However, existing contrastive learning methods primarily focus on one single data level, which fails to fully exploit the intricate nature of medical time series.

The interstellar space rock shows off the illuminating effects of its brush with the sun. Breakthroughs, discoveries, and DIY tips sent six days a week. After months of unprecedented observations, astronomers are bidding goodbye to the beloved comet 3I/ATLAS . First spotted in July 2025, the frigid, dusty space rock is only the third known interstellar object to pass through the solar system, offering researchers the rare opportunity to examine a visitor from deep space. Among other discoveries, scientists have since confirmed that the interstellar comet is the fastest ever recorded as well as covered in ice volcanoes --and definitely not extraterrestrial tourists .

Science Space Deep Space Halley's comet may need a new, medieval name Astronomers suggest the honor should go to an 11th century monk known for a disastrous flying attempt. Breakthroughs, discoveries, and DIY tips sent six days a week. One of most recognizable comets in astronomy may require rebranding. But even if everyone continues to call the famed space rock Halley's comet, some researchers say an eccentric 11th century monk deserves at least credit. According to a review of historical materials including the famous Bayeux tapestry, a team from Leiden University in the Netherlands believes it makes more sense to name the icy space rock in honor of Aethelmaer of Malmesbury --a member of the Order of Saint Benedict who also lived with an ill-fated fascination with flying.

Contrastive representation learning is crucial in medical time series analysis as it alleviates dependency on labor-intensive, domain-specific, and scarce expert annotations. However, existing contrastive learning methods primarily focus on one single data level, which fails to fully exploit the intricate nature of medical time series. To address this issue, we present COMET, an innovative hierarchical framework that leverages data consistencies at all inherent levels in medical time series. Our meticulously designed model systematically captures data consistency from four potential levels: observation, sample, trial, and patient levels. By developing contrastive loss at multiple levels, we can learn effective representations that preserve comprehensive data consistency, maximizing information utilization in a self-supervised manner. We conduct experiments in the challenging patient-independent setting. We compare COMET against six baselines using three diverse datasets, which include ECG signals for myocardial infarction and EEG signals for Alzheimer's and Parkinson's diseases. The results demonstrate that COMET consistently outperforms all baselines, particularly in setup with 10% and 1% labeled data fractions across all datasets. These results underscore the significant impact of our framework in advancing contrastive representation learning techniques for medical time series.

This paper presents the first large-scale field study of the adoption, usage intensity, and use cases of general-purpose AI agents operating in open-world web environments. Our analysis centers on Comet, an AI-powered browser developed by Perplexity, and its integrated agent, Comet Assistant. Drawing on hundreds of millions of anonymized user interactions, we address three fundamental questions: Who is using AI agents? How intensively are they using them? And what are they using them for? Our findings reveal substantial heterogeneity in adoption and usage across user segments. Earlier adopters, users in countries with higher GDP per capita and educational attainment, and individuals working in digital or knowledge-intensive sectors -- such as digital technology, academia, finance, marketing, and entrepreneurship -- are more likely to adopt or actively use the agent. To systematically characterize the substance of agent usage, we introduce a hierarchical agentic taxonomy that organizes use cases across three levels: topic, subtopic, and task. The two largest topics, Productivity & Workflow and Learning & Research, account for 57% of all agentic queries, while the two largest subtopics, Courses and Shopping for Goods, make up 22%. The top 10 out of 90 tasks represent 55% of queries. Personal use constitutes 55% of queries, while professional and educational contexts comprise 30% and 16%, respectively. In the short term, use cases exhibit strong stickiness, but over time users tend to shift toward more cognitively oriented topics. The diffusion of increasingly capable AI agents carries important implications for researchers, businesses, policymakers, and educators, inviting new lines of inquiry into this rapidly emerging class of AI capabilities.

