Informatics Metrics and Measures for a Smart Public Health Systems Approach: Information Science Perspective

Public health informatics is an evolving domain in which practices constantly change to meet the demands of a highly complex public health and healthcare delivery system. Given the emergence of various concepts, such as learning health systems, smart health systems, and adaptive complex health systems, health informatics professionals would benefit from a common set of measures and capabilities to inform our modeling, measuring, and managing of health system “smartness.” Here, we introduce the concepts of organizational complexity, problem/issue complexity, and situational awareness as three codependent drivers of smart public health systems characteristics. We also propose seven smart public health systems measures and capabilities that are important in a public health informatics professional’s toolkit

Simulating galaxies in the reionization era with FIRE-2: morphologies and sizes

We study the morphologies and sizes of galaxies at z>5 using high-resolution cosmological zoom-in simulations from the Feedback In Realistic Environments project. The galaxies show a variety of morphologies, from compact to clumpy to irregular. The simulated galaxies have more extended morphologies and larger sizes when measured using rest-frame optical B-band light than rest-frame UV light; sizes measured from stellar mass surface density are even larger. The UV morphologies are usually dominated by several small, bright young stellar clumps that are not always associated with significant stellar mass. The B-band light traces stellar mass better than the UV, but it can also be biased by the bright clumps. At all redshifts, galaxy size correlates with stellar mass/luminosity with large scatter. The half-light radii range from 0.01 to 0.2 arcsec (0.05-1 kpc physical) at fixed magnitude. At z>5, the size of galaxies at fixed stellar mass/luminosity evolves as (1+z)^{-m}, with m~1-2. For galaxies less massive than M_star~10^8 M_sun, the ratio of the half-mass radius to the halo virial radius is ~10% and does not evolve significantly at z=5-10; this ratio is typically 1-5% for more massive galaxies. A galaxy's "observed" size decreases dramatically at shallower surface brightness limits. This effect may account for the extremely small sizes of z>5 galaxies measured in the Hubble Frontier Fields. We provide predictions for the cumulative light distribution as a function of surface brightness for typical galaxies at z=6.Comment: 11 pages, 11 figures, resubmitted to MNRAS after revision for referee's comment

Formation of Globular Cluster Candidates in Merging Proto-galaxies at High Redshift: A View from the FIRE Cosmological Simulations

Using a state-of-the-art cosmological simulation of merging proto-galaxies at high redshift from the FIRE project, with explicit treatments of star formation and stellar feedback in the interstellar medium, we investigate the formation of star clusters and examine one of the formation hypothesis of present-day metal-poor globular clusters. We find that frequent mergers in high-redshift proto-galaxies could provide a fertile environment to produce long-lasting bound star clusters. The violent merger event disturbs the gravitational potential and pushes a large gas mass of ~> 1e5-6 Msun collectively to high density, at which point it rapidly turns into stars before stellar feedback can stop star formation. The high dynamic range of the reported simulation is critical in realizing such dense star-forming clouds with a small dynamical timescale, t_ff <~ 3 Myr, shorter than most stellar feedback timescales. Our simulation then allows us to trace how clusters could become virialized and tightly-bound to survive for up to ~420 Myr till the end of the simulation. Because the cluster's tightly-bound core was formed in one short burst, and the nearby older stars originally grouped with the cluster tend to be preferentially removed, at the end of the simulation the cluster has a small age spread.Comment: 14 pages, 14 figures, Accepted for publication in the Monthly Notices of the Royal Astronomical Society, High-resolution version of this article also available at http://www.jihoonkim.org/index/research.html#g

Star formation histories of dwarf galaxies in the FIRE simulations: dependence on mass and Local Group environment

