ABSTRACT
Our comprehensive study on EuFe_{2}As_{2} reveals a dramatic reduction of magnetic detwinning fields compared to other AFe_{2}As_{2} (A=Ba, Sr, Ca) iron pnictides by indirect magnetoelastic coupling of the Eu^{2+} ions. We find that only â¼0.1 T are sufficient for persistent detwinning below the local Eu^{2+} ordering; above T_{Eu}=19 K, higher fields are necessary. Even after the field is switched off, a significant imbalance of twin domains remains constant up to the structural and electronic phase transition (190 K). This persistent detwinning provides the unique possibility to study the low temperature electronic in-plane anisotropy of iron pnictides without applying any symmetry-breaking external force.
ABSTRACT
The development of a kinematic model of the pro- and supination, that can be used to predict the influence of angulations of ulna and radius on the pronation and supination is based on the precise knowledge of the pronation and supination movement. We performed two parallel studies for examining the pronation and supination motion of the human forearm. The first experiment dealt with MRI-studies on 18 probands (36 examined forearms). As a result we observed an evasive movement of the ulna during the rotation of 7, 14 degrees medial. In order to prove whether the evasive movement was caused by a rotation of the humerus or by an evasion in the articulatio humeroulnaris, we carried out a second experiment, using 30 preparations. The measurement of the pro- and supination motion with a fixed humerus was expedited using a special experimental setup which guaranteed that the ulna could move freely. In all cases we found the same magnitude of the evasive motion of the ulna. Therefore we demonstrated, that the ulna performs an evasive motion during the pro- and supination motion of the forearm that influences the kinematic behavior of the pro- and supination motion significantly.
Subject(s)
Elbow Joint/physiology , Magnetic Resonance Imaging , Pronation/physiology , Supination/physiology , Adult , Anthropometry , Elbow Joint/anatomy & histology , Female , Humans , Image Processing, Computer-Assisted , Male , Range of Motion, Articular , Reference ValuesABSTRACT
We introduce a new kinematic model describing the motion of the human forearm bones, ulna and radius, during forearm rotation. During this motion between the two forearm extrem-positions, referred to as supination (palm up) and pronation (palm down), effects occur, that cannot be explained by the the established kinematic model of R. Fick from 1904. Especially, the motion of the ulna is not properly reproduced by Fick's model. During forearm rotation an evasive motion of the ulna is observed by various authors, using magnetic resonance imaging MRI) technology. Our new kinematic model also simulates this evasive motion. Furthermore, the model is enlarged to include angulations of the forearm bones. Using these results the influence of forearm fractures on the range of forearm motion can be predicted. This knowledge can be used by surgeons to choose the optimal therapy in re-establishing free forearm mobility.
Subject(s)
Forearm/physiology , Models, Biological , Supination/physiology , Biomechanical Phenomena , HumansABSTRACT
The content and the synthesis of membrane bound and free ribosomes in growing yeast cells was investigated after photodynamic treatment of the cells with thiopyronine and visible light. It was shown that the synthesis of ribosomes is inhibited after photodynamic treatment and that as a consequence, the content of ribosomes in the cell is diminished.
