34 research outputs found
Measuring the photo-ionization rate, neutral fraction and mean free path of HI ionizing photons at from a large sample of XShooter and ESI spectra
We measure the mean free path (), photo-ionization rate
() and neutral fraction () of hydrogen in 12 redshift bins at from a large sample
of moderate resolution XShooter and ESI QSO absorption spectra. The
fluctuations in ionizing radiation field are modeled by post-processing
simulations from the Sherwood suite using our new code ''EXtended reionization
based on the Code for Ionization and Temperature Evolution'' (EX-CITE). EX-CITE
uses efficient Octree summation for computing intergalactic medium attenuation
and can generate large number of high resolution fluctuation
models. Our simulation with EX-CITE shows remarkable agreement with simulations
performed with the radiative transfer code Aton and can recover the simulated
parameters within uncertainty. We measure the three parameters by
forward-modeling the Ly forest and comparing the effective optical
depth () distribution in simulations and observations. The
final uncertainties in our measured parameters account for the uncertainties
due to thermal parameters, modeling parameters, observational systematics and
cosmic variance. Our best fit parameters show significant evolution with
redshift such that and
decreases and increases by a factor and , respectively
from to . By comparing our ,
and evolution
with that in state-of-the-art Aton radiative transfer simulations and the
Thesan and CoDa-III simulations, we find that our best fit parameter evolution
is consistent with a model in which reionization completes by .Comment: 30 pages (+14 pages appendices), 14 figures (+18 figures appendices);
submitted to MNRAS; Main results are summarized in Fig. 10, Fig. 11 and Table
Anemia prevalence in women of reproductive age in low- and middle-income countries between 2000 and 2018
Anemia is a globally widespread condition in women and is associated with reduced economic productivity and increased mortality worldwide. Here we map annual 2000â2018 geospatial estimates of anemia prevalence in women of reproductive age (15â49 years) across 82 low- and middle-income countries (LMICs), stratify anemia by severity and aggregate results to policy-relevant administrative and national levels. Additionally, we provide subnational disparity analyses to provide a comprehensive overview of anemia prevalence inequalities within these countries and predict progress toward the World Health Organizationâs Global Nutrition Target (WHO GNT) to reduce anemia by half by 2030. Our results demonstrate widespread moderate improvements in overall anemia prevalence but identify only three LMICs with a high probability of achieving the WHO GNT by 2030 at a national scale, and no LMIC is expected to achieve the target in all their subnational administrative units. Our maps show where large within-country disparities occur, as well as areas likely to fall short of the WHO GNT, offering precision public health tools so that adequate resource allocation and subsequent interventions can be targeted to the most vulnerable populations
Measuring the photo-ionization rate, neutral fraction and mean free path of HI ionizing photons at 4.9â€zâ€6.0 from a large sample of XShooter and ESI spectra
We measure the mean free path (â λmfp,HIâ ), photo-ionization rate (â âšÎHIâ©â ) and neutral fraction (â âšfHIâ©â ) of hydrogen in 12 redshift bins at 4.85 < z < 6.05 from a large sample of moderate resolution XShooter and ESI QSO absorption spectra. The fluctuations in ionizing radiation field are modeled by post-processing simulations from the Sherwood suite using our new code âEXtended reionization based on the Code for Ionization and Temperature Evolutionâ (EX-CITE). EX-CITE uses efficient Octree summation for computing intergalactic medium attenuation and can generate large number of high resolution ÎHI fluctuation models. Our simulation with EX-CITE shows remarkable agreement with simulations performed with the radiative transfer code Aton and can recover the simulated parameters within 1Ï uncertainty. We measure the three parameters by forward-modeling the Lyα forest and comparing the effective optical depth (â Ïeff,HIâ ) distribution in simulations and observations. The final uncertainties in our measured parameters account for the uncertainties due to thermal parameters, modeling parameters, observational systematics and cosmic variance. Our best fit parameters show significant evolution with redshift such that λmfp,HI and âšfHIâ© decreases and increases by a factor âŒ6 and âŒ104, respectively from z ⌠5 to z ⌠6. By comparing our λmfp,HIâ , âšÎHIâ© and âšfHIâ© evolution with that in state-of-the-art Aton radiative transfer simulations and the Thesan and CoDa-III simulations, we find that our best fit parameter evolution is consistent with a model in which reionization completes by z ⌠5.2. Our best fit model that matches the Ïeff,HI distribution also reproduces the dark gap length distribution and transmission spike height distribution suggesting robustness and accuracy of our measured parameters
Modeling COVID-19 scenarios for the United States
We use COVID-19 case and mortality data from 1 February 2020 to 21 September 2020 and a deterministic SEIR (susceptible, exposed, infectious and recovered) compartmental framework to model possible trajectories of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections and the effects of non-pharmaceutical interventions in the United States at the state level from 22 September 2020 through 28 February 2021. Using this SEIR model, and projections of critical driving covariates (pneumonia seasonality, mobility, testing rates and mask use per capita), we assessed scenarios of social distancing mandates and levels of mask use. Projections of current non-pharmaceutical intervention strategies by stateâwith social distancing mandates reinstated when a threshold of 8 deaths per million population is exceeded (reference scenario)âsuggest that, cumulatively, 511,373 (469,578â578,347) lives could be lost to COVID-19 across the United States by 28 February 2021. We find that achieving universal mask use (95% mask use in public) could be sufficient to ameliorate the worst effects of epidemic resurgences in many states. Universal mask use could save an additional 129,574 (85,284â170,867) lives from September 22, 2020 through the end of February 2021, or an additional 95,814 (60,731â133,077) lives assuming a lesser adoption of mask wearing (85%), when compared to the reference scenario