An column by Troy Wolverton on today looks at Apple’s spending on research and development. According to the report, while Apple’s profits have risen significantly, the company has not increased its R&D budget accordingly. “Even while Apple’s revenue has skyrocketed in recent years — and even as expectations for future products and success have exploded — what the company has spent on R&D has risen only modestly,” writes Wolverton. “As a portion of overall sales, such expenses have actually fallen by more than half. Though analysts generally praise Apple for its frugality, some warn there’s a limit to how much longer the company can squeeze juicier near-term profits out of its R&D line.”