Body stalk anomaly in monozygotic twinning: a case report

We describe a case of concordant body stalk anomaly in a monozygotic twin. Autopsy of the fetus showed abnormalities compatible with the maldevelopment of embryonic folding. Abdominal viscera were in a sac covered by the amnion and were attached directly to the placenta. The anus was not visible and no discernible external genitalia were noted. Other findings included a neural tube defect and a rectal duplication as an enteric cyst. Umbilical cord had only one vein and an artery. No abnormalities were found on pathologic examination of the placenta

Spring tube braces for seismic isolation of buildings

A new low-cost seismic isolation system based on spring tube bracings has been proposed and studied at the Structural and Earthquake Engineering Laboratory of Istanbul Technical University. Multiple compression-type springs are positioned in a special cylindrical tube to obtain a symmetrical response in tension and compression-type axial loading. An isolation floor, which consists of pin-ended steel columns and spring tube bracings, is constructed at the foundation level or any intermediate level of the building. An experimental campaign with three stages was completed to evaluate the capability of the system. First, the behavior of the spring tubes subjected to axial displacement reversals with varying frequencies was determined. In the second phase, the isolation floor was assessed in the quasi-static tests. Finally, a ¼ scaled 3D steel frame was tested on the shake table using actual acceleration records. The transmitted acceleration to the floor levels is greatly diminished because of the isolation story, which effects longer period and higher damping. There are no stability and self-centering problems in the isolation floor.</p