Results 201 to 210 of about 1,042 (247)
The Huang–Yang Formula for the Low‐Density Fermi Gas: Upper Bound
ABSTRACT We study the ground state energy of a gas of spin 1/2$1/2$ fermions with repulsive short‐range interactions. We derive an upper bound that agrees, at low density ϱ$\varrho$, with the Huang–Yang conjecture. The latter captures the first three terms in an asymptotic low‐density expansion, and in particular the Huang–Yang correction term of order
Emanuela L. Giacomelli +3 more
wiley +1 more source
Invariant Measure and Universality of the 2D Yang–Mills Langevin Dynamic
ABSTRACT We prove that the Yang–Mills (YM) measure for the trivial principal bundle over the two‐dimensional torus, with any connected, compact structure group, is invariant for the associated renormalised Langevin dynamic. Our argument relies on a combination of regularity structures, lattice gauge‐fixing and Bourgain's method for invariant measures ...
Ilya Chevyrev, Hao Shen
wiley +1 more source
Edge‐Length Preserving Embeddings of Graphs Between Normed Spaces
ABSTRACT The concept of graph embeddability, initially formalized by Belk and Connelly and later expanded by Sitharam and Willoughby, extends the question of embedding finite metric spaces into a given normed space. A finite simple graph G = ( V , E ) is said to be ( X , Y )‐embeddable if any set of induced edge lengths from an embedding of G into a ...
Sean Dewar +3 more
wiley +1 more source
Machine Learning Approaches to Forecast the Realized Volatility of Crude Oil Prices
ABSTRACT This paper presents an evaluation of the accuracy of machine learning (ML) techniques in forecasting the realized volatility of West Texas Intermediate (WTI) crude oil prices. We compare several ML algorithms, including regularization, regression trees, random forests, and neural networks, to several heterogeneous autoregressive (HAR) models ...
Talha Omer +3 more
wiley +1 more source
A Numerical Alternative to MR Thermometry for Safety Validation of Multi‐Channel RF Transmit Coils
ABSTRACT Purpose This study proposes a numerical technique to estimate peak local specific absorption rate (SAR) uncertainty of multi‐channel RF coils during the process of safety validation as an alternative to experimental temperature and electric‐field measurements, and demonstrates its use to enable human studies at 10.5 T.
Alireza Sadeghi‐Tarakameh +14 more
wiley +1 more source
Phase‐Pole‐Free Images and Smooth Coil Sensitivity Maps by Regularized Nonlinear Inversion
ABSTRACT Purpose Phase singularities are a common problem in image reconstruction with auto‐calibrated sensitivities due to an inherent ambiguity of the estimation problem. The purpose of this work is to develop a method for detecting and correcting phase poles in non‐linear inverse (NLINV) reconstruction of MR images and coil sensitivity maps ...
Moritz Blumenthal, Martin Uecker
wiley +1 more source
ABSTRACT While recent Anderson acceleration (AA) convergence theory [Pollock et al., IMA Num. An., 2021] requires that the AA optimization norm match the Hilbert space norm associated with the fixed point operator, in implementations the ℓ2$$ {\ell}^2 $$ norm is the most common choice. So far there is little research done regarding this discrepancy. To
Elizabeth Hawkins, Leo G. Rebholz
wiley +1 more source
Abstract In light of the centennial of the Schrödinger equation, this article addresses the popular idea that quantum mechanical effects play an important role in biological systems. We start by defining what is qualified as a quantum effect. We then clarify the idea that quantum mechanical tunneling is a crucial factor in enzyme catalysis.
Aoxuan Zhang, Arieh Warshel
wiley +1 more source
Geometric Planted Matchings Beyond the Gaussian Model
ABSTRACT We consider the problem of recovering an unknown matching between a set of n$$ n $$ randomly placed points in ℝd$$ {\mathbb{R}}^d $$ and random perturbations of these points. This can be seen as a model for particle tracking and more generally, entity resolution.
Lucas R. Schwengber, Roberto I. Oliveira
wiley +1 more source
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An invariant subspace method for large-scale algebraic Riccati equation
Applied Numerical Mathematics, 2010The linear time-invariant dynamical system \[ \begin{cases} \dot x(t) = Ax(t) + Bu(t),\quad x(0)=x_0,\\ y(t) ~=~ Cx(t), \end{cases} \tag{S} \] where \(A\), \(B\), \(C\) are matrices, is considered. In practice the square matrix \(A\) is \(n \times n\), and \(n\) is very large (of the order \(10^5\) or \(10^6\)).
Amodei, Luca, Buchot, Jean-Marie
exaly +4 more sources

