About 500,000 utility customers at a time in checkerboard patterns were denied power by Pacific Gas and Electric for about an hour, then had service restored as another block was blacked out.
As each block was placed into position, the vertical face mating with the beam or another block was coated with repair material and pressed together.
(See Fig. 1; Wymer (1993) and Donaghy et al. (2007) provide details of the estimation algorithm).8 In estimating each block, some variables that were, in theory, endogenously determined in the complete model (and were treated endogenously in another block) were of necessity treated as exogenous.
Another stumbling block is consumer behaviour.
Another stumbling block is the potentially huge cost of organising an election abroad.
Another stumbling block is the Holy See's recognition of Taiwan, which Beijing considers a renegade province.
Another stumbling block is Apple's penchant for secrecy, withholding information about products until they are finished.
Another stumbling block is that some states make it very difficult for insurers to provide this product.
According to Guillette, another stumbling block is the accepted, but unproven, dogma that an embryo will develop as a normal female barring any hormonal signals to become male.
Another potential stumbling block is the concentration of the United States market; the four largest players control 90percentt.
