Search results for "iTED"
showing 10 items of 2408 documents
Fast, low-level detection of strontium-90 and strontium-89 in environmental samples by collinear resonance ionization spectroscopy
1993
Environmental assessment in the wake of a nuclear accident requires the rapid determination of the radiotoxic isotopes 89Sr and 90Sr. Useful measurements must be able to detect 108 atoms in the presence of about 1018 atoms of the stable, naturally occurring isotopes. This paper describes a new approach to this problem using resonance ionization spectroscopy in collinear geometry, combined with classical mass separation. After collection and chemical separation, the strontium from a sample is surface-ionized and the ions are accelerated to an energy of about 30 keV. Initially, a magnetic mass separator provides an isotopic selectivity of about 106. The ions are then neutralized by charge exc…
Reflexiones sobre cómo evaluar y mejorar la respuesta a la pandemia de COVID-19
2020
La pandemia de COVID-19 ha afectado de manera particularmente intensa a España, pese a su nivel de desarrollo y la elogiada solidez de su Sistema Nacional de Salud. Para comprender qué ha pasado e identificar cómo mejorar la respuesta creemos imprescindible una evaluación independiente multidisciplinaria de la esfera sanitaria, política y socioeconómica. En este trabajo proponemos objetivos, principios, metodología y dimensiones a evaluar, además de esbozar el tipo de resultados y conclusiones esperadas. Nos inspiramos en los requerimientos formulados por el panel independiente de la Organización Mundial de la Salud y en las experiencias evaluativas en otros países, y detallamos la propuest…
Diagnosis of polycystic ovary syndrome: from NIH criteria to ESHRE-ASRM guidelines.
2004
In the past, the diagnosis of polycystic ovary syndrome (PCOS) was based on National Institute of Health (NIH) criteria (hyperandrogenism and chronic anovulation) or on sonographic findings of polycystic ovaries. Diffe-rences in diagnosis criteria made it difficult to compare the data of studies coming from different countries. Moreover, there was criticism of both the methods used. In 2003, at a joint meeting of the European Society for Human Reproduction (ESHRE) and the American Society of Reproductive Medicine (ASRM), new guidelines for the diagnosis of PCOS were suggested. According to these guidelines, it is possible to reach a diagnosis of PCOS when at least 2 of these 3 elements are …
Health care systems of developed non-U.S. nations: strengths, weaknesses, and recommendations for the United States--observations from internationall…
2010
The purpose of this article is to survey imaging experts from developed nations on their impression of their own health care system and recommendations for the U.S. health care system as it seeks to enact health care reform.A survey was sent to individual imaging experts from developed nations requesting information on their health care systems (type of system, strengths, and weaknesses) and their recommendations for the United States.Eighteen respondents from 17 developed nations completed the survey. All respondents reported universal health care coverage: four with government-operated health care, one with mixed government and private insurance-operated health care, 10 with predominantly…
Hypoxia: Importance in tumor biology, noninvasive measurement by imaging, and value of its measurement in the management of cancer therapy
2006
The Cancer Imaging Program of the National Cancer Institute convened a workshop to assess the current status of hypoxia imaging, to assess what is known about the biology of hypoxia as it relates to cancer and cancer therapy, and to define clinical scenarios in which in vivo hypoxia imaging could prove valuable.Hypoxia, or low oxygenation, has emerged as an important factor in tumor biology and response to cancer treatment. It has been correlated with angiogenesis, tumor aggressiveness, local recurrence, and metastasis, and it appears to be a prognostic factor for several cancers, including those of the cervix, head and neck, prostate, pancreas, and brain. The relationship between tumor oxy…
Photoluminescence in Carborane–Stilbene Triads : A Structural, Spectroscopic, and Computational Study
2016
A set of triads in which o- and m-carborane clusters are bonded to two stilbene units through Ccluster -CH2 bonds was synthesized, and their structures were confirmed by X-ray diffraction. A study on the influence of the o- and m- isomers on the absorption and photoluminescence properties of the stilbene units in solution revealed no charge-transfer contributions in the lowest excited state, as confirmed by (TD)DFT calculations. The presence of one or two B-I groups in m-carborane derivatives does not affect the emission properties of the stilbenes in solution, probably due to the rather large distance between the iodo substituents and the fluorophore. Nevertheless, a significant redshift o…
Experimental and theoretical study of the energetic, morphological, and photoluminescence properties of CaZrO3:Eu3+
2018
In this study, we present a combined experimental and theoretical study of the geometry, electronic structure, morphology, and photoluminescence properties of CaZrO3:Eu3+ materials. The polymeric precursor method was employed to synthesize CaZrO3:Eu3+ crystals, while density functional theory calculations were performed to determine the geometrical and electronic properties of CaZrO3:Eu3+ in its ground and excited electronic states (singlet and triplet). The results were combined with X-ray diffraction (XRD) measurements to elucidate the local structural changes induced by the introduction of Eu3+ in the crystal lattice. This process results in the formation of intermediate levels in the ba…
Defects at the TiO2(100) surface probed by resonant photoelectron diffraction.
2006
We report photoelectron diffraction (PED) experiments of weakly sub-stoichiometric TiO 2 (100) rutile surfaces. Apart from standard core-level PED from the Ti-2p3/2 line, we have studied valence band PED from the defect induced Ti-3d states in the insulating band gap. For maximum yield, the latter were resonantly excited at the Ti-2p absorption edge. The PED patterns have been analyzed within the forward scattering approximation as well as by comparison with simulated PED patterns obtained in multiple scattering calculations. The analysis shows that the defect induced Ti-3d charge is mainly located on the second layer Ti atoms. © 2007 Elsevier B.V. All rights reserved.
Defect States at theTiO2(110)Surface Probed by Resonant Photoelectron Diffraction
2008
The charge distribution of the defect states at the reduced ${\mathrm{TiO}}_{2}(110)$ surface is studied via a new method, the resonant photoelectron diffraction. The diffraction pattern from the defect state, excited at the $\mathrm{Ti}\mathrm{\text{\ensuremath{-}}}2p\mathrm{\text{\ensuremath{-}}}3d$ resonance, is analyzed in the forward scattering approach and on the basis of multiple scattering calculations. The defect charge is found to be shared by several surface and subsurface Ti sites with the dominant contribution on a specific subsurface site in agreement with density functional theory calculations.
New rotational levels in $^{186}$Re nucleus
2020
International audience; Excited levels of 186 Re have been studied using results of the single γ -ray spectra measurements following the thermal neutron capture reaction. Energies and intensities of more than 500 γ -transitions have been obtained with the high-resolution crystal diffraction spectrometer GAMS5 of ILL. Most of the obtained intense γ -transitions have been placed in the 186 Re level scheme. A number of new levels, as well as the depopulation for levels observed earlier in the 187 Re (p,d)186 Re reaction measurements have been proposed. Structure of 186 Re levels is interpreted in terms of two-quasiparticle plus rotor coupling model and compared with that of the neighbouring do…