scholarly journals Machine learning powered ellipsometry

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Jinchao Liu ◽  
Di Zhang ◽  
Dianqiang Yu ◽  
Mengxin Ren ◽  
Jingjun Xu

AbstractEllipsometry is a powerful method for determining both the optical constants and thickness of thin films. For decades, solutions to ill-posed inverse ellipsometric problems require substantial human–expert intervention and have become essentially human-in-the-loop trial-and-error processes that are not only tedious and time-consuming but also limit the applicability of ellipsometry. Here, we demonstrate a machine learning based approach for solving ellipsometric problems in an unambiguous and fully automatic manner while showing superior performance. The proposed approach is experimentally validated by using a broad range of films covering categories of metals, semiconductors, and dielectrics. This method is compatible with existing ellipsometers and paves the way for realizing the automatic, rapid, high-throughput optical characterization of films.

2010 ◽  
Vol 09 (03) ◽  
pp. 193-199 ◽  
Author(s):  
E. PAKIZEH ◽  
S. M. HOSSEINI ◽  
A. KOMPANY ◽  
M. GHASEMIFARD

Pb(Zr1-x, Tix)O3 (x = 0.05) with pyroelectric properties have been synthesized by sol–gel technique at low temperatures. XRD results indicate that the powder has perovskite structure without secondary phases and the average of particle size was estimated to be about 40 nm in diameters. The optical constants such as refractive index, n, extinction coefficient, k, and the dielectric function of PZT nanopowders have been investigated by Fourier transmittance infrared (FTIR) spectrum and Kramers–Kronig (KK) analysis program. The use of the KK method to analyze the normal incidence infrared (IR) reflectance spectra with a single resonance has also been described. The results indicated that the optical constant increases slowly as temperature of calcinations increases.


1997 ◽  
Vol 51 (6) ◽  
pp. 902-904 ◽  
Author(s):  
Arnulf Röseler ◽  
Ernst-Heiner Korte

The ellipsometric infrared spectra of a metallic island film indicate its potential for surface-enhanced infrared absorption (SEIRA). Such a film is characterized by unique optical constants, and these can be simulated by using an effective-medium approach.


2021 ◽  
Author(s):  
Kristopher Kieft ◽  
Alyssa Adams ◽  
Rauf Salamzade ◽  
Lindsay Kalan ◽  
Karthik Anantharaman

Genome binning has been essential for characterization of bacteria, archaea, and even eukaryotes from metagenomes. Yet, no approach exists for viruses. We developed vRhyme, a fast and precise software for construction of viral metagenome-assembled genomes (vMAGs). vRhyme utilizes single- or multi-sample coverage effect size comparisons between scaffolds and employs supervised machine learning to identity nucleotide feature similarities, which are compiled into iterations of weighted networks and refined bins. Using simulated viromes, we displayed superior performance of vRhyme compared to available binning tools in constructing more complete and uncontaminated vMAGs. When applied to 10,601 viral scaffolds from human skin, vRhyme advanced our understanding of resident viruses, highlighted by identification of a Herelleviridae vMAG comprised of 22 scaffolds, and another vMAG encoding a nitrate reductase metabolic gene, representing near-complete genomes post-binning. vRhyme will enable a convention of binning uncultivated viral genomes and has the potential to transform metagenome-based viral ecology.


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Gorka Muñoz-Gil ◽  
Giovanni Volpe ◽  
Miguel Angel Garcia-March ◽  
Erez Aghion ◽  
Aykut Argun ◽  
...  

AbstractDeviations from Brownian motion leading to anomalous diffusion are found in transport dynamics from quantum physics to life sciences. The characterization of anomalous diffusion from the measurement of an individual trajectory is a challenging task, which traditionally relies on calculating the trajectory mean squared displacement. However, this approach breaks down for cases of practical interest, e.g., short or noisy trajectories, heterogeneous behaviour, or non-ergodic processes. Recently, several new approaches have been proposed, mostly building on the ongoing machine-learning revolution. To perform an objective comparison of methods, we gathered the community and organized an open competition, the Anomalous Diffusion challenge (AnDi). Participating teams applied their algorithms to a commonly-defined dataset including diverse conditions. Although no single method performed best across all scenarios, machine-learning-based approaches achieved superior performance for all tasks. The discussion of the challenge results provides practical advice for users and a benchmark for developers.


