surface segments each with its own charge. In COSMO-RS a strong reduction is introduced by treating the segments as if they are completely independent. In the present study we take into account that the coupling between two patches is essentially dependent on the charge distribution on neighboring segments and on the local geometrical structure of the surface. Two approaches are followed. The first one points out how the model equations, which comprise the optimization of the entropy and conservation of internal energy, can efficiently be solved in general, thus also if the dependency between segments and the local geometry is included in the expression for the coupling energy between segments. In the second method the configuration with maximal entropy and prescribed energy is sought via simulation. Successive molecular configurations of the mixture are simulated and updated via a genetic algorithm to optimize the entropy. The second method is more time consuming but very general

Emergent Coordination of Heading in Soccer:Of Two Players and a Single Ball

Purpose: In many sports situations, two or more players need to coordinate their actions to make sure that one of them intercepts a ball or opponent. We considered how two soccer players head back a thrown ball. Two accounts for the joint decision making by both players were considered. These two accounts not only differ in their theoretical basis but also have vastly different implications for training practice. In a first account, players know their areas of responsibility for interception, and combine this with their prediction of the ball's landing location. In a second account, the coordination emerges from the unfolding dynamics of the system of informationally connected players and ball. According to this second account, especially for balls aimed in between the two players, both of the players may start moving and one player sees that the ball will be interceptable for the other player, and subsequently yields the interception. Methods: We instrumented soccer players and the ball with Kinexon sensors and had pairs of players head back the thrown ball. Results: In line with the second account, the results showed a fair number of instances where the player who intercepted the ball had to move the longest distance. Furthermore, considerable movement by both players was not an exception. Conclusion: The results can be taken as a first step towards an understanding of joint coordination as an emergent phenomenon.</p

Emergent Coordination of Heading in Soccer:Of Two Players and a Single Ball

Purpose: In many sports situations, two or more players need to coordinate their actions to make sure that one of them intercepts a ball or opponent. We considered how two soccer players head back a thrown ball. Two accounts for the joint decision making by both players were considered. These two accounts not only differ in their theoretical basis but also have vastly different implications for training practice. In a first account, players know their areas of responsibility for interception, and combine this with their prediction of the ball's landing location. In a second account, the coordination emerges from the unfolding dynamics of the system of informationally connected players and ball. According to this second account, especially for balls aimed in between the two players, both of the players may start moving and one player sees that the ball will be interceptable for the other player, and subsequently yields the interception. Methods: We instrumented soccer players and the ball with Kinexon sensors and had pairs of players head back the thrown ball. Results: In line with the second account, the results showed a fair number of instances where the player who intercepted the ball had to move the longest distance. Furthermore, considerable movement by both players was not an exception. Conclusion: The results can be taken as a first step towards an understanding of joint coordination as an emergent phenomenon.</p

Height, Size, and/or Gap Width Variation in Jumping Stone Configurations:Which Form of Variation Attracts Children the Most?

Earlier studies revealed that children prefer nonstandardized jumping stone configurations to standardized ones. In the present study, we examined whether children playing on jumping stones prefer variation in stone height, stone size, and/or gap width. In Experiment 1, children could play freely on one standardized configuration and three configurations in which one of the aforementioned factors was varied. It was found that children judged the variation in height as most fun. Yet, the configuration with gap width variation appeared to be most challenging for the children-most overground steps were made in this configuration. In Experiment 2, we examined whether the attractiveness of the configurations increased when height variation was combined with the other forms of variation. Adding size and/or gap width variation to the variation in height did not contribute to the attractiveness of the configuration. In line with experiment 1, it was found that the configurations with gap width variation were judged as the most challenging for children. The implications of these results are discussed in the context of the literature on play.</p

High-precision calculations of In I and Sn II atomic properties

We use all-order relativistic many-body perturbation theory to study 5s^2 nl configurations of In I and Sn II. Energies, E1-amplitudes, and hyperfine constants are calculated using all-order method, which accounts for single and double excitations of the Dirac-Fock wave functions.Comment: 10 pages, accepted to PRA; v2: Introduction changed, references adde

Keeping Your Eyes Continuously on the Ball While Running for Catchable and Uncatchable Fly Balls

When faced with a fly ball approaching along the sagittal plane, fielders need information for the control of their running to the interception location. This information could be available in the initial part of the ball trajectory, such that the interception location can be predicted from its initial conditions. Alternatively, such predictive information is not available, and running to the interception location involves continuous visual guidance. The latter type of control would predict that fielders keep looking at the approaching ball for most of its flight, whereas the former type of control would fit with looking at the ball during the early part of the ball's flight; keeping the eyes on the ball during the remainder of its trajectory would not be necessary when the interception location can be inferred from the first part of the ball trajectory. The present contribution studied visual tracking of approaching fly balls. Participants were equipped with a mobile eye tracker. They were confronted with tennis balls approaching from about 20 m, and projected in such a way that some balls were catchable and others were not. In all situations, participants almost exclusively tracked the ball with their gaze until just before the catch or until they indicated that a ball was uncatchable. This continuous tracking of the ball, even when running close to their maximum speeds, suggests that participants employed continuous visual control rather than running to an interception location known from looking at the early part of the ball flight.</p

