A5028482299- Astrophysics and Star Formation Studies
- Stellar, planetary, and galactic studies
- COVID-19 epidemiological studies
- Molecular Spectroscopy and Structure
- Astrophysical Phenomena and Observations
- Data-Driven Disease Surveillance
- Virology and Viral Diseases
- Astro and Planetary Science
- SARS-CoV-2 and COVID-19 Research
- Astrophysics and Cosmic Phenomena
- Pulsars and Gravitational Waves Research
- COVID-19 Digital Contact Tracing
- Digital Mental Health Interventions
- COVID-19 Clinical Research Studies
- Markov Chains and Monte Carlo Methods
- Vaccine Coverage and Hesitancy
- Galaxies: Formation, Evolution, Phenomena
- demographic modeling and climate adaptation
- Mental Health Research Topics
- Mental Health Treatment and Access
- Image Processing and 3D Reconstruction
- Terahertz technology and applications
- Image and Object Detection Techniques
- Machine Learning in Healthcare
- Spectroscopy and Laser Applications
Institute for Disease Modeling
2020-2024
Gates Foundation
2020-2024
Leeds Beckett University
2023
McGill University
2020-2021
University of Copenhagen
2021
London School of Hygiene & Tropical Medicine
2021
University College London
2021
Center for Astrophysics Harvard & Smithsonian
2012-2018
Harvard University
2011-2015
Smithsonian Astrophysical Observatory
2012
We present a substantial extension of the mm-wave continuum photometry catalog for Taurus circumstellar dust disks. Combining new Submillimeter Array data with measurements in literature, we construct luminosity distribution Class II disks that is statistically complete stellar hosts spectral types earlier than M8.5 and has (3-sigma) depth ~3 mJy. The resulting census eliminates longstanding bias against late-type hosts, thereby reveals strong correlation between L_mm host type. confirm this...
The COVID-19 pandemic has created an urgent need for models that can project epidemic trends, explore intervention scenarios, and estimate resource needs. Here we describe the methodology of Covasim (COVID-19 Agent-based Simulator), open-source model developed to help address these questions. includes country-specific demographic information on age structure population size; realistic transmission networks in different social layers, including households, schools, workplaces, long-term care...
We present high-resolution (03 = 16 AU), high signal-to-noise ratio Submillimeter Array observations of the 870 μm (345 GHz) continuum and CO J 3 − 2 line emission from protoplanetary disk around TW Hya. Using radiative transfer calculations, these data multiwavelength spectral energy distribution are analyzed together in context simple two-dimensional parametric structure models. Under assumptions a radially invariant dust population gas-to-dust mass ratio, we unable to simultaneously...
Magnetic fields near the event horizon Astronomers have long sought to examine a black hole's horizon—the boundary around hole within which nothing can escape. Johnson et al. used sophisticated interferometry techniques combine data from millimeter-wavelength telescopes world. They measured polarization just outside of Sgr A*, supermassive at center our galaxy, Milky Way. The is signature ordered magnetic generated in accretion disk hole. results help explain how holes accrete gas and launch...
Abstract The COVID-19 pandemic has created an urgent need for models that can project epidemic trends, explore intervention scenarios, and estimate resource needs. Here we describe the methodology of Covasim (COVID-19 Agent-based Simulator), open-source model developed to help address these questions. includes country-specific demographic information on age structure population size; realistic transmission networks in different social layers, including households, schools, workplaces,...
Abstract Initial COVID-19 containment in the United States focused on limiting mobility, including school and workplace closures. However, these interventions have had enormous societal economic costs. Here, we demonstrate feasibility of an alternative control strategy, test-trace-quarantine: routine testing primarily symptomatic individuals, tracing their known contacts, placing contacts quarantine. We perform this analysis using Covasim, open-source agent-based model, which has been...
