DNA has been described as a semiflexible polymer. But DNA is chiral, so its bending Hamiltonian contains nonlinear terms coupling the curvature κ to the torsion τ , leading to an average 〈τ〉 independent of κ, and variance 〈∆τ〉 scaling as 1/κ. We perform atomistic MD simulations of 31 base-pair DNA sequences with explicit solvent, in which “restraints” are imposed to “encourage” the DNA to bend....

DNA bending in 86 complexes with sequence-specific proteins has been examined using normal vector plots, matrices of normal vector angles between all base pairs in the helix, and one-digit roll/slide/twist tables. FREEHELIX, a new program especially designed to analyze severely bent and kinked duplexes, generates the foregoing quantities plus local roll, tilt, twist, slide, shift and rise param...

In the pigeon, as in other members of the three groups of vertebrates which have developed advanced powers of flight—the birds, bats and pterosaurs—the bending and torsional strength of the proximal part of the wing lies in the humerus and radio-ulna. The humerus runs obliquely back from the shoulder joint to the elbow, and from there the radio-ulna runs obliquely forward to the wrist. In fligh...

A substantial fraction of the warps in spiral galaxies may result from bending instabilities if the disks are essentially self-gravitating. With N-body simulations, we show that galaxies with self-gravitating disks as thick as HI disks are subject to bending instabilities generating S-shaped, U-shaped or asymmetric warps. S-shaped warps persist during several rotations and keep the line of node...

Changes in bending of the DNA helix axis caused by the introduction of conformationally locked nucleotide analogs into the center region of the palindromic Dickerson dodecamer, d(CGCGAATTCGCG)(2), have been studied by NMR measurement of residual one-bond (13)C-(1)H dipolar couplings. Thymidine analogs, in which the deoxyribose was substituted by bicyclo[3.1.0]hexane, were incorporated in the T7...

The self-consistent Eulerian rate-type elastoplastic model based on the logarithmic rate is used to study finite bending of a compressible elastic-perfectly plastic rectangular block. It is found that an explicit closed-form solution for this typical inhomogeneous finite deformation mode may be available in a general case of compressible deformation with a stretch normal to the bending plane, w...

Assessment of the curve flexibility is a crucial step in a surgeon's pre-operative planning for scoliosis surgery. Many techniques have been described. These include traction films, supine side bending films, push prone techniques, traction under general anaesthesia as well as fulcrum bending film. In this study, we studied the pre- and immediate post-operative radiographs of twenty eight adole...

Laser bending of tubes is a process in which laser-induced thermal distortion is used to bend tubes without hard tooling or external forces. Mechanisms of the process are examined to better understand the deformation characteristics such as wall thickness variation, cross-section ovalization, bending radius, and asymmetry. Factors important to these characteristics are experimentally and numeri...

We discuss how light can be efficiently bent by nanoscale-width slit waveguides in metals. The discussion is based on accurate numerical solutions of Maxwell's equations. Our results, using a realistic model for silver at optical wavelengths, show that good right-angle bending transmission can be achieved for wavelengths lambda> 600 nm. An approximate stop-band at lower wavelengths also occurs,...

Bending of DNA is a feature essential to the function of many DNA-binding proteins. Bending angles can be estimated with a variety of techniques, but most directly from images obtained using scanning force microscopy (SFM). Direct measurement of the bending angle using a tangent method often produces angles that deviate significantly from values obtained using other techniques. Here, we describ...