Adaptive laboratory evolution of Clostridium autoethanogenum to metabolize CO2 and H2 enhances growth rates in chemostat and unravels proteome and metabolome alterations.

Gas fermentation of CO2 and H2 is an attractive means to sustainably produce fuels and chemicals. Clostridium autoethanogenum is a model organism for industrial CO to ethanol and presents an opportunity for CO2-to-ethanol processes. As we have previously characterized its CO2/H2 chemostat growth, here we use adaptive laboratory evolution (ALE) with the aim of improving growth with CO2/H2. Seven ALE lineages were generated, all with improved specific growth rates. ALE conducted in the presence of 2% CO along with CO2/H2 generated Evolved lineage D, which showed the highest ethanol titres amongst all the ALE lineages during the fermentation of CO2/H2. Chemostat comparison against the parental strain shows no change in acetate or ethanol production, while Evolved D could achieve a higher maximum dilution rate. Multi-omics analyses at steady state revealed that Evolved D has widespread proteome and intracellular metabolome changes. However, the uptake and production rates and titres remain unaltered until investigating their maximum dilution rate. Yet, we provide numerous insights into CO2/H2 metabolism via these multi-omics data and link these results to mutations, suggesting novel targets for metabolic engineering in this bacterium.

Epitope Mapping of Japanese Encephalitis Virus Neutralizing Antibodies by Native Mass Spectrometry and Hydrogen/Deuterium Exchange.

Japanese encephalitis virus (JEV) remains a global public health concern due to its epidemiological distribution and the existence of multiple strains. Neutralizing antibodies against this infection have shown efficacy in in vivo studies. Thus, elucidation of the epitopes of neutralizing antibodies can aid in the design and development of effective vaccines against different strains of JEV. Here, we describe a combination of native mass spectrometry (native-MS) and hydrogen/deuterium exchange mass spectrometry (HDX-MS) to complete screening of eight mouse monoclonal antibodies (MAbs) against JEV E-DIII to identify epitope regions. Native-MS was used as a first pass to identify the antibodies that formed a complex with the target antigen, and it revealed that seven of the eight monoclonal antibodies underwent binding. Native mass spectra of a MAb (JEV-27) known to be non-binding showed broad native-MS peaks and poor signal, suggesting the protein is a mixture or that there are impurities in the sample. We followed native-MS with HDX-MS to locate the binding sites for several of the complex-forming antibodies. This combination of two mass spectrometry-based approaches should be generally applicable and particularly suitable for screening of antigen-antibody and other protein-protein interactions when other traditional approaches give unclear results or are difficult, unavailable, or need to be validated.

Yersiniabactin is a quorum-sensing autoinducer and siderophore in uropathogenic Escherichia coli.

Siderophores are secreted ferric ion chelators used to obtain iron in nutrient-limited environmental niches, including human hosts. While all Escherichia coli express the enterobactin (Ent) siderophore system, isolates from patients with urinary tract infections additionally express the genetically distinct yersiniabactin (Ybt) siderophore system. To determine whether the Ent and Ybt systems are functionally redundant for iron uptake, we compared the growth of different isogenic siderophore biosynthetic mutants in the presence of transferrin, a human iron-binding protein. We observed that Ybt expression does not compensate for deficient Ent expression following low-density inoculation. Using transcriptional and product analysis, we found this non-redundancy to be attributable to a density-dependent transcriptional stimulation cycle in which Ybt functions as an autoinducer. These results distinguish the Ybt system as a combined quorum-sensing and siderophore system. These functions may reflect Ybt as a public good within bacterial communities or as an adaptation to confined, subcellular compartments in infected hosts. This combined functionality may contribute to the extraintestinal pathogenic potential of E. coli and related Enterobacterales.IMPORTANCEPatients with urinary tract infections are often infected with Escherichia coli strains carrying adaptations that increase their pathogenic potential. One of these adaptations is the accumulation of multiple siderophore systems, which scavenge iron for nutritional use. While iron uptake is important for bacterial growth, the increased metabolic costs of siderophore production could diminish bacterial fitness during infections. In a siderophore-dependent growth condition, we show that the virulence-associated yersiniabactin siderophore system in uropathogenic E. coli is not redundant with the ubiquitous E. coli enterobactin system. This arises not from differences in iron-scavenging activity but because yersiniabactin is preferentially expressed during bacterial crowding, leaving bacteria dependent upon enterobactin for growth at low cell density. Notably, this regulatory mode arises because yersiniabactin stimulates its own expression, acting as an autoinducer in a previously unappreciated quorum-sensing system. This unexpected result connects quorum-sensing with pathogenic potential in E. coli and related Enterobacterales.

