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An electron is usually considered to have only one form of kinetic energy, but could it have more, for its spin and charge, by exciting other electrons? In one dimension (1D), the physics of interacting electrons is captured well at low energies by the Tomonaga-Luttinger model, yet little has been observed experimentally beyond this linear regime. Here, we report on measurements of many-body modes in 1D gated-wires using tunnelling spectroscopy. We observe two parabolic dispersions, indicative of separate Fermi seas at high energies, associated with spin and charge excitations, together with the emergence of two additional 1D 'replica' modes that strengthen with decreasing wire length. The effective interaction strength is varied by changing the amount of 1D inter-subband screening by over 45%. Our findings demonstrate the existence of spin-charge separation in the whole energy band outside the low-energy limit of validity of the Tomonaga-Luttinger model, and also set a constraint on the validity of the newer nonlinear Tomonaga-Luttinger theory., Comment: 51 pages, 14 figures

This work studies the power loss in a real axle box gear transmission under no-load operating conditions. The influence of the rotational speed and of the lubricant viscosity was considered. An experimental strategy was adopted in order to measure the overall power loss of the axle box, as well as to isolate the power loss contribution of the major components: crown wheel, pinion, seals, and the tandem taper roller bearings supporting the pinion shaft and the crown assembly. Although it was not possible to directly measure the power loss generated by each component, the results allowed to identify the major contributions to the rear axle inefficiency. In particular, those from the crown wheel churning, from the lubricant squeezing due to the pocketing between the pinion and crown gear teeth, and from the friction in the preloaded tapered roller bearings of the pinion shaft and of the crown assembly. In average, the tapered roller bearings supporting the pinion shaft are responsible for 74% of the overall power loss of the axle box. A numerical model was developed to predict the power loss of the axle box and of its components, which was correlated with the experimental measurements with high accuracy (R2 = 0.9990). The combination of the experimental measurements with the model predictions allowed a full understanding of the axle box power loss behavior under no-load operating conditions. This analysis can be used for the design of an axle box with improved efficiency.