The interstellar object is still soaring through our solar system. Breakthroughs, discoveries, and DIY tips sent every weekday. It's understandable why every space agency and astronomy enthusiast around the world is trying to catch a glimpse of 3I/ATLAS . Not only is it the third-known interstellar object to pass through our solar system,it's also the fastest comet ever recorded . But even as it races at 130,00 miles per hour towards its closest distance from Earth, NASA's Hubble Space Telescope recently caught another stunning glimpse of the icy rock.

It's still not aliens, but the interstellar comet keeps getting weirder. Breakthroughs, discoveries, and DIY tips sent every weekday. As comet 3I/ATLAS continues its exciting journey through our solar system, scientists are still learning everything they can about this special space rock. It is only the second interstellar object ever tracked through our solar system and is among the fastest comets ever observed. As the 3I/ATLAS nears its closest distance to Earth, an international team of astronomers now says the space rock may be covered in active, icy cryovolcanoes.

Coaxial bi-copter autonomous aerial vehicles (AAVs) have garnered attention due to their potential for improved rotor system efficiency and compact form factor. However, balancing efficiency, maneuverability, and compactness in coaxial bi-copter systems remains a key design challenge, limiting their practical deployment. This letter introduces COMET, a coaxial bi-copter AAV platform featuring a dual swashplate mechanism. The coaxial bi-copter system's efficiency and compactness are optimized through bench tests, and the whole prototype's efficiency and robustness under varying payload conditions are verified through flight endurance experiments. The maneuverability performance of the system is evaluated in comprehensive trajectory tracking tests. The results indicate that the dual swashplate configuration enhances tracking performance and improves flight efficiency compared to the single swashplate alternative. Successful autonomous flight trials across various scenarios verify COMET's potential for real-world applications.

Winter officially arrives on Sunday, December 21. A view of the Geminid meteor shower and stargazing at the Tunnel View of Yosemite National Park on December 14, 2023. Breakthroughs, discoveries, and DIY tips sent every weekday. As one might expect from a month full of long, dark nights, December is a highlight for those with a penchant for looking to the stars . This year, the stargazing on offer promises to be particularly good.

Karoline Leavitt's family member was swarmed by ICE agents while picking up son from school as child's father tell her to'self deport' Deaths from highly infectious virus are growing... as states brace for widespread outbreaks My book on the Kennedys was used as a'mistress manual' by Olivia Nuzzi... then this wannabe Carolyn Bessette had the nerve to hound me with these outrageous texts: MAUREEN CALLAHAN Katy Perry's legal victory as judge orders disabled veteran to pay singer nearly $2m over Montecito mansion Trump reveals next DC renovation project to remove'Biden filth' after White House ballroom Cracker Barrel CEO whines that she got'fired by America' for woke redesign Kroger employee reveals shocking amount laundry products have increased by... 'biggest price jump I've seen in a single week' Hollywood heir, 23, whose mom Anne Heche died in horror car fireball has secret LOVE CHILD with 43-year-old... now she's telling all Missing Melodee Buzzard's mom'left her daughter with strangers she met at the zoo' Rachel Zoe reveals why she dumped husband of 26 years... and if she has started dating again Horrific moment cops found body of Cowboys star Marshawn Kneeland after he shot himself at end of 145 mph chase'This is pretty lurid' Jenny McCarthy, 53, reveals health emergency that involved NINE surgeries, her'teeth falling out' and'growth' on her eyeballs Maryland grandma, 58, dragged across floor after being deported to country she'has never even visited' The United Nations (UN) has confirmed that Earth's planetary defenses will be observing the interstellar comet 3I/ATLAS as it races through our solar system . Starting on November 27, a global team of scientists with the International Asteroid Warning Network (IAWN) will kick off a two-month campaign to track the comet as it nears our planet . 'While it poses no threat, comet 3I/ATLAS presents a great opportunity for the IAWN community to perform an observing exercise due to its prolonged observability from Earth and high interest to the scientific community,' the UN explains on its website. 'This 3I/ATLAS campaign is the 8th IAWN observing exercise since 2017 - IAWN holds these exercises roughly once a year.' While 3I/ATLAS was only discovered in July 2025, the UN explained that this'comet campaign' has long been planned.