Publications by authors named "Tim van der Zee"

Article Synopsis
  • Skeletal muscles take time to produce force, which is influenced by several processes like calcium activation and cross-bridge cycling, but these have not been fully integrated in existing muscle models.
  • Researchers examined how these processes contribute to force development in two common muscle models (Hill-type and cross-bridge) and found that neither could accurately recreate classic muscle data, indicating the need for additional dynamics like cooperative myofilament interactions.
  • They proposed a new 'force facilitation dynamics' model that accurately represents force development across different excitations and highlighted that the main contributors to force dynamics in human quadriceps are largely attributed to these facilitation processes rather than calcium activation or cross-bridge cycling alone.*
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The biomechanics of human walking are well documented for standard conditions such as for self-selected step length and preferred speed. However, humans can and do walk with a variety of other step lengths and speeds during daily living. The variation of biomechanics across gait conditions may be important for describing and determining the mechanics of locomotion.

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Ultrasound imaging is valuable for non-invasively estimating fascicle lengths and other features of pennate muscle, especially when performed computationally. Effective analysis techniques to date typically use optic flow to track displacements from image sequences, but are sensitive to integration drift for longer sequences. We here present an alternative algorithm that objectively estimates geometric features of pennate muscle from ultrasound images, without drift sensitivity.

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Humans perform mechanical work during walking, some by leg joints actuated by muscles, and some by passive, dissipative soft tissues. Dissipative losses must be restored by active muscle work, potentially in amounts sufficient to cost substantial metabolic energy. The most dissipative, and therefore costly, walking conditions might be predictable from the pendulum-like dynamics of the legs.

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Muscles consume metabolic energy for active movement, particularly when performing mechanical work or producing force. Less appreciated is the cost for activating muscle quickly, which adds considerably to the overall cost of cyclic force production. However, the cost magnitude relative to the cost of mechanical work, which features in many movements, is unknown.

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The metabolic cost per unit force is generally thought to increase with the mechanical work done by the muscle fibres. It is currently unclear how the metabolic cost of doing alternating positive and negative muscle fibre mechanical work relates to the metabolic cost of doing zero muscle fibre mechanical work at similar muscle force. The current study aimed to investigate this issue by comparing metabolic power between a dynamic and an isometric near-constant force production task.

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Background: We present the results of a reanalysis of four articles from the Cornell Food and Brand Lab based on data collected from diners at an Italian restaurant buffet.

Method: We calculated whether the means, standard deviations, and test statistics were compatible with the sample size. Test statistics and values were recalculated.

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The last decade has seen a dramatic rise in the number of studies that utilize the probe-caught method of collecting mind-wandering reports. This method involves stopping participants during a task, presenting them with a thought probe, and asking them to choose the appropriate report option to describe their thought-state. In this experiment we manipulated the framing of this probe, and demonstrated a substantial difference in mind-wandering reports as a function of whether the probe was presented in a mind-wandering frame compared with an on-task frame.

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People are known to be very poor at visually judging acceleration. Yet, they are extremely proficient at intercepting balls that fall under gravitational acceleration. How is this possible? We previously found that people make systematic errors when trying to tap on targets that move with different constant accelerations or decelerations on interleaved trials.

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Background: Patients who display disruptive behaviours in the clinical encounter (the so-called 'difficult patients') may negatively affect doctors' diagnostic reasoning, thereby causing diagnostic errors. The present study aimed at investigating the mechanisms underlying the negative influence of difficult patients' behaviours on doctors' diagnostic performance.

Methods: A randomised experiment with 74 internal medicine residents.

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Background: Literature suggests that patients who display disruptive behaviours in the consulting room fuel negative emotions in doctors. These emotions, in turn, are said to cause diagnostic errors. Evidence substantiating this claim is however lacking.

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