Interhemispheric antiphasing of neotropical precipitation during the past millennium.

Uncertainty about the influence of anthropogenic radiative forcing on the position and strength of convective rainfall in the Intertropical Convergence Zone (ITCZ) inhibits our ability to project future tropical hydroclimate change in a warmer world. Paleoclimatic and modeling data inform on the timescales and mechanisms of ITCZ variability; yet a comprehensive, long-term perspective remains elusive. Here, we quantify the evolution of neotropical hydroclimate over the preindustrial past millennium (850 to 1850 CE) using a synthesis of 48 paleo-records, accounting for uncertainties in paleo-archive age models. We show that an interhemispheric pattern of precipitation antiphasing occurred on multicentury timescales in response to changes in natural radiative forcing. The conventionally defined "Little Ice Age" (1450 to 1850 CE) was marked by a clear shift toward wetter conditions in the southern neotropics and a less distinct and spatiotemporally complex transition toward drier conditions in the northern neotropics. This pattern of hydroclimatic change is consistent with results from climate model simulations indicating that a relative cooling of the Northern Hemisphere caused a southward shift in the thermal equator across the Atlantic basin and a southerly displacement of the ITCZ in the tropical Americas, with volcanic forcing as the principal driver. These findings are at odds with proxy-based reconstructions of ITCZ behavior in the western Pacific basin, where changes in ITCZ width and intensity, rather than mean position, appear to have driven hydroclimate transitions over the last millennium. This reinforces the idea that ITCZ responses to external forcing are region specific, complicating projections of the tropical precipitation response to global warming.

Two Weeks Versus One Week of Maximal Patient-Intensivist Continuity for Adult Medical Intensive Care Patients: A Two-Center Target Trial Emulation.

OBJECTIVES: To compare outcomes for 2 weeks vs. 1 week of maximal patient-intensivist continuity in the ICU. DESIGN: Retrospective cohort study. SETTING: Two U.S. urban, teaching, medical ICUs where intensivists were scheduled for 2-week service blocks: site A was in the Midwest and site B was in the Northeast. PATIENTS: Patients 18 years old or older admitted to a study ICU between March 1, 2017, and February 28, 2020. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We applied target trial emulation to compare admission during an intensivist's first week (as a proxy for 2 wk of maximal continuity) vs. admission during their second week (as a proxy for 1 wk of maximal continuity). Outcomes included hospital mortality, ICU length of stay, and, for mechanically ventilated patients, duration of ventilation. Exploratory outcomes included imaging, echocardiogram, and consultation orders. We used inverse probability weighting to adjust for baseline differences and random-effects meta-analysis to calculate overall effect estimates. Among 2571 patients, 1254 were admitted during an intensivist's first week and 1317 were admitted during a second week. At sites A and B, hospital mortality rates were 25.8% and 24.2%, median ICU length of stay were 4 and 2 days, and median mechanical ventilation durations were 3 and 3 days, respectively. There were no differences in adjusted mortality (odds ratio [OR], 1.01 [95% CI, 0.96-1.06]) or ICU length of stay (-0.25 d [-0.82 d to +0.32 d]) for 2 weeks vs. 1 week of maximal continuity. Among mechanically ventilated patients, there were no differences in adjusted mortality (OR, 1.00 [0.87-1.16]), ICU length of stay (+0.06 d [-0.78 d to +0.91 d]), or duration of mechanical ventilation (+0.37 d [-0.46 d to +1.21 d]) for 2 weeks vs. 1 week of maximal continuity. CONCLUSIONS: Two weeks of maximal patient-intensivist continuity was not associated with differences in clinical outcomes compared with 1 week in two medical ICUs.

Mountaintop Removal Coal Mining Contaminates Snowpack across a Broad Region.

