43 research outputs found
3D Correlations in the Lyman- Forest from Early DESI Data
We present the first measurements of Lyman- (Ly) forest
correlations using early data from the Dark Energy Spectroscopic Instrument
(DESI). We measure the auto-correlation of Ly absorption using 88,509
quasars at , and its cross-correlation with quasars using a further
147,899 tracer quasars at . Then, we fit these correlations using
a 13-parameter model based on linear perturbation theory and find that it
provides a good description of the data across a broad range of scales. We
detect the BAO peak with a signal-to-noise ratio of , and show that
our measurements of the auto- and cross-correlations are fully-consistent with
previous measurements by the Extended Baryon Oscillation Spectroscopic Survey
(eBOSS). Even though we only use here a small fraction of the final DESI
dataset, our uncertainties are only a factor of 1.7 larger than those from the
final eBOSS measurement. We validate the existing analysis methods of
Ly correlations in preparation for making a robust measurement of the
BAO scale with the first year of DESI data
The Lyman- forest catalog from the Dark Energy Spectroscopic Instrument Early Data Release
We present and validate the catalog of Lyman- forest fluctuations for
3D analyses using the Early Data Release (EDR) from the Dark Energy
Spectroscopic Instrument (DESI) survey. We used 96,317 quasars collected from
DESI Survey Validation (SV) data and the first two months of the main survey
(M2). We present several improvements to the method used to extract the
Lyman- absorption fluctuations performed in previous analyses from the
Sloan Digital Sky Survey (SDSS). In particular, we modify the weighting scheme
and show that it can improve the precision of the correlation function
measurement by more than 20%. This catalog can be downloaded from
https://data.desi.lbl.gov/public/edr/vac/edr/lya/fuji/v0.3 and it will be used
in the near future for the first DESI measurements of the 3D correlations in
the Lyman- forest
Overview of the instrumentation for the Dark Energy Spectroscopic Instrument
The Dark Energy Spectroscopic Instrument (DESI) embarked on an ambitious 5 yr survey in 2021 May to explore the nature of dark energy with spectroscopic measurements of 40 million galaxies and quasars. DESI will determine precise redshifts and employ the baryon acoustic oscillation method to measure distances from the nearby universe to beyond redshift z > 3.5, and employ redshift space distortions to measure the growth of structure and probe potential modifications to general relativity. We describe the significant instrumentation we developed to conduct the DESI survey. This includes: a wide-field, 3.°2 diameter prime-focus corrector; a focal plane system with 5020 fiber positioners on the 0.812 m diameter, aspheric focal surface; 10 continuous, high-efficiency fiber cable bundles that connect the focal plane to the spectrographs; and 10 identical spectrographs. Each spectrograph employs a pair of dichroics to split the light into three channels that together record the light from 360â980 nm with a spectral resolution that ranges from 2000â5000. We describe the science requirements, their connection to the technical requirements, the management of the project, and interfaces between subsystems. DESI was installed at the 4 m Mayall Telescope at Kitt Peak National Observatory and has achieved all of its performance goals. Some performance highlights include an rms positioner accuracy of better than 0.âł1 and a median signal-to-noise ratio of 7 of the [O ii] doublet at 8 Ă 10â17 erg sâ1 cmâ2 in 1000 s for galaxies at z = 1.4â1.6. We conclude with additional highlights from the on-sky validation and commissioning, key successes, and lessons learned
Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study
Summary
Background Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally.
Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies
have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of
the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income
countries globally, and identified factors associated with mortality.
Methods We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to
hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis,
exomphalos, anorectal malformation, and Hirschsprungâs disease. Recruitment was of consecutive patients for a
minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical
status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary
intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause,
in-hospital mortality for all conditions combined and each condition individually, stratified by country income status.
We did a complete case analysis.
Findings We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital
diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal
malformation, and 517 with Hirschsprungâs disease) from 264 hospitals (89 in high-income countries, 166 in middleincome
countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male.
Median gestational age at birth was 38 weeks (IQR 36â39) and median bodyweight at presentation was 2·8 kg (2·3â3·3).
Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income
countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups).
Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in lowincome
countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries;
pâ€0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients
combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88â4·11],
p<0·0001; middle-income vs high-income countries, 2·11 [1·59â2·79], p<0·0001), sepsis at presentation (1·20
[1·04â1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention
(ASA 4â5 vs ASA 1â2, 1·82 [1·40â2·35], p<0·0001; ASA 3 vs ASA 1â2, 1·58, [1·30â1·92], p<0·0001]), surgical safety
checklist not used (1·39 [1·02â1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed
(ventilation 1·96, [1·41â2·71], p=0·0001; parenteral nutrition 1·35, [1·05â1·74], p=0·018). Administration of
parenteral nutrition (0·61, [0·47â0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65
[0·50â0·86], p=0·0024) or percutaneous central line (0·69 [0·48â1·00], p=0·049) were associated with lower mortality.
