149 research outputs found
Coprophagia in an 8-Year-Old Hospitalized Patient: Case Report and Review of the Literature
Consult-liaison psychiatrists often encounter difficult clinical scenarios. We present a pediatric case of presumptive coprophagia. After a negative medical work-up, the pediatrics team asked psychiatry to assist them in managing this relatively rare disorder in the hospital setting. Little is known about the etiology and treatment of coprophagia in the pediatric population. Using the case as a catalyst, we discuss what is known about this disorder as well as treatment strategies in the hospital setting
Thermodynamics of zinc insertion in CuGaS2:Ti, used as a modulator agent in an intermediate-band photovoltaic material
An intermediate-bandphotovoltaicmaterial, which has an isolated metallic band located between the top of the valence band and bottom of the conduction band of some semiconductors, has been proposed as third generation solar cell to be used in photovoltaic applications. Density functional theory calculations of Zn in CuGaS2:Ti have previously shown that, the intermediate-band position can be modulated in proportion of Zn insertion in such a way that increasing Zn concentration can lead to aband-gap reduction, and an adjustment of the intermediate-band position. This could be interesting in the formation of an intermediate-bandmaterial, that has the maximum efficiency theoretically predicted for the intermediate-band solar cell. In this work, the energetics of several reaction schemes that could lead to the decomposition of the modulated intermediate-bandphotovoltaicmaterial, CuGaS2:Ti:Zn, is studied in order to assess the thermodynamic stability of this material. Calculations of the total free energy and disorder entropy have been taken into account, to get the reaction energy and free energy of the compound decomposition, which is found to be thermodynamically favorabl
A study of transition metal K-edge x-ray absorption spectra of LaBO3 (B=Mn, Fe, Co, Ni), La2CuO4 and SrMnO3 using partial density of states
The transition metal K-edge x-ray absorption near edge structure (XANES)
studies have been carried on LaBO3 (B=Mn, Fe, Co, Ni), La2CuO4 and SrMnO3
compounds. The theoretical spectra have been calculated using transition metal
(TM) 4p density of states (DOS) obtained from full-potential LMTO density
functional theory. The exchange-correlation functional used in this calculation
is taken under local density approximation (LDA). The comparison of
experimental spectra with the calculated ones indicates that single-particle
transitions under LDA are sufficient to generate all the observed XANES
including those which have earlier been attributed to many-body shake-up
transitions and core-hole potentials. The present study reveals that all the
experimentally observed features are mainly due to distribution in TM 4p DOS
influenced by hybridization with other orbitals. Specifically, for LaMnO3, the
feature earlier attributed to shake-up process is seen to arise from
hybridization of Mn 4p with La 6p and O 2p orbitals; in La2CuO4 the features
attributed to core hole potential correspond to hybridization of Cu 4p with La
6p, La 5d and O 2p orbitals. To see the effect of inhomogeneous electronic
charge distribution and on-site Coulomb and exchange interaction (U) on the
XANES of these compounds generalized-gradient approximation and U corrections
are incorporated in the calculations. These corrections do not generate any new
features in the spectra but affect the detailed intensity and positions of some
of the features.Comment: 23 pages, 8 figures. To appear in J. Phys.: Condens. Matte
X-ray Absorption Near-Edge Structure calculations with pseudopotentials. Application to K-edge in diamond and alpha-quartz
We present a reciprocal-space pseudopotential scheme for calculating X-ray
absorption near-edge structure (XANES) spectra. The scheme incorporates a
recursive method to compute absorption cross section as a continued fraction.
The continued fraction formulation of absorption is advantageous in that it
permits the treatment of core-hole interaction through large supercells
(hundreds of atoms). The method is compared with recently developed
Bethe-Salpeter approach. The method is applied to the carbon K-edge in diamond
and to the silicon and oxygen K-edges in alpha-quartz for which polarized XANES
spectra were measured. Core-hole effects are investigated by varying the size
of the supercell, thus leading to information similar to that obtained from
cluster size analysis usually performed within multiple scattering
calculations.Comment: 11 pages, 4 figure
Coprophagia in an 8-Year-Old Hospitalized Patient: A Case Report and Review of the Literature
Consult-liaison psychiatrists often encounter difficult clinical scenarios. We present a pediatric case of presumptive coprophagia. After a negative medical work-up, the pediatrics team asked psychiatry to assist them in managing this relatively rare disorder in the hospital setting. Little is known about the etiology and treatment of coprophagia in the pediatric population. Using the case as a catalyst, we discuss what is known about this disorder as well as treatment strategies in the hospital setting
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