Mountaintop removal coal mining is a source of downstream pollution. Here, we show that mountaintop removal coal mining also pollutes ecosystems downwind. We sampled regional snowpack near the end of winter along a transect of sites located 3-60 km downwind of coal mining in the Elk River valley of British Columbia, Canada. Vast quantities of polycyclic aromatic compounds (PACs), a toxic class of organic contaminants, are emitted and transported atmospherically far from emission sources. Summed PAC (ΣPAC) snowpack concentrations ranged from 29-94,866 ng/L. Snowpack ΣPAC loads, which account for variable snowpack depth, ranged from <10 µg/m2 at sites >50 km southeast of the mines to >1000 µg/m2 at sites in the Elk River valley near mining operations, with one site >15,000 µg/m2. Outside of the Elk River valley, snowpack ΣPAC loads exhibited a clear spatial pattern decreasing away from the mines. The compositional fingerprint of this PAC pollution matches closely with Elk River valley coal. Beyond our study region, modeling results suggest a depositional footprint extending across western Canada and the northwestern United States. These findings carry important implications for receiving ecosystems and for communities located close to mountaintop removal coal mines exposed to air pollution elevated in PACs.

Paleolimnological evaluation of metal(loid) enrichment from oil sands and gold mining operations in northwestern Canada.

Abundant reserves of metals and oil have spurred large-scale mining developments across northwestern Canada during the past 80 years. Historically, the associated emissions footprint of hazardous metal(loid)s has been difficult to identify, in part, because monitoring records are too short and sparse to have characterized their natural concentrations before mining began. Stratigraphic analysis of lake sediment cores has been employed where concerns of pollution exist to determine pre-disturbance metal(loid) concentrations and quantify the degree of enrichment since mining began. Here, we synthesize the current state of knowledge via systematic re-analysis of temporal variation in sediment metal(loid) concentrations from 51 lakes across four key regions spanning 670 km from bitumen mining in the Alberta Oil Sands Region (AOSR) to gold mining (Giant and Con mines) at Yellowknife in central Northwest Territories. Our compilation includes upland and floodplain lakes at varying distances from the mines to evaluate dispersal of pollution-indicator metal(loid)s from bitumen (vanadium and nickel) and gold mining (arsenic and antimony) via atmospheric and fluvial pathways. Results demonstrate 'severe' enrichment of vanadium and nickel at near-field sites (≤20 km) within the AOSR and 'severe' (near-field; ≤ 40 km) to 'considerable' (far-field; 40-80 km) enrichment of arsenic and antimony due to gold mining at Yellowknife via atmospheric pathways, but no evidence of enrichment of vanadium or nickel via atmospheric or fluvial pathways at the Peace-Athabasca Delta and Slave River Delta. Findings can be used by decision makers to evaluate risks associated with contaminant dispersal by the large-scale mining activities. In addition, we reflect upon methodological approaches to be considered when evaluating paleolimnological data for evidence of anthropogenic contributions to metal(loid) deposition and advocate for proactive inclusion of paleolimnology in the early design stage of environmental contaminant monitoring programs.

Dissolved polycyclic aromatic compounds in Canada's Athabasca River in relation to Oil Sands from 2013 through 2019.

The Canada-Alberta Oil Sands Monitoring (OSM) Program began long-term surface water quality monitoring on the lower Athabasca River in 2012. Sampling of low level, bio-accumulative polycyclic aromatic compounds (PACs) targeted a suite of parent and alkylated compounds in the Athabasca River (AR) mainstem using semi-permeable membrane devices (SPMDs). Samples were collected along a gradient from upstream reference near Athabasca, Alberta, through exposure to the Athabasca oil sands deposit (AOSD), various tributary inflows, and mining activities within the OSMA, to downstream recovery near Wood Buffalo National Park (WBNP) and reference on the Slave River. The program adapted over the years, shifting in response to program review and environmental events. The AOSD chemical fingerprint was present in samples collected within the AOSD, through the oil sands mineable area (OSMA), downstream to recovery from 2013 to 2019. PACs were dominated by alkylated phenanthrenes/anthracenes (PAs) and dibenzothiophenes (Ds), with elevated levels of alkylated fluorenes (Fs), naphthalenes (Ns), fluoranthenes/pyrenes (FlPys) and benzo[a]anthracenes/chrysenes (BaACs), increasing in concentration from C1 < C2 < C3 < C4. Concentrations of these petrogenic PACs were at their highest within the OSMA and downstream of tributaries. The AOSD fingerprint was absent from sites located outside of the influence of the AOSD and downstream of the Peace-Athabasca Delta on the Slave River. PAC concentrations in the AR increased with mainstem discharge and loadings from tributaries, were moderated by the PAD, and diluted by the Peace River. This work bolsters the baseline PAC information previously reported for the Athabasca River and waters downstream, reporting 7 years of data, from all sites within the mainstem monitoring program, and exploring potential regional and hydrological drivers of these between sites and over time.

