Doppler vortography : detection and quantification of the vortices in the left ventricle

Nous proposons une nouvelle méthode pour quantifier la vorticité intracardiaque (vortographie Doppler), basée sur l’imagerie Doppler conventionnelle. Afin de caractériser les vortex, nous utilisons un indice dénommé « Blood Vortex Signature (BVS) » (Signature Tourbillonnaire Sanguine) obtenu par l’application d’un filtre par noyau basé sur la covariance. La validation de l’indice BVS mesuré par vortographie Doppler a été réalisée à partir de champs Doppler issus de simulations et d’expériences in vitro. Des résultats préliminaires obtenus chez des sujets sains et des patients atteints de complications cardiaques sont également présentés dans ce mémoire. Des corrélations significatives ont été observées entre la vorticité estimée par vortographie Doppler et la méthode de référence (in silico: r2 = 0.98, in vitro: r2 = 0.86). Nos résultats suggèrent que la vortographie Doppler est une technique d’échographie cardiaque prometteuse pour quantifier les vortex intracardiaques. Cet outil d’évaluation pourrait être aisément appliqué en routine clinique pour détecter la présence d’une insuffisance ventriculaire et évaluer la fonction diastolique par échocardiographie Doppler.

High resolution optogalvanic study in nitrogen discharge

Doppler limited high resolution spectrum in the wavelength region 17224 to 17236 cm−1 of the first positive system (B 3Π g −A 3Σ u + ) of the N2 molecule is recorded by optogalvanic spectroscopic technique using a single mode ring dye laser. It is observed that the intensity and line width of the rotational line increase with the discharge current. Dependence of the collision broadening coefficient on the current was also evaluated.

Hyperfine structure and isotopic shift of the n^2 P_J levels (n = 7-10) of ^203,205 TI measured by Doppler-free two-photon spectroscopy

Using Doppler-free two-photon absorption spectroscopy, we have measured hyperfine splitting constants as well as isotopic level shifts of the 6s^2 np ^2 P_l/2,3/2 states in (n=7-10) in ^203 TI and ^205 TI. Calculations for hyperfine constants and electron density at the nucleus have been performed by the Dirac-Fock method. The experimental results are compared with these calculations as well as with the predictions of the semiempirical theory.

Correlación entre los hallazgos de índice de pulsatilidad en Doppler de arterias uterinas durante primer y segundo trimestre de gestación

Se trata de un estudio prospectivo en el cual se compararon los resultados del índice de pulsatilidad y Notch en Doppler de arterias uterinas en primer y segundo trimestre de gestación con el objetivo de reconocer si los valores alterados en segundo trimestre se correlacionaban con los encontrados en primer trimestre y de esta manera implementar tamizaje mas tempranamente con Doppler de arterias uterinas.

Evaluación características operativas: ecografía 2D y Doppler color para diagnóstico de acretismo placentario, clínica universitaria colombia, bogotá.

La placenta ácreta es la implantación anómala de la placenta en la pared uterina. Se presenta en 0.9% de todos los embarazos; actualmente es una de las causas más importantes de morbimortalidad materna. Ecografía 2D y Doppler placentario son métodos diagnósticos de primera y segunda línea. Objetivo: Evaluar la utilidad diagnóstica de ecográfica 2D y Doppler color Placentario para diagnóstico de acretismo placentario en gestantes con factores de riesgo comparándolos con diagnóstico clínico e histopatológico; y determinar incidencia de acretismo placentario en población asistente a Clínica Universitaria Colombia. Metodología: Estudio de evaluación de tecnología diagnóstica. Entre Agosto a Noviembre de 2010 se incluyeron 53 gestantes entre 24 y 40 semanas de gestación con factores de riesgo para acretismo placentario. El desempeño diagnóstico de las pruebas se determinará por sensibilidad, especificidad, valores predictivos positivo y negativo. Las características demográficas de las pacientes y resultados neonatales se analizaron mediante proporción, media y rango. Resultados: Se determinó incidencia de acretismo placentario en 4,54% de las gestantes con presencia de factores de riesgo para esta patología. Los datos hasta el momento no nos permiten calcular valores de desempeño diagnóstico. Un caso termino en histerectomía por acretismo placentario. Conclusión: Con los datos preliminares registramos una incidencia de acretismo placentario de 1 en 22 pacientes. Revisión de literatura sustenta la necesidad de realización diagnostica prenatal que impacte en la morbimortalidad materna y fetal, haciendo necesario la evaluación diagnostica valida de herramientas como el Eco 2D y Doppler color en población a riesgo.

