Simulation of the optical system in the GroundBIRD telescope.

GroundBIRD is a ground-based telescope for measuring the polarization of cosmic microwave background radiation, and it is soon to be operational at the Teide Observatory. The GroundBIRD telescope employs Mizuguchi-Dragone dual reflectors and 161 kinetic inductance detectors coupled with single polarization antennas as photon detectors. We present the results of our optical simulation on the pointing direction, stray light response, and influence of the blackbody radiation from the baffle. We also find that the power of the baffle radiation incident on the detectors is reduced by 99.95% when corrugated feed horns are coupled to the detectors.

Open reduction and internal fixation for intraarticular fracture of metacarpal head.

Intraarticular fracture of the metacarpophalangeal (MP) joint presents complex problems related to the sophisticated functional aspects of the hand. Injury to the metacarpal head may have a severe effect on hand function but few studies have investigated the management of this condition. In this study, we applied open reduction and internal fixation for the displaced fracture of the metacarpal head and report the clinical and radiographic outcomes of our experience. Thirteen patients (12 men, 1 woman; mean age 21 years) were included in this study, and medical records and radiographs were reviewed retrospectively. The average follow-up period was 12.5 months. Range of motion (ROM) and Disabilities of the Arm, Shoulder, and Hand (DASH) scores were analyzed, and functional results and serial radiographs were investigated for the maintenance of articular congruity and fracture union. The injured fingers were 5 long, 4 small, 2 ring, and 2 index. Five cases were fixed with K­wires, 5 cases with headless screws, and 3 cases with screw and K­wire. The average range of injured MP joint motion was 89°, total active range of motion (TAM) was 265°, and the average DASH score was 3.8 at the last follow-up. All patients showed fracture union on the radiographs and no patient showed significant articular surface incongruence or degenerative change. Open reduction and internal fixation of the metacarpal head fracture had favorable outcomes in our study. The authors suggest accurate reduction and stable fixation for better functional results in metacarpal head fractures.