We analyze electronic, magnetic, and structural properties of the spinel compound MgTi\(_2\)O\(_4\) using the local density approximation+U method. We show how MgTi\(_2\)O\(_4\) undergoes to a canted ...orbital-spin ordered state, where charge, spin and orbital degrees of freedom are frozen in a geometrically frustrated network by electron interactions. In our picture orbital order stabilize the magnetic ground state and controls the degree of structural distortions. The latter is dynamically derived from the cubic structure in the correlated LDA+U potential. Our ground-state theory provides a consistent picture for the dimerized phase of MgTi\(_2\)O\(_4\), and might be applicable to frustrated materials in general.
A chronic mucocutaneous infection due to yeasts to the Candida genus can be part of the autoimmune polyglandular syndrome, described as APECS, APECED, SPA type I, CES. The authors describe the case ...of a young patient affected by mucocutaneous candidiasis, hypoparathyroidism and adrenal insufficiency. Chronic mucocutaneous candidiasis was diagnosed first in early childhood and was followed by the development of hypoparathyroidism (4 yrs) and adrenal insufficiency (5 yrs). The initial lesion of this syndrome is still unknown as the reason of the marked susceptibility to mucocutaneous candidiasis without systemic candidiasis. The treatment of mucocutaneous candidiasis has been improved by the introduction of orally active antifungal drugs as Ketoconazole, first, and fluconazole now.
The \(\gamma\)-ray strength function of \(^{56}\)Fe has been measured from proton-\(\gamma\) coincidences for excitation energies up to \(\approx 11\) MeV. The low-energy enhancement in the ...\(\gamma\)-ray strength function, which was first discovered in the (\(^3\)He,\(\alpha\gamma\))\(^{56}\)Fe reaction, is confirmed with the (\(p,p^\prime\gamma\))\(^{56}\)Fe experiment reported here. Angular distributions of the \(\gamma\) rays give for the first time evidence that the enhancement is dominated by dipole transitions.
The 2-aminoisobutyric acid transport in hepatocytes isolated from 3- and 24-month-old rats was studied and some age-related differences were observed. The basal uptake appeared to be almost constant ...in cells from old animals during the incubation time, while, in the cells from adults, it showed a progressive increase, interpreted as being due to a derepression mechanism. Epinephrine and glucagon increased the transport in hepatocytes from animals of both ages, even if with a slightly different pattern; the hormones increased the Vmax, while the Km was unchanged at each age tested. However, the glucagon-induced increase in Vmax was lower in the older animals. The mechanism of hormonal action appeared to be similar in adult and old rats. In fact the uptake stimulation by glucagon and epinephrine showed a dependence on protein synthesis. The epinephrine effect was mediated by alpha-adrenergic receptors. No effect was exerted by extracellular amino acids on hepatocytes from 24-month-old animals, suggesting a loss of adaptative regulation mechanism with aging. This behaviour was reflected in the kinetic parameters; in fact the Vmax was not modified by extracellular amino acids at 24 months of age, while it appeared to be strongly decreased in the adult.
Nucl.Phys. A736 (2004) 223-240 The validity of the K-quantum number in rapidly rotating warm nuclei is
investigated as a function of thermal excitation energy U and angular momentum
I, for the ...rare-earth nucleus 163Er. The quantal eigenstates are described with
a shell model which combines a cranked Nilsson mean-field and a residual
two-body interaction, together with a term which takes into account the angular
momentum carried by the K-quantum number in an approximate way. K-mixing is
produced by the interplay of the Coriolis interaction and the residual
interaction; it is weak in the region of the discrete rotational bands (U
\lesim 1MeV), but it gradually increases until the limit of complete violation
of the K-quantum number is approached around U \sim 2 - 2.5 MeV. The calculated
matrix elements between bands having different K-quantum numbers decrease
exponentially as a function of $\Delta K$, in qualitative agreement with recent
data.
El objetivo de este estudio es indagar en el potencial que posee el género discursivo reseña, como género de formación, en el proceso de transición de estudiantes de pedagogía de primer año hacia un ...dominio discursivo propio del ámbito académico en el que se insertan. Se analizaron las reseñas académicas producidas por 36 estudiantes de primer año de la carrera de pedagogía en castellano de una universidad chilena, católica y privada. El instrumento de evaluación es una rúbrica con tres subcompetencias: lingüística, discursiva y sociolingüística. Los resultados muestran que la implementación de una unidad didáctica con énfasis en la producción de reseñas académicas desde una perspectiva sociocognitiva y pragmalingüística permitió que los estudiantes mejoraran la calidad de sus escritos en la competencia discursiva y sociolingüística. Se concluye que los resultados marcan una tendencia que abre un campo de estudios en torno al valor de la reseña en la educación terciaria.
The doping induced insulator-metal transition in \(La_{1-x}Sr_{x}TiO_{3}\) is studied using the ab-initio LDA+DMFT method. Combining the LDA bandstructure for the actual, distorted structure found ...recently with multi-orbital DMFT to treat electronic correlations, we find: \((i)\) ferro-orbital order in the Mott insulating state without orbital degeneracy, \((ii)\) a continuous filling induced transition to the paramagnetic metal (PM) with \(x\), and \((iii)\) excellent quantitative agreement with published photoemission data for the case of 6% doping. Our results imply that this system can be described as a Mott-Hubbard system without orbital (liquid) degeneracy.
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