Increasing a microscope's effective field of view via overlapped imaging and machine learning.

This work demonstrates a multi-lens microscopic imaging system that overlaps multiple independent fields of view on a single sensor for high-efficiency automated specimen analysis. Automatic detection, classification and counting of various morphological features of interest is now a crucial component of both biomedical research and disease diagnosis. While convolutional neural networks (CNNs) have dramatically improved the accuracy of counting cells and sub-cellular features from acquired digital image data, the overall throughput is still typically hindered by the limited space-bandwidth product (SBP) of conventional microscopes. Here, we show both in simulation and experiment that overlapped imaging and co-designed analysis software can achieve accurate detection of diagnostically-relevant features for several applications, including counting of white blood cells and the malaria parasite, leading to multi-fold increase in detection and processing throughput with minimal reduction in accuracy.

Polycyclic Aromatic Compounds in Rivers Dominated by Petrogenic Sources after a Boreal Megafire.

Polycyclic aromatic compounds (PACs) threaten the health of aquatic ecosystems. In northeastern Alberta, Canada, decades of oil sands mining and upgrading activities have increased PAC delivery into freshwaters. This PAC pollution adds to natural inputs from river erosion of bitumen-bearing McMurray Formation outcrops and wildfire inputs. Quantifying these petrogenic and pyrogenic PAC inputs, which is key for understanding industrial impacts, remains a challenge. To distinguish petrogenic from pyrogenic inputs, we characterized river water PACs before and after the 2016 Fort McMurray wildfire, one of the largest natural disasters in Canadian history. Samples of wildfire ash and outcropping bitumen allow us to distinguish between these important PAC sources. River PAC concentrations ranged over multiple orders of magnitude (10s-10 000s ng/L). Petrogenic PACs dominated most of the postfire period with only short-term episodes of pyrogenic signatures in burned watersheds due to the wash-in of ash from the watershed. Wildfire PAC inputs during these events resulted in exceptional increases in concentrations that met or exceeded high (petrogenic) background concentrations, driven by the natural erosion of outcropping bitumen. Our dataset offers the first quantification of these two important PAC sources in this industrialized region and provides new insight into the impacts of increasing wildfire frequency and severity across the Boreal Forest.

Caribbean Lead and Mercury Pollution Archived in a Crater Lake.

Lead and mercury have long histories of anthropogenic use and release to the environment extending into preindustrial times. Yet, the timing, magnitude, and persistence of preindustrial emissions remain enigmatic, especially for mercury. Here, we quantify tropical lead and mercury deposition over the past ∼3000 years using a well-dated sediment core from a small crater lake (Lake Antoine, Grenada). Preindustrial increases in lead and mercury concentrations can be explained by varying inputs of watershed mineral and organic matter, which in turn reflect climate-driven changes in the lake level. We find no evidence that preindustrial lead and mercury use raised deposition rates in this remote ecosystem, and our results underscore the need to carefully evaluate common normalization approaches for changing lithogenic inputs and sedimentation rates. Industrial-era lead and mercury accumulation rates in Lake Antoine have been accelerated by land use and land cover change within the crater rim, yet global industrial pollution remains evident. After correcting for watershed inputs, we find that recent atmospheric lead and mercury deposition rates averaged 2925 and 24 µg/m2/y, respectively, which are in close agreement with monitoring data. Our results challenge recent assessments suggesting preindustrial mercury use raised atmospheric deposition rates globally, highlighting the unique nature of 20th Century industrial pollution.

