The challenges of estimating potential output in real time

Potential output is an estimate of the level of gross domestic product attainable when the economy is operating at a high rate of resource use. A summary measure of the economy's productive capacity, potential output plays an important role in the Congressional Budget Office (CBO)'s economic forecast and projection. The author briefly describes the method the CBO uses to estimate and project potential output, outlines some of the advantages and disadvantages of that approach, and describes some of the challenges associated with estimating and projecting potential output. Chief among these is the difficulty of estimating the underlying trends in economic data series that are volatile, subject to structural change, and frequently revised. Those challenges are illustrated using examples based on recent experience with labor force growth, the Phillips curve, and labor productivity growth.Economic development ; Economic conditions

Ultrasound of the knee during voluntary quadriceps contraction: A technique for detecting otherwise occult effusions

Objective To describe 1) a technique that can detect synovial effusions not seen on static ultrasound (US) examination and 2) the characteristics of patients with knee osteoarthritis (OA) for whom this technique proved useful. Methods From reviewed records of 76 patients with knee OA (112 knees) that we had seen for US-guided injections over a defined period, we found 45 knees with no detectable effusion on static US, of which 18 (14 patients) showed fluid when scanned during voluntary quadriceps contraction. For all patients, we had recorded effusion features (physical examination, presence and size on US), and success of joint entry was determined by getting synovial fluid and/or seeing an air echo or inflow of injected material. Results The 14 patients we studied were obese (mean ± SEM body mass index 32.7 ± 2.3 kg/m 2 ; 3 morbidly obese), with moderate to severe OA by radiography in most (Kellgren/Lawrence class 3 or 4 in 10 of 14 knees for which radiographs were available). The suprapatellar synovial space seen by US was small (mean ± SEM depth 0.38 ± 0.04 cm). Arthrocentesis obtained 0.5–16 ml of synovial fluid (mean ± SEM 2.9 ± 0.6 ml), which correlated with the depth of effusion as seen on US with the quadriceps in maximum contraction (Spearman's Ρ = 0.5597, P = 0.0157). In 4 knees where arthrocentesis failed to retrieve fluid, we observed at injection the inflow of material and a linear air echo. Conclusion US of the knee during voluntary quadriceps contraction can find effusions not detectable on static US. Such effusions provide targets for accurate aspiration and injection that would not be appreciated with static US.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75770/1/20047_ftp.pd

FERAL SWINE---ARE THEY A DISEASE THREAT TO LIVESTOCK IN THE UNITED STATES?

Feral swine populations provide both benefits and liabilities to citizens of the United States. Their expanding range and increasing densities, however, have raised concern over the adverse environmental and agricultural effects and the increased risk of disease transmission between feral swine and livestock. We discuss the role of feral swine in the transmission of wildlife diseases and, in particular, in diseases of national significance to the livestock industry. We also discuss available management tools and strategies for reducing feral swine populations, minimizing damage or disease occurrences and eradicating populations when deemed appropriate. Finally, we note areas of research that may provide valuable management tools in the future