A neck-like vertebral motion in fish

Tetrapods use their neck to move the head three-dimensionally, relative to the body and limbs. Fish lack this anatomical neck, yet during feeding many species elevate (dorsally rotate) the head relative to the body. Cranial elevation is hypothesized to result from the craniovertebral and cranial-most intervertebral joints acting as a neck, by dorsally rotating (extending). However, this has never been tested due to the difficulty of visualizing and measuring vertebral motion in vivo . I used X-ray reconstruction of moving morphology to measure three-dimensional vertebral kinematics in rainbow trout ( Oncorhynchus mykiss ) and Commerson's frogfish ( Antennarius commerson ) during feeding. Despite dramatically different morphologies, in both species dorsoventral rotations extended far beyond the craniovertebral and cranial intervertebral joints. Trout combine small (most less than 3°) dorsal rotations over up to a third of their intervertebral joints to elevate the neurocranium. Frogfish use extremely large (often 20–30°) rotations of the craniovertebral and first intervertebral joint, but smaller rotations occurred across two-thirds of the vertebral column during cranial elevation. Unlike tetrapods, fish rotate large regions of the vertebral column to rotate the head. This suggests both cranial and more caudal vertebrae should be considered to understand how non-tetrapods control motion at the head–body interface.

Site Response Analysis for “Side” Soil Profiles

The authors suggest a new procedure of Site Response Analysis (SRA) for the so-called “side” (or additional) soil profiles – Low Boundary (LB) and Upper Boundary (UB). Standards require the analyses of these profiles in addition to the Best Estimate profile (BE) to account for the uncertainty in the input data about soil properties. The authors suggest stopping using the same input time history for all three profiles as a control motion at the surface, because it corresponds to the different physical seismic excitations coming form the depth. This is not in linewith the ideology of Standards. Instead the authors suggest using the same time history as a control motion at the outcropped surface of the underlying half-space. This is also not completely correct, because for these three profiles (BE, UB and LB) the underlying half-spaces are also different. However, due to the physical considerations if all half-spaces are stiff enough, the error should not be so important. The effect of the proposed change is demonstrated on a particular site. The changes in the velocity and damping profiles have proved to be negligible, but the difference in the resulting response spectra at the outcropped surface of the foundation mat has proved to be significant. Generally, the response spectra for the “side” profiles came closer to spectrum for the BE profile. This result reflects the real world logic.

Research on the Establishing of the Control System of the SlS Rapid Prototyping Machine

In the current time, mastering the rapid prototyping technology and equipments is a complicated question in Vietnam because of shorting of ability and finance for investment. In order to save currency from imported machine, the demand of research and mastering the new technology of rapid prototype machine, especially a program of control motion in Selected Laser Sintering (SLS) rapid prototype machine, is essential in our country in the purpose of manufacture a domestic SLS rapid prototype machine. This paper presents the design of a control program for the SLS rapid prototyping machine that is corporated to the hardward of our typical manufactured SLS machine in our laboratory. From the result of empiriments we considered that the performed program of control motion responded all the requirements of control as well as experimental adjustments of the technological parameters in our manufactured SLS machine. The results of testing the program via manufacture model products by SLS rapid prototyping machine are accepted.

Cadenza

A focused point for the two soloists, the Cadenza movement of Alfred Schnittke’s Concerto Grosso no. 1 further engages with its themes of autonomy and control, motion and arrest, consonance and dissonance. This chapter considers the first performances of the Concerto Grosso no. 1, focusing on those by Gidon Kremer and Tatiana Grindenko in both the Soviet Union and Europe, specifically the 1977 European tour of the two soloists with the Lithuanian Chamber Ensemble conducted by Saulius Sondeckis. The chapter also discusses the early performances of the composition by violinists Oleh Krysa and Liana Isakadze, who first recorded it in the Soviet Union in the early 1980s. Schnittke was embarrassed by how well the composition did, telling Kremer that he now would need to write something unpopular, for “it is too dangerous to ride a wave of success.”

A comparison of dart thrower’s range of motion following radioscapholunate fusion, four-corner fusion and proximal row carpectomy

Dart thrower’s motion is the functional coupled movement of the wrist from radial extension to ulnar flexion. The aim of this study was to evaluate dart thrower’s motion following three surgeries: radioscapholunate fusion, four-corner fusion and proximal row carpectomy. Six fresh-frozen cadaver forearms were dissected. Sequential loading of tendons resulted in radial extension and ulnar flexion allowing dart thrower’s motion measurements at end range before and then again after each surgery. After radioscapholunate fusion, 74% of both radial extension and ulnar flexion were maintained. After four-corner fusion, radial extension decreased to 53% and ulnar flexion to 84% of control motion. Proximal row carpectomy did not statistically significantly alter radial extension, but decreased ulnar flexion to 87%. We found that dart thrower’s motion is well maintained in three of these commonly used surgical treatments. These results may aid surgeons in managing patients by providing comparative functional movement following these procedures.