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Search Results: 1 - 10 of 7319 matches for " v/q mismatch "
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Fisiopatología del intercambio gaseoso en el SDRA
Fernández Fernández,R.;
Medicina Intensiva , 2006,
Abstract: ards is produced in a pulmonary edema picture due to increased vascular patency. in this way, the initial alteration consists in an alveolar occupation due to protein rich edema. this occupation reduces the alveolar surface available for gas exchange, increasing the pulmonary areas with poor or null v/q ratio. as ards progresses, vascular phenomena occur that affect the gas exchange differently, giving rise to heterogeneity in the v/q ratio. this situation worsens due to the appearance of areas with null ventilation in relationship with the appearance of atelectasis in lung dependent zones. all these factors form the hypoxemia picture refractory to the increase of the inspired oxygen fraction characteristic of this clinical entity. in this article, we make a review of these physiological mechanisms and the effect on the oxygenation of different ventilatory and drug maneuvers.
Fisiopatología del intercambio gaseoso en el SDRA Pathophysiology of gas exchangein ARDS
R. Fernández Fernández
Medicina Intensiva , 2006,
Abstract: En el síndrome de distrés respiratorio agudo (SDRA) se produce un cuadro de edema pulmonar por aumento de la permeabilidad vascular. De esta forma, la alteración inicial consiste en una ocupación alveolar por edema rico en proteínas, esta ocupación reduce la superficie alveolar disponible para el intercambio gaseoso, incrementando las áreas pulmonares con pobre o nula relación V/Q. A medida que el SDRA progresa, se producen fenómenos vasculares que afectan de forma diferente al intercambio gaseoso, dando lugar a heterogeneidad en la relación V/Q. Esta situación se agrava por la aparición de zonas con nula ventilación en relación con la aparición de atelectasias en zonas dependientes del pulmón. Todos estos factores configuran el cuadro de hipoxemia refractaria al aumento de la fracción de oxígeno inspirado característica de esta entidad clínica. En el presente artículo se hace un repaso de estos mecanismos fisiológicos y del efecto sobre la oxigenación de diferentes maniobras ventilatorias y farmacológicas. ARDS is produced in a pulmonary edema picture due to increased vascular patency. In this way, the initial alteration consists in an alveolar occupation due to protein rich edema. This occupation reduces the alveolar surface available for gas exchange, increasing the pulmonary areas with poor or null V/Q ratio. As ARDS progresses, vascular phenomena occur that affect the gas exchange differently, giving rise to heterogeneity in the V/Q ratio. This situation worsens due to the appearance of areas with null ventilation in relationship with the appearance of atelectasis in lung dependent zones. All these factors form the hypoxemia picture refractory to the increase of the inspired oxygen fraction characteristic of this clinical entity. In this article, we make a review of these physiological mechanisms and the effect on the oxygenation of different ventilatory and drug maneuvers.
A Novel Approach to Blind I/Q Mismatch & Carrier Offset Compensation  [PDF]
Sunita Panda, Siba P. Panigrahi, Sasmita Kumari Padhy
Journal of Signal and Information Processing (JSIP) , 2011, DOI: 10.4236/jsip.2011.21003
Abstract: This paper proposes a novel approach for I/Q mismatch compensation. Simulation results proves the superior per-formance of the proposed technique.
基于静态等值的在线实时电压稳定性分析
付英李兴源,宋永华
电力系统自动化 , 1997,
Abstract: 在综合分析电压稳定及等值方法的基础上,结合电力系统自身的特点和要求,基于电压稳定的基本概念提出了一种静态等值的新方法,利用这种方法可以迅速作出Q—V,P—V或P—Q曲线,适合于在线实时分析电压的稳定性,并通过数字仿真证明了该方法的有效性。
Blind I/Q Signal Separation-Based Solutions for Receiver Signal Processing
Valkama Mikko,Renfors Markku,Koivunen Visa
EURASIP Journal on Advances in Signal Processing , 2005,
Abstract: This paper introduces some novel digital signal processing (DSP)-based approaches to some of the most fundamental tasks of radio receivers, namely, channel equalization, carrier synchronization, and I/Q mismatch compensation. The leading principle is to show that all these problems can be solved blindly (i.e., without training signals) by forcing the I and Q components of the observed data as independent as possible. Blind signal separation (BSS) is then introduced as an efficient tool to carry out these tasks, and simulation examples are used to illustrate the performance of the proposed approaches. The main application area of the presented carrier synchronization and I/Q mismatch compensation techniques is in direct-conversion type receivers, while the proposed channel equalization principles basically apply to any radio architecture.
