NEW YORK (AP) ¿ Teekay Offshore Partners LP fell to a third-quarter loss as revenue fell by one-fifth during a downturn in shipping. The partnership said it lost $23.7 million, of which $11 million was attributable to partners, compared with a gain of $40.8 million, or $20.6 million attributable to partners, a year earlier. Excluding a variety of items, such as foreign exchange losses, deferred tax expenses and losses on derivative investments, the partnership said it would have earned $8 million. It did not provide a similar figure for the third quarter of 2008. Revenue fell to $206.9 million from $252.2 million a year ago. The shares rose 31 cents to $17.34 in afternoon trading.