We study star formation histories (SFHs) of $\simeq500$ dwarf galaxies (stellar mass $M_\ast = 10^5 - 10^9\,M_\odot$) from FIRE-2 cosmological zoom-in simulations. We compare dwarfs around individual Milky Way (MW)-mass galaxies, dwarfs in Local Group (LG)-like environments, and true field (i.e. isolated) dwarf galaxies. We reproduce observed trends wherein higher-mass dwarfs quench later (if at all), regardless of environment. We also identify differences between the environments, both in terms of "satellite vs. central" and "LG vs. individual MWvs. isolated dwarf central." Around the individual MW-mass hosts, we recover the result expected from environmental quenching: central galaxies in the "near field" have more extended SFHs than their satellite counterparts, with the former more closely resemble isolated ("true field") dwarfs (though near-field centrals are still somewhat earlier forming). However, this difference is muted in the LG-like environments, where both near-field centrals and satellites have similar SFHs, which resemble satellites of single MW-mass hosts. This distinction is strongest for $M_\ast = 10^6 - 10^7\,M_\odot$ but exists at other masses. Our results suggest that the paired halo nature of the LG may regulate star formation in dwarf galaxies even beyond the virial radii of the MW and Andromeda. Caution is needed when comparing zoom-in simulations targeting isolated dwarf galaxies against observed dwarf galaxies in the LG.Comment: Main text: 11 pages, 8 figures; appendices: 4 pages, 4 figures. Submitted to MNRAS; comments welcom

An Adaptive Decision Framework for the Conservation of a Threatened Plant

This is the publisher's version, also available electronically from http://www.fwspubs.org/.Mead's milkweed Asclepias meadii, a long-lived perennial herb of tallgrass prairie and glade communities of the central United States, is a species designated as threatened under the U.S. Endangered Species Act. Challenges to its successful management include the facts that much about its life history is unknown, its age at reproductive maturity is very advanced, certain life stages are practically unobservable, its productivity is responsive to unpredictable environmental events, and most of the known populations occur on private lands unprotected by any legal conservation instrument. One critical source of biological uncertainty is the degree to which fire promotes growth and reproductive response in the plant. To aid in its management, we developed a prototype population-level state-dependent decision-making framework that explicitly accounts for this uncertainty and for uncertainties related to stochastic environmental effects and vital rates. To parameterize the decision model, we used estimates found in the literature, and we analyzed data from a long-term monitoring program where fates of individual plants were observed through time. We demonstrate that different optimal courses of action are followed according to how one believes that fire influences reproductive response, and we show that the action taken for certain population states is informative for resolving uncertainty about competing beliefs regarding the effect of fire. We advocate the use of a model-predictive approach for the management of rare populations, particularly when management uncertainty is profound. Over time, an adaptive management approach should reduce uncertainty and improve management performance as predictions of management outcome generated under competing models are continually informed and updated by monitoring data

Partial pressure of arterial carbon dioxide after resuscitation from cardiac arrest and neurological outcome: A prospective multi-center protocol-directed cohort study

Aims Partial pressure of arterial carbon dioxide (PaCO2) is a regulator of cerebral blood flow after brain injury. We sought to test the association between PaCO2 after resuscitation from cardiac arrest and neurological outcome. Methods A prospective protocol-directed cohort study across six hospitals. Inclusion criteria: age ≥ 18, non-traumatic cardiac arrest, mechanically ventilated after return of spontaneous circulation (ROSC), and receipt of targeted temperature management. Per protocol, PaCO2 was measured by arterial blood gas analyses at one and six hours after ROSC. We determined the mean PaCO2 over this initial six hours after ROSC. The primary outcome was good neurological function at hospital discharge, defined a priori as a modified Rankin Scale ≤ 3. Multivariable Poisson regression analysis was used to test the association between PaCO2 and neurological outcome. Results Of the 280 patients included, the median (interquartile range) PaCO2 was 44 (37-52) mmHg and 30% had good neurological function. We found mean PaCO2 had a quadratic (inverted “U” shaped) association with good neurological outcome, with a mean PaCO2 of 68 mmHg having the highest predictive probability of good neurological outcome, and worse neurological outcome at higher and lower PaCO2. Presence of metabolic acidosis attenuated the association between PaCO2 and good neurological outcome, with a PaCO2 of 51 mmHg having the highest predictive probability of good neurological outcome among patients with metabolic acidosis. Conclusion PaCO2 has a “U” shaped association with neurological outcome, with mild to moderate hypercapnia having the highest probability of good neurological outcome