Evaluación características operativas : ecografía 2d y doppler color para diagnóstico de acretismo placentario, clínica universitaria Colombia, Bogotá

La placenta ácreta es la implantación anómala de la placenta en la pared uterina. Se presenta en 0.9% de todos los embarazos; actualmente es una de las causas más importantes de morbimortalidad materna. Ecografía 2D y Doppler placentario son métodos diagnósticos de primera y segunda línea. Objetivo: Evaluar la utilidad diagnóstica de ecográfica 2D y Doppler color Placentario para diagnóstico de acretismo placentario en gestantes con factores de riesgo comparándolos con diagnóstico clínico e histopatológico; y determinar incidencia de acretismo placentario en población asistente a Clínica Universitaria Colombia. Metodología: Estudio de evaluación de tecnología diagnóstica. Entre Agosto a octubre 2011 se incluyeron 137 gestantes entre 24 y 40 semanas de gestación con factores de riesgo para acretismo placentario. El desempeño diagnóstico de las pruebas se determinará por sensibilidad, especificidad, valores predictivos positivo y negativo. Las características demográficas de las pacientes y resultados neonatales se analizaron mediante proporción, media y rango. Resultados: En un grupo de 137 pacientes con factores de riesgo de acretismo placentario analizadas se obtuvo el dato de 119 en cuanto a la finalización del embarazo. Se observaron 4 casos con diagnóstico clínico e histopatológico de acretismo placentario, evidenciando una prevalencia del 2,9%. La ecografía 2D y Doppler en la detección de acretismo placentario con un nivel de confianza del 95%, presentaron sensibilidad del 100% (IC95% 87,5-100) y especificidad de 100% (IC95% 99,6-100). Conclusión: Con los datos analizados registramos una incidencia de acretismo placentario de 4 en 132 pacientes. Revisión de literatura sustenta la necesidad de realización diagnostica prenatal que impacte en la morbimortalidad materna y fetal, haciendo necesario la evaluación diagnostica valida de herramientas como el Eco 2D y Doppler color en población a riesgo.

Avaliação de Índices de Função Sistólica do Ventrículo Esquerdo em Canis lupus familiaris por Técnica de Ecocardiografia Doppler

A função cardíaca é fortemente condicionada pela mioarquitectura do coração, pelo que o estudo da relação morfologia-função ventricular nos mamíferos é de grande importância no diagnóstico e tratamento de patologias cardíacas. O cálculo dos volumes cardíacos durante todo o ciclo cardíaco tem uma importância fundamental para o estudo da função ventricular e para a definição dos padrões hemodinâmicos. Foi objectivo deste trabalho, o estudo de índices de função sistólica ventricular esquerda, em 25 cães (Cannis lupus familiaris), através da utilização de diferentes técnicas ecocardiográficas, como o Modo M, ecocardiografia bidimensional, Doppler tecidular e a ecocardiografia de contraste. Foi utilizado contraste ultrasonográfico, para melhorar a definição do endocárdio e possibilitar maior rigor no cálculo dos volumes ventriculares, e na avaliação da função ventricular sisto-diastólica global e regional. Os resultados apresentados foram sujeitos a tratamento estatístico com software Analyze-it. O Doppler tecidular mostrou ser um método robusto para avaliar a função sistólica. A ecocardiografia de contraste permitiu não só obter uma melhor definição endocárdica, como obter valores de fracção de ejecção com diferença estatisticamente significativa. Como os três métodos utilizados avaliam diferentes aspectos da função sistólica, função ventricular radial, circunferencial e longitudinal, não podem ser comparados directamente entre si.

Broadening our scope: Supporting the need for oral deaf educators in rural communities

This paper supports the need for oral deaf educators in rural communities and their importance in the education of children who are deaf and hard of hearing.

Theory and observations of ice particle evolution in cirrus using Doppler radar: evidence for aggregation

Vertically pointing Doppler radar has been used to study the evolution of ice particles as they sediment through a cirrus cloud. The measured Doppler fall speeds, together with radar-derived estimates for the altitude of cloud top, are used to estimate a characteristic fall time tc for the `average' ice particle. The change in radar reflectivity Z is studied as a function of tc, and is found to increase exponentially with fall time. We use the idea of dynamically scaling particle size distributions to show that this behaviour implies exponential growth of the average particle size, and argue that this exponential growth is a signature of ice crystal aggregation.

