ABSTRACT
The present study provides new insights into the pressure dependence of magnetism by tracking the hybridization between crystal orbitals for pressures up to 600 GPa in the known hcp, bcc and fcc iron. The Birch-Murnaghan equation of state parameters are; bcc: V0 = 11.759 A(3)/atom, K0 = 177.72 GPa; hcp: V0 = 10.525 A(3)/atom, K0 = 295.16 GPa; and fcc: V0 = 10.682 A(3)/atom, K0 = 274.57 GPa. These parameters compare favorably with previous studies. Consistent with previous studies we find that the close-packed hcp and fcc phases are non-magnetic at pressures above 50 GPa and 60 GPa, respectively. The principal features of magnetism in iron are predicted to be invariant, at least up to â¼6% overextension of the equilibrium volume. Our results predict that magnetism for overextended fcc iron disappears via an intermediate spin state. This feature suggests that overextended lattices can be used to stabilize particular magnetic states. The analysis of the orbital hybridization shows that the magnetic bcc structure at high pressures is stabilized by splitting the majority and minority spin bands. The bcc phase is found to be magnetic at least up to 600 GPa; however, magnetism is insufficient to stabilize the bcc phase itself, at least at low temperatures. Finally, the analysis of the orbital contributions to the total energy provides evidence that non-magnetic hcp and fcc phases are likely more stable than bcc at core earth pressures.
ABSTRACT
OBJECTIVE: The present study investigated the associations of stature, lower leg length (LLL) and demi-arm span (demi-AS) with major predisposing cardiovascular risk factors and coronary heart disease. STUDY DESIGN AND SUBJECTS: Cross-sectional study set at Glasgow Royal Infirmary of a subsample of 543 men and 646 women aged 25-66 y from the random MONICA sample. ASSOCIATED MEASURES: LLL, demi-AS, blood pressure, plasma total cholesterol, diabetes mellitus and coronary heart disease (angina, angioplasty, heart attack, and coronary artery bypass graft). RESULTS: The numbers (and proportions) of men and women, respectively, with hypertension were 126 (23.6%) and 80 (14.0%), hypercholesterolaemia 155 (29.0%) and 171 (30.1%), coronary heart disease 53 (10.1%) and 47 (8.4%), and diabetes 15 (2.9%) and 9 (1.6%). Results were adjusted for age, social class and smoking. Analysis of variance showed that in men, shortness of height, LLL or demi-AS were all associated significantly (P < 0.05) with hypercholesterolaemia. Long LLL, high ratios of LLL:height or LLL:demi-As were associated significantly (P < 0.05) with diabetes mellitus. In women, shortness of height or LLL were associated with significantly (P < 0.05) with coronary heart disease. High ratio of demi-AS:height or low ratio of LLL:demi-AS was associated significantly (P < 0.05) with coronary heart disease. CONCLUSIONS: Short stature and limb lengths, and also altered skeletal proportions, which may reflect interrupted early growth, are associated with several metabolic disorders. Skeletal disproportion associates with diabetes in men and coronary heart disease in women.
