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“Dark Stars” – A Brief History of Black Holes

Artist’s concept illustration of a supermassive black hole emitting an x-ray jet. Credit: NASA/JPL-Caltech Late in 2018, the gravitational wave observatory, LIGO, announced that they had detected the most distant and massive source of ripples of spacetime ever monitored: gravitational waves triggered by pairs of black holes colliding in deep space. Only since 2015 have we been able to observe these invisible astronomical bodies, which at that time could be detected only by their gravitational attraction. Then in a breakthrough in 2019, the Event Horizon Telescope captured an image of a black hole and its shadow for the first time.…

Tantalizing Tectonics: Monstrous “Claw Mark” Scratches on the Surface of Mars

This image from ESA’s Mars Express shows part of a large fault system on Mars known as Tantalus Fossae. This image comprises data gathered by Mars Express’ High Resolution Stereo Camera (HRSC) on July 19, 2021. It was created using data from the nadir channel, the field of view aligned perpendicular to the surface of Mars, and the color channels of the HRSC. It is a ‘true color’ image, reflecting what would be seen by the human eye if looking at this region of Mars. The ground resolution is approximately 18 m/pixel and the images are centered at about 43°N/257°E.…

Researchers Track COVID-19 Infection Dynamics in the Saliva and Nasal Cavities

Lead Image: Light micrograph (LM) of the nasal cavity of a healthy (uninfected) person. A research team led by scientists at the University of Illinois Urbana-Champaign (UIUC) tracked the rise and fall of SARS-CoV-2 (the virus that caused COVID-19) in the saliva and nasal cavities of people newly infected with the virus. The study was the first to follow acute COVID-19 infections over time through repeated sampling and to compare results from different testing methodologies. The findings were reported in the journal Nature Microbiology. “We capture the most complete, high-resolution, quantitative picture of how SARS-CoV-2 replicates and sheds in people…

Plug-and-Play Human Organ-on-a-Chip Can Be Customized to the Patient

Lead Image: The new multi-organ chip has the size of a glass microscope slide and allows the culture of up to four human engineered tissues, whose location and number can be tailored to the question being asked. These tissues are connected by vascular flow, but the presence of a selectively permeable endothelial barrier maintains their tissue-specific niche. Credit: Kacey Ronaldson-Bouchard/Columbia Engineering Major advance from Columbia Engineering team demonstrates the first multi-organ chip made of engineered human tissues linked by vascular flow for improved modeling of systemic diseases like cancer. Engineered tissues have become an essential component for modeling diseases and…

Unpacking Black-Box Models: ExSum Mathematical Framework To Evaluate Explanations of Machine-Learning Models

Researchers create a mathematical framework to evaluate explanations of machine-learning models and quantify how well people understand them. Credit: MIT News with images from iStockphoto MIT researchers create a mathematical framework to evaluate explanations of machine-learning models and quantify how well people understand them. Modern machine-learning models, such as neural networks, are often referred to as “black boxes” because they are so complex that even the people who design them can’t fully understand how they make predictions. To provide some insights, scientists employ explanation methods that seek to describe individual model decisions. They may, for example, highlight words in a…