The accuracy of Doppler radar wind retrievals using insects as targets

Insect returns from the UK's Doppler weather radars were collected in the summers of 2007 and 2008, to ascertain their usefulness in providing information about boundary layer winds. Such observations could be assimilated into numerical weather prediction models to improve forecasts of convective showers before precipitation begins. Significant numbers of insect returns were observed during daylight hours on a number of days through this period, when they were detected at up to 30 km range from the radars, and up to 2 km above sea level. The range of detectable insect returns was found to vary with time of year and temperature. There was also a very weak correlation with wind speed and direction. Use of a dual-polarized radar revealed that the insects did not orient themselves at random, but showed distinct evidence of common orientation on several days, sometimes at an angle to their direction of travel. Observation minus model background residuals of wind profiles showed greater bias and standard deviation than that of other wind measurement types, which may be due to the insects' headings/airspeeds and to imperfect data extraction. The method used here, similar to the Met Office's procedure for extracting precipitation returns, requires further development as clutter contamination remained one of the largest error contributors. Wind observations derived from the insect returns would then be useful for data assimilation applications.

Comparison of balloon-carried atmospheric motion sensors with Doppler lidar turbulence measurements

Magnetic sensors have been added to a standard weather balloon radiosonde package to detect motion in turbulent air. These measure the terrestrial magnetic field and return data over the standard uhf radio telemetry. Variability in the magnetic sensor data is caused by motion of the instrument package. A series of radiosonde ascents carrying these sensors has been made near a Doppler lidar measuring atmospheric properties. Lidar-retrieved quantities include vertical velocity (w) profile and its standard deviation (w). w determined over 1 h is compared with the radiosonde motion variability at the same heights. Vertical motion in the radiosonde is found to be robustly increased when w>0.75 m s−1 and is linearly proportional to w. ©2009 American Institute of Physics

Evaluation of a large-eddy model simulation of a mixed-phase altocumulus cloud using microwave radiometer, lidar and Doppler radar data

Using the Met Office large-eddy model (LEM) we simulate a mixed-phase altocumulus cloud that was observed from Chilbolton in southern England by a 94 GHz Doppler radar, a 905 nm lidar, a dual-wavelength microwave radiometer and also by four radiosondes. It is important to test and evaluate such simulations with observations, since there are significant differences between results from different cloud-resolving models for ice clouds. Simulating the Doppler radar and lidar data within the LEM allows us to compare observed and modelled quantities directly, and allows us to explore the relationships between observed and unobserved variables. For general-circulation models, which currently tend to give poor representations of mixed-phase clouds, the case shows the importance of using: (i) separate prognostic ice and liquid water, (ii) a vertical resolution that captures the thin layers of liquid water, and (iii) an accurate representation the subgrid vertical velocities that allow liquid water to form. It is shown that large-scale ascents and descents are significant for this case, and so the horizontally averaged LEM profiles are relaxed towards observed profiles to account for these. The LEM simulation then gives a reasonable. cloud, with an ice-water path approximately two thirds of that observed, with liquid water at the cloud top, as observed. However, the liquid-water cells that form in the updraughts at cloud top in the LEM have liquid-water paths (LWPs) up to half those observed, and there are too few cells, giving a mean LWP five to ten times smaller than observed. In reality, ice nucleation and fallout may deplete ice-nuclei concentrations at the cloud top, allowing more liquid water to form there, but this process is not represented in the model. Decreasing the heterogeneous nucleation rate in the LEM increased the LWP, which supports this hypothesis. The LEM captures the increase in the standard deviation in Doppler velocities (and so vertical winds) with height, but values are 1.5 to 4 times smaller than observed (although values are larger in an unforced model run, this only increases the modelled LWP by a factor of approximately two). The LEM data show that, for values larger than approximately 12 cm s(-1), the standard deviation in Doppler velocities provides an almost unbiased estimate of the standard deviation in vertical winds, but provides an overestimate for smaller values. Time-smoothing the observed Doppler velocities and modelled mass-squared-weighted fallspeeds shows that observed fallspeeds are approximately two-thirds of the modelled values. Decreasing the modelled fallspeeds to those observed increases the modelled IWC, giving an IWP 1.6 times that observed.