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Rotation of Asymmetric Top

Rotation of Asymmetric Top

By definition, a spherically symmetric body has the same moment of inertia about any axis passing through its center of mass. This situation changes if there is no spherical symmetry. Since most rigid bodies are not spherically symmetric, these require special treatment.
The relationship between the angular momentum of any rigid body and its angular velocity, both of which are vectors, involves the moment of inertia. The moment of inertia is a scalar quantity only for spherically symmetric...

Torsion in Vector Calculus

Torsion in Vector Calculus

A toy train ascending a winding track that curves and tilts offers an intuitive view of torsion, a key geometric concept in the study of space curves. While curvature measures how sharply a path bends, torsion captures how the path twists out of the plane of bending. This twisting behavior is crucial in understanding three-dimensional motion and is precisely described using the Frenet–Serret framework.At each point along a space curve, the Frenet–Serret frame consists of three orthogonal unit...

Torsion of Noncircular Members

Torsion of Noncircular Members

Circular shafts undergoing torsional stress maintain their cross-sectional integrity due to their axisymmetric nature. This symmetry ensures an even distribution of stress, allowing the shaft to withstand torsion without distorting. In contrast, square bars, lacking this axial symmetry, experience significant distortion across their cross-sections when subjected to torsion, with the exception of along their diagonals and at lines connecting midpoints. A detailed examination of a cubic element...

Eccentric Axial Loading in a Plane of Symmetry

Eccentric Axial Loading in a Plane of Symmetry

Eccentric axial loading occurs when an axial load is applied away from the centroidal axis of a structural member. This scenario is common in engineering, where structural elements may not be directly aligned due to various design or functional requirements.

Deformation in a Circular Shaft

Deformation in a Circular Shaft

One of the distinctive characteristics of circular shafts is their ability to maintain their cross-sectional integrity under torsion. In other words, each cross-section continues to exist as a flat, unaltered entity, simply rotating like a solid, rigid slab. To understand the distribution of shearing stress within such a shaft, consider a cylindrical section inside this circular shaft. This section has a length of L and a radius of R, with one end fixed. The radius of the cylindrical section is...

Chair Conformation of Cyclohexane

Chair Conformation of Cyclohexane

The chair conformation is the most stable form of cyclohexane due to the absence of angle and torsional strain. The absence of angle strain is a result of cyclohexane’s bond angle being very close to the ideal tetrahedral bond angle of 109.5° in its chair conformer. Similarly, the torsional strain is also absent owing to the perfectly staggered arrangement of bonds.
The hydrogen atoms linked to carbons are arranged in two different axial and equatorial orientations to achieve this staggered...

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Related Experiment Video

Updated: Jul 12, 2026

Clinical Efficacy of an Innovative Multidimensional Traction Therapy in Moderate Adolescent Idiopathic Scoliosis

Clinical Efficacy of an Innovative Multidimensional Traction Therapy in Moderate Adolescent Idiopathic Scoliosis

Published on: February 10, 2026

[Supine cyclotorsion and asphericity].

R Lehnert¹, M Müller, A Liekfeld

¹Klinik und Poliklinik für Augenheilkunde, Charité - Universitätsmedizin Berlin, Campus Virchow-Klinikum.

Klinische Monatsblatter Fur Augenheilkunde

|August 25, 2007

Summary

Patient positioning during eye exams impacts refractive surgery outcomes. Changes in astigmatism and asphericity occur when moving from seated to supine positions, potentially affecting customized laser ablation results.

Area of Science:

Ophthalmology and Optometry
Corneal Surgery and Refractive Error Correction

Context:

Customized laser ablation for refractive errors is increasingly important.
Preoperative eye examinations are typically performed seated, while laser surgery is done supine.
Known cyclotorsion occurs between seated and supine positions, but its impact on astigmatism, RMS, and asphericity is under-investigated.

Purpose:

To investigate changes in astigmatism, root mean square (RMS), and asphericity when patients transition from a seated to a supine position.
To assess the clinical relevance of these positional changes for customized refractive surgery.

Summary:

A study involving 18 eyes measured parameters in both seated and supine positions using a mobile videokeratoscope.
While cyclotorsion was not statistically significant overall, individual changes were noted.

Related Experiment Videos

Last Updated: Jul 12, 2026

Clinical Efficacy of an Innovative Multidimensional Traction Therapy in Moderate Adolescent Idiopathic Scoliosis

Clinical Efficacy of an Innovative Multidimensional Traction Therapy in Moderate Adolescent Idiopathic Scoliosis

Published on: February 10, 2026

Statistically significant changes in asphericity were observed (p=0.04), with minor, non-significant changes in astigmatism and RMS.

Impact:

Positional changes between preoperative measurement and surgery can lead to statistically significant alterations in corneal asphericity.
These changes may contribute to suboptimal outcomes in customized refractive surgery.
Consideration should be given to performing preoperative measurements in the supine position to align with the surgical position.