Turbulence can transport angular momentum in protoplanetary disks and influence the growth evolution of planets. With spatially spectrally resolved molecular emission line measurements provided by (sub)millimeter interferometric observations, it is possible to directly measure non-thermal motions disk gas that be attributed this turbulence. We report a new constraint on turbulence around HD 163296, nearby young A star, determined from ALMA Science Verification observations four CO lines (the...
Theory predicts that giant planets and low mass stellar companions shape circumstellar disks by opening annular gaps in the gas dust spatial distribution. For more than a decade it has been debated whether this is dominant process leads to formation of transitional disks. In paper, we present millimeter-wave interferometric observations disk around young intermediate star LkHa330. These reveal lopsided ring 1.3 mm thermal emission characterized radius about 100 AU an azimuthal intensity...
We analyze sensitive, sub-arcsecond resolution ALMA science verification observations of CO emission lines in the protoplanetary disk hosted by young, isolated Ae star HD 163296. The observed spatial morphology 12CO J = 3–2 line is asymmetric across major axis disk; 2–1 features a much less pronounced, but similar, asymmetry. from and its main isotopologues have no resolved associate this behavior with direct signature vertical temperature gradient layered molecular structure disk. This...
We present a detailed analysis of the spatially and spectrally resolved 12CO J=2-1 J=3-2 emission lines from TW Hya circumstellar disk, based on science verification data Atacama Large Millimeter/Submillimeter Array (ALMA). These exhibit substantial in their high-velocity wings (with projected velocities out to 2.1 km/s, corresponding intrinsic orbital >20 km/s) that trace molecular gas as close 2 AU central star. However, we are not able reproduce intensity these general spatio-kinematic...
Protoplanetary "transition" disks have large, mass-depleted central cavities, yet also deliver gas onto their host stars at rates comparable to without holes. The paradox of simultaneous transparency and accretion can be explained if flows inward much higher radial speeds inside the cavity than outside cavity, since surface density (and by extension optical depth) varies inversely with inflow velocity fixed rate. Radial within might even approach free-fall values explain huge contrasts...
We present sensitive, sub-arcsecond resolution Submillimeter Array observations of the protoplanetary disk around nearby, pre-main sequence spectroscopic binary V4046 Sgr. report for first time a large inner hole (r = 29 AU) spatially resolved in 1.3 mm continuum emission and study structure this using radiative transfer calculations to model spectral energy distribution, visibilities, line CO its main isotopologues. Our modeling scheme demonstrates that majority dust mass is distributed...
The Galactic Center black hole Sagittarius A* (Sgr A*) is a prime observing target for the Event Horizon Telescope (EHT), which can resolve 1.3 mm emission from this source on angular scales comparable to that of general relativistic shadow. Previous EHT observations have used visibility amplitudes infer morphology millimeter-wavelength emission. Potentially much richer information contained in phases. We report phase Sgr obtained with total 13 nights over 4 years. Closure phases, sum phases...
Background Recently, artificial intelligence-powered devices have been put forward as potentially powerful tools for the improvement of mental healthcare. An important question is how these impact physician-patient interaction. Aims Aifred an clinical decision support system (CDSS) treatment major depression. Here, we explore use a simulation centre environment in evaluating usability Aifred, particularly its on physician–patient Method Twenty psychiatry and family medicine attending staff...
Policymakers must make management decisions despite incomplete knowledge and conflicting model projections. Little guidance exists for the rapid, representative, unbiased collection of policy-relevant scientific input from independent modeling teams. Integrating approaches decision analysis, expert judgment, aggregation, we convened multiple teams to evaluate COVID-19 reopening strategies a mid-sized United States county early in pandemic. Projections seventeen distinct models were...
We present 1.3 mm ALMA Cycle 0 observations of the edge-on debris disk around nearby, ∼10 Myr old, M-type star AU Mic. These obtain 06 (6 AU) resolution and reveal two distinct emission components: (1) previously known dust belt that extends to a radius 40 (2) newly recognized central peak remains unresolved. The cold mass ∼1 MMoon is resolved in radial direction with rising profile peaks sharply at location outer edge "birth ring" planetesimals hypothesized explain midplane scattered light...
