No abstract

Tuberculosis (TB) of the musculoskeletal system is a rare clinical condition. Multifocal bone involvement is extremely rare and difficult to recognize. Thus, due to the diverse and atypical clinical manifestations of multifocal skeletal TB, the disease is easy to misdiagnose. In the present study, a rare case of atypical disseminated multifocal skeletal TB was reported, which exhibited uncommon findings in radiological images that were more suggestive of a hematological malignancy or metastatic disease. In conclusion, the diagnosis of this condition by conventional diagnostic methods is challenging. The importance of CT-guided needle biopsy and open biopsy in the diagnosis of skeletal TB was emphasized.

A scheme to measure multiple Jones–Mueller matrices over a fibre system is proposed based on the concept of system estimation. The method modulates the input state of polarization (SOP) of each piece of testing fibre by using a rotatable coiled fibre wave plate, rather than measuring the input SOP with an in-line polarization state analyser as conventional methods do. The Jones–Mueller matrix can be expressed as a set of quadratic equations and estimated with least square optimization. A scheme to determine the retardance of the rotating fibre wave plate instantly is proposed for calibrating the environmental sensitivity of the rotating fibre wave plate. Moreover, the measurement uncertainty of the scheme is simulated and the Mueller matrices of two pieces of fibre are measured experimentally.

No abstract

The system estimation by least squares optimization is employed to obtain physical polarization parameters of optical devices. The method is proved flexible and convenient for measuring polarization parameters in different systems where the input state of polarization (SOP) of the devices is either measurable or not, providing the analytical estimation equations and adequate measurements are available. The estimation error for the measurement system with a rotating wave-plate (WP) as the polarization state generator is analyzed and simulated. Better estimation precision can be obtained by involving more SOP measurements in estimations and choosing a WP with retardance around 3π /4. Two experiments are demonstrated. One is to estimate the polarization parameters of a fiber polarization controller with measurable input SOP, and the other is to measure the retardance of a glass quarter-wave plate whose input SOP is immeasurable. The standard deviations of estimated polarization parameters are within 0.0011-0.0103.