Effect of body position on the pathogenesis of asymmetric primary open angle glaucoma

AIM： To explore the pathogenesis of asymmetric primary open angle glaucoma（POAG） in both eyes by comparing the intraocular pressure（IOP） of patients who sleep in different positions and to investigate the relationship between IOP variations and sleep positions.METHODS： One hundred and thirty-one patients with asymmetric POAG and forty-six healthy volunteers were enrolled. All participants completed a questionnaire that provided information about their sleep laterality. The cup disc ratio（C/D） and visual field defect established binocular asymmetry. The IOP of both eyes was measured using i Care parameters after the patients were asked to change body position. The ＂worse＂ and ＂better＂ eyes were identified according to the diagnosis, whereas the ＂dependent＂ and ＂independent＂ eyes were defined according to the lateral position. RESULTS： No significant difference in sleep laterality was observed between healthy people and patients with POAG（F=3.195, P=0.362）. Among the enrolled patients, the IOP of the dependent eye was always greater than that of the independent eye in the lateral position（P〈0.05）. In the patients with binocular asymmetric POAG, the questionnaire clearly showed that 85.7% of left side preferences were found their left eyes to be the worse eyes and the right eyes of 71.4% patients with a right side preference were the more serious. When the asymmetric C/D ratio was greater than or equal to 0.2, the worse eye of patients with POAG and a preferred sleeping position was the dependent eye（χ~2=16.762, P=0.001）.CONCLUSION： A higher IOP was measured in the dependent eye in the lateral position. The long-term tendency to choose a lateral sleeping position might lead the dependent eye to manifest more severe symptoms than the independent eye. Thus, the lateral sleeping position might be one cause of asymmetric POAG.

Modified Burzynski criterion with non-associated flow rule for anisotropic asymmetric metals in plane stress problems

The Burzynski criterion is developed for anisotropic asymmetric metals with the non-associated flow rule （NAFR） for plane stress problems. The presented pressure depending on the yield criterion can be calibrated with ten experimental data, i.e., the tensile yield stresses at 0°, 45°, and 90°, the compressive yield stresses at 0°, 15°, 30°, 45°, 75°, and 90° from the rolling direction, and the biaxial tensile yield stress. The corresponding pressure independent plastic potential function can be calibrated with six experimental data, i.e., the tensile R-values at 0°, 15°, 45°, 75°, and 90° from the rolling direction and the tensile biaxial R-value. The downhill simplex method is used to solve these ten and six high nonlinear equations for the yield and plastic potential functions, respectively. The results show that the presented new criterion is appropriate for anisotropic asymmetric metals.

Asymmetric Rock Pressure on Shallow Tunnel in Strata with Inclined Ground Surface

By building a tunnel model with a semi-circular crown, the asymmetric rock pressure applied to the shallow tunnel in strata with inclined ground surface is analyzed. Formulae, which not only include the parameters .related to both tunnel structure and surrounding rock mass, but the overburden depth, are developed. The computation for four tunnel models show that the method presented is feasible and convenient. Furthermore, the influence of the overburden depth on the rock pressure is elaborated, and the criterion to identify the deep or shallow tunnels is formulated as well.

Analysis of Rolling Pressure in Asymmetrical Rolling Process by Slab Method

The plane strain asymmetrical rolling was analyzed using slab method. The contact arc was replaced by parabola, and the constant surface friction status was adopted during the analysis. The deformation area was divided into three zones according to the direction of the friction. Then, the three zones were studied, respectively. A rolling force model and a rolling torque model were developed based on the analysis, and they were used to analyze the influ- ence of asymmetrical rolling factors on deformation area and unit pressure if they had good precision which was determined by comparing the calculated results with the measured ones.

Temperature characteristics research of SOI pressure sensor based on asymmetric base region transistor

Based on the asymmetric base region transistor, a pressure sensor with temperature compensation circuit is proposed in this paper. The pressure sensitive structure of the proposed sensor is constructed by a C-type silicon cup and a Wheatstone bridge with four piezoresistors（R_1, R_2, R_3 and R_4/locating on the edge of a square silicon membrane. The chip was designed and fabricated on a silicon on insulator（SOI） wafer by micro electromechanical system（MEMS） technology and bipolar transistor process. When the supply voltage is 5.0 V, the corresponding temperature coefficient of the sensitivity（TCS） for the sensor before and after temperature compensation are -1862 and -1067 ppm/℃, respectively. Through varying the ratio of the base region resistances r_1 and r_2, the TCS for the sensor with the compensation circuit is -127 ppm/℃. It is possible to use this compensation circuit to improve the temperature characteristics of the pressure sensor.