The Impact of Depression, Anxiety and Personality Disorders on the Outcome of Patients with Functional Limb Weakness - Individual Patient Data Meta-Analysis.

OBJECTIVE: Psychiatric comorbidities such as depression, anxiety, and personality disorders are common in patients with functional limb weakness/paresis (FND-par). The impact of these conditions on the prognosis of FND-par has not been systematically reviewed. The aim of this study was to identify a potential prognostic effect of comorbid depression, anxiety, and/or personality disorder on prognosis in patients with FND-par. METHODS: A systematic review was performed to identify studies that reported measures of baseline depression, anxiety, and/or personality disorder, and physical disability. An individual patient data meta-analysis was subsequently performed. RESULTS: Eight studies comprising 348 individuals were included (7 prospective cohorts; 1 case-control study). There was heterogeneity in sample size, follow-up duration, and treatment modality. Depression and anxiety were present in 51.4% and 53.0% of FND-par patients, respectively. In individuals whose FND-par improved, there was no significant difference between those with versus without depression (52.6% vs 47.4%, p = 0.69) or those with versus without anxiety (50.3% vs 49.7%, p = 0.38). Meta-analysis showed no clear impact of baseline depression or anxiety per se [pooled OR for depression 0.85 (95%CI 0.50-1.45; p = 0.40) and anxiety 0.84 (95%CI 0.51-1.38; p = 0.91)]; and of depression or anxiety severity [pooled OR for depression 1.23 (95%CI 0.63-2.39; p = 0.91) and anxiety 1.40 (95%CI 0.70-2.78; p = 0.58)] on FND-par outcome. Insufficient data were available to assess the impact of personality disorders. CONCLUSION: We found no evidence that depression or anxiety influenced outcome in FND-par. Large-scale, prospective studies in FND-par, and other FND subtypes, are needed to fully contextualize the impact of concurrent mental health concerns on outcomes.

Yersiniabactin is a quorum sensing autoinducer and siderophore in uropathogenic Escherichia coli.

Siderophores are secreted ferric ion chelators used to obtain iron in nutrient-limited environmental niches, including human hosts. While all E. coli encode the enterobactin (Ent) siderophore system, isolates from patients with urinary tract infections additionally encode the genetically distinct yersiniabactin (Ybt) siderophore system. To determine whether the Ent and Ybt systems are functionally redundant for iron uptake, we compared growth of different isogenic siderophore biosynthesis mutants in the presence of transferrin, a human iron-binding protein. We observed that the Ybt system does not compensate for loss of the Ent system during siderophore-dependent, low density growth. Using transcriptional and product analysis, we found that this non-redundancy is attributable to a density-dependent transcriptional stimulation cycle in which Ybt assume an additional autoinducer function. These results distinguish the Ybt system as a combined quorum-sensing and siderophore system. These functions may reflect Ybt as a public good within bacterial communities or as an adaptation to confined, subcellular compartments in infected hosts. The efficiency of this arrangement may contribute to the extraintestinal pathogenic potential of E. coli and related Enterobacterales. IMPORTANCE: Urinary tract infections (UTIs) are one of the most common human bacterial infections encountered by physicians. Adaptations that increase the pathogenic potential of commensal microbes such as E.coli are of great interest. One potential adaptation observed in clinical isolates is accumulation of multiple siderophore systems, which scavenge iron for nutritional use. While iron uptake is important for bacterial growth, the increased metabolic costs of siderophore production could diminish bacterial fitness during infections. In a siderophore-dependent growth conditions, we show that the virulence-associated yersiniabactin siderophore system in uropathogenic E. coli is not redundant with the ubiquitous E. coli enterobactin system. This arises not from differences in iron scavenging activity but because yersiniabactin is preferentially expressed during bacterial crowding, leaving bacteria dependent upon enterobactin for growth at low cell density. Notably, this regulatory mode arises because yersiniabactin stimulates its own expression, acting as an autoinducer in a previously unappreciated quorum-sensing system. This unexpected result connects quorum-sensing with pathogenic potential in E. coli and related Enterobacterales.

