83 resultados para Gómez, Carlos Bernabé
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Using the once and thrice energy-weighted moments of the random-phase-approximation strength function, we have derived compact expressions for the average energy of surface collective oscillations of clusters and spheres of metal atoms. The L=0 volume mode has also been studied. We have carried out quantal and semiclassical calculations for Na and Ag systems in the spherical-jellium approximation. We present a rather thorough discussion of surface diffuseness and quantal size effects on the resonance energies.
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Nonlocal approximations for the electronic exchange and correlation effects are used to compute, within density-functional theory, the polarizability and surface-plasma frequencies of small jelliumlike alkali-metal clusters. The results are compared with those obtained using the local-density approximation and with available experimental data, showing the relevance of these effects in obtaining an accurate description of the surface response of metallic clusters.
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We report on the growth of epitaxial YBa2Cu3O7 thin films on X-cut LiNbO3 single crystals. The use of double CeO2/YSZ buffer layers allows a single in-plane orientation of YBa2Cu3O7, and results in superior superconducting properties. In particular, surface resistance Rs values of 1.4 m¿ have been measured at 8 GHz and 65 K. The attainment of such low values of Rs constitutes a key step toward the incorporation of high Tc materials as electrodes in photonic and acoustic devices.
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El conocimiento de la Meseta Superior en la Antigüedad es muy desigual y obras como la presente, que sintetizan y reúnen aspectos dispersos en multitud de publicaciones, cubren un importante hueco. Por diversas causas la investigación venía atendiendo con mayor interés las etapas de cambio histórico, los pueblos prerromanos y los primeros tiempos de la implantación romana, la crisis del siglo III y su transformación posterior, etc. Se echaba en falta una obra monotemática sobre la maduración romanizadora, que indagara en los motivos de crisis que ya en ella se intuyen, durante ese siglo falsamente "anodino", es decir, el espacio de tiempo comprendido entre los años 96-198.
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Conjugates of a dicarba analogue of octreotide, a potent somatostatin agonist whose receptors are overexpressed on tumor cells, with [PtCl2(dap)] (dap = 1-(carboxylic acid)-1,2-diaminoethane) (3), [(η6-bip)Os(4-CO2-pico)Cl] (bip = biphenyl, pico = picolinate) (4), [(η6-p-cym)RuCl(dap)]+ (p-cym = p-cymene) (5), and [(η6-p-cym)RuCl(imidazole-CO2H)(PPh3)]+ (6), were synthesized by using a solid-phase approach. Conjugates 35 readily underwent hydrolysis and DNA binding, whereas conjugate 6 was inert to ligand substitution. NMR spectroscopy and molecular dynamics calculations showed that conjugate formation does not perturb the overall peptide structure. Only 6 exhibited antiproliferative activity in human tumor cells (IC50 = 63 ± 2 μM in MCF-7 cells and IC50 = 26 ± 3 μM in DU-145 cells) with active participation of somatostatin receptors in cellular uptake. Similar cytotoxic activity was found in a normal cell line (IC50 = 45 ± 2.6 μM in CHO cells), which can be attributed to a similar level of expression of somatostatin subtype-2 receptor. These studies provide new insights into the effect of receptor-binding peptide conjugation on the activity of metal-based anticancer drugs, and demonstrate the potential of such hybrid compounds to target tumor cells specifically.
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The aim of this paper is to test the effectiveness of wage-irrelevant goal setting policies in a laboratory environment. In our design, managers can assign a goal to their workers by setting a certain level of performance on the work task. We establish our theoretical conjectures by developing a model where assigned goals act as reference points to workers’ intrinsic motivation. Consistent with our model, we find that managers set goals which are challenging but attainable for an average-ability worker. Workers respond to these goals by increasing effort, performance and by decreasing on-the-job leisure activities with respect to the no-goal setting baseline. Finally, we study the interaction between goal setting and monetary rewards and find that goal setting is most effective when monetary incentives are strong. These results suggest that goal setting may produce intrinsic motivation and increase workers’ performance beyond what is achieved using solely monetary incentives.
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Mediante el estudio de este caso se pretende concienciar al orientadorde su papel como agente conector y mediador de los dos contextos másrelevantes del desarrollo cognitivo, personal y social del adolescente, sufamilia y la escuela. Estos dos contextos conforman un contexto más amplio de desarrollo, denominado por Bronfenbrenner (2002), el mesosistema.
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We report on the growth of epitaxial YBa2Cu3O7 thin films on X-cut LiNbO3 single crystals. The use of double CeO2/YSZ buffer layers allows a single in-plane orientation of YBa2Cu3O7, and results in superior superconducting properties. In particular, surface resistance Rs values of 1.4 m¿ have been measured at 8 GHz and 65 K. The attainment of such low values of Rs constitutes a key step toward the incorporation of high Tc materials as electrodes in photonic and acoustic devices.
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Award-winning
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