An initial three-station version of the Event Horizon Telescope, a millimeter-wavelength very-long baseline interferometer, has observed Sagittarius A* (Sgr A*) repeatedly from 2007 to 2013, resulting in measurement variety interferometric quantities. Of particular importance, there is now large set closure phases, measured over number independent observing epochs. We analyze these observations within context realization semi-analytic radiatively inefficient disk models, implicated by low...
Abstract Policymakers make decisions about COVID-19 management in the face of considerable uncertainty. We convened multiple modeling teams to evaluate reopening strategies for a mid-sized county United States, novel process designed fully express scientific uncertainty while reducing linguistic and cognitive biases. For scenarios considered, consensus from 17 distinct models was that second outbreak will occur within 6 months reopening, unless schools non-essential workplaces remain closed....
We present 870 μm observations of dust continuum emission from the LkCa 15 protoplanetary disk at high angular resolution (with a characteristic scale 025 = 35 AU), obtained with IRAM Plateau de Bure interferometer and supplemented by slightly lower Submillimeter Array. fit these data simple morphological models to characterize spectacular ring-like structure this disk. Our analysis indicates that small amount (∼5 mJy) originates inside large (40–50 AU radius) low optical depth cavity. This...
We present sensitive, arcsecond-resolution Submillimeter Array observations of the 12CO J=2-1 line emission from circumstellar disk orbiting double-lined spectroscopic binary star V4046 Sgr. Based on a simple model structure, we use novel Monte Carlo Markov Chain technique to extract Keplerian velocity field these data and estimate total mass central binary. Assuming distance inferred kinematic parallax measurements in literature (d is approximately 73 pc), determine stellar M_star =...
Modern radio interferometers enable observations of spectral lines with unprecedented spatial resolution and sensitivity. In spite these technical advances, many interest are still at best weakly detected therefore necessitate detection analysis techniques specialized for the low signal-to-noise ratio (SNR) regime. Matched filters can leverage knowledge source structure kinematics to increase sensitivity line observations. Application filter in native Fourier domain improves SNR while...
The English SARS-CoV-2 epidemic has been affected by the emergence of new viral variants such as B.1.177, Alpha and Delta, changing restrictions. We used statistical models agent-based model Covasim, in June 2021, to estimate B.1.177 be 20% more transmissible than wild type, 50-80% Delta 65-90% Alpha. Using these estimates Covasim (calibrated 1 September 2020 20 2021), we found that due high transmissibility resurgence infections driven variant would not prevented, but strongly reduced...
We report the first detection of c-C3H2 in a circumstellar disk. The J = 6–5 line (217.882 GHz) is detected and imaged through Atacama Large Millimeter Array (ALMA) Science Verification observations toward disk around Herbig Ae star HD 163296 at 08 resolution. emission consistent with that arising from Keplerian rotating Two additional transitions are also tentatively detected, bolstering identification this species, but insufficient signal-to-noise ratio to constrain spatial distribution....
The radio emission from Sgr A$^\ast$ is thought to be powered by accretion onto a supermassive black hole of $\sim\! 4\times10^6~ \rm{M}_\odot$ at the Galactic Center. At millimeter wavelengths, Very Long Baseline Interferometry (VLBI) observations can directly resolve bright innermost region A$^\ast$. Motivated addition many sensitive, long baselines in north-south direction, we developed full VLBI capability Large Millimeter Telescope Alfonso Serrano (LMT). We successfully detected 3.5~mm...
Abstract Initial COVID-19 containment in the United States focused on limiting mobility, including school and workplace closures. However, these interventions have had enormous societal economic costs. Here we demonstrate feasibility of an alternative control strategy, test-trace-quarantine: routine testing primarily symptomatic individuals, tracing their known contacts, placing contacts quarantine. We performed this analysis using Covasim, open-source agent-based model, which was calibrated...