Analytical tools for unravelling the metabolism of gas-fermenting Clostridia.

Acetogens harness the Wood-Ljungdahl Pathway, a unique metabolic pathway for C1 capture close to the thermodynamic limit. Gas fermentation using acetogens is already used for CO-to-ethanol conversion at industrial-scale and has the potential to valorise a range of C1 and waste substrates to short-chain and medium-chain carboxylic acids and alcohols. Advances in analytical quantification and metabolic modelling have helped guide industrial gas fermentation designs. Further advances in the measurements of difficult to measure metabolites are required to improve kinetic modelling and understand the regulation of acetogen metabolism. This will help guide future synthetic biology designs needed to realise the full potential of gas fermentation in stimulating a circular bioeconomy.

Light and flow regimes regulate the metabolism of rivers.

Mean annual temperature and mean annual precipitation drive much of the variation in productivity across Earth's terrestrial ecosystems but do not explain variation in gross primary productivity (GPP) or ecosystem respiration (ER) in flowing waters. We document substantial variation in the magnitude and seasonality of GPP and ER across 222 US rivers. In contrast to their terrestrial counterparts, most river ecosystems respire far more carbon than they fix and have less pronounced and consistent seasonality in their metabolic rates. We find that variation in annual solar energy inputs and stability of flows are the primary drivers of GPP and ER across rivers. A classification schema based on these drivers advances river science and informs management.

The Difference in Practice Expense Costs Between Telehealth and In-Office Care Could Serve as the Basis for Differential Reimbursement Structures.

Background: There has been much recent discussion about the reimbursement of telehealth virtual visits. Advocates argue strongly for payment parity with in-person encounters, whereas payers insist that telehealth visits should be reimbursed at a lower value. Methods: Using the Resource-Based Relative Value Scale structure as a guideline (where physician compensation is divided into categories: time/medical decision making/malpractice expense and practice expense), we developed a framework to examine the difference in practice expense of an in-person practice compared with a scaled virtual practice. Results: We found that for current procedural terminology (CPT) code 99213, the total relative value unit (RVU) for a virtual visit would be 1.62. The in-office RVU for CPT code 99213 is 2.09. This difference could serve as the basis for a rational discussion on differential reimbursement for virtual visits.

Residential yard management and landscape cover affect urban bird community diversity across the continental USA.

Urbanization has a homogenizing effect on biodiversity and leads to communities with fewer native species and lower conservation value. However, few studies have explored whether or how land management by urban residents can ameliorate the deleterious effects of this homogenization on species composition. We tested the effects of local (land management) and neighborhood-scale (impervious surface and tree canopy cover) features on breeding bird diversity in six US metropolitan areas that differ in regional species pools and climate. We used a Bayesian multiregion community model to assess differences in species richness, functional guild richness, community turnover, population vulnerability, and public interest in each bird community in six land management types: two natural area park types (separate and adjacent to residential areas), two yard types with conservation features (wildlife-certified and water conservation) and two lawn-dominated yard types (high- and low-fertilizer application), and surrounding neighborhood-scale features. Species richness was higher in yards compared with parks; however, parks supported communities with high conservation scores while yards supported species of high public interest. Bird communities in all land management types were composed of primarily native species. Within yard types, species richness was strongly and positively associated with neighborhood-scale tree canopy cover and negatively associated with impervious surface. At a continental scale, community turnover between cities was lowest in yards and highest in parks. Within cities, however, turnover was lowest in high-fertilizer yards and highest in wildlife-certified yards and parks. Our results demonstrate that, across regions, preserving natural areas, minimizing impervious surfaces and increasing tree canopy are essential strategies to conserve regionally important species. However, yards, especially those managed for wildlife support diverse, heterogeneous bird communities with high public interest and potential to support species of conservation concern. Management approaches that include the preservation of protected parks, encourage wildlife-friendly yards and acknowledge how public interest in local birds can advance successful conservation in American residential landscapes.

A Multiscale Approach to Timescale Analysis: Isolating Diel Signals from Solute Concentration Time Series.

