نتایج جستجو برای: gradient ratio

تعداد نتایج: 619653  

Journal: :AJNR. American journal of neuroradiology 2001
C A Szabo J Xiong J L Lancaster L Rainey P Fox

BACKGROUND AND PURPOSE Amygdalar and hippocampal volume measurements indicate a right-greater-than-left asymmetry for right-handed normal participants in most studies. The purpose of this study was to compare amygdalar and hippocampal volume ratios between right- and left-handed participants. METHODS Amygdalar and hippocampal volume measurements were performed in 34 (20 right-handed and 14 le...

2005
Gary F. Sholler John F. Keane

We evaluated dilation technique (n=80) and aortic valve morphology by two-dimensional echocardiography (n = 58) in patients with congenital aortic valve stenosis to determine their influence on outcome. Patients' age (9 ± 9 years; range, 1 day-39 years) and a history of surgical valvotomy did not influence outcome. The number of dilating balloons (one vs. two) and balloon:annulus ratio based on...

2015
Aviv Tamar Yonatan Glassner Shie Mannor

Conditional Value at Risk (CVaR) is a prominent risk measure that is being used extensively in various domains. We develop a new formula for the gradient of the CVaR in the form of a conditional expectation. Based on this formula, we propose a novel sampling-based estimator for the gradient of the CVaR, in the spirit of the likelihood-ratio method. We analyze the bias of the estimator, and prov...

Journal: :CoRR 2017
Matteo Pirotta Marcello Restelli

In this paper we propose a novel approach to automatically determine the batch size in stochastic gradient descent methods. The choice of the batch size induces a trade-off between the accuracy of the gradient estimate and the cost in terms of samples of each update. We propose to determine the batch size by optimizing the ratio between a lower bound to a linear or quadratic Taylor approximatio...

Journal: :Circulation 2003
Jean-Luc Monin Jean-Paul Quéré Mehran Monchi Hélène Petit Serge Baleynaud Christophe Chauvel Camélia Pop Patrick Ohlmann Claude Lelguen Patrick Dehant Christophe Tribouilloy Pascal Guéret

BACKGROUND The prognostic value of dobutamine stress hemodynamic data in the setting of low-gradient aortic stenosis has been addressed in small, single-center studies. Larger studies are needed to define the criteria for selecting the patients who will benefit from valve replacement. METHODS AND RESULTS Six centers prospectively enrolled 136 patients with aortic stenosis (96 men; median age,...

Journal: :Magnetic resonance in medicine 2007
Jon-Fredrik Nielsen Krishna S Nayak

A technique for rapid in-plane phase-contrast imaging with high signal-to-noise ratio (SNR) is described. Velocity-encoding is achieved by oscillating the readout gradient, such that each 2DFT phase-encode is acquired three times following a single RF slice-selective excitation. Three images are reconstructed, from which both flow velocity and local resonance offset are calculated. This techniq...

Journal: :Physical review letters 2001
G T Hoang C Bourdelle X Garbet G Giruzzi T Aniel M Ottaviani W Horton P Zhu R V Budny

In Tore Supra plasmas with fast wave electron heating, a critical threshold in the electron temperature gradient (inverted DeltaT(e)) is clearly observed, i.e., a finite value of inverted DeltaT(e) for which the turbulent heat diffusivity vanishes. The radial profile of this critical gradient is experimentally determined from a set of discharges characterized by similar plasma parameters with f...

2008
JOSÉ A. CARRILLO LEI NI

We show that gradient shrinking, expanding or steady Ricci solitons have potentials leading to suitable reference probability measures on the manifold. For shrinking solitons, as well as expanding soltions with nonnegative Ricci curvature, these reference measures satisfy sharp logarithmic Sobolev inequalities with lower bounds characterized by the geometry of the manifold. The geometric invari...

Journal: :The Journal of the Acoustical Society of America 2002
D A Geller G W Swift

The theory for thermoacoustic mixture separation is extended to include the effects of a nonzero concentration gradient. New data are presented, which are in excellent agreement with this theory. The maximum concentration gradient which may be achieved in a binary mixture of gases through this separation process is intrinsically limited by the fractional pressure amplitude, by the tidal displac...

Journal: :Journal of chromatography. A 2006
Melvin R Euerby Federico Scannapieco Hans-Jürgen Rieger Imre Molnar

An optimization strategy for ternary solvent-strength gradient elution RP chromatography is described in which a two-dimensional model of gradient time (2 levels) against ternary proportions of organic modifiers (4 levels) was constructed. From the resolution surface the optimum ratio of organic modifiers could be selected. Excellent retention time and acceptable peak width and resolution simul...

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