Simulating the impact during human jumping by means of a 4-degrees-of-freedom model with time-dependent properties

The authors simulated the vertical movements of a jumper and the force time courses by means of a 4-degrees-of-freedom model consisting of 4 masses, springs, and dampers. Of the motions simulated, only that of the mass imitating the trunk corresponded to the measured data. The best fit to the measured force curves were obtained in the simulation in which time-dependent model parameters were used. From the results, the authors concluded that at the beginning of the landing, a jumper behaves like a 2-mass model in which the leg segments (thighs, shanks, and feet) effectively combine into 1 mass. After approximately 60 ms, the connections between the leg segments become more compliant and the jumper behaves like a 4-mass model with a soft coupling between the leg segments. The process is equivalent to an increase of the degrees of freedom of the movements. At the end of the ground contact phase during hopping, the jumper has to contract the muscles in order to reach the envisaged jump height. In the model, that contraction could not be satisfactorily simulated.     

Higher-Order Contingentism,Part 1: Closure and Generation

This paper is a study of higher-order contingentism – the view, roughly, that it is contingent what properties and propositions there are. We explore the motivations for this view and various ways in which it might be developed, synthesizing and expanding on work by Kit Fine, Robert Stalnaker, and Timothy Williamson. Special attention is paid to the question of whether the view makes sense by its own lights, or whether articulating the view requires drawing distinctions among possibilities that, according to the view itself, do not exist to be drawn. The paper begins with a non-technical exposition of the main ideas and technical results, which can be read on its own. This exposition is followed by a formal investigation of higher-order contingentism, in which the tools of variable-domain intensional model theory are used to articulate various versions of the view, understood as theories formulated in a higher-order modal language. Our overall assessment is mixed: higher-order contingentism can be fleshed out into an elegant systematic theory, but perhaps only at the cost of abandoning some of its original motivations.     

The face of fluency: Semantic coherence automatically elicits a specific pattern of facial muscle reactions

This study shows that high conceptual fluency induced by hidden semantic coherence automatically triggers a specific pattern of facial expressions. In the present study, word triads that either had or had not a common remote associate were read by individuals while automatic facial responses were recorded. Although participants were ignorant about the underlying semantic structure, participants’ faces showed an activation of the smiling muscle zygomaticus major (indicating increased positive affect), a relaxation of the frowning muscle corrugator supercilii (indicating decreased negative affect and mental effort), and a relaxation of the forehead muscle frontalis (indicating increased familiarity) after reading coherent compared to incoherent word triads. Implications for intuitive judgements of semantic coherence are discussed.     

The Experiences of Self-Injury Amongst Adolescents and Young Adults within a South African Context

The aim of the study was to explore the experiences of self-injury among adolescents and young adults within the South African context. The participants were twelve university students who had self-injured in their adolescence (females = 92%). The data were collected through interviews, personal writings and collages and analysed using phenomenological data analysis. The findings indicate that self-injury is a strategy used to alleviate intense intrapersonal and interpersonal distress. To understand the complexity of self-injury, an integrative theoretical approach, encompassing a developmental and biopsychosocial perspective was used.     

Evaluation of fixed momentary dro schedules under signaled and unsignaled arrangements

Fixed momentary schedules of differential reinforcement of other behavior (FM DRO) generally have been ineffective as treatment for problem behavior. Because most early research on FM DRO included presentation of a signal at the end of the DRO interval, it is unclear whether the limited effects of FM DRO were due to (a) the momentary response requirement of the schedule per se or (b) discrimination of the contingency made more salient by the signal. To separate these two potential influences, we compared the effects of signaled versus unsignaled FM DRO with 4 individuals with developmental disabilities whose problem behavior was maintained by social-positive reinforcement. During signaled FM DRO, the experimenter presented a visual stimulus 3 s prior to the end of the DRO interval and delivered reinforcement contingent on the absence of problem behavior at the second the interval elapsed. Unsignaled DRO was identical except that interval termination was not signaled. Results indicated that signaled FM DRO was effective in decreasing 2 subjects' problem behavior, whereas an unsignaled schedule was required for the remaining 2 subjects. These results suggest that the response requirement per se of FM DRO may not be problematic if it is not easily discriminated.     

Job stressors, emotional exhaustion, and need for recovery: A multi-source study on the benefits of psychological detachment

This paper examines psychological detachment (i.e., mentally “switching off”) from work during non-work time as a partial mediator between job stressors and low work-home boundaries on the one hand and strain reactions (emotional exhaustion, need for recovery) on the other hand. Survey data were collected from a sample of protestant pastors (N = 136) and their spouses (N = 97). Analyses showed that high workload, emotional dissonance, and low spatial work-home boundaries were related to poor psychological detachment from work during non-work time. Poor psychological detachment in turn predicted high levels of emotional exhaustion and need for recovery. Psychological detachment was a partial mediator between job stressors and strain reactions. This study avoids same-source bias and demonstrates the importance of psychological detachment in the stressor–strain relationship.     

Effects of number and location of bins on plastic recycling at a university

The proportion of plastic bottles that consumers placed in appropriate recycling receptacles rather than trash bins was examined across 3 buildings on a university campus. We extended previous research on interventions to increase recycling by controlling the number of recycling receptacles across conditions and by examining receptacle location without the use of posted signs. Manipulating the appearance or number of recycling bins in common areas did not increase recycling. Consumers recycled substantially more plastic bottles when the recycling bins were located in classrooms.