RESUMEN
We propose a theoretical model to describe the strain-induced linear electro-optic (Pockels) effect in centro-symmetric crystals. The general formulation is presented and the specific case of the strained silicon is investigated in detail because of its attractive properties for integrated optics. The outcome of this analysis is a linear relation between the second order susceptibility tensor and the strain gradient tensor, depending generically on fifteen coefficients. The proposed model greatly simplifies the description of the electro-optic effect in strained silicon waveguides, providing a powerful and effective tool for design and optimization of optical devices.
RESUMEN
Se solicitó radiografía de tórax a todos los recién nacidos que presentaran tos durante consultas de morbilidad o por control de niño de sano en tres policlínicas de Santiago. Los resultados fueron clasificados como positivos (imagen de condensación o infiltrado bilateral evidente), dudosos (infiltrado intersticial unilateral) y negativos (sin alteraciones). Se estudiaron 35 recién nacidos con tos, en 17 (48,6%) la radiografía dio resultados positivos, en 11 (31,4%) negativos y en 7 dudosos. En cuatro casos de niños con radiografía positiva, que debieron hospitalizarse por bronconeumonía, las madres acudieron a control sano sin percatarse de la enfermedad; tres tenían examen pulmonar clínicamente normal. Ninguno de 30 recién nacidos sin tos, a los que se solicitó radiografía de tórax por otra causa, tenía signos radiológicos de afección pulmonar. La tos es un signo alarmante en recién nacidos
Asunto(s)
Humanos , Masculino , Femenino , Recién Nacido , Tos/fisiopatología , Infecciones del Sistema Respiratorio/diagnóstico , Estudios de Casos y Controles , Enfermedades Pulmonares/diagnósticoRESUMEN
The study was carried out on twenty nine geriatric patients with malnutrition of variable aetiology. The effectiveness of a temporary parenteral nutritional supplement was evaluated both clinically and by means of some metabolic indexes: nitrogen balance, serum albumin, blood electrolytes, acid-base parameters, hemocytometry. The treatment was devoid of metabolic complications, and promoted a positive nitrogen balance as well as clinical improvement in most patients.
Asunto(s)
Trastornos Nutricionales/dietoterapia , Nutrición Parenteral Total , Anciano , Anciano de 80 o más Años , Peso Corporal , Estudios de Evaluación como Asunto , Estudios de Seguimiento , Humanos , Persona de Mediana Edad , Trastornos Nutricionales/etiología , Trastornos Nutricionales/metabolismo , Factores de TiempoRESUMEN
The age effect on the kinetics of piroxicam at the steady-state after oral administration of piroxicam beta-cyclodextrin was evaluated. The mean plasma concentration of piroxicam at the steady-state was significantly higher in elderly subjects (9.30 +/- 0.69 micrograms/ml mean +/- s.e.) than in younger adults (6.24 +/- 0.58 micrograms/ml mean +/- s.e.). Even though the distribution volume tended to be lower in elderly subjects (106.37 ml/kg), it did not show substantial differences in the two groups whereas the correlation between clearance and age was significant (p less than 0.05). It is therefore confirmed that piroxicam beta-cyclodextrin has the same pharmacokinetic behaviour at the steady-state in elderly subjects, as the active principle in a non-complexed form.