Each business day, TheStreet.com Ratings compiles a list of the top five stocks in one of five categories -- fast-growth, all-around value, large-cap, mid-cap and small-cap -- based on data from the close of the previous trading session. Today we focus on mid-caps.These are stocks of companies that have market capitalizations of between $500 million and $10 billion that rank near the top of all stocks rated by our proprietary quantitative model, which looks at more than 60 factors. The stocks must also be followed by at least one financial analyst who posts estimates on the Institutional Brokers' Estimate System. They are ordered by their potential to appreciate. Note that no provision is made for off-balance-sheet assets such as unrealized appreciation/depreciation of investments, market value of real estate or contingent liabilities that might affect book value. This could be material for some companies with large underfunded pension plans. Landauer ( LDR) offers personnel radiation monitoring to measure the dosages of x-rays, gamma radiation and other penetrating ionizing radiation to which a person has been exposed. Our buy rating for Landauer has not changed since November 2001. Our rating is supported by the company's revenue growth, largely solid financial position, and increases in net income and earnings per share. For the third quarter of fiscal 2008, Landauer reported that its revenue rose 6.4% year over year. This appears to have helped boost EPS, which improved by 47.6% when compared with the same quarter a year ago. Net income also increased for the third quarter, rising 48.3% from $3.91 million to $5.79 million. Landauer has no debt to speak of, and with a quick ratio of 1.69 should be able to cover its short-term liquidity needs. Additionally, Landauer also increased its net operating cash flow slightly by 5.24% when compared with the same quarter last year.