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This paper provides an analysis of the linearized inverse problem in multifrequency electrical impedance tomography. We consider an isotropic conductivity distribution with a finite number of unknown inclusions with different frequency…

Numerical Analysis · Mathematics 2016-10-06 Giovanni S. Alberti , Habib Ammari , Bangti Jin , Jin-Keun Seo , Wenlong Zhang

We introduce a supervised dimensionality reduction methodology for categorical (and discretized mixed-type) data based on a density-matrix construction induced by class-conditional frequencies. Given a labeled dataset encoded in a one-hot…

Machine Learning · Statistics 2026-03-03 Raquel Bosch-Romeu , Antonio Falcó , osé-Antonio Rodríguez-Gallego

The dynamics and radiation of ultrarelativistic electrons in strong counterpropagating laser beams are investigated. Assuming that the particle energy is the dominant scale in the problem, an approximate solution of classical equations of…

Plasma Physics · Physics 2021-06-21 Q. Z. Lv , E. Raicher , C. H. Keitel , K. Z. Hatsagortsyan

We consider the continuous quantum measurement of a two-level system, for example, a single-Cooper-pair box measured by a single-electron transistor or a double-quantum dot measured by a quantum point contact. While the approach most…

Mesoscale and Nanoscale Physics · Physics 2009-10-31 Alexander N. Korotkov

I consider two problems in machine learning and statistics: the problem of estimating the joint probability density of a collection of random variables, known as density estimation, and the problem of inferring model parameters when their…

Machine Learning · Statistics 2019-10-30 George Papamakarios

We present and compare two families of ensembles of random density matrices. The first, static ensemble, is obtained foliating an unbiased ensemble of density matrices. As criterion we use fixed purity as the simplest example of a useful…

Quantum Physics · Physics 2015-10-20 Carlos Pineda , Thomas H. Seligman

We revisit the problem of model-based object recognition for intensity images and attempt to address some of the shortcomings of existing Bayesian methods, such as unsuitable priors and the treatment of residuals with a non-robust error…

Computer Vision and Pattern Recognition · Computer Science 2010-12-14 Vasileios Zografos , Bernard Buxton

The properties of the reduced density matrix describing an interval of N sites in an infinite chain of free electrons are investigated. A commuting operator is found for arbitrary filling and also for open chains. For a half filled periodic…

Statistical Mechanics · Physics 2009-11-10 Ingo Peschel

The density matrix of a spin s is fixed uniquely if the probabilities to obtain the value s upon measuring n.S are known for 4s(s+1) appropriately chosen directions n in space. These numbers are just the expectation values of the density…

Quantum Physics · Physics 2009-10-31 Jean-Pierre Amiet , Stefan Weigert

The challenge of imaging low-density objects in an electron microscope without causing beam damage is significant in modern TEM. This is especially true for life science imaging, where the sample, rather than the instrument, still…

Optics · Physics 2025-01-29 Francisco Vega Ibáñez , Jo Verbeeck

The wavefront measurement of a light beam is a complex task, which often requires a series of spatially resolved intensity measurements. For instance, a detector array may be used to measure the local phase gradient in the transverse plane…

We demonstrate that the matter density distribution in the surface region is determined well by the use of the relatively low-intensity beams that become available at the upcoming radioactive beam facilities. Following the method used in…

Nuclear Theory · Physics 2009-11-07 Akihisa Kohama , Ryoichi Seki , Akito Arima , Shuhei Yamaji

We consider deconvolution from repeated observations with unknown error distribution. So far, this model has mostly been studied under the additional assumption that the errors are symmetric. We construct an estimator for the non-symmetric…

Statistics Theory · Mathematics 2014-07-15 Johanna Kappus , Fabienne Comte

The microbunching instability has been a long-standing issue for high-brightness free-electron lasers (FELs), and is a significant show-stopper to achieving full longitudinal coherence in the x-ray regime. This paper reports the first…

In modern high-gain free-electron lasers, ultra-fast photon pulses designed for studying chemical, atomic and biological systems are generated from a serial of behaviors of high-brightness electron beam at the time-scale ranging from…

Accelerator Physics · Physics 2015-10-22 Guanglei Wang , Meng Zhang , Wei Zhang , Haixiao Deng , Xueming Yang

For a finite set of integers such that the first few gaps between its consecutive elements equal $a$, while the remaining gaps equal $b$, we study dense packings of its translates on the line. We obtain an explicit lower bound on the…

Combinatorics · Mathematics 2025-09-29 Alexander Natalchenko , Arsenii Sagdeev

We study an inverse problem for Light Sheet Fluorescence Microscopy (LSFM), where the density of fluorescent molecules needs to be reconstructed. Our first step is to present a mathematical model to describe the measurements obtained by an…

Analysis of PDEs · Mathematics 2020-08-26 Evelyn Cueva , Matias Courdurier , Axel Osses , Victor Castañeda , Benjamin Palacios , Steffen Härtel

We consider uniform moment convergence of lag-window spectral density estimates for univariate and multivariate stationary processes. Optimal rates of convergence are obtained under mild and easily verifiable conditions. Our theory…

Methodology · Statistics 2015-05-15 Wei Biao Wu , Paolo Zaffaroni

The density matrices are positively semi-definite Hermitian matrices of unit trace that describe the state of a quantum system. The goal of the paper is to develop minimax lower bounds on error rates of estimation of low rank density…

Machine Learning · Statistics 2016-04-19 Vladimir Koltchinskii , Dong Xia

In this work, we introduce an original self-consistent scheme based on the one-body reduced density matrix ($\gamma$) formalism. A significant feature of this methodology is the utilization of an optimal unitary transformation of the…

Strongly Correlated Electrons · Physics 2023-11-10 Quentin Marécat , Benjamin Lasorne , Emmanuel Fromager , Matthieu Saubanère