New Evolving Directions for Device Performance Optimization Based Integration of Compound Semiconductor Devices on Silicon
Partha Mukhopadhyay,Palash Das,Edward Y. Chang,Dhrubes Biswas
Journal of Nano- and Electronic Physics , 2011,
Abstract: Rapid advances in Compound Semiconductor (CS) technologies over last several decades have lead to high performances in peak power, power added efficiency (PAE) and linearity, but these devices are not amenable for integration on mainstream silicon technologies. A strategic direction has been presented for the growth of CS devices on silicon with challenges abounding in scalability, compatibility and cost effectiveness while extracting optimized device performances. The approach at IIT Kharagpur has been simulation and experimental development of customized metamorphic buffers that are scalable and compatible to silicon without sacrificing any CS performances, primarily for electronic applications. This has evolved into a new strategic paradigm for performance optimization of seemingly competing and disparate properties which otherwise will not be supported by conventional process technologies. Simulation of these next generation structures reveals assimilation of superior device properties, with a novel five Indium content composite channel MHEMT indicating improvements over existing composite channel MHEMT in terms of linearity and higher current performances.
VERY LOW PROBABILITY LUNG SCAN FINDINGS: A NEED FOR CHANGE
Daniel F Worsley,Edward B Silberstein,Abass Alavi,A Elgazzar
Iranian Journal of Nuclear Medicine , 1997,
Abstract: This study was conducted to determine the prevalence of PE in patients with V/Q scans interpreted as representing a very low probability (VLP) of PE (1-3 small segmental perfusion defects with a normal chest radiograph). An analysis of the entire data set obtained during the PIOPED study was performed. Of the total of 1,359 patients in whom the presence or absence of PE was confirmed, 80 (6%) patients had the VLP pattern. Only 2 of 80 patients (2.5%) had PE, both patients had partially occlusive thrombus within a single lower lobe segment. Both patients were also referred from surgicl wards, had a history of previous surgery within 3 months and a history of immobilization within 3 days prior to scan. Both patients with PE and VLP patterns had intermediate pretest odds. However, 36 patients with similar lung scan findings and no evidence of PE also had intermediate pretest odds. The remaining 40 patients had low pretest odds (two patients did not have pretest odds entered into the data base). We conclude that the very law probability interpretation criterion is a valid diagnostic category and should be a separate part of any schema for interpreting V/Q lung scans. The pretest clinical likelihood of PE did not change the post test probability of PE for very low probability lung scan interpretation as they did for low, intermediate or high probability lung scan interpretations.
La estabilidad de la tensión de los sistemas eléctricos de potencia utilizando el programa “PSAF”
Boza Valerino,Juan Gualberto; Estrada Nú?ez,Raúl; Herrera Díaz,Annavell; Barreto Banderas,Moisés;
Ingenier?-a Energ??tica , 2012,
Abstract: in the work is carried out a brief historical review on the different programs used in the studies of the steady state and transient operation in the electric union. the results exposed are obtained by means of the program power systems analysis framework (psaf), acquired recently for the electricity engineering and project-making enterprise (inel). emphasis is made in the static methods employees for the voltage stability analysis: p-v curves, v-q curves and the modal analysis. a procedure is applied in the work to the, system of 14 bus of the ieee. the procedure has been developed assisting to the information, the approaches of voltage stability and the results that it provides the program psaf. the results obtained with the case study used are considered appropriate when being validated with cases of the revised literature.
QqQq'' States in Chiral SU(3) Quark Model
Qq^- Q ^- q' States in Chiral SU(3) Quark Model

ZHANG Hai-Xia,ZHANG Min,ZHANG Zong-Ye,
张海霞
,张敏,张宗烨

中国物理快报 , 2007,
Abstract: We study the masses of QqQq' states with JPC=0++, 1++, 1+- and 2++ in the chiral SU(3) quark model, where Q is the heavy quark (c or b) and q (q') is the light quark (u, d or s). According to our numerical results, it is improbable to make the interpretation of cncn]1++ and cncn]2++ (n=u, d) states as X(3872) and Y(3940), respectively. However, it is interesting to find the tetraquarks in the bqbq' system.
脂肪组织RNA提取方法的改进
吴江维,杨公社,孙超
生物技术通报 , 2005,
Abstract: 本试验以猪脂肪组织为材料,应用TRIzol、V-gene、H.Q.&.Q三种总RNA提取试剂盒分别提取脂肪组织RNA,发现直接按照试剂盒说明书操作提取的RNA效果不理想。通过反复试验,分别改进了提取过程中的部分操作步骤,结果表明:三种试剂盒操作方法改进后与改进前相比,提取RNA的纯度和得率表现为差异极显着(P<0.01);三种试剂盒操作方法改进后提取RNA的纯度差异不显着(P>0.05),但在得率方面,Trizol比其它两种高,表现为差异极显着(P<0.01)。三种试剂盒操作方法改进后提取的RNA经RT-PCR扩增猪-βactin基因,电泳结果显示,扩增条带清晰、特异,说明提取的RNA完全符合后续的分子生物学实验要求。
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