2014 ◽  
Vol 28 (25) ◽  
pp. 1450196 ◽  
Author(s):  
Minglin Zhao ◽  
Jie Lian ◽  
Zhaozong Sun ◽  
Xiao Wang ◽  
Wenfu Zhang ◽  
...  

Optical characterization of TiAlON film applied in solar energy is presented in this paper. TiAlON -based films with different thicknesses have been deposited by magnetron sputtering. The spectrophotometer and spectroscopic ellipsometry (GES5) have been used to study the samples. Surface morphology and component of the films were investigated using scanning electron microscope (SEM), X-ray diffraction (XRD), atomic force microscope (AFM) and X-ray photoelectron spectroscopy (XPS). The optical constants and film thicknesses of TiAlON films with different thicknesses have been obtained by theoretical modeling analysis fitting (Cauchy model) and point-to-point analysis fitting. Results show that the refraction coefficient and extinction coefficient change with the film thickness increased. Those optical properties are useful for selecting the layers with adequate optical constants and thickness to design a solar selective absorber.


2015 ◽  
Vol 29 (18) ◽  
pp. 1550088 ◽  
Author(s):  
Mehmet Isik ◽  
Nizami Gasanly

Optical properties of [Formula: see text] crystals grown by Bridgman method were investigated by transmission, reflection and ellipsometry measurements. Analysis of the transmission and reflection measurements performed in the wavelength range of 400–1100 nm at room temperature indicated the presence of indirect and direct transitions with 2.28 eV and 2.38 eV band gap energies. Ellipsometry measurements were carried out in the 1.2–6.0 eV spectral region to get information about optical constants, real and imaginary parts of the pseudodielectric function. Moreover, the critical point (CP) analysis of the second derivative spectra of the pseudodielectric constant in the above band gap region was accomplished. The analysis revealed the presence of five CPs with energies of 3.87, 4.16, 4.41, 4.67 and 5.34 eV.


2020 ◽  
Vol 12 (4) ◽  
pp. 04022-1-04022-4
Author(s):  
Piyush Patel ◽  
◽  
S. M. Vyas ◽  
Vimal Patel ◽  
Himanshu Pavagadhi ◽  
...  

2014 ◽  
Vol 01 (999) ◽  
pp. 1-1
Author(s):  
Wei Zhu ◽  
Qihui Shen ◽  
Xinjian Bao ◽  
Xiao Bai ◽  
Tingting Li ◽  
...  

2020 ◽  
Author(s):  
Mikołaj Morzy ◽  
Bartłomiej Balcerzak ◽  
Adam Wierzbicki ◽  
Adam Wierzbicki

BACKGROUND With the rapidly accelerating spread of dissemination of false medical information on the Web, the task of establishing the credibility of online sources of medical information becomes a pressing necessity. The sheer number of websites offering questionable medical information presented as reliable and actionable suggestions with possibly harmful effects poses an additional requirement for potential solutions, as they have to scale to the size of the problem. Machine learning is one such solution which, when properly deployed, can be an effective tool in fighting medical disinformation on the Web. OBJECTIVE We present a comprehensive framework for designing and curating of machine learning training datasets for online medical information credibility assessment. We show how the annotation process should be constructed and what pitfalls should be avoided. Our main objective is to provide researchers from medical and computer science communities with guidelines on how to construct datasets for machine learning models for various areas of medical information wars. METHODS The key component of our approach is the active annotation process. We begin by outlining the annotation protocol for the curation of high-quality training dataset, which then can be augmented and rapidly extended by employing the human-in-the-loop paradigm to machine learning training. To circumvent the cold start problem of insufficient gold standard annotations, we propose a pre-processing pipeline consisting of representation learning, clustering, and re-ranking of sentences for the acceleration of the training process and the optimization of human resources involved in the annotation. RESULTS We collect over 10 000 annotations of sentences related to selected subjects (psychiatry, cholesterol, autism, antibiotics, vaccines, steroids, birth methods, food allergy testing) for less than $7 000 employing 9 highly qualified annotators (certified medical professionals) and we release this dataset to the general public. We develop an active annotation framework for more efficient annotation of non-credible medical statements. The results of the qualitative analysis support our claims of the efficacy of the presented method. CONCLUSIONS A set of very diverse incentives is driving the widespread dissemination of medical disinformation on the Web. An effective strategy of countering this spread is to use machine learning for automatically establishing the credibility of online medical information. This, however, requires a thoughtful design of the training pipeline. In this paper we present a comprehensive framework of active annotation. In addition, we publish a large curated dataset of medical statements labelled as credible, non-credible, or neutral.


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