Solute concentration time series reflect hydrological and biological drivers through various frequencies, phases, and amplitudes of change. Untangling these signals facilitates the understanding of dynamic ecosystem conditions and transient water quality issues. A case in point is the inference of biogeochemical processes from diel solute concentration variations. This analysis requires approaches capable of isolating subtle diel signals from background variability at other scales. Conventional time series analyses typically assume stationary or deterministic background variability; however, most rivers do not respect such niceties. We developed a time-series filtering method that uses empirical mode decomposition to decompose a measured solute concentration time series into intrinsic mode frequencies. Based on externally supplied mechanistic knowledge, we then filter these modes by periodicity, phase, and coherence with neighboring days. This method is tested on three synthetic series that incorporate environmental variability and sensor noise and on a year of 15 min sampled concentration time series from three hydrologically and ecologically distinct rivers in the eastern United States. The proposed method successfully isolated signals in the measured data sets that corresponded with variability in gross primary productivity. The strength the diel signal isolated through this method was smaller compared to the true signal in the synthetic series; however, uncertainty analysis showed that the process-model-based estimates derived from these signals were similar to other inference methods. This signal decomposition method retains information that can be used for further process modeling while making different assumptions about the data than Fourier and wavelet analyses.

Strategies to improve viability of a circular carbon bioeconomy-A techno-economic review of microbial electrosynthesis and gas fermentation.

A circular carbon bioeconomy has potential to halt atmospheric accumulation of greenhouse gases causing climate change and sustainably produce chemical, agricultural and fuel products. Here, we report application of a simplified technoeconomic assessment to critically review two approaches in this space - microbial electrosynthesis and gas fermentation. For microbial electrosynthesis, decoupling of surface-dependant abiotic process for electron delivery from volume-dependant biotic carbon fixation, is shown as the only economically viable strategy to scale-up due to comparatively low biofilm electron consumption rate. This is effectively an electrolyser-assisted gas fermentation system. Targeting high-value products, such as protein for human food consumption is one of the few pathways forward for electrolyser-assisted gas fermentation. Alternatively, gas fermentation of reformed biogas presents an interesting and potentially more sustainable implementation pathway to improve economic viability of chemicals. This critical review suggests linking water treatment resource recovery with gas fermentation is attractive for bioplastics and butanol in terms of competitiveness and market demand.

Transcriptional control of Clostridium autoethanogenum using CRISPRi.

Gas fermentation by Clostridium autoethanogenum is a commercial process for the sustainable biomanufacturing of fuels and valuable chemicals using abundant, low-cost C1 feedstocks (CO and CO2) from sources such as inedible biomass, unsorted and nonrecyclable municipal solid waste, and industrial emissions. Efforts toward pathway engineering and elucidation of gene function in this microbe have been limited by a lack of genetic tools to control gene expression and arduous genome engineering methods. To increase the pace of progress, here we developed an inducible CRISPR interference (CRISPRi) system for C. autoethanogenum and applied that system toward transcriptional repression of genes with ostensibly crucial functions in metabolism.

Municipal regulation of residential landscapes across US cities: Patterns and implications for landscape sustainability.

Local regulations on residential landscapes (yards and gardens) can facilitate or constrain ecosystem services and disservices in cities. To our knowledge, no studies have undertaken a comprehensive look at how municipalities regulate residential landscapes to achieve particular goals and to control management practices. Across six U.S. cities, we analyzed 156 municipal ordinances to examine regional patterns in local landscape regulations and their implications for sustainability. Specifically, we conducted content analysis to capture regulations aimed at: 1) goals pertaining to conservation and environmental management, aesthetics and nuisance avoidance, and health and wellbeing, and 2) management actions including vegetation maintenance, water and waste management, food production, and chemical inputs. Our results reveal significant variation in local and regional regulations. While regulatory goals stress stormwater management and nuisance avoidance, relatively few municipalities explicitly regulate residential yards to maintain property values, mitigate heat, or avoid allergens. Meanwhile, biological conservation and water quality protection are common goals, yet regulations on yard management practices (e.g., non-native plants or chemical inputs) sometimes contradict these purposes. In addition, regulations emphasizing aesthetics and the maintenance of vegetation, mowing of grass and weeds, as well as the removal of dead wood, may inhibit wildlife-friendly yards. As a whole, landscaping ordinances largely ignore tradeoffs between interacting goals and outcomes, thereby limiting their potential to support landscape sustainability. Recommendations therefore include coordinated, multiobjective planning through partnerships among planners, developers, researchers, and non-government entities at multiple scales.

Enhancing CO2-Valorization Using Clostridium autoethanogenum for Sustainable Fuel and Chemicals Production.

