Velocity V

14,000,000 Leading Edge Experts on the ideXlab platform

Scan Science and Technology

Contact Leading Edge Experts & Companies

Scan Science and Technology

Contact Leading Edge Experts & Companies

The Experts below are selected from a list of 139920 Experts worldwide ranked by ideXlab platform

M J Uren - One of the best experts on this subject based on the ideXlab platform.

  • on the temperature and carrier density dependence of electron saturation Velocity in an algan gan hemt
    IEEE Transactions on Electron Devices, 2006
    Co-Authors: C H Oxley, M J Uren, A J Coates, D G Hayes
    Abstract:

    The temperature and carrier density dependence of electron intrinsic saturation Velocity (V/sub si/) in a 0.3-/spl mu/m gate length AlGaN/GaN HEMT was extracted from multibias S-parameter measurements. It was found that V/sub si/ fell rapidly with increasing sheet carrier concentration (n/sub s/), but was only a Very weak function of ambient temperature (T/sub amb/). This behaVior is consistent with the hot-phonon model of carrier transport.

  • measurements of unity gain cutoff frequency and saturation Velocity of a gan hemt transistor
    IEEE Transactions on Electron Devices, 2005
    Co-Authors: C H Oxley, M J Uren
    Abstract:

    The measured intrinsic saturation Velocity (V/sub si/) of carriers in a gallium nitride (GaN) high electron mobility transistor (HEMT) is Very much lower than that predicted using Monte Carlo simulation. A noVel method of extraction of the intrinsic saturation Velocity (V/sub si/) of carriers has been deVeloped utilising the deembedded s-parameters, thus enabling the calculation of V/sub si/ oVer a wide range of bias conditions. The method is equally applicable for gallium arsenide (GaAs) and indium phosphide (InP) based transistors. The measurements indicate for GaN-based HEMT a maximum deembedded saturation Velocity of 1.1/spl times/10/sup 5/ m/s close to the pinchoff Voltage (V/sub P/). It was found that self-heating had only a weak effect on the saturation Velocity up to junction temperatures approaching 140/spl deg/C aboVe ambient.

C H Oxley - One of the best experts on this subject based on the ideXlab platform.

  • on the temperature and carrier density dependence of electron saturation Velocity in an algan gan hemt
    IEEE Transactions on Electron Devices, 2006
    Co-Authors: C H Oxley, M J Uren, A J Coates, D G Hayes
    Abstract:

    The temperature and carrier density dependence of electron intrinsic saturation Velocity (V/sub si/) in a 0.3-/spl mu/m gate length AlGaN/GaN HEMT was extracted from multibias S-parameter measurements. It was found that V/sub si/ fell rapidly with increasing sheet carrier concentration (n/sub s/), but was only a Very weak function of ambient temperature (T/sub amb/). This behaVior is consistent with the hot-phonon model of carrier transport.

  • measurements of unity gain cutoff frequency and saturation Velocity of a gan hemt transistor
    IEEE Transactions on Electron Devices, 2005
    Co-Authors: C H Oxley, M J Uren
    Abstract:

    The measured intrinsic saturation Velocity (V/sub si/) of carriers in a gallium nitride (GaN) high electron mobility transistor (HEMT) is Very much lower than that predicted using Monte Carlo simulation. A noVel method of extraction of the intrinsic saturation Velocity (V/sub si/) of carriers has been deVeloped utilising the deembedded s-parameters, thus enabling the calculation of V/sub si/ oVer a wide range of bias conditions. The method is equally applicable for gallium arsenide (GaAs) and indium phosphide (InP) based transistors. The measurements indicate for GaN-based HEMT a maximum deembedded saturation Velocity of 1.1/spl times/10/sup 5/ m/s close to the pinchoff Voltage (V/sub P/). It was found that self-heating had only a weak effect on the saturation Velocity up to junction temperatures approaching 140/spl deg/C aboVe ambient.

Vassanelli C. - One of the best experts on this subject based on the ideXlab platform.

  • Renal arterial pulsatility predicts progression of chronic kidney disease in chronic heart failure patients.
    2013
    Co-Authors: Cicoira M, Conte L, Rossi A, Bonapace S, D'agostini G, Dugo C, Lupo A, Ronco C, Vassanelli C.
    Abstract:

    Chronic kidney disease (CKD) is frequent in CHF patients, and is associated with adVerse prognosis. The pathophysiology of kidney dysfunction in CHF patients is multifactorial and has not yet been clearly defined. In CKD it has recently been reported that the assessment of renal Doppler pulsatility index (PI), a Doppler deriVed index dependent on downstream renal artery resistance and stiffness, correlates with the degree of intrarenal damage and is a predictor of subsequent renal function. In order to inVestigate whether an increased PI may correlate with the progression of CKD in CHF, 68 consecutiVe patients underwent renal ultrasonography. The focal zone of the pulsed Doppler was positioned at the leVel of the right renal segmental arteries. We determined the peak systolic Velocity (V max), the end-diastolic Velocity (V min) and the mean Velocity (V mean) in order to calculate the dimensionless PI Value: (V max − V min) / V mean. Renal function was assessed at baseline and after 6 months of follow-up. Estimated glomerular filtration rate (eGFR) was calculated according to the CKD-EPI equation

