Thermal Resonance in Signal Transmission

We use temperature tuning to control signal propagation in simple one-dimensional arrays of masses connected by hard anharmonic springs and with no local potentials. In our numerical model a sustained signal is applied at one site of a chain immersed in a thermal environment and the signal-to-noise ratio is measured at each oscillator. We show that raising the temperature can lead to enhanced signal propagation along the chain, resulting in thermal resonance effects akin to the resonance observed in arrays of bistable systems.Comment: To appear in Phys. Rev.

Pressure area care for the City and Hackney Health Authority Prevention plan for patients at risk from developing pressure sores; policy for the management of pressure sores

SIGLEAvailable from British Library Document Supply Centre- DSC:q90/23962(Pressure) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Reaction of thiones with dihalogens: comparison of the solid state structures of 4,5-bis(methylsulfanyl)-1,3-dithiole-2-thione-diiodine, -dibromine and -iodine monobromide

Reaction of 4,5-bis(methylsulfanyl)-1,3-dithiole-2-thione 1 with diiodine or iodine monobromide in CH2Cl2 resulted in the formation of molecular charge-transfer complexes 1 . I-2 and 1 . IBr respectively. Both complexes have been characterised crystallographically and contain a linear S-I-X (X = I or Br) moiety with the sulfur adopting a tetrahedral geometry taking into account the stereochemically active lone pairs. The S-I [2.716(3)] and I-I [2.808(3) Angstrom] bond lengths in 1 . I-2 are similar to those reported for diiodine complexes of related thione donors. The adduct 1 . IBr is the first crystallographically characterised thione-iodine monobromide charge-transfer complex. The S-I distance [2.589(2) Angstrom] is shorter than that in 1 . I-2, consistent with IBr being a stronger acceptor than I-2. The I-Br distance [2.7138(11) Angstrom] is lengthened with respect to that in unco-ordinated IBr, but within bonding distance when compared to the sum of the van der Waals radii for iodine and bromine (3.75 Angstrom). Treatment of 1 with dibromine under identical conditions resulted in the formation of the adduct 1 . Br-2 and the dithiolylium salt [C5H6S4Br][Br-3]. 1/2Br(2) 2. Treatment of 1 with Br-2 in toluene led to the isolation of 1 . Br-2 only. The crystal structure of 1 . Br-2 shows the compound to contain a linear Br-S-Br moiety with the sulfur in a T-shaped or Psi-trigonal bipyramidal environment (taking into account the stereochemically active lone pairs). The structure of 2 reveals a three component system consisting of the [C5H6S4Br](+) cation, the [Br-3](-) anion and a molecule of Br-2 in a 2:2:1 ratio. These components are held in the lattice by a series of weak intermolecular interactions which link the tribromide ions and dibromine molecules into zigzag chains