The structure of coumaran (2,3-dihydrobenzofuran) is characterized by a non-planar skeleton, due to the position of the most far apart carbon in the dihydrofuran ring. We have measured 133 , and type lines of the rotational spectrum in the millimeter-wave region (59-78GHz), characterized by a doubling typical of an inversion motion such as the ring-puckering of the five-membered ring. By using ...

A series of cyclobutenes bearing group 14 elements at the 3-position were synthesized, and their thermal ring-opening reactions were studied. Carbon-substituted cyclobutene underwent the ring-opening reaction through an outward pathway to afford the E-diene exclusively. On the other hand, the ring-opening reaction of the silyl, germyl, and stannyl substituted cyclobutenes occurred in both outwa...

UNLABELLED Missed torsional femur deformities may contribute to reasons for failure after open and more likely arthroscopic hip preservation surgery. A number of surgical approaches have been described for addressing torsion abnormalities. This report describes a subtrochanteric osteotomy technique in a consecutive series of patients with complex hip pathologies, for which intertrochanteric ost...

Habitual patellar dislocations are rare in adults. Treatment is difficult, and often associated with significant morbidity. A 30-year-old man, construction worker, presented a habitual patellofemoral dislocation which was caused by direct trauma to the knee as a child. Clinical examination showed a 3 cm leg-length discrepancy with no rotational deformities. The patient had a limp and loss of fu...

BACKGROUND We performed a retrospective and descriptive study to determine the feasibility of proximal humerus derotational osteotomy in younger patients with significant humeral head depression, who may not be good candidates for shoulder arthroplasty. METHODS Rotational osteotomy was done on four patients with a mean age of 40 for locked posterior dislocation associated with a reverse Hill-...

in this paper, we investigate various kinds of extensions of twin-good rings. moreover, we prove that every element of an abelian neat ring r is twin-good if and only if r has no factor ring isomorphic to z2  or z3. the main result of [24] states some conditions that any right self-injective ring r is twin-good. we extend this result to any regular baer ring r by proving that every element of a...

Using the inverse scattering method we construct an exact stationary asymptotically flat 4+1-dimensional vacuum solution describing “black saturn”: a spherical black hole surrounded by a black ring. Angular momentum keeps the configuration in equilibrium. Black saturn reveals a number of interesting gravitational phenomena: (1) The balanced solution exhibits 2-fold continuous non-uniqueness for...

Mound formation in the cellular slime mould Dictyostelium results from the chemotactic aggregation of competent cells. Periodic cAMP signals propagate as multiarmed spiral waves and coordinate the movement of the cells. In the late aggregate stage the cells differentiate into prespore and several prestalk cell types. Prestalk cells sort out chemotactically to form the tip, which then controls a...

In the present paper a geometrization of electrodynamics is proposed, which makes use of a generalization of Riemannian geometry considered already by Einstein and Cartan in the 20ies. Cartan’s differential forms description of a teleparallel space–time with torsion is modified by introducing distortion 1-forms which correspond to the distortion tensor in dislocation theory. Under the condition...

Purpose. Rotating hinge knee prostheses should provide a stable situation following reconstruction. We performed a biomechanical analysis to establish the association between design of the central rotational stem (peg) and implant's stability, in a theoretical setting. Methods. Six different rotating hinge designs were tested, and three observers performed two different measurements with a cust...