[Study of the effect of occupational exposure to glyphosate on hepatorenal function].

Objective: To explore the effect of occupational exposure to glyphosate on hepatorenal function. Methods: 526 workers who were occupationally exposed to glyphosate from 5 glyphosate-producing factories were selected as cases; and another 442 administrative staffs who were not exposed to glyphosate were selected as controls from April to November, 2014. All the subjects accepted occupational health examination. The concentration level of glyphosate in the air of workshop was detected and the time weighted average concentration (TWA) was calculated. And analyze the difference of hepatorenal fuction between case group and control group. Result: The age of the subjects in the case and control groups were separately (35.6±10.3), (34.3±9.7) years old, with the length of working for (6.5±5.7), (7.7±6.8) years. The TWA of glyphosate in the case group was between <0.03-48.91 mg/m(3), with the geometric mean at 3.78 mg/m(3). The overall rates of abnormal hepatic and renal function in the case group were 14.4% (76 cases) and 16.2% (85 cases), respectively; while those were 5.0% (22 cases) and 4.8% (21 cases), respectively in control group, and the difference showed statistical significance (P<0.05). When TWA reached <0.03-6.00 mg/m(3), the difference of hepatorenal fuction between case group and control group showed statistical significance, and the rates of abnormal hepatic and renal function was 8.0% (36/447) and 9.8% (44/447) respectively in case group. When cumulative exposure level reached <1.56-68.64 g, the difference of hepatorenal fuction between case group and control group showed statistical significance, and the rates increased to 9.2% (37/404) and 10.4% (42/404) respectively in group of cases. Conclusion: Glyphosate can affect the hepatic and renal function among occupational exposure population, and there was an association between the effect and the exposure dose.

ON THE COMPUTATION OF THE AVERAGE OF SPATIAL DISPLACEMENTS.

Many applications in biomechanics and medical imaging call for the analysis of the kinematic errors in a group of patients statistically using the average displacement and the standard deviations from the average. This paper studies the problem of computing the average displacement from a set of given spatial displacements using three types of parametric representations: Euler angles and translation vectors, unit quaternions and translation vectors, and dual quaternions. It has been shown that the use of Euclidean norm in the space of unit quaternions reduces the problem to that of computing the average for each quaternion component separately and independently. While the resulting algorithm is simple, the change of the sign of a unit quaternion could lead to an incorrect result. A novel kinematic measure based on dual quaternions is introduced to capture the separation between two spatial displacement. This kinematic measure is then used to formulate a constrained least squares minimization problem. It has been shown that the problem decomposes into that of finding the optimal translation vector and the optimal unit quaternion. The former is simply the centroid of the set of given translation vectors and the latter can be obtained as the eigenvector corresponding to the least eigenvalue of a 4 × 4 positive definite symmetric matrix. It is found that the weight factor used in combining rotations and translations in the formulation does not play a role in the final outcome. Examples are provided to show the comparisons of these methods.

A DUAL QUATERNION BASED METHOD FOR ESTIMATING MARGINS FOR PLANNING TARGET VOLUMES IN RADIOTHERAPY.

This objective of this paper is to develop a dual quaternion based method for estimating target volumes in radiation therapy for head and neck cancer. Inaccuracies in radiation targeting are responsible for incidental exposure of healthy adjacent tissues, causing significant morbidity and mortality. This paper focuses on inaccuracies incurred when a tumor is displaced during treatment. To address this problem, the clinical target must be expanded to cover the region through which the tumor might move. The resulting expanded target is known as the Planning Target Volume (PTV). In the current practice, the rotational components of displacements are neglected, producing planning target volumes that either miss the true target motion or are larger than needed to cover the target path. By using the dual quaternion based kinematic formulation, this paper represents and captures both translational and rotational inaccuracies. It then presents a framework for calculating the PTV swept out by the target as it shifts within its range of translations and rotations.