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Many modern ultrasound beamformers report improved image quality when evaluated using classical criteria like the contrast ratio and contrast-to-noise ratio, which are based on summary statistics of regions of interest (ROIs). However,…

Medical Physics · Physics 2026-02-03 Dongwoon Hyun

Speed-of-sound (SoS) is a novel imaging biomarker for assessing biomechanical characteristics of soft tissues. SoS imaging in pulse-echo mode using conventional ultrasound systems with hand-held transducers has the potential to enable new…

Medical Physics · Physics 2023-03-21 Dieter Schweizer , Richard Rau , Can Deniz Bezek , Rahel A. Kubik-Huch , Orcun Goksel

Coronal holes are the observational manifestation of the solar magnetic field open to the heliosphere and are of pivotal importance for our understanding of the origin and acceleration of the solar wind. Observations from space missions…

Photonic integrated circuits (PICs) are enabling major breakthroughs in a number of areas, including quantum computing, neuromorphic processors, wearable devices, and more. Nevertheless, existing PIC measurement methods lack the spectral…

The LOng Range Reconnaissance Imager (LORRI) is a panchromatic (360--910 nm), narrow-angle (field of view = 0.29 deg), high spatial resolution (pixel scale = 1.02 arcsec) visible light imager used on NASA's New Horizons (NH) mission for…

The radioheliograph image is essential for the study of solar short term activities and long term variations, while the continuity and granularity of radioheliograph data is not so ideal, due to the short visible time of the sun and the…

Solar and Stellar Astrophysics · Physics 2021-01-13 PeiJin Zhang , Chuanbing Wang , Guanshan Pu

We present a model for atmospheric absorption of solar ultraviolet (UV) radiation. The initial motivation for this work is to predict this effect and correct it in Sounding Rocket (SR) experiments. In particular, the Full-sun Ultraviolet…

Atmospheric and Oceanic Physics · Physics 2023-02-17 Nicolas Donders , Genevieve Vigil , Adam Kobelski , Amy Winebarger , Larry Paxton , Charles Kankelborg , Gary Zank

Measurements of the temperature and density structure of the solar corona provide critical constraints on theories of coronal heating. Unfortunately, the complexity of the solar atmosphere, observational uncertainties, and the limitations…

Solar and Stellar Astrophysics · Physics 2009-07-22 Harry P. Warren , David H. Brooks

We discuss in some details a novel algorithm for performing partial-sky spherical harmonic transforms (SHT), building on the Fourier-sphere method of Reinecke et al (2023) handling efficiently high numbers of arbitrary locations on the…

Cosmology and Nongalactic Astrophysics · Physics 2026-03-20 Julien Carron , Martin Reinecke

In this work we investigate the dynamic behavior of inter-network regions of the solar chromosphere. We observed the chromosphere of the quiet Sun using a narrow-band Lyot filter centered at the Ca II K 2v emission peak with a bandpass of…

Astrophysics · Physics 2009-11-11 F. Wöger , S. Wedemeyer-Böhm , W. Schmidt , O. von der Lühe

The Swedish 1-m Solar Telescope (SST) offers excellent imaging quality, but it has a comparatively small field of view. This means that while observing the solar photosphere, there has been no convenient way of calibrating the image scale…

Instrumentation and Methods for Astrophysics · Physics 2013-11-21 Alexander Norén

The Airborne Infrared Spectrometer (AIR-Spec) offers an unprecedented opportunity to explore the Near Infra-Red (NIR) wavelength range. It has been flown at two total solar eclipses, in 2017 and 2019. The wavelength range of the much…

Solar and Stellar Astrophysics · Physics 2023-03-01 G. Del Zanna , J. Samra , A. Monaghan , C. Madsen , P. Bryans , E. DeLuca , H. Mason , B. Berkey , A. de Wijn , Y. Rivera

Resourcesat-3S/3SA, an upcoming Indian satellite, is designed with Aft and Fore payloads capturing stereo images at look angles of -5deg and 26deg, respectively. Operating at 632.6 km altitude, it features a panchromatic (PAN) band offering…

Image and Video Processing · Electrical Eng. & Systems 2024-11-01 Ankur Garg , Meenakshi Sarkar , S. M. Moorthi , Debajyoti Dhar

In an effort to transcend the limitations of differential imaging of exoplanets in the era of extremely large telescopes (ELTs), the first paper in this series established a rigorous, fully polarimetric framework for determining the science…

Instrumentation and Methods for Astrophysics · Physics 2016-02-18 Richard A. Frazin

Advances in hydrodynamical simulations have provided new insights into the effects of convection on the frequencies of solar oscillations. As more accurate observations become available, this may lead to an improved understanding of the…

Solar Ring (SOR) is a proposed space science mission to monitor and study the Sun and inner heliosphere from a full 360{\deg} perspective in the ecliptic plane. It will deploy three 120{\deg}-separated spacecraft on the 1-AU orbit. The…

Stellar intensity interferometry (SII) is based on the correlation of the light intensity fluctuations of a star detected at two or more telescopes, with no need to combine the collected photons directly. A measurement of the correlation in…

Instrumentation and Methods for Astrophysics · Physics 2024-04-30 Alessia Spolon , Michele Fiori , Luca Zampieri , Marco Landoni

The uncertainty of measurement of solar diameter is depending on the observational time scale. Full-disc images of SDO/HMI and the images from ground observations in Huairou Solar Observing Station have been analyzed to get the values of…

Solar and Stellar Astrophysics · Physics 2015-06-11 Xiaofan Wang , Costantino Sigismondi

Stellar intensity interferometers correlate photons within their coherence time and could overcome the baseline limitations of existing amplitude interferometers. Intensity interferometers do not rely on phase coherence of the optical…

Instrumentation and Methods for Astrophysics · Physics 2022-02-24 Sebastian Karl , Andreas Zmija , Stefan Richter , Naomi Vogel , Dmitry Malyshev , Adrian Zink , Thilo Michel , Gisela Anton , Joachim von Zanthier , Stefan Funk

In this paper, we propose that the accelerated electrons in the quiet Sun could collide with the solar atmosphere to emit Hard X-rays (HXRs) via non-thermal bremsstrahlung, while some of these electrons would move upwards and escape into…

Solar and Stellar Astrophysics · Physics 2016-05-31 Wen Wang , Linghua Wang , Sam Krucker , Iain Hannah