Cyclic animation using Partial differential Equations

YesThis work presents an efficient and fast method for achieving cyclic animation using Partial Differential Equations (PDEs). The boundary-value nature associ- ated with elliptic PDEs offers a fast analytic solution technique for setting up a framework for this type of animation. The surface of a given character is thus cre- ated from a set of pre-determined curves, which are used as boundary conditions so that a number of PDEs can be solved. Two different approaches to cyclic ani- mation are presented here. The first consists of using attaching the set of curves to a skeletal system hold- ing the animation for cyclic motions linked to a set mathematical expressions, the second one exploits the spine associated with the analytic solution of the PDE as a driving mechanism to achieve cyclic animation, which is also manipulated mathematically. The first of these approaches is implemented within a framework related to cyclic motions inherent to human-like char- acters, whereas the spine-based approach is focused on modelling the undulatory movement observed in fish when swimming. The proposed method is fast and ac- curate. Additionally, the animation can be either used in the PDE-based surface representation of the model or transferred to the original mesh model by means of a point to point map. Thus, the user is offered with the choice of using either of these two animation repre- sentations of the same object, the selection depends on the computing resources such as storage and memory capacity associated with each particular application

The role of leadership in salespeople’s price negotiation behavior

Salespeople assume a key role in defending firms’ price levels in price negotiations with customers. The degree to which salespeople defend prices should critically depend upon their leaders’ influence. However, the influence of leadership on salespeople’s price defense behavior is barely understood, conceptually or empirically. Therefore, building on social learning theory, the authors propose that salespeople might adopt their leaders’ price defense behavior given a transformational leadership style. Furthermore, drawing on the contingency leadership perspective, the authors argue that this adoption fundamentally depends on three variables deduced from the motivation–ability–opportunity (MAO) framework, that is, salespeople’s learning motivation, negotiation efficacy, and perceived customer lenience. Results of a multi-level model using data from 92 salespeople and 264 salesperson–customer interactions confirm these predictions. The first to explore contingencies of salespeople’s adoption of their transformational leaders’ price negotiation behaviors, this study extends marketing theory and provides actionable guidance to practitioners

Good for the Self:Self-Compassion and Other Self-Related Constructs in Relation to Symptoms of Anxiety and Depression in Non-clinical Youths

This study examined relationships among self-compassion, self-esteem, and self-efficacy and symptoms of anxiety disorders and depression in a sample of 132 non-clinical adolescents aged 12-17 years. The results first of all indicated that the Shortened Self-Compassion Scale for Adolescents was reliable (i.e., all Cronbach's alphas were >.70) and valid in terms of both construct (as demonstrated by a principal components analysis which revealed the hypothesized three-factor structure) and concurrent validity (i.e., as shown by means of positive correlations with self-esteem and self-efficacy). Further, the expected negative correlations were found between self-compassion and anxiety and depression, indicating that higher levels of this self-related construct are associated with lower symptom levels, and vice versa. Of the three components of self-compassion, mindfulness appeared most convincingly related to symptoms of anxiety and depression. Finally, when controlling for other self-related constructs, self-compassion no longer accounted for a significant proportion in the variance of symptom levels. In contrast, self-esteem (depression) and in particular self-efficacy (anxiety and depression) did show unique explanatory power

Visual perspective and feedback guidance for VR free-throw training

Accurate distance perception and natural interactions are mandatory conditions when training precision aiming tasks in VR. However, many factors specific to virtual environments (VEs) lead to differences in the way users execute a motor task in VR versus the real world. To investigate these differences, the authors performed a study on basketball beginners' free-throw performance in VEs under different visual conditions. Although the success rate is not statistically different, some adaptations occurred in the way the users performed the task, depending on the visual conditions. In the third-person perspective visual condition, the release parameters indicate that the users more accurately estimated distance to target. Adding visual guidance information (gradual depth information showing the ideal ball trajectory) also led to more natural motor behavior. The final aim of this study was to develop a reliable basketball free-throw training system in VEs, so the authors compared beginners' performances in VR with experts' models of performance. Their results show that most of the performance variables tended to evolve closer to the experts' performance during the training in the VE

Effect of applied stresses on alkali-silica reaction-induced expansions

International audienceThe mechanical effects of alkali-silica reaction (ASR) have to be modeled in order to assess the deterioration level and the stability of ASR-damaged concrete structures. Several experimental programs have shown the effects of compressive stresses on ASR-induced strains. The effect is so significant that assessment models have to take into account the modification of ASR expansions due to applied stresses and the consequences on the mechanical response of damaged structures. This paper presents and analyzes measurements performed on concrete specimens subjected to several states of stresses along the three directions (due to applied stresses and to passive restraint). Mechanical calculations show that the volumetric expansion imposed by ASR is constant whatever the stresses conditions. They point out the “expansion transfer” occurring along the directions which are less compressed; thus, the effect of stresses on ASR expansions anisotropy can be precisely quantified. (C) 2005 Elsevier Ltd. All rights reserved