Isotopic Analyses Fingerprint Sources of Polycyclic Aromatic Compound-Bearing Dust in Athabasca Oil Sands Region Snowpack.

Fugitive dust associated with surface mining activities is one of the principal vectors for transport of airborne contaminants in Canada's Athabasca oil sands region (AOSR). Effective environmental management requires quantitative identification of the sources of this dust. Using natural abundance radiocarbon (Δ14C) and dual (δ13C, δ2H) compound-specific isotope analysis (CSIA), this study investigated the sources of dust and particulate-bound polycyclic aromatic compounds (PACs) deposited in AOSR lake snowpack. Lower Δ14C values, higher particulate and PAC loadings, and lower δ13C values for phenanthrene and C1-alkylated phenanthrenes/anthracenes (C1-Phen) at sites closer to the mining operations indicated unprocessed oil sand and/or petroleum coke (petcoke-a byproduct of bitumen upgrading) as major sources of anthropogenic fugitive dust. However, a Bayesian isotopic mixing model that incorporated both δ13C and δ2H could discriminate petcoke from oil sand, and determined that petcoke comprised between 44 and 95% (95% credibility intervals) of a C1-Phen isomer at lakes <25 km from the heart of the mining operations, making it by far the most abundant source. This study is the first to demonstrate the potential of CSIA to provide accurate PAC source apportionment in snowpack and reveals that petcoke rather than oil sand is the main source of mining-related particulate PACs deposited directly to AOSR lakes.

Quantification of Spatial and Temporal Trends in Atmospheric Mercury Deposition across Canada over the Past 30 Years.

Mercury (Hg) is a pollutant of concern across Canada and transboundary anthropogenic Hg sources presently account for over 95% of national anthropogenic Hg deposition. This study applies novel statistical analyses of 82 high-resolution dated lake sediment cores collected from 19 regions across Canada, including nearby point sources and in remote regions and spanning a full west-east geographical range of ∼4900 km (south of 60°N and between 132 and 64°W) to quantify the recent (1990-2018) spatial and temporal trends in anthropogenic atmospheric Hg deposition. Temporal trend analysis shows significant synchronous decreasing trends in post-1990 anthropogenic Hg fluxes in western Canada in contrast to increasing trends in the east, with spatial patterns largely driven by longitude and proximity to known point source(s). Recent sediment-derived Hg fluxes agreed well with the available wet deposition monitoring. Sediment-derived atmospheric Hg deposition rates also compared well to the modeled values derived from the Hg model, when lake sites located nearby (<100 km) point sources were omitted due to difficulties in comparison between the sediment-derived and modeled values at deposition "hot spots". This highlights the applicability of multi-core approaches to quantify spatio-temporal changes in Hg deposition over broad geographic ranges and assess the effectiveness of regional and global Hg emission reductions to address global Hg pollution concerns.

Development and Reporting of Prediction Models: Guidance for Authors From Editors of Respiratory, Sleep, and Critical Care Journals.

Prediction models aim to use available data to predict a health state or outcome that has not yet been observed. Prediction is primarily relevant to clinical practice, but is also used in research, and administration. While prediction modeling involves estimating the relationship between patient factors and outcomes, it is distinct from casual inference. Prediction modeling thus requires unique considerations for development, validation, and updating. This document represents an effort from editors at 31 respiratory, sleep, and critical care medicine journals to consolidate contemporary best practices and recommendations related to prediction study design, conduct, and reporting. Herein, we address issues commonly encountered in submissions to our various journals. Key topics include considerations for selecting predictor variables, operationalizing variables, dealing with missing data, the importance of appropriate validation, model performance measures and their interpretation, and good reporting practices. Supplemental discussion covers emerging topics such as model fairness, competing risks, pitfalls of "modifiable risk factors", measurement error, and risk for bias. This guidance is not meant to be overly prescriptive; we acknowledge that every study is different, and no set of rules will fit all cases. Additional best practices can be found in the Transparent Reporting of a multivariable prediction model for Individual Prognosis Or Diagnosis (TRIPOD) guidelines, to which we refer readers for further details.

