347 research outputs found
Calculation of The Band Gap Energy and Study of Cross Luminescence in Alkaline-Earth Dihalide Crystals
The band gap energy as well as the possibility of cross luminescence
processes in alkaline-earth dihalide crystals have been calculated using the ab
initio Perturbed-Ion (PI) model. The gap is calculated in several ways: as a
difference between one-electron energy eigenvalues and as a difference between
total energies of appropriate electronic states of the crystal, both at the HF
level and with inclusion of Coulomb correlation effects. In order to study the
possibility of ocurrence of cross luminescence in these materials, the energy
difference between the valence band and the upmost core band for some
representative crystals has been calculated. Both calculated band gap energies
and cross luminescence predictions compare very well with the available
experimental results.Comment: LaTeX file containing 8 pages plus 1 postscript figure. Final version
accepted for publication in The Journal of the Physical Society of Japan. It
contains a more complete list of references, as well as a more detailed
comparison with previous theoretical investigations on the subjec
Lattice Distortions Around a Tl+ Impurity in NaI:Tl+ and CsI:Tl+ Scintillators. An Ab Initio Study Involving Large Active Clusters
Ab initio Perturbed Ion cluster-in-the-lattice calculations of the impurity
centers NaI:Tl+ and CsI:Tl+ are pressented. We study several active clusters of
increasing complexity and show that the lattice relaxation around the Tl+
impurity implies the concerted movement of several shells of neighbors. The
results also reveal the importance of considering a set of ions that can
respond to the geometrical displacements of the inner shells by adapting
selfconsistently their wave functions. Comparison with other calculations
involving comparatively small active clusters serves to assert the significance
of our conclusions. Contact with experiment is made by calculating absorption
energies. These are in excellent agreement with the experimental data for the
most realistic active clusters considered.Comment: 7 pages plus 6 postscript figures, LaTeX. Submmited to Phys, Rev.
Theory of hyperfine interactions in positive ions isoelectronic with the noble-metal atoms
Congenital epulis of the jaw: a series of five cases and review of literature
This article describes five cases of congenital epulis, a rare and benign swelling in the mouth of a newborn, which is not widely known. We present five cases: four cases presented as single pedunculated nodules of the gingiva and in one case two nodules were present. Of all, 50% were located at the maxilla. Excision was performed in four of the five cases and in one case, spontaneous regression was awaited. No recurrence was reported. The characteristic features of congenital epulis are a pedunculated, flesh-pink coloured tumour with a predominant occurrence on the anterior maxillary alveolar ridge in a female newborn. Although the aetiology is unknown, most authors suggest a mesenchymal, rather than an odontogenic, origin. Endogenous hormonal factors might influence growth prenatally. Histological findings include granular cells with eosinophilic cytoplasm and small, eccentric nuclei. Despite the fact that the lesion can be a striking sight, spontaneous regression is possible and can be awaited. Indications for non-radical excision under local anaesthesia are severe upper airway obstruction and interference with feeding technique. In conclusion, we provide clinical and histological information about congenital epulis, so that this entity will be more easily recognised and relevant information given to parent
Life cycle of the East Carpathian orogen; Erosion history of a doubly vergent critical wedge assessed by fission track thermochronology
Interprofessional Consensus Regarding Design Requirements for Liquid-Based Perinatal Life Support (PLS) Technology
Liquid-based perinatal life support (PLS) technology will probably be applied in a first-in-human study within the next decade. Research and development of PLS technology should not only address technical issues, but also consider socio-ethical and legal aspects, its application area, and the corresponding design implications. This paper represents the consensus opinion of a group of healthcare professionals, designers, ethicists, researchers and patient representatives, who have expertise in tertiary obstetric and neonatal care, bio-ethics, experimental perinatal animal models for physiologic research, biomedical modeling, monitoring, and design. The aim of this paper is to provide a framework for research and development of PLS technology. These requirements are considering the possible respective user perspectives, with the aim to co-create a PLS system that facilitates physiological growth and development for extremely preterm born infants
The Causal Effect of Family Income on Child Health: A Re-Examination Using an Instrumental Variables Approach
Risk Factors for Necrotizing Enterocolitis:A Prospective Multicenter Case-Control Study
BACKGROUND: The identification of independent clinical risk factors for necrotizing enterocolitis (NEC) may contribute to early selection of infants at risk, allowing for the development of targeted strategies aimed at the prevention of NEC. OBJECTIVE: The objective of this study was to identify independent risk factors contributing to the development of NEC in a large multicenter cohort. METHODS: This prospective cohort study was performed in 9 neonatal intensive care units. Infants born at a gestational age </=30 weeks were included. Demographic and clinical data were collected daily until day 28 postnatally. Factors predictive of the development of NEC were identified using univariate and multivariable analyses in a 1: 5 matched case-control cohort. RESULTS: In total, 843 infants (56 NEC cases) were included in this study. In the case-control cohort, univariate analysis identified sepsis prior to the onset of NEC and formula feeding to be associated with an increased risk of developing NEC, whereas the administration of antibiotics directly postpartum was inversely associated with NEC. In a multivariable logistic regression model, enteral feeding type and the number of days parenterally fed remained statistically significantly associated with NEC, whereas the administration of antibiotics directly after birth was associated with a lower risk of developing NEC. CONCLUSIONS: Formula feeding and prolonged (duration of) parenteral feeding were associated with an increased risk of NEC. Contrary to expectations, the initiation of treatment with antibiotics within 24 h after birth was inversely associated with NEC
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