Some algebraic properties of cyclic homology groups

In [10], see also [8], a cyclic homology theory HC _* ^– was introduced. The purpose of this paper is to study algebraically the properties of this version of cyclic homology. First we study its relation to Connes cyclic cohomology theory HC ^* and to the usual cyclic homology theory HC _* studied by Loday and Quillen in [15]. We explain the precise sense in which HC _* ^– is dual to HC ^*. Next we study products and describe a general method for constructing product operations in cyclic homology and cohomology theories. Finally we examine the relation between the theory HC _* ^– and algebraic K-theory.     

Studies of the thiadiazine, taurolidine-I. Identification of the molecular species present in aqueous solutions by (1)H- and (13)C-NMR spectroscopy

The equilibria in deuterium oxide solutions of the diamine, 4,4'-methylenebis(tetrahydro-1,2,4-thiadiazine-1,1-dioxide), were studied using highfield (1)H- and (13)C-NMR with the aid of solutions of tetrahydro-2H-1,2,4-thiadiazine-1,1-dioxide (taurultam), its two N-methyl detivatives and methylene glycol. Comparison of the (1)H-NMR spectrum of taurolidine with the one obtained from a mixture of taurultam and methylene glycol indicated that the same equilibria exists in both these solutions. It was concluded that taurolidine, taurultam and its 4-hydroxymethyl adduct and methylene glycol are the major components present. To facilitate the interpretation of the (13)C-spectra, (13)C-enriched methylene glycol was added to solutions of taurultam. The (13)C-studies confirmed the (1)H-NMR study.     

Optical properties of a polydiacetylene crystal: poly-[1,6-di(N-carbazolyl)-2,4-hexadiyne]

Normal incidence reflection spectra and Kramers-Kronig transforms are reported for a polydiacetylene crystal, DCHD (substituent group: N-carbazolymethyl). The lowest energy optical transition for the polymer backbone is found at 15 300 cm^?1, the lowest value obtained thus far for a polydiacetylene. The polymer chain and the carbazolyl substituent group may be treated as isolated chromophores - the former dominating the visible portion of the spectra and the latter dominating the UV portion. Polarization studies for the (001) and (10$\text{1}\text{?}$) faces of DCHD permit unambiguous assignment of the two lowest energy transitions in the carbazolyl group at 28 750 cm^?1 and 33 250 cm^?1 as short- and long-axis polarized, respectively.     

Insulator to metal transition in fluid deuterium

We have investigated the insulator to metal transition in fluid deuterium using first principles simulations. Both density functional and quantum Monte Carlo calculations indicate that the electronic energy gap of the liquid vanishes at about ninefold compression and 3000 K. At these conditions the computed conductivity values are characteristic of a poor metal. These findings are consistent with those of recent shock wave experiments but the computed conductivity is larger than the measured value. From our ab initio results we conclude that the transition is driven by molecular dissociation rather than disorder and that both temperature and pressure play a key role in determining structural changes in the fluid.     

The associated charged particle multiplicity of high-pTπ0 and single-photon events

The associated charged particle multiplicities of high-p_Tπ⁰ and single-photon events were measured at the CERN intersecting storage rings using lead/liquid-argon calorimeters and a scintillation counter array placed around the intersection region. The average multiplicity on the trigger side for the single-photon events was found to be significantly lower than that for the π⁰ events. The away-side multiplicity for both π⁰ and single-photon events increases with the trigger particle p_T, but, at a fixed p_T, the direct photon sample was found to have a slightly lower average multiplicity. The differences in the event structure can be explained if a large fraction of the single photons are produced via qg → γq constituent scattering.     

A cylindrical lens for a high power transmitting array in a sector scanning sonar

The design of a plano-convex cylindrical acoustic lens, which is used in conjunction with a plane array of PZT-4 elements to provide a high power, wide beam sonar projector is outlined. Test results are detailed and compared to those computed from simple theoretical considerations.     

A study of the bonding in phosphine by an electron impact coincidence experiment

The binding-energy spectrum of phosphine has been obtained over the range 0–30 eV using the binary (e, 2e) coincidence method. The momentum distribut     

Prospects for release-node quantum Monte Carlo

We perform release-node quantum Monte Carlo simulations on the first row diatomic molecules in order to assess how accurately their ground-state energies can be obtained. An analysis of the fermion-boson energy difference is shown to be strongly dependent on the nuclear charge, Z, which in turn determines the growth of variance of the release-node energy. It is possible to use maximum entropy analysis to extrapolate to ground-state energies only for the low Z elements. For the higher Z dimers beyond boron, the error growth is too large to allow accurate data for long enough imaginary times. Within the limit of our statistics we were able to estimate, in atomic units, the ground-state energy of Li(2) (-14.9947(1)), Be(2) (-29.3367(7)), and B(2)(-49.410(2)).     

High-resolution gadolinium-enhanced 3D MRA of the infrapopliteal arteries. Lessons for improving bolus-chase peripheral MRA

Peripheral magnetic resonance angiography (MRA) is growing in use. However, methods of performing peripheral MRA vary widely and continue to be optimized, especially for improvement in illustration of infrapopliteal arteries. The main purpose of this project was to identify imaging factors that can improve arterial visualization in the lower leg using bolus chase peripheral MRA. Eighteen healthy adults were imaged on a 1.5T MR scanner. The calf was imaged using conventional three-station bolus chase three-dimensional (3D) MRA, two dimensional (2D) time-of-flight (TOF) MRA and single-station Gadolinium (Gd)-enhanced 3D MRA. Observer comparisons of vessel visualization, signal to noise ratios (SNR), contrast to noise ratios (CNR) and spatial resolution comparisons were performed. Arterial SNR and CNR were similar for all three techniques. However, arterial visualization was dramatically improved on dedicated, arterial-phase Gd-enhanced 3D MRA compared with the multi-station bolus chase MRA and 2D TOF MRA. This improvement was related to optimization of Gd-enhanced 3D MRA parameters (fast injection rate of 2 mL/sec, high spatial resolution imaging, the use of dedicated phased array coils, elliptical centric k-space sampling and accurate arterial phase timing for image acquisition). The visualization of the infrapopliteal arteries can be substantially improved in bolus chase peripheral MRA if voxel size, contrast delivery, and central k-space data acquisition for arterial enhancement are optimized. Improvements in peripheral MRA should be directed at these parameters.