Interpretation Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between lowincome,
middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will
be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger
than 5 years by 2030
Reversible Crosslinked Polymer Binder for Recyclable Lithium Sulfur Batteries with High Performance
Owing to the negative impact of the extensive utilization of batteries on the environment, sustainability of the cells needs to be included in the systemic research of batteries. Herein, a dissolvable ionic crosslinked polymer (DICP) is exploited as a binder for lithiumâsulfur batteries by crosslinking the polyacrylic acid and polyethyleneimine through carboxy-amino ionic interaction. This interaction is pH-controlled, and therefore, the crosslinked binder network can be readily dissociated under basic conditions, providing a facile strategy enabling valuable components recycled through a convenient washing method. The sulfur cathode prepared using the recycled carbonâsulfur composite can deliver comparable capacity as that of fresh electrode. In addition, evidence from cell performance and characterizations, such as in situ X-ray absorption spectroscopy, in situ UVâvisible spectroscopy, X-ray photoelectron spectroscopy, and density functional theory calculation, confirms that DICP is a more effective binder than its commercial counterpart on suppressing polysulfide dissolution in the electrolyte. Exploiting reversible crosslinked polymer binder for recyclable LiâS batteries with ameliorated electrochemical performance, this study illuminates sustainable development for large-scale energy storage systems
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Reversible Crosslinked Polymer Binder for Recyclable Lithium Sulfur Batteries with High Performance
Owing to the negative impact of the extensive utilization of batteries on the environment, sustainability of the cells needs to be included in the systemic research of batteries. Herein, a dissolvable ionic crosslinked polymer (DICP) is exploited as a binder for lithiumâsulfur batteries by crosslinking the polyacrylic acid and polyethyleneimine through carboxy-amino ionic interaction. This interaction is pH-controlled, and therefore, the crosslinked binder network can be readily dissociated under basic conditions, providing a facile strategy enabling valuable components recycled through a convenient washing method. The sulfur cathode prepared using the recycled carbonâsulfur composite can deliver comparable capacity as that of fresh electrode. In addition, evidence from cell performance and characterizations, such as in situ X-ray absorption spectroscopy, in situ UVâvisible spectroscopy, X-ray photoelectron spectroscopy, and density functional theory calculation, confirms that DICP is a more effective binder than its commercial counterpart on suppressing polysulfide dissolution in the electrolyte. Exploiting reversible crosslinked polymer binder for recyclable LiâS batteries with ameliorated electrochemical performance, this study illuminates sustainable development for large-scale energy storage systems
Analysis of the critical failure modes and developing an aging assessment methodology for lithium iron phosphate batteries
Validation of the DESI 2024 Lyman Alpha Forest BAL Masking Strategy
International audienceBroad absorption line quasars (BALs) exhibit blueshifted absorption relative to a number of their prominent broad emission features. These absorption features can contribute to quasar redshift errors and add absorption to the Lyman-alpha (LyA) forest that is unrelated to large-scale structure. We present a detailed analysis of the impact of BALs on the Baryon Acoustic Oscillation (BAO) results with the LyA forest from the first year of data from the Dark Energy Spectroscopic Instrument (DESI). The baseline strategy for the first year analysis is to mask all pixels associated with all BAL absorption features that fall within the wavelength region used to measure the forest. We explore a range of alternate masking strategies and demonstrate that these changes have minimal impact on the BAO measurements with both DESI data and synthetic data. This includes when we mask the BAL features associated with emission lines outside of the forest region to minimize their contribution to redshift errors. We identify differences in the properties of BALs in the synthetic datasets relative to the observational data, as well as use the synthetic observations to characterize the completeness of the BAL identification algorithm, and demonstrate that incompleteness and differences in the BALs between real and synthetic data also do not impact the BAO results for the LyA forest
3D Correlations in the Lyman- Forest from Early DESI Data
International audienceWe present the first measurements of Lyman- (Ly) forest correlations using early data from the Dark Energy Spectroscopic Instrument (DESI). We measure the auto-correlation of Ly absorption using 88,509 quasars at , and its cross-correlation with quasars using a further 147,899 tracer quasars at . Then, we fit these correlations using a 13-parameter model based on linear perturbation theory and find that it provides a good description of the data across a broad range of scales. We detect the BAO peak with a signal-to-noise ratio of , and show that our measurements of the auto- and cross-correlations are fully-consistent with previous measurements by the Extended Baryon Oscillation Spectroscopic Survey (eBOSS). Even though we only use here a small fraction of the final DESI dataset, our uncertainties are only a factor of 1.7 larger than those from the final eBOSS measurement. We validate the existing analysis methods of Ly correlations in preparation for making a robust measurement of the BAO scale with the first year of DESI data
3D Correlations in the Lyman- Forest from Early DESI Data
International audienceWe present the first measurements of Lyman- (Ly) forest correlations using early data from the Dark Energy Spectroscopic Instrument (DESI). We measure the auto-correlation of Ly absorption using 88,509 quasars at , and its cross-correlation with quasars using a further 147,899 tracer quasars at . Then, we fit these correlations using a 13-parameter model based on linear perturbation theory and find that it provides a good description of the data across a broad range of scales. We detect the BAO peak with a signal-to-noise ratio of , and show that our measurements of the auto- and cross-correlations are fully-consistent with previous measurements by the Extended Baryon Oscillation Spectroscopic Survey (eBOSS). Even though we only use here a small fraction of the final DESI dataset, our uncertainties are only a factor of 1.7 larger than those from the final eBOSS measurement. We validate the existing analysis methods of Ly correlations in preparation for making a robust measurement of the BAO scale with the first year of DESI data