RESUMEN
We present long-term records of the (137)Cs and (90)Sr activity concentrations in soil, grass and milk from two lowland and two alpine pastures of Switzerland. The data is used for better understanding the long-term behavior of these radionuclides in the environment. Transfer factors between compartments are used as qualitative indicators of the magnitude of transfer and as a way to compare different elements (e.g. Cs and Sr) in similar conditions. The long-term behavior was quantified by means of the effective half-life which integrates all processes that cause a decrease of activity in a given medium such as leaching, fixation, erosion and radioactive decay. Our study shows that (90)Sr is more likely transferred from alpine soil to grass than (137)Cs. This is explained by a stronger fixation of Cs in the soils. We observed higher transfers of (90)Sr to grass in soils with lower Ca concentrations, and vice versa. In contrast, the transfer of (137)Cs to grass was not affected by the variations of the K content in the soil. We provide evidence that shows that (137)Cs, after intake by dairy cattle, is more likely transferred to milk than (90)Sr. However, as the (90)Sr and Ca transfers to milk are influenced by parameters/processes that were not taken into account in our study, our result cannot be entirely validated. The effective half-lives of (137)Cs and (90)Sr in soil, grass and milk corresponded with previous estimates in alpine soils. We have found that processes other than radioactive decay are responsible for a major decrease of the (90)Sr activity in soil. For (137)Cs, on the other hand, radioactive decay is among the most relevant process. Our data shows to be of interest in studying the trends of behavior of radionuclides in alpine regions.
Asunto(s)
Radioisótopos de Cesio/análisis , Contaminación Radiactiva de Alimentos/análisis , Leche/química , Poaceae/química , Contaminantes Radiactivos del Suelo/análisis , Radioisótopos de Estroncio/análisis , Animales , Bovinos/metabolismo , Radioisótopos de Cesio/metabolismo , Leche/metabolismo , Poaceae/metabolismo , Monitoreo de Radiación , Contaminantes Radiactivos del Suelo/metabolismo , Radioisótopos de Estroncio/metabolismo , SuizaRESUMEN
BACKGROUND: Bispectal index (BIS) monitoring may reduce drug usage and hasten recovery in propofol and inhalation anesthesia. The faster emergence profile of desflurane may reduce the effect of BIS monitoring on recovery from desflurane compared with propofol. This study compared hypnotic drug usage, recovery, patient satisfaction and incidence of inadequate sedation in BIS monitored and nonmonitored women anesthetized with desflurane or propofol. METHODS: One hundred and sixty patients scheduled for elective gynecological surgery were randomly assigned to desflurane or propofol anesthesia with and without BIS monitoring. Fentanyl, vecuronium and remifentanil were administered according to clinical criteria. The BIS monitor was used in all patients, but the monitor screen was covered in the controls. A BIS level between 45 and 55 was targeted in the BIS monitored patients whereas depth of anesthesia was assessed by clinical criteria in the controls. RESULTS: The mean (SD) desflurane MAC-hours administered with and without BIS were 0.70 (0.15) and 0.76 (0.12), respectively, resulting in extubation times of 6.5 (4.1) and 8.3 (6.1) min. (NS). Bispectal index monitoring was associated with improved patient satisfaction, reduced postoperative nausea and antiemetic drug requirement, and fewer episodes with sustained BIS levels > 60. The mean (SD) propofol infusion rates were 6.0 (1.4) and 6.6 (0.9) mg kg(-1)h(-1) with and without the BIS monitor (P = 0.023), resulting in mean (SD) extubation times of 6.8 (4.6) and 10.5 min (5.9), respectively (P < 0.05). CONCLUSION: Bispectal index monitoring reduced propofol usage and hastened recovery after propofol anesthesia, whereas in desflurane anesthesia it was associated with improved patient satisfaction, probably because of decreased postoperative nausea and fewer episodes of inadequate hypnosis.
Asunto(s)
Anestesia General , Anestésicos por Inhalación , Anestésicos Intravenosos , Electroencefalografía/efectos de los fármacos , Isoflurano , Isoflurano/análogos & derivados , Monitoreo Intraoperatorio , Propofol , Adulto , Periodo de Recuperación de la Anestesia , Anestésicos por Inhalación/administración & dosificación , Anestésicos Intravenosos/administración & dosificación , Concienciación/efectos de los fármacos , Desflurano , Femenino , Procedimientos Quirúrgicos Ginecológicos , Hemodinámica/efectos de los fármacos , Humanos , Intubación Intratraqueal , Isoflurano/administración & dosificación , Recuerdo Mental/efectos de los fármacos , Persona de Mediana Edad , Satisfacción del Paciente , Náusea y Vómito Posoperatorios/epidemiología , Propofol/administración & dosificación , Estudios Prospectivos , Encuestas y CuestionariosRESUMEN
Optical damage thresholds at lambda = 2.94 microm have been investigated in one single-mode (11-microm core, 125-microm cladding) and five multimode fluoride glass fibers. (These five fibers consist of three conventional ones, 70-microm core, 140-microm cladding, 150-microm core, 200-microm cladding, and 200-microm core, 250-microm cladding, and two low-attenuation ones, 200-microm core, 250-microm cladding, and 350-microm core, 400-microm cladding.) The induced surface damage is discussed by means of electron microscopic analysis. Power limits for safe transmission are presented.