Using an atomic force microscope to nanopattern a substrate for liquid crystal alignment, a bend distortion is imposed on a liquid crystal. In regions of large bend the smectic-A phase melts into the nematic phase, and the width of the melted region is measured as a function of temperature. The results are consistent with type-I superconducting (nematic — smectic-A) behavior, wherein a large ma...

Proteins that bend DNA are important regulators of biological processes. Sequence-specific DNA bending ligands have been designed that bind two noncontiguous sites in the major groove and induce a bend in the DNA. An oligonucleotide containing pyrimidine segments separated by a central variable linker domain simultaneously binds by triple helix formation two 15-bp purine tracts separated by 10 ...

Type II DNA topoisomerases actively reduce the fractions of knotted and catenated circular DNA below thermodynamic equilibrium values. To explain this surprising finding, we designed a model in which topoisomerases introduce a sharp bend in DNA. Because the enzymes have a specific orientation relative to the bend, they act like Maxwell's demon, providing unidirectional strand passage. Quantitat...

A fiber-optic structure based on a section of a double-clad fiber with depressed inner cladding is investigated for bend sensing. The structure is formed by splicing a section of SM630 fiber between two standard fibers SMF-28. The operation principle relies on the sensitivity of cladding modes that are induced at a splice of fibers having different refractive index profiles. The transmission sp...

Motivated by diverse phenomena in cellular biophysics, including bacterial flagellar motion and DNA transcription and replication, we study the overdamped nonlinear dynamics of a rotationally forced filament with twist and bend elasticity. Competition between twist injection, twist diffusion, and writhing instabilities is described by a novel pair of coupled PDEs for twist and bend evolution. A...

We report on an easy-to-evaluate expression for the prediction of the bend-loss for a large mode area photonic crystal fiber (PCF) with a triangular air-hole lattice. The expression is based on a recently proposed formulation of the V-parameter for a PCF and contains no free parameters. The validity of the expression is verified experimentally for varying fiber parameters as well as bend radius...

We characterize an approach to make ultra-low-loss waveguides using stable and reproducible stoichiometric Si3N4 deposited with low-pressure chemical vapor deposition. Using a high-aspect-ratio core geometry, record low losses of 8-9 dB/m for a 0.5 mm bend radius down to 3 dB/m for a 2 mm bend radius are measured with ring resonator and optical frequency domain reflectometry techniques. From a ...

In an orthogonal drawing of a plane graph, any edge is drawn as a sequence of line segments, each having either a horizontal or a vertical direction. A bend is a point where an edge changes its direction. A drawing is called a bend-minimum orthogonal drawing if the number of bends is minimum among all orthogonal drawings. This paper presents a linear-time algorithm to find a bend-minimum orthog...

Twist stiffness and an asymmetric bending stiffness of a polymer or a polymer bundle is captured by the elastic ribbon model. We investigate the effects a ring geometry induces to a thermally fluctuating ribbon, finding bend-bend coupling in addition to twist-bend coupling. Furthermore, due to the geometric constraint the polymer's effective bending stiffness increases. A new parameter for expe...

ICP4, the major regulatory polypeptide of herpes simplex virus type 1, is expressed at the earliest stages of virus infection and is required for the activation of transcription from the majority of viral promoters. It is a DNA binding protein which specifically recognises bipartite sites related to the sequence ATCGTnnnnnCGG. In this report we show that both partially purified ICP4, and its is...