Psychometrika - We propose a two-step procedure to estimate structural equation models (SEMs). In a first step, the latent variable is replaced by its conditional expectation given the observed... 相似文献
Impairment of motor learning skills in developmental coordination disorder (DCD) has been reported in several studies. Some hypotheses on neural mechanisms of motor learning deficits in DCD have emerged but, to date, brain‐imaging investigations are scarce. The aim of the present study is to assess possible changes in communication between brain areas during practice of a new bimanual coordination task in teenagers with DCD (n =10) compared to matched controls (n =10). Accuracy, stability and number of mirror movements were computed as behavioural variables. Neural variables were assessed by electroencephalographic coherence analyses of intra‐hemispheric and inter‐hemispheric fronto‐central electrodes. In both groups, accuracy of the new coordination increased concomitantly with right intra‐hemispheric fronto‐central coherence. Compared to typically developing teenagers, DCD teenagers presented learning difficulties expressed by less stability, no stabilization of the new coordination and a greater number of mirror movements despite practice. These measures correlated with reduced inter‐hemispheric communication, even after practice of the new coordination. For the first time, these findings provide neuro‐imaging evidence of a kind of inter‐hemispheric ‘disconnection’ related to altered inhibition of mirror movements during motor learning in DCD. 相似文献
Background: Although diabetes is a frequent complication of cystic fibrosis (CF), patients’ behaviours tend not to comply with best practice recommendations. Using Leventhal’s Common-Sense Model, we address this issue by exploring patients’ representations of CF-related diabetes (CFRD) to better understand the discrepancy between patients’ expected and observed health behaviours.
Methods: Semi-structured individual interviews were conducted with patients (n = 39) in six CF clinics in Quebec, Canada. These interviews were part of a larger research project on screening and management practices for CFRD.
Results: Illness representations differed between two groups of interviewed patients: (1) one group had either CF without dysglycemia or CF with impaired glucose tolerance; and (2) the other group had CFRD. Both representations were internally consistent and encompassed Leventhal’s five dimensions of illness representation: illness identity, cause, timeline, consequences and control.
Conclusions: Patients require specific information on CFRD. The screening phase could be a crucial time to help patients adjust their representations to fit the reality of CFRD. 相似文献
It is difficult to walk without vision to a nearby destination if there is a time delay between watching the destination and walking toward it. Indeed, path deviation occurred when delays were introduced before initiating straight ahead blindfolded walking (R. A. Tyrrell, K. K., Rudolph, B. G., Eggers, &; H. W. Leibowitz, 1993Tyrrell, R. A., Rudolph, K. K., Eggers, B. G., &; Leibowitz, H. W. (1993). Evidence for the persistence of visual guidance information. Perception &; Psychophysics, 54, 431–438.[Crossref], [PubMed], [Google Scholar]). The questions are whether the location of a 60-s delay in the walking path and whether performing a cognitive task during the delay influence the accuracy in reaching a previously seen target while walking without vision. Thirty young adults walked blindfolded and stopped when they believed they had reached a target at 8 m. Delays were 60 s in duration, were located at 0, 4, and 7 m, and involved waiting or backward counting. Significant differences were found between 0-m and 4-m delay locations for distance to target, distance travelled and path deviation (p < .05). Significant effect of backward counting during the 60-s delay was found at the 0-m delay for distance travelled (p < .05). The interaction between retaining visual guidance information during 60 s and performing a cognitive task likely influenced target-directed blind navigation. 相似文献
We first advocate that the AUML (Agent Unified Modeling Language) notation, even in its new version, is not precise enough to adequately describe protocols. This problem was long identified by Harel and we propose to follow his solution: extend sequence diagrams with a “prechart”, i.e. single out the initiation sequence of the protocol. This new notation keeps readability and intuition, but is also technically adequate and is given a formal semantics. It actually is a form of simple temporal logics, equipped with a game-based semantics, which is appropriate for modeling agent-based systems. We then go on to study its complexity. Unsurprisingly, the version with protocol roles is undecidable. The main interesting problem is to synthesize agents that follow the protocol described. Surprisingly, it is undecidable even if we remove roles, alternatives, loops, asynchronous communication, conditions, constraints, negations (already removed in AUML). The complexity of checking whether a society of agents obeys a protocol given in this trivial notation is also surprisingly high: it is PSPACE-complete, like temporal logic, while we show that this simple language is strongly less expressive than temporal logic. Notations in-between have the expected increase in expressiveness, but no increase in complexity. This justifies the use of a language including alternatives, asynchronous communication and conditions, since it increases expressiveness with no cost in complexity. 相似文献
Most agents can acquire information about their environments as they operate. A good plan for such an agent is one that not only achieves the goal, but is also executable, i.e., ensures that the agent has enough information at every step to know what to do next. In this paper, we present a formal account of what it means for an agent to know how to execute a plan and to be able to achieve a goal. Such a theory is a prerequisite for producing specifications of planners for agents that can acquire information at run time. It is also essential to account for cooperation among agents. Our account is more general than previous proposals, correctly handles programs containing loops, and incorporates a solution to the frame problem. It can also be used to prove programs containing sensing actions correct. 相似文献