  • Renal arterial pulsatility predicts progression of chronic kidney disease in chronic heart failure patients.
    'Elsevier BV', 2012
    Co-Authors: Cicoira M, Conte L, Rossi A, Bonapace S, Dugo C, Lupo A, Ronco C, Vassanelli C.
    Abstract:

    Chronic kidney disease (CKD) is frequent in CHF patients, and is associated with adVerse prognosis. In CKD it has recently been reported that the assessment of renal Doppler pulsatility index (PI) correlates with the degree of intrarenal damage and is a predictor of subsequent renal function. In order to inVestigate whether an increased PI may correlate with the progression of CKD in CHF, 68 consecutiVe patients underwent renal ultrasonography. The focal zone of the pulsed Doppler was positioned at the leVel of the right renal segmental arteries. We determined the peak systolic Velocity (V max), the end-diastolic Velocity (V min) and the mean Velocity (V mean) in order to calculate the dimensionless PI Value: (V max 12V min)/V mean. Renal function was assessed at baseline and after 6 months of follow-up. Estimated glomerular filtration rate (eGFR) was calculated according to the CKD-EPI equation. Absolute and percent difference between follow-up and baseline eGFR, (\u394eGFR and \u394eGFR%) and s-creatinine (\u394s-Creat, \u394s-Creat%) were calculated. Patients with PI aboVe median (1.47) were significantly older, had higher NYHA class and left Ventricular Volumes and lower ejection fraction as compared with patients with low PI. At follow-up, patients with PI aboVe median had on aVerage a worsening of eGFR and s-creatinine. When diViding the study population according to median PI, we found that patients with higher PI leVels had a significant worsening of CKD stage as compared with patients with lower PI. The main finding of the present study was that a high renal PI proVed to be the only independent predictor of decline in kidney function in CHF patients oVer a six-month follow-up

Françoise Courboulex - One of the best experts on this subject based on the ideXlab platform.

Cicoira M - One of the best experts on this subject based on the ideXlab platform.

  • Renal arterial pulsatility predicts progression of chronic kidney disease in chronic heart failure patients.
    2013
    Co-Authors: Cicoira M, Conte L, Rossi A, Bonapace S, D'agostini G, Dugo C, Lupo A, Ronco C, Vassanelli C.
    Abstract:

    Chronic kidney disease (CKD) is frequent in CHF patients, and is associated with adVerse prognosis. The pathophysiology of kidney dysfunction in CHF patients is multifactorial and has not yet been clearly defined. In CKD it has recently been reported that the assessment of renal Doppler pulsatility index (PI), a Doppler deriVed index dependent on downstream renal artery resistance and stiffness, correlates with the degree of intrarenal damage and is a predictor of subsequent renal function. In order to inVestigate whether an increased PI may correlate with the progression of CKD in CHF, 68 consecutiVe patients underwent renal ultrasonography. The focal zone of the pulsed Doppler was positioned at the leVel of the right renal segmental arteries. We determined the peak systolic Velocity (V max), the end-diastolic Velocity (V min) and the mean Velocity (V mean) in order to calculate the dimensionless PI Value: (V max − V min) / V mean. Renal function was assessed at baseline and after 6 months of follow-up. Estimated glomerular filtration rate (eGFR) was calculated according to the CKD-EPI equation

  • Renal arterial pulsatility predicts progression of chronic kidney disease in chronic heart failure patients.
    'Elsevier BV', 2012
    Co-Authors: Cicoira M, Conte L, Rossi A, Bonapace S, Dugo C, Lupo A, Ronco C, Vassanelli C.
    Abstract:

    Chronic kidney disease (CKD) is frequent in CHF patients, and is associated with adVerse prognosis. In CKD it has recently been reported that the assessment of renal Doppler pulsatility index (PI) correlates with the degree of intrarenal damage and is a predictor of subsequent renal function. In order to inVestigate whether an increased PI may correlate with the progression of CKD in CHF, 68 consecutiVe patients underwent renal ultrasonography. The focal zone of the pulsed Doppler was positioned at the leVel of the right renal segmental arteries. We determined the peak systolic Velocity (V max), the end-diastolic Velocity (V min) and the mean Velocity (V mean) in order to calculate the dimensionless PI Value: (V max 12V min)/V mean. Renal function was assessed at baseline and after 6 months of follow-up. Estimated glomerular filtration rate (eGFR) was calculated according to the CKD-EPI equation. Absolute and percent difference between follow-up and baseline eGFR, (\u394eGFR and \u394eGFR%) and s-creatinine (\u394s-Creat, \u394s-Creat%) were calculated. Patients with PI aboVe median (1.47) were significantly older, had higher NYHA class and left Ventricular Volumes and lower ejection fraction as compared with patients with low PI. At follow-up, patients with PI aboVe median had on aVerage a worsening of eGFR and s-creatinine. When diViding the study population according to median PI, we found that patients with higher PI leVels had a significant worsening of CKD stage as compared with patients with lower PI. The main finding of the present study was that a high renal PI proVed to be the only independent predictor of decline in kidney function in CHF patients oVer a six-month follow-up