Penton Media Inc., publisher of Machine Design and producer of the Internet World trade shows, posted a first-quarter net loss of $5.1 million, compared with a net loss of $43.9 million a year earlier. The 2002 figure included a non-cash asset impairment charge of $39.7 million. Revenue fell to $54.4 million in this year's first quarter, a decline of 11% from a year earlier. However, EBITDA (earnings before interest, taxes, depreciation and amortization) climbed to $9.3 million, compared with $5.2 million in the first quarter of 2002. Penton expects the difficult market conditions