Focusing on the Few: the Role of Large Taxpayer Units in the Revenue Strategies of Developing Countries

Part I of this paper first reviews the spread of LTUs, and briefly describes the experience of LTUs in a few selected countries. This section takes up the question of the LTU as an enclave administrative reform versus semi-autonomous revenue agencies and "whole of government" reform involving broad based wages, human resources planning and anti-corruption measures.Part II examines the emergence of the LTU and its relationships to the remainder of the tax administration system in different kinds of developing and transition economies, such as (i)capable developing states, (ii) administratively weak but governance improving states, and (iii)captured states. The relative success of LTUs can improve our understanding of the enclave approach to governance reforms as well as yielding insights that are intrinsic to the challenge of improving revenue mobilization. LTUs and their roles in developing country economies can also be interpreted through the prism of recent revisionist writings on best policies for the tax mix in the presence of a major informal sector and a government sector with a highly constrained taxing capacity and high vulnerability to corruption.Working Paper Number 04-44

Risk based bridge data collection and asset management and the role of structural health monitoring

Peer reviewedPostprin

Guidelines for data collection and monitoring for asset management of New Zealand road bridges

Publisher PD

Crossover from 2-dimensional to 1-dimensional collective pinning in NbSe3

We have fabricated NbSe$_3$ structures with widths comparable to the Fukuyama-Lee-Rice phase-coherence length. For samples already in the 2-dimensional pinning limit, we observe a crossover from 2-dimensional to 1-dimensional collective pinning when the crystal width is less than 1.6 $\mu$m, corresponding to the phase-coherence length in this direction. Our results show that surface pinning is negligible in our samples, and provide a means to probe the dynamics of single domains giving access to a new regime in charge-density wave physics.Comment: 4 pages, 2 figures, and 1 table. Accepted for publication in Physical Review

Impurity effect on low-temperature polarisation of the charge-density-waves in o-TaS3_3

The temperature dependence of the low-temperature dielectric response is studied in o-TaS$_3$ samples doped by Nb, Se, and Ni and for nominally pure ones. It is found, that the low-temperature dielectric constant depends anomalously on doping and is higher for doped crystals, whereas the temperature dependence of the characteristic time of all samples follows the activation law with nearly the same activation energy $\sim 400$ K (T>20 K). The observed behaviour is inconsistent with all available explanations of the low-temperature dielectric anomaly.Comment: RevTex, 12 pages, epsf, 2 postscript Figures. Accepted for publication in Physics Letters

Temporally ordered collective creep and dynamic transition in the charge-density-wave conductor NbSe3

We have observed an unusual form of creep at low temperatures in the charge-density-wave (CDW) conductor NbSe$_3$. This creep develops when CDW motion becomes limited by thermally-activated phase advance past individual impurities, demonstrating the importance of local pinning and related short-length-scale dynamics. Unlike in vortex lattices, elastic collective dynamics on longer length scales results in temporally ordered motion and a finite threshold field. A first-order dynamic phase transition from creep to high-velocity sliding produces "switching" in the velocity-field characteristic.Comment: 4 pages, 4 eps figures; minor clarifications To be published in Phys. Rev. Let

Thermal Rounding of the Charge Density Wave Depinning Transition

The rounding of the charge density wave depinning transition by thermal noise is examined. Hops by localized modes over small barriers trigger ``avalanches'', resulting in a creep velocity much larger than that expected from comparing thermal energies with typical barriers. For a field equal to the $T=0$ depinning field, the creep velocity is predicted to have a {\em power-law} dependence on the temperature $T$; numerical computations confirm this result. The predicted order of magnitude of the thermal rounding of the depinning transition is consistent with rounding seen in experiment.Comment: 12 pages + 3 Postscript figure