Perceiving affordances in sports through a momentum lens

In this experimental study, we tested whether athletes’ judgments of affordances and of environmental features vary with psychological momentum (PM). We recruited golf, hockey, and tennis players, who were assigned to a positive or negative momentum condition. We designed a golf course on which participants made practice putts, after which they were asked to place the ball at their maximum “puttable” distance and to judge the hole size. Next, participants played a golf match against an opponent, in which the first to take a lead of 5 points would win the match. Participants were told that they could win a point by making the putt or by being closest to the hole. They wore visual occlusion goggles to prevent them from seeing the actual result, and the experimenter manipulated the scoring pattern to induce positive or negative PM. Participants in the positive momentum condition came back from a four-point lag to a four-point lead, whereas those in the negative momentum condition underwent the opposite scenario. We then asked the participants again to indicate their maximum puttable distance from the hole and to judge the hole size. After the manipulation, participants judged the maximum puttable distance to be longer in the positive momentum condition and shorter in the negative momentum condition. For the hole-size judgments, there were no significant effects. These results provide first indications for the idea that athletes’ affordances change when they experience positive PM compared to negative PM. This sheds a new light on the dynamics of perception-action processes and PM in sports

Movements of Individual Digits in Bimanual Prehension Are Coupled into a Grasping Component

The classic understanding of prehension is that of coordinated reaching and grasping. An alternative view is that the grasping in prehension emerges from independently controlled individual digit movements (the double-pointing model). The current study tested this latter model in bimanual prehension: participants had to grasp an object between their two index fingers. Right after the start of the movement, the future end position of one of the digits was perturbed. The perturbations resulted in expected changes in the kinematics of the perturbed digit but also in adjusted kinematics in the unperturbed digit. The latter effects showed up when the end position of the right index finger was perturbed, but not when the end position of the left index finger was perturbed. Because the absence of a coupling between the digits is the core assumption of the double-pointing model, finding any perturbation effects challenges this account of prehension; the double-pointing model predicts that the unperturbed digit would be unaffected by the perturbation. The authors conclude that the movement of the digits in prehension is coupled into a grasping component

When a fly ball is out of reach: catchability judgments are not based on optical acceleration cancelation.

The optical acceleration cancelation (OAC) strategy, based on Chapman’s (1968) analysis of the outfielder problem, has been the dominant account for the control of running to intercept fly balls approaching head on. According to the OAC strategy, outfielders will arrive at the interception location just in time to catch the ball when they keep optical acceleration zero. However, the affordance aspect of this task, that is, whether or not an approaching fly ball is catchable, is not part of this account. The present contribution examines whether the scope of the OAC strategy can be extended to also include the affordance aspect of running to catch a fly ball. This is done by considering a fielder’s action boundaries (i.e., maximum running velocity and – acceleration) in the context of the OAC strategy. From this, only when running velocity is maximal and optical acceleration is non-zero, a fielder would use OAC to perceive a fly ball as uncatchable. The present contribution puts this hypothesis to the test. Participants were required to try to intercept fly balls projected along their sagittal plane. Some fly balls were catchable whereas others were not. Participants were required to catch as many fly balls as possible and to call ‘no’ when they perceived a fly ball to be uncatchable. Participants’ running velocity and –acceleration at the moment of calling ‘no’ were examined. Results showed that participants’ running velocity was submaximal before or while calling ‘no’. Also running acceleration was often submaximal. These results cannot be explained by the use of OAC in judging catchability and ultimately call for a new strategy of locomotor control in running to catch a fly ball

Scale of Emotional Development – Short: reliability and validity in adults with intellectual disability

Background Intellectual disability (ID) is often associated with delays in emotional development (ED). The Scale of Emotional Development – Short (SED-S) was developed to assess the level of ED and to adapt treatment and care accordingly. Methods In a sample of 724 adults from five study sites in three countries, a confirmatory factor analysis with a one-factor model was conducted on the entire dataset as well as in different subgroups. Furthermore, internal consistency was investigated using Cronbach's alpha. Results The confirmatory factor analysis indicated that a single-factor model fits the SED-S data well. The subgroup analyses revealed good model fit, regardless of the severity of ID and irrespective of sex or the presence of autism spectrum disorder or psychiatric disorders. Internal consistency was excellent for the entire sample (Cronbach's alpha = 0.93) and various subgroups (0.869–0.938). Conclusion The results of this study suggest that the SED-S is psychometrically sound and can be used to assess the level of ED in adults with ID