Observation on the curative effects of different surgical methods for small strabismus degree of basic intermittent exotropia

AIM: To compare unilateral lateral rectus recession surgery and unilateral small lateral rectus recession combines with small medial rectus shortening surgery treatment efficacy for small strabismus degree of basic intermittent exotropia.<p>METHODS: The 73 cases of small strabismus degree(strabismus degree in -15～-30PD)of basic intermittent exotropia hospitalized patients were analyzed retrospectively. The selected cases are divided into A, B groups: Group A underwent unilateral lateral rectus recession surgery; Group B unilateral small lateral rectus recession combines with small medial rectus shortening surgery. Eyes position, the same time visual, fusion visual, far and near stereoscopic visual postoperative follow-up 6 months were observed and analyzed in both groups.Compare postoperative eyes position anteroposterior rate, undercorrection rate and overcorrection rate; Compare binocular vision recovery rate, undercorrection rate and overcorrection rate. Compare relationships between age and binocular vision recovery rate. <p>RESULTS: Postoperative anteroposterior ratio of eye position follow-up 6 months: group B was significantly higher than that of group A and difference between the two groups is statistically significance. Postoperative follow-up 6 months binocular fusion function, far and near stereoscopic visual function recovery rate, group B was significantly higher than that of group A and difference between the two groups is statistically significance(<i>P</i><0.05); Postoperative follow-up 6 months age and single eyes visual function recovery rate: binocular fusion function, far and near stereoscopic visual function recovery rate, 4-12 years old group are higher than 13-30 years old group, difference between the two age groups is statistically significance(<i>P</i><0.05).<p>CONCLUSION: Using unilateral small lateral rectus recession combines with small medial rectus shortening surgery curative effect for the treatment of small strabismus degree of intermittent exotropia. Postoperative anteroposterior ratio eye position, binocular single visual function recovery rate are better than unilateral lateral rectus recession surgery; Early surgery is more advantageous to the binocular visual function recovery

Collapse simulation of a typical super-tall RC frame-core tube building exposed to extreme fire

The previous fire accidents proofed that reinforced concrete (RC) structures may experience progressive collapse subjected to extreme fires. In consequence, the study on the extreme fire-induced progressive collapse of RC structures is important for the safety of buildings. However, limited study has been performed on the extreme fire-induced progressive collapse of super-tall buildings. In this work, a finite element (FE) model and the corresponding elemental deactivation technology is proposed to simulate the extreme fire-induced progressive collapse of a typical super-tall RC frame-core tube building. The simulation discovered that the collapse of the building is initiated by the flexural failure of perimeter columns because of the thermal expansion of the floor system. The mechanism that discovered can provide a reference for related research of the fire safety of RC buildings

Differential measurement of atmospheric refraction with a telescope with double fields of view

For the sake of complete theoretical research of atmospheric refraction, the atmospheric refraction under the condition of lower angles of elevation is still worthy to be analyzed and explored. In some engineering applications, the objects with larger zenith distance must be observed sometimes. Carrying out observational research of the atmospheric refraction at lower angles of elevation has an important significance. It has been considered difficult to measure the atmospheric refraction at lower angles of elevation. A new idea for determining atmospheric refraction by utilizing differential measurement with double fields of view is proposed. Taking the observational principle of HIPPARCOS satellite as a reference, a schematic prototype with double fields of view was developed. In August of 2013, experimental observations were carried out and the atmospheric refractions at lower angles of elevation can be obtained by the schematic prototype. The measured value of the atmospheric refraction at the zenith distance of 78.8 degree is $240.23"\pm0.27"$, and the feasibility of differential measurement of atmospheric refraction with double fields of view was justified. The limitations of the schematic prototype such as inadequate ability of gathering light, lack of accurate meteorological data recording and lower automatic level of observation and data processing were also pointed out, which need to be improved in subsequent work.Comment: 10 pages, 6 figure