Special Configurations of Planes Associated with Convex Compacta

Several combinatorial geometry properties of convex compact sets are proved by topological methods. It is proved that if K ₁,... ,K _n-1 are convex compacta in , then there is an (n-2)-plane such that for each i=1,2,... ,n-1 there exist three (two orthogonal) hyperplanes containing E and dividing _Ki into six (four) parts of equal volume. It is also proved that for every two bounded continuous distributions of masses in centrally symmetric with respect to the origin there are three planes dividing both masses into eight equal parts. Bibliography: 9 titles.     

Transverse-momentum spectra in Au+Au and d+Au collisions at sqrt[s(NN)]=200 GeV and the pseudorapidity dependence of high-p(T) suppression

We present spectra of charged hadrons from Au+Au and d+Au collisions at sqrt[s(NN)]=200 GeV measured with the BRAHMS experiment at RHIC. The spectra for different collision centralities are compared to spectra from p+(-)p collisions at the same energy scaled by the number of binary collisions. The resulting ratios (nuclear modification factors) for central Au+Au collisions at eta=0 and eta=2.2 evidence a strong suppression in the high p(T) region (>2 GeV/c). In contrast, the d+Au nuclear modification factor (at eta=0) exhibits an enhancement of the high p(T) yields. These measurements indicate a high energy loss of the high p(T) particles in the medium created in the central Au+Au collisions. The lack of suppression in d+Au collisions makes it unlikely that initial state effects can explain the suppression in the central Au+Au collisions.     

Evolution of the nuclear modification factors with rapidity and centrality in d + Au collisions at (sqrt)[N(S)N]=200 GeV

We report on a study of the transverse momentum dependence of nuclear modification factors R(dAu) for charged hadrons produced in deuteron + gold collisions at sqrt[s(NN)]=200 GeV, as a function of collision centrality and of the pseudorapidity (eta=0, 1, 2.2, 3.2) of the produced hadrons. We find a significant and systematic decrease of R(dAu) with increasing rapidity. The midrapidity enhancement and the forward rapidity suppression are more pronounced in central collisions relative to peripheral collisions. These results are relevant to the study of the possible onset of gluon saturation at energies reached at BNL RHIC.     

Synthesis,crystal and molecular structure of 3,7-ditosyl-1,5-diphenyl-3,7-diazabicyclo[3.3.1]nonane

3,7-Ditosyl-1,5-diphenyl-3,7-diazabicyclo[3.3.1]nonane has been found to adopt a chair–chair conformation in the crystalline state in contrast to 3,7-ditosyl-1,5-diphenyl-3,7-diazabicyclo[3.3.1]nonan-9-one, which had been previously found to exist in a chair-boat conformation.     

Affine images of the rhombo-dodecahedron that are circumscribed about a three-dimensional convex body

The main result of the paper is dual to the author's earlier theorem on the affine images of the cube-octahedron (the convex hull of the midpoints of edges of a cube) inscribed in a three-dimensional convex body. The rhombododecahedron is the polyhedron dual to the cube-octahedron. Let us call a convex body in Κ⊂ℝ³ exceptional if it contains a parallelogram P and is contained in a cylinder with directrix P. It is proved that any nonexceptional convex body is inscribed in an affine image of the rhombo-dodecahedron. The author does not know if the assertion is true for all three-dimensional convex bodies. Bibliography: 2 titles. Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 246, 1997, pp. 191–195. Translated by N. Yu. Netsvetaev.     

Approximation of plane cross sections of a convex body

Three theorems on approximation of plane sections of convex bodies by affine-regular polygons, ellipses, or circles are proved by topological means. In particular, it is proved that if K is a convex body in ℝ³ (resp., ℝ⁴), then for every interior point O of K there is a plane cross section of K through O which is circumscribed about an affine-regular hexagon (resp., octagon) with center O. Bibliography: 8 titles. Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 246, 1997, pp. 174–183. Translated by N. Yu. Netsvetaev.     

Magnetic Properties of Barium Hexaferrite Compacted Nanopowders

Technical Physics - The magnetic characteristics of compact BaFe12O19 powders have been studied by magnetic force microscopy and magnetometry methods. Powders have been obtained by a chemical...     

Peculiarities of Registration of the Nuclear Magnetic Resonance Spectrum of a Condensed Medium During Express Control of Its State

Optics and Spectroscopy - The necessity of recording the spectrum of nuclear magnetic resonance (NMR) in a weak field from a condensed medium during express control of its state is substantiated....