Tree scattering amplitudes of the spin-4/3 fractional superstring I: the untwisted sectors

Scattering amplitudes of the spin-4/3 fractional superstring are shown to satisfy spurious state decoupling and cyclic symmetry (duality) at tree-level in the string perturbation expansion. This fractional superstring is characterized by the spin-4/3 fractional superconformal algebra---a parafermionic algebra studied by Zamolodchikov and Fateev involving chiral spin-4/3 currents on the world-sheet in addition to the stress-energy tensor. Examples of tree scattering amplitudes are calculated in an explicit c=5 representation of this fractional superconformal algebra realized in terms of free bosons on the string world-sheet. The target space of this model is three-dimensional flat Minkowski space-time with a level-2 Kac-Moody so(2,1) internal symmetry, and has bosons and fermions in its spectrum. Its closed string version contains a graviton in its spectrum. Tree-level unitarity (i.e., the no-ghost theorem for space-time bosonic physical states) can be shown for this model. Since the critical central charge of the spin-4/3 fractional superstring theory is 10, this c=5 representation cannot be consistent at the string loop level. The existence of a critical fractional superstring containing a four-dimensional space-time remains an open question.Comment: 42 pages, 4 figures, latex, IASSNS-HEP-93/57, CLNS-92/117

Current-Induced Effects in Nanoscale Conductors

We present an overview of current-induced effects in nanoscale conductors with emphasis on their description at the atomic level. In particular, we discuss steady-state current fluctuations, current-induced forces, inelastic scattering and local heating. All of these properties are calculated in terms of single-particle wavefunctions computed using a scattering approach within the static density-functional theory of many-electron systems. Examples of current-induced effects in atomic and molecular wires will be given and comparison with experimental results will be provided when available.Comment: revtex, 10 pages, 8 figure

Estimation of Total Body Water from Foot-To-Foot Bioelectrical Impedance Analysis in Patients with Cancer Cachexia - Agreement Between Three Prediction Methods and Deuterium Oxide Dilution

Introduction: Bioelectrical impedance analysis (BIA) is a useful bedside measure to estimate total body water (TBW). The aim of this study was to determine the agreement between three equations for the prediction of TBW using BIA against the criterion method, deuterium oxide dilution, in patients with cancer cachexia. Methods: Eighteen measurements of TBW using foot-to-foot BIA in seven outpatients with cancer cachexia (five male and two female, age 56.4 +/- 6.7 years) at an Australian hospital. Three prediction formulae were used to estimate TBW - TBWca-radiotherapy developed in patients with cancer undergoing radiotherapy, TBWca-underweight and TBWca-normal weight developed in underweight and normal weight patients with cachexia. TBW was measured using the deuterium oxide dilution technique as the gold standard. Results: Mean measured TBW was 39.5 +/- 6.0 L. There was no significant difference in measured TBW and estimates from prediction equations TBWca-underweight and TBWca-radiotherapy. There was a significant difference in measured TBW and TBWca-normal weight. All prediction equations overestimated TBW in comparison with measured TBW. The smallest bias was observed with TBWca-underweight (0.38 L). The limits of agreement are wide (> 7.4 L) for each of the prediction equations compared with measured TBW. Conclusions: At a group level, TBWca-underweight is the best predictor of measured TBW in patients with cancer cachexia. For an individual however, the limits of agreement are wide for all prediction equations and are unsuitable for use. Practitioners need to be aware of the limitations of using TBW prediction equations for individuals

A comparison of the Siconolfi and Cole-Cole procedures for multifrequency impedance data analysis

The established Cole-Cole and newer Siconolfi methods for analysis of multifrequency impedance data were compared in a group of normal healthy individuals studied under bedside conditions. Impedance quotients derived from each procedure Here similarly well correlated with independent dilutional estimates of total body water. Although both methods estimated resistance at zero frequency, were highly correlated. and provided impedance quotients with very similar correlations with extracellular water, these estimates were significantly different and thus mag not be used interchangeably. The Siconolfi procedure demonstrated no significant advantage over the Cole-Cole method. In view of the sound theoretical basis for the latter, it is concluded that analysis of MFBIA data by the Cole-Cole method is to be preferred