Highly curved image sensors: a practical approach for improved optical performance.

The significant optical and size benefits of using a curved focal surface for imaging systems have been well studied yet never brought to market for lack of a high-quality, mass-producible, curved image sensor. In this work we demonstrate that commercial silicon CMOS image sensors can be thinned and formed into accurate, highly curved optical surfaces with undiminished functionality. Our key development is a pneumatic forming process that avoids rigid mechanical constraints and suppresses wrinkling instabilities. A combination of forming-mold design, pressure membrane elastic properties, and controlled friction forces enables us to gradually contact the die at the corners and smoothly press the sensor into a spherical shape. Allowing the die to slide into the concave target shape enables a threefold increase in the spherical curvature over prior approaches having mechanical constraints that resist deformation, and create a high-stress, stretch-dominated state. Our process creates a bridge between the high precision and low-cost but planar CMOS process, and ideal non-planar component shapes such as spherical imagers for improved optical systems. We demonstrate these curved sensors in prototype cameras with custom lenses, measuring exceptional resolution of 3220 line-widths per picture height at an aperture of f/1.2 and nearly 100% relative illumination across the field. Though we use a 1/2.3" format image sensor in this report, we also show this process is generally compatible with many state of the art imaging sensor formats. By example, we report photogrammetry test data for an APS-C sized silicon die formed to a 30° subtended spherical angle. These gains in sharpness and relative illumination enable a new generation of ultra-high performance, manufacturable, digital imaging systems for scientific, industrial, and artistic use.

Effects of neck strength training on isometric neck strength in rugby union players.

OBJECTIVE: To investigate the effectiveness of a neck strengthening program on the isometric neck strength profile of male rugby union players. DESIGN: Controlled laboratory study. SETTING: Professional rugby union club. PARTICIPANTS: Fifteen professional and 10 semiprofessional rugby union players. INTERVENTIONS: The 15 professional players undertook a 5-week neck strengthening intervention, which was performed twice per week, whereas the 10 semiprofessional players acted as the control group. MAIN OUTCOME MEASURES: Isometric strength of the neck musculature was tested using a hand-held dynamometer, for flexion (F), extension (E), left-side flexion (LSF), and right-side flexion (RSF). Preintervention and postintervention evaluations were undertaken. RESULTS: No significant between-group differences in isometric neck strength were noted preintervention. A significant main effect for time was observed (P < 0.05), whereby the intervention group increased isometric neck strength in all planes after the 5-week intervention (F preintervention = 334.45 ± 39.31 N vs F postintervention 396.05 ± 75.55 N; E preintervention = 606.19 ± 97.34 vs E postintervention = 733.88 ± 127.16 N; LSF preintervention = 555.56 ± 88.34 N vs LSF postintervention = 657.14 ± 122.99 N; RSF preintervention = 570.00 ± 106.53 N vs RSF postintervention = 668.00 ± 142.18 N). No significant improvement in neck strength was observed for control group participants. CONCLUSIONS: The results of the present study indicate that a 5-week neck strengthening program improves isometric neck strength in rugby union players, which may have implications for injury prevention, screening, and rehabilitation. CLINICAL RELEVANCE: The strengthening program described in the present study may facilitate rehabilitation specialists in the development of neck injury prevention, screening, and rehabilitation protocols.

Intrarater reliability of neck strength measurement of rugby union players using a handheld dynamometer.

OBJECTIVE: The purpose of this study was to investigate the isometric neck strength profiles of rugby union players and to assess the intrarater reliability of isometric neck strength measurement using a handheld dynamometer. METHODS: Twenty-five male, academy-level, rugby union players (forwards [n = 16], backs [n = 9]) were tested on 2 occasions during a training week 2 days apart. Isometric strength of the neck musculature was tested using a handheld dynamometer, for flexion (F), extension (E), left side flexion (LSF), and right side flexion (RSF). The average of 3 trials for each test position was used for statistical analysis. The following isometric neck strength values were obtained: F, E, F:E, LSF, RSF, LSF:RSF, and total isometric strength. RESULTS: Intrarater reliability intraclass correlation coefficients ranged from 0.80 to 0.92 (intraclass correlation coefficient values: F, 0.85; E, 0.85; F:E, 0.85; LSF, 0.80; RSF, 0.85; LSF:RSF, 0.91; total isometric strength, 0.92), thus indicating excellent reliability in all instances. Forwards recorded significantly greater E scores compared with backs (637.10 ± 75.15 N vs 537.87 ± 82.25 N). Forwards also recoded significantly greater total isometric neck strength scores (2151.96 ± 231.11 N vs 1814.21 ± 211.26 N). CONCLUSION: The results of this study provide isometric neck strength values for the forward and back units in the rugby union and indicate that a handheld dynamometer may be a reliable tool for assessing isometric neck strength in this population.

Millimeter- and submillimeter-wave characterization of various fabrics.

Transmission measurements of 14 fabrics are presented in the millimeter-wave and submillimeter-wave electromagnetic regions from 130 GHz to 1.2 THz. Three independent sources and experimental set-ups were used to obtain accurate results over a wide spectral range. Reflectivity, a useful parameter for imaging applications, was also measured for a subset of samples in the submillimeter-wave regime along with polarization sensitivity of the transmitted beam and transmission through doubled layers. All of the measurements were performed in free space. Details of these experimental set-ups along with their respective challenges are presented.

Management of infected femoral closure devices.

An increase in infectious complications has been noted with the introduction of percutaneous femoral artery closure devices. We report five cases of infected groins and/or femoral arteries following angiographic procedures that were completed using the Perclose Suture Mediated Closure Device (Perclose). Each patient required drainage of the abscess and removal of the Perclose suture. Most patients required more extensive vascular reconstructive procedures. When these complications arise, we recommend expeditious drainage of the abscess, removal of the suture, and adequate exposure of the femoral artery to facilitate repair of the vessel.