Results 11 to 20 of about 3,040,184 (131)

Eigenvalue Based Detection by Combining Eigenvector-Correlated Signal in Low SNR Environment

IET Signal Processing
Eigenvalue detection is extensively utilized in numerous applications, including spectrum sensing in cognitive radio. However, the characteristics of the Tracy–Widom (TW2) distribution and its lack of accurate close-form expression limit the detection ...
Wei Ge, Chao Yang, Yizhou Feng, Xiaofang Deng, Lin Zheng   +4 more
doaj   +3 more sources

Marchenko-Pastur law with relaxed independence conditions [PDF]

Random Matrices. Theory and Applications, 2019
We prove the Marchenko-Pastur law for the eigenvalues of $p \times p$ sample covariance matrices in two new situations where the data does not have independent coordinates.
Bryson, Jennifer, Vershynin, Roman, Zhao, Hongkai   +2 more
core   +3 more sources

Enhanced 2D Spiral Cine DENSE MRI Using Low-Rank Denoising for Improved Apparent Signal-to-Noise Ratio, Spatial Resolution, Efficiency, Accuracy, and Accessibility. [PDF]

Magn Reson Med
ABSTRACT Purpose To develop a denoising technique for displacement encoding with stimulated echoes (DENSE) MRI that improves spatial resolution, efficiency, and accuracy, and enhances accessibility by implementing DENSE MRI at 0.55 T. Methods We developed a low‐rank denoising technique, which leverages multidimensional spiral cine DENSE MRI data for ...
Shih SF, Wu Y, Li S, Ming Z, Pogosyan A, Han F, Wu HH, Finn JP, Nguyen KL, Zhong X.   +9 more
europepmc   +2 more sources

Marchenko-Pastur law for a random tensor model [PDF]

Electronic Communications in Probability, 2021
We study the limiting spectral distribution of large-dimensional sample covariance matrices associated with symmetric random tensors formed by $\binom{n}{d}$ different products of $d$ variables chosen from $n$ independent standardized random variables ...
P. Yaskov
semanticscholar   +1 more source

Sampling of non-Gaussian Ensemble Average Propagators for the simulation of diffusion magnetic resonance images. [PDF]

Magn Reson Med
Abstract Purpose (a) To design a methodology for drawing random samples of any Ensemble Average Propagator (EAP) (b) to modify the KomaMRI simulator to accommodate them as realistic spin movements to simulate diffusion MRI (dMRI) and (c) to compare these simulations with those based on the Diffusion Tensor (DT) model.
Rodríguez-Galván JR, Villacorta-Aylagas P, Merino-Caviedes S, Simmross-Wattenberg F, Castillo-Passi C, Irarrazaval P, Tristán-Vega A, Alberola-López C.   +7 more
europepmc   +2 more sources

Reducing thermal noise in high-resolution quantitative magnetic resonance imaging rotating frame relaxation mapping of the human brain at 3 T. [PDF]

NMR Biomed
Whole‐brain rotating frame relaxation (RFR) mapping is generally implemented at moderate spatial resolutions. Our results showed that applying transform domain NORDIC (T‐NORDIC) before fitting improves the reliability of RFR parameter estimations, especially at higher spatial resolution, a benefit that can be critical for clinical applications ...
Ponticorvo S, Canna A, Moeller S, Akcakaya M, Metzger GJ, Filip P, Eberly LE, Michaeli S, Mangia S.   +8 more
europepmc   +2 more sources

Local Marchenko–Pastur law at the hard edge of the sample covariance ensemble

Journal of Mathematics and Physics, 2023
Consider an N by N matrix X of complex entries with iid real and imaginary parts. We show that the local density of eigenvalues of X*X converges to the Marchenko–Pastur law on the optimal scale with probability 1.
Anastasis Kafetzopoulos, A. Maltsev
semanticscholar   +1 more source

Distribution of Singular Values of Random Band Matrices; Marchenko–Pastur Law and More [PDF]

Journal of statistical physics, 2016
We consider the limiting spectral distribution of matrices of the form $$\frac{1}{2b_{n}+1} (R + X)(R + X)^{*}$$12bn+1(R+X)(R+X)∗, where X is an $$n\times n$$n×n band matrix of bandwidth $$b_{n}$$bn and R is a non random band matrix of bandwidth $$b_{n}$$
Indrajit Jana, A. Soshnikov
semanticscholar   +2 more sources

Feasibility of strong diffusion encoding and fast readout using a plug-and-play head gradient insert at 7 T. [PDF]

Magn Reson Med
Purpose Diffusion weighting is achieved by the application of external field gradients typically for tens of milliseconds, during which the signal also substantially decays due to inherent T2 relaxation. Employing strong gradients will shorten the echo time (TE) and increase the signal‐to‐noise ratio.
Arends GC, Versteeg E, De Luca A, Marc F, Roos THM, Klomp DWJ, Froeling M, Siero JCW, Tax CMW.   +8 more
europepmc   +2 more sources

Compressed sensing reconstruction for high-SNR, rapid dissolved ¹²⁹Xe gas exchange MRI. [PDF]

Magn Reson Med
Abstract Purpose Three‐dimensional hyperpolarized 129Xe gas exchange imaging suffers from low SNR and long breath‐holds, which could be improved using compressed sensing (CS). The purpose of this work was to assess whether gas exchange ratio maps are quantitatively preserved in CS‐accelerated dissolved‐phase 129Xe imaging and to investigate the ...
Pilgrim-Morris JH, Collier GJ, Munro RS, Norquay G, Stewart NJ, Wild JM.   +5 more
europepmc   +2 more sources