RESUMEN
Equilibrium heat relaxation experiments provide evidence that the ground state of the commensurate spin-density-wave compound (TMTTF)2Br after the application of a sufficient magnetic field is different from the conventional ground state. The experiments are interpreted on the basis of the local model of strong pinning as the deconfinement of soliton-antisoliton pairs triggered by the Zeeman coupling to spin degrees of freedom, resulting in a magnetic-field-induced density-wave glass for the spin carrying the phase configuration.
RESUMEN
It has been noted that natural proteins adapt only a limited number of folds. Several researchers have investigated why and how nature has selected this small number of folds. Using simple models of protein folding, we demonstrate systematically that there is a "designability principle" behind nature's selection of protein folds. The designability of a structure (fold) is measured by the number of sequences that can design the structure--that is, sequences that possess the structure as their unique ground state. Structures differ drastically in terms of their designability. A small number of highly designable structures emerge with a number of associated sequences much larger than the average. These highly designable structures possess proteinlike secondary structures, motifs, and even tertiary symmetries. In addition, they are thermodynamically more stable and fold faster than other structures. These results suggest that protein structures are selected in nature because they are readily designed and stable against mutations, and that such a selection simultaneously leads to thermodynamic stability.
Asunto(s)
Conformación Proteica , Pliegue de Proteína , Proteínas/química , Secuencias de Aminoácidos , Simulación por Computador , Humanos , Matemática , Modelos Moleculares , Estructura Secundaria de Proteína , Estructura Terciaria de Proteína , TermodinámicaRESUMEN
The authors evaluated the costs involved when alcoholic patients were admitted to a hospital medical department. Costs which were identical for all patients, such as basic services and hospitalization fees, were discounted, and only those for individual investigations and treatment were calculated. These costs were then compared with the average daily costs for non-alcoholic patients in the same department over the same period. The results are discussed in relation to other similar studies.