Inelastic light scattering and the excited states of many-electron quantum dots

A consistent calculation of resonant inelastic (Raman) scattering amplitudes for relatively large quantum dots, which takes account of valence-band mixing, discrete character of the spectrum in intermediate and final states, and interference effects, is presented. Raman peaks in charge and spin channels are compared with multipole strengths and with the density of energy levels in final states. A qualitative comparison with the available experimental results is given.Comment: 5 pages, accepted in J. Phys.: Condens. Matte

Social Work and Follow Up to Graduates at the Universidad Tecnica De Manabi

The article presents an analysis of social work in the areas of health, education and social protection, exposing the role that should characterize social work professionals in the areas analyzed. It is characterized by the analysis of data related to the province of Manabí and especially to the city of Portoviejo. Some results related to the follow-up activities for graduates at the Universidad Tecnica de Manabí are presented, based on documentation investigated by the Monitoring Committee for Graduates and Labor Insertion of the career of Social Work of the university, in relation to the jobs That occupy the professionals and their intervention in the labor field. A survey was applied to 161 social workers who were graduated in the period 1984-2017, the results obtained demonstrate the significant aspects that allowed the graduates to insert themselves in the work to be done finding as more significant aspects to have the title of the career, personality And pre-professional experience

Varying efficacy of intermittent preventive treatment for malaria in infants in two similar trials: public health implications.

BACKGROUND\ud \ud Intermittent preventive treatment (IPTi) with sulphadoxine-pyrimethamine (SP) in infants resulted in different estimates of clinical malaria protection in two trials that used the same protocol in Ifakara, Tanzania, and Manhiça, Mozambique. Understanding the reasons for the discrepant results will help to elucidate the action mechanism of this intervention, which is essential for rational policy formulation.\ud \ud METHODS\ud \ud A comparative analysis of two IPTi trials that used the same study design, follow-up, intervention, procedures and assessment of outcomes, in Tanzania and Mozambique was undertaken. Children were randomised to receive either SP or placebo administered 3 times alongside routine vaccinations delivered through the Expanded Program on Immunisation (EPI). Characteristics of the two areas and efficacy on clinical malaria after each dose were compared.\ud \ud RESULTS\ud \ud The most relevant difference was in ITN's use ; 68% in Ifakara and zero in Manhiça. In Ifakara, IPTi was associated with a 53% (95% CI 14.0; 74.1) reduction in the risk of clinical malaria between the second and the third dose; during the same period there was no significant effect in Manhiça. Similarly, protection against malaria episodes was maintained in Ifakara during 6 months after dose 3, but no effect of IPTi was observed in Manhiça.\ud \ud CONCLUSION\ud \ud The high ITN coverage in Ifakara is the most likely explanation for the difference in IPTi efficacy on clinical malaria. Combination of IPTi and ITNs may be the most cost-effective tool for malaria control currently available, and needs to be explored in current and future studies.\ud \ud TRIAL REGISTRATION\ud \ud Manhiça study registration number: NCT00209795Ifakara study registration number: NCT88523834

Resonant hyper-Raman scattering in spherical quantum dots

A theoretical model of resonant hyper-Raman scattering by an ensemble of spherical semiconductor quantum dots has been developed. The electronic intermediate states are described as Wannier-Mott excitons in the framework of the envelope function approximation. The optical polar vibrational modes of the nanocrystallites (vibrons) and their interaction with the electronic system are analized with the help of a continuum model satisfying both the mechanical and electrostatic matching conditions at the interface. An explicit expression for the hyper-Raman scattering efficiency is derived, which is valid for incident two-photon energy close to the exciton resonances. The dipole selection rules for optical transitions and Fr\"ohlich-like exciton-lattice interaction are derived: It is shown that only exciton states with total angular momentum $L=0,1$ and vibrational modes with angular momentum $l_p=1$ contribute to the hyper-Raman scattering process. The associated exciton energies, wavefunctions, and vibron frequencies have been obtained for spherical CdSe zincblende-type nanocrystals, and the corresponding hyper-Raman scattering spectrum and resonance profile are calculated. Their dependence on the dot radius and the influence of the size distribution on them are also discussed.Comment: 12 pages REVTeX (two columns), 2 tables, 8 figure

Residual Expression of the Reprogramming Factors Prevents Differentiation of iPSC Generated from Human Fibroblasts and Cord Blood CD34+ Progenitors

Human induced pluripotent stem cells (hiPSC) have been generated from different tissues, with the age of the donor, tissue source and specific cell type influencing the reprogramming process. Reprogramming hematopoietic progenitors to hiPSC may provide a very useful cellular system for modelling blood diseases. We report the generation and complete characterization of hiPSCs from human neonatal fibroblasts and cord blood (CB)-derived CD34+ hematopoietic progenitors using a single polycistronic lentiviral vector containing an excisable cassette encoding the four reprogramming factors Oct4, Klf4, Sox2 and c-myc (OKSM). The ectopic expression of OKSM was fully silenced upon reprogramming in some hiPSC clones and was not reactivated upon differentiation, whereas other hiPSC clones failed to silence the transgene expression, independently of the cell type/tissue origin. When hiPSC were induced to differentiate towards hematopoietic and neural lineages those hiPSC which had silenced OKSM ectopic expression displayed good hematopoietic and early neuroectoderm differentiation potential. In contrast, those hiPSC which failed to switch off OKSM expression were unable to differentiate towards either lineage, suggesting that the residual expression of the reprogramming factors functions as a developmental brake impairing hiPSC differentiation. Successful adenovirus-based Cre-mediated excision of the provirus OKSM cassette in CB-derived CD34+ hiPSC with residual transgene expression resulted in transgene-free hiPSC clones with significantly improved differentiation capacity. Overall, our findings confirm that residual expression of reprogramming factors impairs hiPSC differentiation