Multi-element microscope optimization by a learned sensing network with composite physical layers.

Standard microscopes offer a variety of settings to help improve the visibility of different specimens to the end microscope user. Increasingly, however, digital microscopes are used to capture images for automated interpretation by computer algorithms (e.g., for feature classification, detection, or segmentation), often without any human involvement. In this work, we investigate an approach to jointly optimize multiple microscope settings, together with a classification network, for improved performance with such automated tasks. We explore the interplay between optimization of programmable illumination and pupil transmission, using experimentally imaged blood smears for automated malaria parasite detection, to show that multi-element "learned sensing" outperforms its single-element counterpart. While not necessarily ideal for human interpretation, the network's resulting low-resolution microscope images (20X-comparable) offer a machine learning network sufficient contrast to match the classification performance of corresponding high-resolution imagery (100X-comparable), pointing a path toward accurate automation over large fields-of-view.

Trends in Hospital Utilization After Medicaid Expansion.

BACKGROUND: Medicaid expansion was associated with an increase in hospitalizations funded by Medicaid. Whether this increase reflects an isolated payer shift or broader changes in case-mix among hospitalized adults remains uncertain. RESEEARCH DESIGN: Difference-in-differences analysis of discharge data from 4 states that expanded Medicaid in 2014 (Arizona, Iowa, New Jersey, and Washington) and 3 comparison states that did not (North Carolina, Nebraska, and Wisconsin). SUBJECTS: All nonobstetric hospitalizations among patients aged 19-64 years of age admitted between January 2012 and December 2015. MEASURES: Outcomes included state-level per-capita rates of insurance coverage, several markers of admission severity, and admission diagnosis. RESULTS: We identified 6,516,576 patients admitted during the study period. Per-capita admissions remained consistent in expansion and nonexpansion states, though Medicaid-covered admissions increased in expansion states (274.6-403.8 per 100,000 people vs. 268.9-262.8 per 100,000; P<0.001). There were no significant differences after Medicaid expansion in hospital utilization, based on per-capita rates of patients-designated emergent, admitted via the emergency department, admitted via clinic, discharged within 1 day, or with lengths of stay ≥7 days. Similarly, there were no differences in diagnosis category at admission, admission severity, comorbidity burden, or mortality associated with Medicaid expansion (P>0.05 for all comparisons). CONCLUSIONS: Medicaid expansion was associated with a shift in payers among nonelderly hospitalized adults without significant changes in case-mix or in several markers of acuity. These findings suggest that Medicaid expansion may reduce uncompensated care without shifting admissions practices or acuity among hospitalized adults.

Accumulating Mercury and Methylmercury Burdens in Watersheds Impacted by Oil Sands Pollution.

Bitumen mining and upgrading in northeastern Alberta, Canada, releases toxic pollutants into the atmosphere, including mercury (Hg) and methylmercury (MeHg). This Hg and MeHg is then deposited to the surrounding landscape; however, the fate of these contaminants remains unknown. Here, we compare snowpack chemistry to high-frequency measurements of river water quality across six watersheds (five impacted by oil sands development and one unimpacted). Catchment scale snowpack Hg and MeHg loads normalized to watershed area were highest near oil sands operations. River water Hg concentrations and loads tracked discharge and tended to be higher downstream of mining operations, while MeHg concentrations and loads increased through the summer, reflecting peak summer MeHg production rates. Except in the reference watershed, snowpack Hg and MeHg loads equaled or exceeded the amount of Hg and MeHg exported during freshet and, in some cases, the entire hydrologic year. This suggests landscapes across the oil sands region, which are dominated by low-relief wetlands and other shallow-water systems, are accumulating Hg and MeHg. Importantly, during years of high discharge, these low-relief systems appear to become better connected and flush MeHg (and Hg) from the watershed. Thus, these watersheds may act as temporary, rather than as permanent, natural repositories of oil sands contaminants.

