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Nonlinear optical frequency conversion, where optical fields interact with a nonlinear medium to generate new frequencies, is a key phenomenon in modern photonic systems. However, a major challenge with these techniques lies in the…

Materials Science · Physics 2024-12-05 Simone Grillo , Elena Cannuccia , Maurizia Palummo , Olivia Pulci , Claudio Attaccalite

The magnetotropic susceptibility $k(\omega)$ probes ultra-low-frequency uniform fluctuations. For a crystal mounted on an oscillating cantilever in a magnetic field, it is defined as the ratio of torque to angular-displacement amplitude.…

Strongly Correlated Electrons · Physics 2026-05-04 João C. Inácio , J. Schwab , G. Rakhmanova , S. Safari , V. Zambra , H. Nasir , S. Paschen , K. A. Modic , Fakher F. Assaad , Toshihiro Sato

We analyze the concept of causality for the conductivity of graphene described by the Dirac model. It is recalled that the condition of causality leads to the analyticity of conductivity in the upper half-plane of complex frequencies and to…

Mesoscale and Nanoscale Physics · Physics 2018-04-11 G. L. Klimchitskaya , V. M. Mostepanenko

An extension of the Kramers-Kronig method for treatment of polarized infrared reflectance spectra from the face of low-symmetry crystals, where directions of principal dielectric axes depend on frequency, is proposed. It is shown, how to…

Materials Science · Physics 2008-02-03 A. B. Kuz'menko , E. A. Tishchenko , A. S. Krechetov

Raman spectroscopy plays a key role in studies of graphene and related carbon systems. Graphene is perhaps the most promising material of recent times for many novel applications, including electronics. In this paper, the traditional and…

Materials Science · Physics 2015-12-07 Eric J. Heller , Yuan Yang , Lucas Kocia , Wei Chen , Shiang Fang , Mario Borunda , Efthimios Kaxiras

We compute the spectral statistics of the sum H of two independent complex Wishart matrices, each of which is correlated with a different covariance matrix. Random matrix theory enjoys many applications including sums and products of random…

Mathematical Physics · Physics 2016-07-05 Gernot Akemann , Tomasz Checinski , Mario Kieburg

Correctly capturing the symmetry transformations of data can lead to efficient models with strong generalization capabilities, though methods incorporating symmetries often require prior knowledge. While recent advancements have been made…

We consider the problem of designing sparse sampling strategies for multidomain signals, which can be represented using tensors that admit a known multilinear decomposition. We leverage the multidomain structure of tensor signals and…

Information Theory · Computer Science 2019-06-26 Guillermo Ortiz-Jiménez , Mario Coutino , Sundeep Prabhakar Chepuri , Geert Leus

Multireference alignment (MRA) is the problem of estimating a signal from many noisy and cyclically shifted copies of itself. In this paper, we consider an extension called heterogeneous MRA, where $K$ signals must be estimated, and each…

Information Theory · Computer Science 2018-02-02 Nicolas Boumal , Tamir Bendory , Roy R. Lederman , Amit Singer

The non-linear response of infinite periodic solids to homogenous electric fields and collective atomic displacements is discussed in the framework of density functional perturbation theory. The approach is based on the 2n + 1 theorem…

Materials Science · Physics 2007-05-23 M. Veithen , X. Gonze , Ph. Ghosez

Generative models for graphs are increasingly becoming a popular tool for researchers to generate realistic approximations of graphs. While in the past, focus was on generating graphs which follow general laws, such as the power law for…

Social and Information Networks · Computer Science 2017-10-20 Suchismit Mahapatra , Varun Chandola

Let G be a semisimple linear algebraic group defined over rational numbers, K be a maximal compact subgroup of its real points and {\Gamma} be an arithmetic lattice. One can associate a probability measure {\mu}(H) on {\Gamma}\G for each…

Dynamical Systems · Mathematics 2021-01-15 Runlin Zhang

The increasing use of data-driven control strategies gives rise to the problem of learning-based state observation. Motivated by this need, the present work proposes a data-driven approach for the synthesis of state observers for…

Systems and Control · Electrical Eng. & Systems 2025-09-26 Wentao Tang

Contrastive learning (CL), a self-supervised learning approach, can effectively learn visual representations from unlabeled data. Given the CL training data, generative models can be trained to generate synthetic data to supplement the real…

Computer Vision and Pattern Recognition · Computer Science 2022-11-29 Yawen Wu , Zhepeng Wang , Dewen Zeng , Yiyu Shi , Jingtong Hu

The effective nonlinear response of films of random composites consisting of a binary composite with nonlinear particles randomly embedded in a linear host is theoretically and numerically studied. A theoretical expression for the effective…

Disordered Systems and Neural Networks · Physics 2009-11-10 P. M. Hui , C. Xu , D. Stroud

We present a novel Rotational Anisotropy Nonlinear Harmonic Generation (RA-NHG) apparatus based primarily upon reflective optics. The data acquisition scheme used here allows for fast accumulation of RA-NHG traces, mitigating low frequency…

Instrumentation and Detectors · Physics 2019-05-22 Baozhu Lu , Jason D. Tran , Darius H. Torchinsky

High-dimensional compositional data, such as those from human microbiome studies, pose unique statistical challenges due to the simplex constraint and excess zeros. While dimension reduction is indispensable for analyzing such data,…

Methodology · Statistics 2025-09-09 Junyoung Park , Cheolwoo Park , Jeongyoun Ahn

We introduce Contrastive Multivariate Singular Spectrum Analysis, a novel unsupervised method for dimensionality reduction and signal decomposition of time series data. By utilizing an appropriate background dataset, the method transforms a…

Machine Learning · Statistics 2018-11-01 Abdi-Hakin Dirie , Abubakar Abid , James Zou

Negative sampling (NS) loss plays an important role in learning knowledge graph embedding (KGE) to handle a huge number of entities. However, the performance of KGE degrades without hyperparameters such as the margin term and number of…

Machine Learning · Computer Science 2022-07-08 Hidetaka Kamigaito , Katsuhiko Hayashi

Decreasing magnetic resonance (MR) image acquisition times can potentially make MR examinations more accessible. Prior arts including the deep learning models have been devoted to solving the problem of long MRI imaging time. Recently, deep…

Image and Video Processing · Electrical Eng. & Systems 2022-08-23 Zongjiang Tu , Chen Jiang , Yu Guan , Shanshan Wang , Jijun Liu , Qiegen Liu , Dong Liang