Interring twisting (change in the dihedral angle between conjugated rings) of polythiophene was studied theoretically using periodic boundary conditions (PBC) at the B3LYP/6-31G(d) level. We find that the band gap of polymers is strongly dependent on the interring twist angle; yet twisting requires very little energy. A twist of 30 degrees increases the band gap by 0.75 eV in polythiophene, whi...

Twisting generators for pseudorandom numbers may use a congruential array to simulate stochastic sequences. Typically, the computer program controls the quantity of elements in array to limit the random access memory. This technique may have limitations in situations where the stochastic sequences have an insufficient size for some application tasks, ranging from theoretical mathematics and tec...

The chirality transfer in liquid crystals induced by two helical perylenequinones (namely, the natural compounds cercosporin and phleichrome) was investigated by integrating measurements of helical twisting power with a conformational analysis by DFT calculations and with the prediction of their twisting ability by the surface-chirality method. The two quasi-enantiomeric derivatives induce oppo...

This paper describes the results of an experimental study aimed at evaluating the biomechanical effects of working in a spatially restricted environment on manual lifting tasks. The main objective of the study is to estimate the biomechanical loading (in terms of peak compression and shear forces) on the lumbar spine for the selected combinations of limited headroom heights and twisting angles....

The ability of m-phenylene to ferromagnetically couple spin-containing substituents that are substantially twisted out of conjugation is investigated. The "bis(TMM)" strategy is employed, in which two triplet TMM biradicals are linked through m-phenylene to produce relatively stable, organic tetraradicals that are characterized by EPR spectroscopy. Under conditions of moderate twisting (4), fer...

The aim of the present study is to determine the feasibility of making a rectangular twist waveguide used to rotate electromagnetic waves. For this purpose, the process of fabricating an aluminum rectangular twist waveguide was simulated by making use of finite element method and Deform software. The optimum length and angle of the twist die for manufacturing a twist waveguide with inner cross ...

We construct a family of time and angular dependent, regular S-brane solutions which corresponds to a simple analytical continuation of the Zipoy-Voorhees 4-dimensional vacuum spacetime. The solutions are asymptotically flat and turn out to be free of singularities without requiring a twist in space. They can be considered as the simplest non-singular generalization of the singular S0-brane sol...

For a finite-dimensional Hopf algebra H over a field k and an Hcomodule algebra A, we study properties of A which are preserved when A is twisted by a Hopf 2-cocycle σ on H. We prove that if there exists σ such that Aσ is super-commutative, then A being affine imples that A is Noetherian. If also Hσ is commutative, then A is integral over a central subring of AcoH . We also consider when A sati...

Additivity plays a key role in program analysis. It is the basis for designing Galois connection based abstract interpretations, it makes a Data-Flow Analysis (DFA) problem easy being convertible into a Kildall’s general form, and provides a lattice-theoretic model for disjunctive analysis. In this paper we consider reversible transformers respectively making any monotone function additive and ...

OBJECTIVES To find associations between the prevalence of low back pain and occupational activities. METHODS Interviews of a random sample of 5185 19-59 year old Danish employees analysed by logistic regression. RESULTS Increased risks of low back pain were found for "vibration affecting the whole body" (odds ratio (OR) = 1.28), "physically hard work" (OR = 1.28), "frequently twisting or be...