Hospital Variation in Renal Replacement Therapy for Sepsis in the United States.

OBJECTIVES: Acute renal replacement therapy in patients with sepsis has increased dramatically with substantial costs. However, the extent of variability in use across hospitals-and whether greater use is associated with better outcomes-is unknown. DESIGN: Retrospective cohort study. SETTING: Nationwide Inpatient Sample in 2011. PATIENTS: Eighteen years old and older with sepsis and acute kidney injury admitted to hospitals sampled by the Nationwide Inpatient Sample in 2011. INTERVENTIONS: We estimated the risk- and reliability-adjusted rate of acute renal replacement therapy use for patients with sepsis and acute kidney injury at each hospital. We examined the association between hospital-specific renal replacement therapy rate and in-hospital mortality and hospital costs after adjusting for patient and hospital characteristics. MEASUREMENTS AND MAIN RESULTS: We identified 293,899 hospitalizations with sepsis and acute kidney injury at 440 hospitals, of which 6.4% (n = 18,885) received renal replacement therapy. After risk and reliability adjustment, the median hospital renal replacement therapy rate for patients with sepsis and acute kidney injury was 3.6% (interquartile range, 2.9-4.5%). However, hospitals in the top quintile of renal replacement therapy use had rates ranging from 4.8% to 13.4%. There was no significant association between hospital-specific renal replacement therapy rate and in-hospital mortality (odds ratio per 1% increase in renal replacement therapy rate: 1.03; 95% CI, 0.99-1.07; p = 0.10). Hospital costs were significantly higher with increasing renal replacement therapy rates (absolute cost increase per 1% increase in renal replacement therapy rate: $1,316; 95% CI, $157-$2,475; p = 0.03). CONCLUSIONS: Use of renal replacement therapy in sepsis varied widely among nationally sampled hospitals without associated differences in mortality. Improving renal replacement standards for the initiation of therapy for sepsis may reduce healthcare costs without increasing mortality.

All-Cause Hospital Admissions Among Older Adults After a Natural Disaster.

STUDY OBJECTIVE: We characterize hospital admissions among older adults for any cause in the 30 days after a significant natural disaster in the United States. The main outcome was all-cause hospital admissions in the 30 days after natural disaster. Separate analyses were conducted to examine all-cause hospital admissions excluding the 72 hours after the disaster, ICU admissions, all-cause inhospital mortality, and admissions by state. METHODS: A self-controlled case series analysis using the 2011 Medicare Provider and Analysis Review was conducted to examine exposure to natural disaster by elderly adults located in zip codes affected by tornadoes during the 2011 southeastern superstorm. Spatial data of tornado events were obtained from the National Oceanic and Atmospheric Administration's Severe Report database, and zip code data were obtained from the US Census Bureau. RESULTS: All-cause hospital admissions increased by 4% for older adults in the 30 days after the April 27, 2011, tornadoes (incidence rate ratio 1.04; 95% confidence interval 1.01 to 1.07). When the first 3 days after the disaster that may have been attributed to immediate injuries were excluded, hospitalizations for any cause also remained higher than when compared with the other 11 months of the year (incidence rate ratio 1.04; 95% confidence interval 1.01 to 1.07). There was no increase in ICU admissions or inhospital mortality associated with the natural disaster. When data were examined by individual states, Alabama, which had the highest number of persons affected, had a 9% increase in both hospitalizations and ICU admissions. CONCLUSION: When all time-invariant characteristics were controlled for, this natural disaster was associated with a significant increase in all-cause hospitalizations. This analysis quantifies acute care use after disasters through examining all-cause hospitalizations and represents an important contribution to building models of resilience-the ability to recover from a disaster-and hospital surge capacity.

Climate, Fire, and Vegetation Mediate Mercury Delivery to Midlatitude Lakes over the Holocene.

