The Marr Conjecture and Uniqueness of Wavelet Transforms

The inverse question of identifying a function from the nodes (zeroes) of its wavelet transform arises in a number of fields. These include whether the nodes of a heat or hypoelliptic equation solution determine its initial conditions, and in mathematical vision theory the Marr conjecture, on whether an image is mathematically determined by its edge information. We prove a general version of this conjecture by reducing it to the moment problem, using a basis dual to the Taylor monomial basis $x^\alpha$ on $\mathbb {R}^n$.Comment: 52 pages, 4 figure

Spatial de-correlation of the UTRA-FDD radio channel

For smart antenna deployment in Frequency Division Duplex (FDD) applications the downlink weight vector can be derived from the uplink steering vector, assuming a degree of correlation between these channels. It is shown here that de-correlation between uplink and downlink power azimuth spectrums (PAS) is significant for frequency offsets as small as 5MHz in urban environments. Results reported here are computed from measured data taken within the UTRA (UMTS Terrestrial Radio Interface) frequency band for cluttered urba

Trade costs, barriers to entry, and export diversification in developing countries

This paper finds that a 1 percent reduction in the cost of exporting or the cost of international transport is associated with an export diversification gain of 0.3 percent or 0.4 percent respectively. Lower domestic market entry costs can also promote diversification, but the elasticity is weaker (-0.1). To obtain these results, the authors construct new measures of export diversification for 118 developing countries using highly detailed 8-digit mirror data from the European Union. The analysis also incorporates new export cost data from the World Bank's Doing Business database, covering document preparation, inland transport, administrative fees, and port/customs charges. Findings are highly robust, including to the use of geography and colonial history as instruments for trade and entry costs. Both the signs and relative magnitudes of these effects are consistent with predictions from a heterogeneous firms model of trade with asymmetric costs.Housing&Human Habitats,E-Finance and E-Security,Mining&Extractive Industry (Non-Energy),Educational Technology and Distance Education,Transport Economics Policy&Planning