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In England and Wales, wholesale electricity is sold in a spot market partly covered by long‐term contracts which hedge the spot price. Two dominant conventional generators can raise spot prices well above marginal costs, and this is profitable in the absence of contracts. If fully hedged, however, the generators lose their incentive to raise prices above marginal costs. Competition in the contract market could lead the generators to sell contracts for much of their output. Since privatisation the generators have indeed covered most of their sales in the contract market.

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This paper evaluates the impact of intermittent wind generation on hourly equilibrium prices and output, using data on expected wind generation capacity and demand for 2020. Hourly wind data for the period [1993][1994][1995][1996][1997][1998][1999][2000][2001][2002][2003][2004][2005] are used to obtain wind output generation profiles for thirty regions (onshore and offshore) across Great Britain. Matching the wind profiles for each month to the actual hourly demand (scaled to possible 2020 values), we find that the volatility of prices will increase, and that there is significant year-to-year variation in generators' profits. Above-average wind speeds lead to belowaverage prices, but annual revenues for British wind generators (producing more in the winter) are almost as great as for base load generators. In the presence of significant market power (the equivalent of two symmetric firms

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Notochord-derived Sonic Hedgehog (Shh) is essential for dorsoventral patterning of the overlying neural tube. Increasing concentration and duration of Shh signal induces progenitors to acquire progressively more ventral fates. We show that Notch signalling augments the response of neuroepithelial cells to Shh, leading to the induction of higher expression levels of the Shh target gene Ptch1 and subsequently induction of more ventral cell fates. Furthermore, we demonstrate that activated Notch1 leads to pronounced accumulation of Smoothened (Smo) within primary cilia and elevated levels of full-length Gli3. Finally, we show that Notch activity promotes longer primary cilia both in vitro and in vivo. Strikingly, these Notch-regulated effects are Shh independent. These data identify Notch signalling as a novel modulator of Shh signalling that acts mechanistically via regulation of ciliary localisation of key components of its transduction machinery.

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