The rise in mercury concentrations in lake sediment deposited over the last ∼150 years is widely recognized to have resulted from human activity. However, few studies in the Great Lakes region have used lake sediment to reconstruct atmospheric mercury deposition on millennial time scales. Here we present a 9000-year mercury record from sediment in Copper Falls; a small closed-basin lake on the Keweenaw Peninsula. Prior to abrupt increases in the 19th and 20th centuries, mercury remains at relatively low concentrations for the last 9000 years. Higher mercury fluxes in the early Holocene (3.4 ± 1.1 µg m-2 yr-1) are attributed to drier conditions and greater forest fire occurrence. The gradual decline in mercury flux over the middle to late Holocene (1.9 ± 0.2 µg m-2 yr-1) is interpreted to reflect a transition to wetter conditions, which reduced forest fires, and promoted the development of soil organic matter and deciduous forests that sequestered natural sources of mercury. The Copper Falls Lake record highlights the sensitivity of watersheds to changes in mercury inputs from both human and natural forcings, and provides millennial-scale context for recent mercury contamination that will aid in establishing baseline values for restoration efforts.

Total Mercury and Methylmercury in Lake Water of Canada's Oil Sands Region.

Increased delivery of mercury to ecosystems is a common consequence of industrialization, including in the Athabasca Oil Sands Region (AOSR) of Canada. Atmospheric mercury deposition has been studied previously in the AOSR; however, less is known about the impact of regional industry on toxic methylmercury (MeHg) concentrations in lake ecosystems. We measured total mercury (THg) and MeHg concentrations for five years from 50 lakes throughout the AOSR. Mean lake water concentrations of THg (0.4-5.3 ng L-1) and MeHg (0.01-0.34 ng L-1) were similar to those of other boreal lakes and <5% of all samples exceeded Provincial water quality guidelines. Lakes with the highest THg concentrations were found >100 km northwest of oil sands mines and received runoff from geological formations high in metals concentrations. MeHg concentrations were highest in those lakes, and in smaller productive lakes closer to oil sands mines. Simulated annual average direct deposition of THg to sampled lakes using an atmospheric chemical transport model showed <2% of all mercury deposited to sampled lakes was emitted from oil sands activities. Consequently, spatial patterns of mercury in AOSR lakes were likely most influenced by watershed and lake conditions, though mercury concentrations in these lakes may be perturbed with future development and climatic change.

An Official American Thoracic Society Systematic Review: The Effect of Nighttime Intensivist Staffing on Mortality and Length of Stay among Intensive Care Unit Patients.

BACKGROUND: Studies of nighttime intensivist staffing have yielded mixed results. GOALS: To review the association of nighttime intensivist staffing with outcomes of intensive care unit (ICU) patients. METHODS: We searched five databases (2000-2016) for studies comparing in-hospital nighttime intensivist staffing with other nighttime staffing models in adult ICUs and reporting mortality or length of stay. We abstracted data on staffing models, outcomes, and study characteristics and assessed study quality, using standardized tools. Meta-analyses used random effects models. RESULTS: Eighteen studies met inclusion criteria: one randomized controlled trial and 17 observational studies. Overall methodologic quality was high. Studies included academic hospitals (n = 10), community hospitals (n = 2), or both (n = 6). Baseline clinician staffing included residents (n = 9), fellows (n = 4), and nurse practitioners or physician assistants (n = 2). Studies included both general and specialty ICUs and were geographically diverse. Meta-analysis (one randomized controlled trial; three nonrandomized studies with exposure limited to nighttime intensivist staffing with adjusted estimates of effect) demonstrated no association with mortality (odds ratio, 0.99; 95% confidence interval, 0.75-1.29). Secondary analyses including studies without risk adjustment, with a composite exposure of organizational factors, stratified by intensity of daytime staffing and by ICU type, yielded similar results. Minimal or no differences were observed in ICU and hospital length of stay and several other secondary outcomes. CONCLUSIONS: Notwithstanding limitations of the predominantly observational evidence, our systematic review and meta-analysis suggests nighttime intensivist staffing is not associated with reduced ICU patient mortality. Other outcomes and alternative staffing models should be evaluated to further guide staffing decisions.