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Instead of directly utilizing an observed image including some outliers, noise or intensity inhomogeneity, the use of its ideal value (e.g. noise-free image) has a favorable impact on clustering. Hence, the accurate estimation of the…

Computer Vision and Pattern Recognition · Computer Science 2020-10-12 Cong Wang , Witold Pedrycz , ZhiWu Li , MengChu Zhou , Jun Zhao

The hot intracluster medium (ICM) provides a unique laboratory to test multi-scale physics in numerical simulations and probe plasma physics. Utilizing archival Chandra observations, we measure density fluctuations in the ICM in a sample of…

High Energy Astrophysical Phenomena · Physics 2024-01-30 Annie Heinrich , Irina Zhuravleva , Congyao Zhang , Eugene Churazov , William Forman , Reinout J. van Weeren

The reduced speed of light approximation (RSLA) has been employed to speed up radiative transfer simulations of reionization by a factor of $\gtrsim 5-10$. However, it has been shown to cause significant errors in the HI-ionizing background…

Cosmology and Nongalactic Astrophysics · Physics 2024-12-20 Christopher Cain

In this paper, several two-dimensional clustering scenarios are given. In those scenarios, soft partitioning clustering algorithms (Fuzzy C-means (FCM) and Possibilistic c-means (PCM)) are applied. Afterward, VAT is used to investigate the…

Machine Learning · Computer Science 2019-05-14 Md. Abu Bakr Siddique , Rezoana Bente Arif , Mohammad Mahmudur Rahman Khan , Zahidun Ashrafi

We develop an effective perturbation theory (and, equivalently, a bias expansion) for the inhomogeneous 21cm radiation field from reionization. Using large-scale simulations of cosmological reionization, we find that this expansion…

Cosmology and Nongalactic Astrophysics · Physics 2018-11-20 Matthew McQuinn , Anson D'Aloisio

On large angular scales, CMB polarization depends mostly on the evolution of the ionization level of the IGM during reionization. In order to avoid biasing parameter estimates, an accurate and model independent approach to reionization is…

Astrophysics · Physics 2009-06-23 Loris P. L. Colombo , Elena Pierpaoli

A key physical quantity during reionization is the size of HII regions. Previous studies found a characteristic bubble size which increases rapidly during reionization, with apparent agreement between simulations and analytic excursion set…

Cosmology and Nongalactic Astrophysics · Physics 2016-10-07 Yin Lin , S. Peng Oh , Steven R. Furlanetto , P. M. Sutter

The Largest Cluster Statistics\,(LCS) analysis of the redshifted 21\,cm maps has been demonstrated to be an efficient and robust method for following the time evolution of the largest ionized regions\,(LIRs) during the Epoch of…

Cosmology and Nongalactic Astrophysics · Physics 2025-10-28 Samit Kumar Pal , Saswata Dasgupta , Abhirup Datta , Suman Majumdar , Satadru Bag , Prakash Sarkar

Sample size determination for cluster randomised trials (CRTs) is challenging as it requires robust estimation of the intra-cluster correlation coefficient (ICC). Typically, the sample size is chosen to provide a certain level of power to…

Applications · Statistics 2023-08-23 S. Faye Williamson , Svetlana V. Tishkovskaya , Kevin J. Wilson

We present up-to-date constraints on the value of the fine-structure constant at the epoch of decoupling from the recent observations made by the Wilkinson Microwave Anisotropy Probe (WMAP) satellite. In the framework of models we…

Astrophysics · Physics 2008-11-26 C. J. A. P. Martins , A. Melchiorri , G. Rocha , R. Trotta , P. P. Avelino , P. Viana

We present an analytic formulation to model the fluctuating component of the HI signal from the epoch of reionization during the phase of partial heating. During this phase, we assume self-ionized regions, whose size distribution can be…

Cosmology and Nongalactic Astrophysics · Physics 2018-06-14 Janakee Raste , Shiv Sethi

Estimating the clutter-plus-noise covariance matrix in high-dimensional STAP is challenging in the presence of Internal Clutter Motion (ICM) and a high noise floor. The problem becomes more difficult in low-sample regimes, where the Sample…

Signal Processing · Electrical Eng. & Systems 2025-05-13 Shashwat Jain , Vikram Krishnamurthy , Muralidhar Rangaswamy , Sandeep Gogineni , Bosung Kang , Sean M. O'Rourke

We study the topology of reionization using accurate three-dimensional radiative transfer calculations post-processed on outputs from cosmological hydrodynamic simulations. In our simulations, reionization begins in overdense regions and…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 K. Finlator , F. Ozel , R. Dave , B. D. Oppenheimer

We predict the 21-cm global signal and power spectra during the Epoch of Reionisation using the MERAXES semi-analytic galaxy formation and reionisation model, updated to include X-ray heating and thermal evolution of the intergalactic…

Cosmology and Nongalactic Astrophysics · Physics 2023-02-21 Sreedhar Balu , Bradley Greig , Yisheng Qiu , Chris Power , Yuxiang Qin , Simon Mutch , J. Stuart B. Wyithe

The EoR 21-cm signal is expected to become highly non-Gaussian as reionization progresses. This severely affects the error-covariance of the EoR 21-cm power spectrum which is important for predicting the prospects of a detection with…

Cosmology and Nongalactic Astrophysics · Physics 2016-11-14 Rajesh Mondal , Somnath Bharadwaj , Suman Majumdar

Provided a random realization of the cosmological model, observations of our cosmic neighborhood now allow us to build simulations of the latter down to the non-linear threshold. The resulting local Universe models are thus accurate up to a…

Cosmology and Nongalactic Astrophysics · Physics 2020-06-10 Jenny G. Sorce

Fourier ptychographic microscopy (FPM) is a recently proposed quantitative phase imaging technique with high resolution and wide field-of-view (FOV). In current FPM imaging platforms, systematic error sources come from the aberrations, LED…

Instrumentation and Detectors · Physics 2017-09-18 An Pan , Yan Zhang , Tianyu Zhao , Zhaojun Wang , Dan Dan , Baoli Yao

The non-Gaussian nature of the epoch of reionization (EoR) 21-cm signal has a significant impact on the error variance of its power spectrum $P({\bf \textit{k}})$. We have used a large ensemble of semi-numerical simulations and an…

Cosmology and Nongalactic Astrophysics · Physics 2016-01-26 Rajesh Mondal , Somnath Bharadwaj , Suman Majumdar

Tomographic three-dimensional 21 cm images from the epoch of reionization contain a wealth of information about the reionization of the intergalactic medium by astrophysical sources. Conventional power spectrum analysis cannot exploit the…

Cosmology and Nongalactic Astrophysics · Physics 2022-02-22 Xiaosheng Zhao , Yi Mao , Cheng Cheng , Benjamin D. Wandelt

Evaluation of clinical prediction models across multiple clusters, whether centers or datasets, is becoming increasingly common. A comprehensive evaluation includes an assessment of the agreement between the estimated risks and the observed…

Methodology · Statistics 2026-04-22 Lasai Barreñada , Bavo D. C. Campo , Laure Wynants , Ben Van Calster