48,850 research outputs found
Classification of finite groups generated by reflections and rotations
We survey the existing parts of a classification of finite groups generated
by orthogonal transformations in a finite-dimensional Euclidean space whose
fixed point subspace has codimension one or two and extend it to a complete
classification. These groups naturally arise in the study of the quotient of a
Euclidean space by a finite orthogonal group and hence in the theory of
orbifolds.Comment: 38 pages, accepted by Transformation Group
Physiology of man and animals in the Tenth Five-Year Plan: Proceedings of the Thirteenth Congress of the I. P. Pavlov All-Union Physiological Society
Research in the field of animal and human physiology is reviewed. The following topics on problems of physiological science and related fields of knowledge are discussed: neurophysiology and higher nervous activity, physiology of sensory systems, physiology of visceral systems, evolutionary and ecological physiology, physiological cybernetics, computer application in physiology, information support of physiological research, history and theory of development of physiology. Also discussed were: artificial intelligence, physiological problems of reflex therapy, correlation of structure and function of the brain, adaptation and activity, microcirculation, and physiological studies in nerve and mental diseases
The Density of Titanium(IV) Oxide Liquid
The density of TiO2 liquid in equilibrium with air has been measured at 1875° to 1925°C using an Ir double bob Archimedean method. The melt density data have been combined with data extrapolated from the CaSiO3─TiO2 join at 1600°C. A combined fit to these density data yields the following description of the density of liquid TiO2: ρ= 3.7611 - 0.00028T(°C), in the temperature range of 1600° to 1925°C. This expansivity value is consistent with those obtained on TiO2-rich melts using a Pt-based system at lower temperature and with multicomponent oxide data. The similarity between the volume of liquid TiO2 and that of crystalline rutile implies a dominantly octahedral coordination of Ti in the liquid state
Docking mechanism for spacecraft
A system is presented for docking a space vehicle to a space station where a connecting tunnel for in-flight transfer of personnel is required. Cooperable coupling mechanisms include docking rings on the space vehicle and space station. The space station is provided with a tunnel structure, a retraction mechanism, and a docking ring. The vehicle coupling mechanism is designed to capture the station coupling mechanism, arrest relative spacecraft motions while limiting loads to acceptable levels, and then realign the spacecraft for final docking and tunnel interconnection. The docking ring of the space vehicle coupling mechanism is supported by linear attentuator actuator devices, each of which is controlled by a control system which receives loading information signals and attenuator stroke information signals from each device and supplies output signals for controlling its linear actuation to attenuate impact loading or to realign the spacecraft for final docking and tunnel interconnection. The retraction mechanism is used to draw the spacecraft together after initial contact and coupling. Tunnel trunnions, cooperative with the latches on the space vehicle constitute the primary structural tie between the spacecraft in final docked configuration
A family of Prym-Tyurin varieties of exponent 3
We investigate a family of correspondences associated to \'etale coverings of
degree 3 of hyperelliptic curves. They lead to Prym-Tyurin varieties of
exponent 3. We identify these varieties and derive some consequences.Comment: names of authors correcte
Fingering Instability in a Water-Sand Mixture
The temporal evolution of a water-sand interface driven by gravity is
experimentally investigated. By means of a Fourier analysis of the evolving
interface the growth rates are determined for the different modes appearing in
the developing front. To model the observed behavior we apply the idea of the
Rayleigh-Taylor instability for two stratified fluids. Carrying out a linear
stability analysis we calculate the growth rates from the corresponding
dispersion relations for finite and infinite cell sizes. Based on the
theoretical results the viscosity of the suspension is estimated to be
approximately 100 times higher than that of pure water, in agreement with other
experimental findings.Comment: 11 pages, 12 figures, RevTeX; final versio
- …