RESUMO
We present a spectroscopic ellipsometry study of Mo-doped VO2 thin films deposited on silicon substrates for the mid-infrared range. The dielectric functions and conductivity were extracted from analytical fittings of Ψ and Δ ellipsometric angles showing a strong dependence on the dopant concentration and the temperature. Insulator-to-metal transition (IMT) temperature is found to decrease linearly with increasing doping level. A correction to the classical Drude model (termed Drude-Smith) has been shown to provide excellent fits to the experimental measurements of dielectric constants of doped/undoped films and the extracted parameters offer an adequate explanation for the IMT based on the carriers backscattering across the percolation transition. The smoother IMT observed in the hysteresis loops as the doping concentration is increased, is explained by charge density accumulation, which we quantify through the integral of optical conductivity. In addition, we describe the physics behind a localized Fano resonance that has not yet been demonstrated and explained in the literature for doped/undoped VO2 films.
RESUMO
In developing countries, antibiotics are the most common sales of drugs and it has been suggested that their irrational use leads to the emergence of resistant bacteria. In order to assess the purchase of antimicrobials in a peri-urban community in Mexico City six local drug stores were randomly selected. A social worker made five visits to each pharmacy and she observed the events during the purchase of the drug and applied a structured questionnaire to the customer immediately after the transaction. Antibiotics were the majority (29%) of the drug sales. Of all purchasers of an antibiotic 43% did it without medical prescription and 72% answered that a physician had influenced on the purchase. Duration of the antibiotic therapy was specified in one out of three prescriptions that were examined and only in 28% of the sales the purchase was enough for a treatment duration of more than four days. More information, from similar surveys in drug stores in other settings, is needed to support the reinforcement of actions to control the sales of antibiotics in the community.
Assuntos
Antibacterianos/administração & dosagem , Uso de Medicamentos , Farmácias , Serviço de Farmácia Hospitalar , Humanos , MéxicoRESUMO
The clinical features of 16 males and 2 females with hypokalemic periodic paralysis (HPP) are presented. Five patients had familial HPP, 4 thyrotoxic HPP and 9 sporadic disease. The age of onset ranged from 6 to 42 years. Clinical pictures varied from paraparesis to severe quadriplegia. The disease onset was earlier in familial HPP (p < 0.05) while sporadic cases showed the most severe, albeit shorter paralysis (p < 0.05). On admission, serum potassium levels ranged from 1.5 to 3.3 mEq/L; they did not correlate with the severity of paralysis. Glucose-insulin provocation test was positive in 5/5 patients. Oral potassium chloride and amiloride were useful to prevent paralysis. Contrasting with reports from USA and Europe, in México, HPP is not exceptional, and should be considered in the differential diagnosis of acute paralysis.