993 resultados para 165-999A
Resumo:
[EN]Hyperventilation, which is common both in-hospital and out-of-hospital cardiac arrest, decreases coronary and cerebral perfusion contributing to poorer survival rates in both animals and humans. Current resucitation guidelines recommend continuous monitoring of exhaled carbon dioxide (CO2) during cardiopulmonary resucitation (CPR) and emphasize good quality of CPR, including ventilations at 8-10 min1. Most of commercial monitors/de- brilators incorporate methods to compute the respiratory rate based on capnography since it shows uctuations caused by ventilations. Chest compressions may induce artifacts in this signal making the calculation of the respiratory rate di cult. Nevertheless, the accuracy of these methods during CPR has not been documented yet. The aim of this project is to analyze whether the capnogram is reliable to compute ventilation rate during CPR. A total of 91 episodes, 63 out-of-hospital cardiac arrest episodes ( rst database) and 28 in-hospital cardiac arrest episodes (second database) were used to develop an algorithm to detect ventilations in the capnogram, and the nal aim is to provide an accurate ventilation rate for feedback purposes during CPR. Two graphic user interfaces were developed to make the analysis easier and another two were adapted to carry out this project. The use of this interfaces facilitates the managment of the databases and the calculation of the algorithm accuracy. In the rst database, as gold standard every ventilation was marked by visual inspection of both the impedance, which shows uctuations with every ventilation, and the capnography signal. In the second database, volume of the respiratory ow signal was used as gold standard to mark ventilation instants since it is not a ected by chest compressions. The capnogram was preprocessed to remove high frequency noise, and the rst di erence was computed to de ne the onset of inspiration and expiration. Then, morphological features were extracted and a decission algorithm built based on the extracted features to detect ventilation instants. Finally, ventilation rate was calculated using the detected instants of ventilation. According to the results obtained in this project, the capnogram can be reliably used to give feedback ventilation rate, and therefore, on hyperventilation in a resucitation scenario.
Resumo:
We report on cooperative downconversion in Yb3+-RE3+ (RE = Tm or Pr) codoped lanthanum borogermanate glasses (LBG), which are capable of splitting a visible photon absorbed by Tm3+ or Pr3+ ions into two near-infrared photons. The results indicate that Pr3+-Yb3+ is a more efficient ion couple than Tm3+-Yb3+ in terms of cooperative downconversion. We have obtained a highest quantum yield of 165% and 138% for Pr3+-Yb3+ and Tm3+-Yb3+ codoped LBG glasses under 468 nm excitation, respectively. However, ultraviolet light excitation to the charge transfer band of Yb3+ does not result in quantum splitting as rapid relaxation from the charge transfer band to 4f(13) levels of Yb3+ dominates. (C) 2008 Optical Society of America
Resumo:
In this paper, some results on visible luminescence performed on Yb3+-doped gadolinium gallium garnets under 165 and 940 nm excitation were presented. The upconversion luminescence was ascribed to Yb3+ cooperative luminescence and the presence of rare earth impurity ions. The gain cross-sections of Yb:GGG crystal as a function of excited-state population fraction P were studied. Emission spectra under 165 nm at 20 K showed there was no charge transfer luminescence in Yb:GGG. (c) 2006 Elsevier B.V. All rights reserved.
Resumo:
Methods for the estimation of zooplankton biomasses, used in the Oceanographic Research Center of Abidjan are presented. They deal with settled and displacement volumes, dry weight and ash-free dry weight, elementary carbon, nitrogen and phosphorus composition. The dry weight method is detailed: elimination of salt by a fresh water stream, preservation of dry samples at -20 degrees Celsius, rehydration during weighing. A few comments on the 'CHN' analysed values are made: at 1,100 degrees Celsius, most of the carbon is organic, only 10% of the mineral fraction being analysed.
Resumo:
Graphs of variations of zooplankton biomasses expressed as ash-free dry weight (i.e. organic matter) are presented for the 1969-1979 period. The graph of the average year shows: an enrichment season from mid-July till mid-November in which the biomass is 2.3 times higher than the rest of the year and characterized by a slight decrease of the biomass in late August or early September. The warm season is divided into a period of moderate biomass from November till February, a period of moderate biomass from November till February and a period of steady decline of the biomass till the start of the upwelling at the end of June.
Resumo:
该成果研究热带亚热带主要植物的光合作用途径和水分关系、光合作用对环境因子变化的响应及具有400多年历史的南亚热带自然林群落植物的主要生态生理特征。首次在国内应用稳定性碳同位素比技术对热带和亚热带植物以及广东鼎湖山片段保护区森林165种植物进行了光合途径的研究和鉴定,新发现36种C4植物和1种CMA植物,提出稳定碳同位素比值与植物生长习性、林地与冠层不同条件有关,可作为叶片受光状况的指标。具有多层次结构的森林中叶片形态结构、光合能力、氮和矿质元素含量、叶片水势和气孔运动的昼夜和季节变化等皆与群落微气候、植物生活型及其在冠层中的位置不同而异。受人类活动干扰的林地中,植物的这些生态生理特性发生了改变。在国内率先建立现代生理生态学整套方法,研究热带和亚热带植物个体和群体、群落结构和功能、植物光合作用与水分关系以及外界环境与植物适应性等关系。这些系统研究居国际先进水平。
Resumo:
Introducción a las contribuciones presentadas al curso "Conflictos, treguas y amnistías en el mundo antiguo", desarrollado en agosto de 1999 en el marco de los XVIII Cursos de Verano de la UPV/EHU en Donostia.