2,448 research outputs found
The space of germs of extremal K\" ahler metrics in one dimension comprises three distinct components
In the 1980s, Eugenio Calabi introduced the concept of {\it extremal K\"
ahler metrics} as critical points of the -norm functional of scalar
curvature in the space of K\" ahler metrics belonging to a fixed K\"ahler class
of a compact complex manifold . Calabi demonstrated that extremal K\" ahler
metrics always degenerate into Einstein metrics on compact Riemann surfaces. We
define a K\"ahler metric on a domain of as a {\it local
extremal K\"ahler metric} of dimension if it satisfies the Euler-Lagrange
equation of this functional, i.e. holomorphic is the -part of the
gradient vector field of the scalar curvature of , in the domain. Our main
result establishes that the space of all germs of local extremal, non-Einstein
K\"ahler metrics of dimension one comprises three components, each
diffeomorphic to .Comment: 14 pages. Yours comments are greatly appreciated
(E)-2-{3-[4-(DiphenylÂamino)styrÂyl]-5,5-dimethylÂcycloÂhex-2-enylÂidene}ÂmalonoÂnitrile
In the title compound, C31H27N3, the cycloÂhexene ring has an envelope configuration. In the crystal structure, there is an 34 Å3 void around the inversion center, but the low electron density (0.13 e Å−3) in the difference Fourier map suggests no solvent molÂecule occupying this void. No hydrogen bonding is found in the crystal structure
2-HydrÂoxy-6,6-dimethylÂbicycloÂ[3.1.1]heptane-2-carboxylic acid
The title compound, C10H16O3, with a bicycloÂ[3.1.1]heptane unit, was obtained by oxidation of β-pinene. The asymmetric unit contains two independent molÂecules with similar geometry: the six-membered rings in both molÂecules adopt envelope conformations. In the crystal, the independent molÂecules exist as O—H⋯O hydrogen-bonded dimers. The dimers are linked into helical chains along the b axis by O—H⋯O hydrogen bonds
THE INFLUENCE OF BACKPACK CARRIAGE ON TRUNK POSTURE IN CHILDREN DURING UNPLANNED GAIT TERMINATION
This study aimed to examine the trunk posture in children with different backpack loads during unplanned gait termination. Twelve school boys aged 9–10 years completed unplanned and planned gait termination with a backpack load of 0%, 10%, and 15% of their body weight (BW) while level walking. Trunk inclination angle and trunk range of motion at sagittal plane and spinal angle at frontal plane were examined. In comparison
with 0% BW load condition, the spinal angle increased significantly at 10% and 15% BW load condition during gait termination (
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