Does volatility improve UK earnings forecasts?

We investigate the relation between UK accounting earnings volatility and the level of future earnings using a unique sample comprising some 10,480 firm-year observations for 1,481 non-financial firms over the 1985-2003 period. The findings confirm the in-sample result of an inverse volatility-earnings relation only for the 1998-2003 sub-period and for the most profitable firms. The out-of-sample forecast accuracy for the top earnings quintile when volatility is added as a regressor is superior to the model including only lagged earnings. The findings are consistent with the over-investment hypothesis and the view that the earnings of the most volatile firms tend to mean-revert more rapidly

Anomalous thermopower and Nernst effect in CeCoIn5\rm CeCoIn_5: entropy-current loss in precursor state

The heavy-electron superconductor CeCoIn$_5$ exhibits a puzzling precursor state above its superconducting critical temperature at $T_c$ = 2.3 K. The thermopower and Nernst signal are anomalous. Below 15 K, the entropy current of the electrons undergoes a steep decrease reaching $\sim$0 at $T_c$. Concurrently, the off-diagonal thermoelectric current $\alpha_{xy}$ is enhanced. The delicate sensitivity of the zero-entropy state to field implies phase coherence over large distances. The prominent anomalies in the thermoelectric current contrast with the relatively weak effects in the resistivity and magnetization.Comment: 5 figures, 4 page

Evidence of phonon-charge-density-waves coupling in ErTe3_3

The vibrational properties of ErTe$_3$ were investigated using Raman spectroscopy and analyzed on the basis of peculiarities of the RTe$_3$ crystal structure. Four Raman active modes for the undistorted structure, predicted by factor-group analysis, are experimentally observed and assigned according to diperiodic symmetry of the ErTe$_3$ layer. By analyzing temperature dependence of the Raman mode energy and intensity we have provided the clear evidence that all Raman modes, active in the normal phase, are coupled to the charge density waves. In addition, new modes have been observed in the distorted state

The Lorenz number in CeCoIn5_5 inferred from the thermal and charge Hall currents

The thermal Hall conductivity $\kappa_{xy}$ and Hall conductivity $\sigma_{xy}$ in CeCoIn$_5$ are used to determine the Lorenz number ${\cal L}_H$ at low temperature $T$. This enables the separation of the observed thermal conductivity into its electronic and non-electronic parts. We uncover evidence for a charge-neutral, field-dependent thermal conductivity, which we identify with spin excitations. At low $T$, these excitations dominate the scattering of charge carriers. We show that suppression of the spin excitations in high fields leads to a steep enhancement of the electron mean-free-path, which leads to an interesting scaling relation between the magnetoresistance, thermal conductivity and $\sigma_{xy}$.Comment: 6 pages, 7 figures Intro para slightly lengthened. Added 2 new re

On the role of fine-sand dune dynamics in controlling water depth changes in Rio Parapeti, Serrania Borebigua (Southern sub-Andean zone of Bolivia)

The role of the fine-dune sand dynamics in controlling the natural regeneration of the upper layer of a riverbed used for filtration is studied at the Choreti test reach of Rio Parapeti, in the Southern sub-Andean zone of Bolivia. Local production of drinking water relies on Riverbed Filtration, the delivery of which depends on the river water depth and the riverbed permeability. There is a strong, natural, declamation process of the upper layer maintained by dune bed-forms migrating downstream. It is thus essential to understand and represent local water depth changes as a function of the incoming discharge. We show the vortex-drag model can be used to correctly calculate the stream velocity in natural environment. Then we study the sand dunes characteristic (wavelength and celerity) in the Rio Parapeti. Because of the shallow-flow configuration the dominant dune length can be easily extracted from satellite images taken at various dates. We also show that it is more than likely that dune movement can be followed by the simple deployment of a pressure probe into the water under stable discharge condition, even if further data and investigation are necessary to confirm this

Comment on "Spatial optical solitons in highly nonlocal media" and related papers

In a recent paper [A. Alberucci, C. Jisha, N. Smyth, and G. Assanto, Phys. Rev. A 91, 013841 (2015)], Alberucci et al. have studied the propagation of bright spatial solitary waves in highly nonlocal media. We find that the main results in that and related papers, concerning soliton shape and dynamics, based on the accessible soliton (AS) approximation, are incorrect; the correct results have already been published by others. These and other inconsistencies in the paper follow from the problems in applying the AS approximation in earlier papers by the group that propagated to the later papers. The accessible soliton theory cannot describe accurately the features and dynamics of solitons in highly nonlocal media.Comment: 2 page

Evidence for electron-phonon interaction in Fe1−x_{1-x}Mx_{x}Sb2_{2} (M=Co, Cr) single crystals

We have measured polarized Raman scattering spectra of the Fe$_{1-x}$Co$_{x}$Sb$_{2}$ and Fe$_{1-x}$Cr$_{x}$Sb$_{2}$ (0$\leq x\leq$0.5) single crystals in the temperature range between 15 K and 300 K. The highest energy $B_{1g}$ symmetry mode shows significant line asymmetry due to phonon mode coupling width electronic background. The coupling constant achieves the highest value at about 40 K and after that it remains temperature independent. Origin of additional mode broadening is pure anharmonic. Below 40 K the coupling is drastically reduced, in agreement with transport properties measurements. Alloying of FeSb$_2$ with Co and Cr produces the B$_{1g}$ mode narrowing, i.e. weakening of the electron-phonon interaction. In the case of A$_{g}$ symmetry modes we have found a significant mode mixing

Kondo Insulator description of spin state transition in FeSb2

The thermal expansion and heat capacity of FeSb2 at ambient pressure agrees with a picture of a temperature induced spin state transition within the Fe t_{2g} multiplet. However, high pressure powder diffraction data show no sign of a structural phase transition up to 7GPa. A bulk modulus B=84(3)GPa has been extracted and the temperature dependence of the Gruneisen parameter has been determined. We discuss here the relevance of a Kondo insulator description for this material.Comment: Physical Review B in press (2005