arXiv subjects

Stuart Feldman

Publications and source records attributed to Stuart Feldman.

4 recordsLinked to original sources

arXiv2026

The Lazuli Space Observatory: Architecture & Capabilities

The Lazuli Space Observatory is a 3-meter aperture astronomical facility designed for rapid-response observations and precision astrophysics across visible to near-infrared wavelengths (400-1700 nm bandpass). An off-axis, freeform telescope delivers diffraction-limited image quality (Strehl $>$0.8 at 633 nm) to three instruments across a wide, flat focal plane. The three instruments provide complementary capabilities: a Wide-field Context Camera (WCC) delivers multi-band imaging over a 35' $\times$ 12' footprint with high-cadence photometry; an Integral Field Spectrograph (IFS) provides continuous 400-1700 nm spectroscopy at R $\sim$ 100-500 for stable spectrophotometry; and an ExtraSolar Coronagraph (ESC) enables high-contrast imaging expected to reach raw contrasts of $10^{-8}$ and post-processed contrasts approaching $10^{-9}$. Operating from a 3:1 lunar-resonant orbit, Lazuli will respond to targets of opportunity in under four hours--a programmatic requirement designed to enable routine temporal responsiveness that is unprecedented for a space telescope of this size. Lazuli's technical capabilities are shaped around three broad science areas: (1) time-domain and multi-messenger astronomy, (2) stars and planets, and (3) cosmology. These capabilities enable a potent mix of science spanning gravitational wave counterpart characterization, fast-evolving transients, Type Ia supernova cosmology, high-contrast exoplanet imaging, and spectroscopy of exoplanet atmospheres. While these areas guide the observatory design, Lazuli is conceived as a general-purpose facility capable of supporting a wide range of astrophysical investigations, with open time for the global community. We describe the observatory architecture and capabilities in the preliminary design phase, with science operations anticipated following a rapid development cycle from concept to launch. [Abstract abridged]

astro-ph.IM↗

arXiv2021

Shifting Polarization and Twitter News Influencers between two U.S. Presidential Elections

Social media are decentralized, interactive, and transformative, empowering users to produce and spread information to influence others. This has changed the dynamics of political communication that were previously dominated by traditional corporate news media. Having hundreds of millions of tweets collected over the 2016 and 2020 U.S. presidential elections gave us a unique opportunity to measure the change in polarization and the diffusion of political information. We analyze the diffusion of political information among Twitter users and investigate the change of polarization between these elections and how this change affected the composition and polarization of influencers and their retweeters. We identify "influencers" by their ability to spread information and classify them into those affiliated with a media organization, a political organization, or unaffiliated. Most of the top influencers were affiliated with media organizations during both elections. We found a clear increase from 2016 to 2020 in polarization among influencers and among those whom they influence. Moreover, 75% of the top influencers in 2020 were not present in 2016, demonstrating that such status is difficult to retain. Between 2016 and 2020, 10% of influencers affiliated with media were replaced by center- or right-orientated influencers affiliated with political organizations and unaffiliated influencers.

cs.SI↗

arXiv2021

Challenges in cybersecurity: Lessons from biological defense systems

We explore the commonalities between methods for assuring the security of computer systems (cybersecurity) and the mechanisms that have evolved through natural selection to protect vertebrates against pathogens, and how insights derived from studying the evolution of natural defenses can inform the design of more effective cybersecurity systems. More generally, security challenges are crucial for the maintenance of a wide range of complex adaptive systems, including financial systems, and again lessons learned from the study of the evolution of natural defenses can provide guidance for the protection of such systems.

cs.CY↗

arXiv2016

The Future of Computing Research: Industry-Academic Collaborations

IT-driven innovation is an enormous factor in the worldwide economic leadership of the United States. It is larger than finance, construction, or transportation, and it employs nearly 6% of the US workforce. The top three companies, as measured by market capitalization, are IT companies - Apple, Google (now Alphabet), and Microsoft. Facebook, a relatively recent entry in the top 10 list by market capitalization has surpassed Walmart, the nation's largest retailer, and the largest employer in the world. The net income of just the top three exceeds $80 billion - roughly 100 times the total budget of the NSF CISE directorate which funds 87% of computing research. In short, the direct return on federal research investments in IT research has been enormously profitable to the nation. The IT industry ecosystem is also evolving. The time from conception to market of successful products has been cut from years to months. Product life cycles are increasingly a year or less. This change has pressured companies to focus industrial R&D on a pipeline or portfolio of technologies that bring immediate, or almost immediate, value to the companies. To defeat the competition and stay ahead of the pack, a company must devote resources to realizing gains that are shorter term, and must remain agile to respond quickly to market changes driven by new technologies, new startups, evolving user experience expectations, and the continuous consumer demand for new and exciting products. Amidst this landscape, the Computing Community Consortium convened a round-table of industry and academic participants to better understand the landscape of industry-academic interaction, and to discuss possible actions that might be taken to enhance those interactions. We close with some recommendations for actions that could expand the lively conversation we experienced at the round-table to a national scale.

cs.CY↗