A comparison of various methods for obtaining confidence intervals for the design lowflow values of streams and rivers

This paper describes an intriguing use of two relatively new statistical procedures, the bootstrap and non-stationary Markov modelling, to obtain confidence intervals for the design low-flow parameter, of great interest to hydrologists. The procedure described is applied to the stream-flow data gathered over more than 50 years from six gauging sites in Georgia, and is found to yield confidence intervals which are typically shorter than those given by traditional methods.     

Proton Spin Relaxation in the Rod Micelles of Type I CM Mesophases

The dynamics of the hydrocarbon chains in lyotropic nematic type I cylindrical micellar liquid crystals prepared with D₂O has been selectively studied by Zeeman and rotating frame nuclear spin-lattice relaxation. The measurements of the proton spin-lattice relaxation time T ₁ as a function of frequency and temperature demonstrate that relatively fast local fluctuations of individual amphiphilic chains relax the proton spins at high magnetic fields. This process is facilitated also by the rapid diffusive motion of the chains within the micellar units. The rotating frame Zeeman relaxation time T _1x, is associated at room temperature with a long correlation time of ~11 μs. Slow micellar orientational fluctuations have been assigned to this characteristic time.     

Interface Anchoring of p-alkyl Phenols in Disc-micelles of Mesophases

Five para-alkyl substituted phenols have been studied as solutes in two chemically different type II DM mesophases. The degrees of order for the aromatic ring, are not significantly affected by the different short alkyl chains, showing that the anchoring of the -OH group at the aqueous interface is the dominant determinant of local motion. The principal change in the diagonal degrees of order between the chemically different mesophases resides in the change in size of disc micelles with consequent changes in their motional freedom. The anchoring of the phenol -OH at the aqueous interface shows little or no perturbation from the chemical variation of neighboring amphiphiles in the micelle bilayer.