Applicability of the Load-Velocity Relationship to Predict 1-Repetition Maximum in the Half-Squat in High-Level Sprinters.

PURPOSE: To investigate the indirect measurement of 1-repetition-maximum (1RM) free-weight half-squat in high-level sprinters using the load-velocity relationship. METHODS: Half-squat load and velocity data from 11 elite sprinters were collected in 2 separate testing sessions. Approximately 24 hours prior to the first testing session, sprinters completed a fatiguing high-intensity training session consisting of running intervals, staircase exercises, and body-weight exercises. Prior to the second testing session, sprinters had rested at least 48 hours. Two different prediction models (multiple-point method, 2-point method) were used to estimate 1RM based on the load and either mean or peak concentric velocity data of submaximal lifts (40%-90% 1RM). The criterion validity of all methods was examined through intraclass correlation coefficients, coefficient of variation (CV%), Bland-Altman plots, and the SEM. RESULTS: None of the estimations were significantly different from the actual 1RM. The multiple-point method showed higher intraclass correlation coefficients (.91 to .97), with CVs from 3.6% to 11.7% and SEMs from 5.4% to 10.6%. The 2-point method showed slightly lower intraclass correlation coefficients (.76 to .95), with CVs 1.4% to 17.5% and SEMs from 9.8% to 26.1%. Bland-Altman plots revealed a mean random bias in estimation of 1RM for both methods (mean and peak velocity) ranging from 1.06 to 13.79 kg. CONCLUSION: Velocity-based methods can be used to roughly estimate 1RM in elite sprinters in the rested and fatigued conditions. However, all methods showed variations that limit their applicability for accurate load prescription for individual athletes.

3D-imaging: a scanning light pattern projector.

The technology of electrically adjustable optical interfaces has found applications in, e.g., camera lenses, where an adjustable focal length provides automatic focusing for the camera. In this paper, we will investigate a liquid lens, where both the focal length and the tilt of this lens can be adjusted electrically. Specifically, the tilting ability of this lens will be tested by combining the liquid lens with a projector in order to scan lines across a three-dimensional (3D) object. The linearity, reproducibility, hysteresis, and time response of its tilting functionality will be tested. Further, crosstalk between the two functionalities of the liquid lens is tested for the specific case, where the focal length is set to infinity. Finally, the liquid lens and the projector in combination with four stereo cameras will be demonstrated as a 3D imaging setup.

Reflective SOA re-modulated 20 Gbit/s RZ-DQPSK over distributed Raman amplified 80 km long reach PON link.

An 80 km bidirectional Raman amplified long reach PON link has been demonstrated. A 20 Gbit/s RZ-DQPSK signal was transmitted downstream, ASK-remodulated at 1.25 Gbit/s by an RSOA and transmitted upstream in the same fiber. Both signals were detected error free without use of EDFAs.

Slow light in a semiconductor waveguide at gigahertz frequencies.

We experimentally demonstrate slow-down of light by a factor of three in a 100 microm long semiconductor waveguide at room temperature and at a record-high frequency of 16.7 GHz. It is shown that the group velocity can be controlled all-optically as well as through an applied bias voltage. A semi-analytical model based on the effect of coherent population oscillations and taking into account propagation effects is derived and is shown to well account for the experimental results. It is shown that the carrier lifetime limits the maximum achievable delay. Based on the general model we analyze fundamental limitations in the application of light slowdown due to coherent population oscillations.