New Wearable Heart Rate Monitor for Contact Sports and Its Potential to Change Training Load Management.

Athletes in all sports face injury or illness if they train too much. Therefore, it is crucial for them to manage their training load. Monitoring the heart rate is one way to estimate training load. However, there are limitations to a monitor's measurement ability in contact sports like rugby. Another method to estimate training load in contact sports is the rating of perceived exertion of a player, which is based on a questionnaire. It however takes a long time to obtain answers to questionnaires in team sports. As a solution to this problem, we developed a wearable heart rate monitor for rugby players. The garment-type monitor with flank electrodes can measure the heart rate even in rugby training situations. We also propose a method to estimate the training load from the measured heart rate. The method can be used instead of a questionnaire administered to the players and can reduce the labor in the estimation of the training load.

Polarization insensitive silicon immersion grating based on total internal reflection.

We describe an immersion grating (IG) with both low polarization-dependent loss (PDL) and high diffraction efficiency. Our immersion grating consists of a silicon (Si) prism and a Si grating coated with dielectric film. We analyze the effect of the refractive index of dielectric film and clarify the refractive index ratio between a Si grating and dielectric film. Selecting an adequate material for the dielectric film, we design the diffraction efficiency of TM polarization without changing that of TE polarization. The simulation results for the optimized IG show a PDL of 0.2 dB and diffraction efficiency of -0.4 dB. A prototype with high dispersion power provides a low PDL of 0.6 dB, while maintaining a high diffraction efficiency of -0.4 dB.

Osteoconduction of a stoichiometric and bovine hydroxyapatite bilayer-coated implant.

OBJECTIVE: To impart rapid and durable osteoconductivity to implants, a commercial titanium screw implant was coated with stoichiometric hydroxyapatite (HA; 50 nm thick), and then with bovine hydroxyapatite (B-HA; 300 nm thick) using the pulsed laser deposition technique. As control specimens, a commercial implant coated with HA (20 µm thick) using the flame spraying method (sprayed implant) and a simple titanium implant (basic implant) was used. METHODS: The osteoconductivities of these three types of implant, after implantation for 4-24 weeks, were histologically evaluated. RESULTS: Peeling of HA from the sprayed implant was observed by scanning electron microscopic observation. In the fourth postoperative week, the bilayered implant was already closely adhered to bone. On the other hand, the basic implant was surrounded by a gap containing connective tissue. With the sprayed implant, the bone adhered to the thick HA coating. CONCLUSION: The bilayer deposition technique supplies quick and long-term fixation of implants to bone, because the B-HA film dissolves to aid osteoconduction right immediately after implantation and the HA thin film maintains osteoconduction without dissolution. Neither of the thin-film fractures easily compared with thick coatings.