Association Between Elevated Mean Arterial Blood Pressure and Neurologic Outcome After Resuscitation From Cardiac Arrest: Results From a Multicenter Prospective Cohort Study

Objective: Laboratory studies suggest elevated blood pressure after resuscitation from cardiac arrest may be protective; however, clinical data are limited. We sought to test the hypothesis that elevated post-resuscitation mean arterial blood pressure (MAP) is associated with neurological outcome. Design: Pre-planned analysis of a prospective cohort study. Setting: Six academic hospitals in the United States. Patients: Adult, non-traumatic cardiac arrest patients treated with targeted temperature management after return of spontaneous circulation (ROSC). Interventions: MAP was measured non-invasively after ROSC and every hour during the initial six hours after ROSC. Measures and Main Results: We calculated the mean MAP and a priori dichotomized subjects into two groups: mean MAP 70–90 and > 90 mmHg. The primary outcome was good neurological function, defined as a modified Rankin Scale (mRS) ≤ 3. The mRS was prospectively determined at hospital discharge. Of the 269 patients included, 159 (59%) had a mean MAP > 90 mmHg. Good neurological function at hospital discharge occurred in 30% of patients in the entire cohort, and was significantly higher in patients with a mean MAP > 90 mmHg (42%) as compared to MAP 70–90 mmHg (15%) [absolute risk difference 27% (95% CI 17%−37%)]. In a multivariable Poisson regression model adjusting for potential confounders, mean MAP > 90 mmHg was associated with good neurological function, adjusted relative risk 2.46 (95% CI 2.09–2.88). Over ascending ranges of mean MAP, there was a dose-response increase in probability of good neurological outcome, with mean MAP > 110 mmHg having the strongest association, adjusted relative risk 2.97 (95% CI 1.86 – 4.76). Conclusions: Elevated blood pressure during the initial six hours after resuscitation from cardiac arrest was independently associated with good neurological function at hospital discharge. Further investigation is warranted to determine if targeting an elevated MAP would improve neurologic outcome after cardiac arrest

The origin of the diverse morphologies and kinematics of Milky Way-mass galaxies in the FIRE-2 simulations

We use hydrodynamic cosmological zoom-in simulations from the Feedback in Realistic Environments project to explore the morphologies and kinematics of 15 Milky Way (MW)-mass galaxies. Our sample ranges from compact, bulge-dominated systems with 90 per cent of their stellar mass within 2.5 kpc to well-ordered discs that reach ≳15 kpc. The gas in our galaxies always forms a thin, rotation-supported disc at z = 0, with sizes primarily determined by the gas mass. For stars, we quantify kinematics and morphology both via the fraction of stars on disc-like orbits and with the radial extent of the stellar disc. In this mass range, stellar morphology and kinematics are poorly correlated with the properties of the halo available from dark matter-only simulations (halo merger history, spin, or formation time). They more strongly correlate with the gaseous histories of the galaxies: those that maintain a high gas mass in the disc after z ∼ 1 develop well-ordered stellar discs. The best predictor of morphology we identify is the spin of the gas in the halo at the time the galaxy formed 1/2 of its stars (i.e. the gas that builds the galaxy). High-z mergers, before a hot halo emerges, produce some of the most massive bulges in the sample (from compact discs in gas-rich mergers), while later-forming bulges typically originate from internal processes, as satellites are stripped of gas before the galaxies merge. Moreover, most stars in z = 0 MW-mass galaxies (even z = 0 bulge stars) form in a disc: ≳60--90 per cent of stars begin their lives rotationally supported