Height, trunk and representativity of knots

Waist and Trunk of Knots

We introduce two numerical invariants, the waist and the trunk of knots. The waist of a closed incompressible surface in the complement of a knot is defined as the minimal intersection number of all compressing disks for the surface in the 3-sphere and the knot. Then the waist of a knot is defined as the maximal waist of all closed incompressible surfaces in the complement of the knot. On the o...

Effects of pushing height on trunk posture and trunk muscle activity when a cart suddenly starts or stops moving.

Unexpected sudden (un)loading of the trunk may induce inadequate responses of trunk muscles and uncontrolled trunk motion. These unexpected perturbations may occur in pushing tasks, when the cart suddenly starts moving (unloading) or is blocked by an obstacle (loading). In pushing, handle height affects the user's working posture, which may influence trunk muscle activity and trunk movement in ...

Cluster Characterization through a Representativity Measure

Clustering is an unsupervised learning task which provides a decomposition of a dataset into subgroups that summarize the initial base and give information about its structure. We propose to enrich this result by a numerical coefficient that describes the cluster representativity and indicates the extent to which they are characteristic of the whole dataset. It is defined for a specific cluster...

A simple construction of high representativity triangulations

Estimation of trunk muscle parameters for a biomechanical model by age, height and weight.

To establish more accurate equations for estimating the moment arm length and cross-sectional area of the erector spinae and rectus abdominis muscles, the effects of height, weight and age on those muscles were analyzed by using a high-order polynomial equation. Data on the moment arm length and cross-sectional area at L3/4 were obtained from MRI images of 152 males and 98 females. The statisti...