Showing papers by "Paris West University Nanterre La Défense published in 1992"
TL;DR: An approach relying on the symmetry analysis and finite-size scaling and new arguments in favor of an ordered ground state for the S=1/2 triangular Heisenberg model are developed.
Abstract: We show how the broken symmetries of the N\'eel state are embodied in the exact spectrum of the triangular Heisenberg antiferromagnet on finite lattices as small as N=21 (spectra up to N=36 have been computer). We present the first numerical evidence of an extensive set of low-lying levels that are below the softest magnons and collapse to the ground state in the thermodynamic limit. This set of quantum states represents the quantum counterpart of the classical N\'eel ground state. We develop an approach relying on the symmetry analysis and finite-size scaling and we provide new arguments in favor of an ordered ground state for the S=1/2 triangular Heisenberg model.
252 citations
TL;DR: Results indicated that the two groups differed for trait-anxiety on one hand, and for the level of anxiety before the final ascent on the other hand, with subjects susceptible to AMS were significantly more anxious than those who were not.
Abstract: This investigation explores the relationship between psychological factors and acute mountain sickness (AMS). AMS occurs in most people staying more than a few hours above 3500 m. Symptoms include headache, nausea, vomiting, insomnia, anorexia, etc. Subjects studied were climbers preparing for an expedition to the Himalayas (80 men and 20 women). The psychological investigation consisted in two mono-factorial tests: STAI (anxiety inventory) and Bortner stress scale. After the expedition, subjects were classified into two groups: those who were susceptible to AMS and those who were not. Results indicated that the two groups differed for trait-anxiety on one hand, and for the level of anxiety before the final ascent on the other hand. In both cases, subjects susceptible to AMS were significantly more anxious than those who were not.
39 citations
TL;DR: In this article, the Neel order was used to break the symmetries of the hamiltonian in quantum antiferromagnet and the construction of a quantum wave packet that mimics the classical groundstate implies the existence of an extensive number of states, with an energy scale much smaller than the spin-waves excitations (magnons).
Abstract: We study how the Neel order breaks the symmetries of the hamiltonian in quantum antiferromagnet. The construction of a quantum wave packet that mimics the classical groundstate implies the existence of an extensive number of states: 1) with an energy scale much smaller than the spin-waves excitations (magnons); 2) with well defined symmetries.