Acetogenic bacteria can convert waste gases into fuels and chemicals. Design of bioprocesses for waste carbon valorization requires quantification of steady-state carbon flows. Here, steady-state quantification of autotrophic chemostats containing Clostridium autoethanogenum grown on CO2 and H2 revealed that captured carbon (460 ± 80 mmol/gDCW/day) had a significant distribution to ethanol (54 ± 3 C-mol% with a 2.4 ± 0.3 g/L titer). We were impressed with this initial result, but also observed limitations to biomass concentration and growth rate. Metabolic modeling predicted culture performance and indicated significant metabolic adjustments when compared to fermentation with CO as the carbon source. Moreover, modeling highlighted flux to pyruvate, and subsequently reduced ferredoxin, as a target for improving CO2 and H2 fermentation. Supplementation with a small amount of CO enabled co-utilization with CO2, and enhanced CO2 fermentation performance significantly, while maintaining an industrially relevant product profile. Additionally, the highest specific flux through the Wood-Ljungdahl pathway was observed during co-utilization of CO2 and CO. Furthermore, the addition of CO led to superior CO2-valorizing characteristics (9.7 ± 0.4 g/L ethanol with a 66 ± 2 C-mol% distribution, and 540 ± 20 mmol CO2/gDCW/day). Similar industrial processes are commercial or currently being scaled up, indicating CO-supplemented CO2 and H2 fermentation has high potential for sustainable fuel and chemical production. This work also provides a reference dataset to advance our understanding of CO2 gas fermentation, which can contribute to mitigating climate change.

Physician Burnout, Engagement and Career Satisfaction in a Large Academic Medical Practice.

OBJECTIVE: To determine (1) if engagement among physicians impacted plans to stay in current role and job satisfaction, (2) what factors impact engagement and burnout, and (3) the relationship between engagement and burnout. Burnout has been described as a syndrome characterized by depersonalization, emotional exhaustion, and a sense of low personal accomplishment resulting in decreased effectiveness at work. Engagement may be regarded as the antonym to burnout and has been described as a connection to one's work characterized by dedication, vigor, and absorption. DESIGN: We extracted data from an academic practice-wide survey conducted at two time-points and evaluated physician burnout and engagement. We used the Maslach Burnout Inventory and the Utrecht Work Engagement Scale to evaluate the association between burnout and engagement and the impact of engagement on mitigating the effect of burnout in a large physician academic faculty practice. SETTING: Large academic practice PARTICIPANTS: Academic physicians METHODS: The authors conducted a hospital-wide physician practice survey in 2014 and 2017 assessing physician burnout and engagement. RESULTS: Of eligible physicians (n=1882), 92.0% completed a survey. High levels of engagement and burnout were shown in 59.5% and 45.6%, respectively. Compared to physicians with high levels of engagement and low levels of burnout, physicians with low engagement and low burnout were less satisfied with their career (OR=0.20, 95% CI=0.11-0.35) and less likely to stay in their current role (OR=0.52, 95% CI= 0.37-0.73). Among physicians with high levels of burnout, highly engaged physicians were more satisfied (OR=0.21; 95% CI=0.12-0.36 vs OR=0.08; 95% CI=0.05-0.12) and more likely to stay in their career (OR=0.34; 95% CI=0.25-0.45 vs OR=0.27; 95% CI=0.21-0.34) than non-engaged physicians. CONCLUSION: Engaged physicians have higher career satisfaction. There are many actionable ways to improve engagement.

Predictors of MRI Leakage Among Patients Attributed to an Academic Medical Center Commercial Risk-Shared Insurance Contract.

PURPOSE: For health care organizations engaged in risk-shared insurance contracts, leakage of advanced diagnostic imaging to imaging sites not affiliated with the risk-sharing organization may undermine performance on financial and quality metrics. The goal of this study was to identify factors that are predictive of leakage of MRI examinations among patients attributed to an academic health care organization's risk-shared commercial insurance contract. METHODS: Administrative claims data from 2015 through 2016 for patients attributed to a single risk-shared commercial insurance contract at a large academic medical center (AMC) were analyzed. Primary outcome was MRI leakage: an outpatient MRI study performed at a site not affiliated with the AMC's integrated health care system. Ordering provider alignment with the AMC's risk-shared insurance contract was categorized as strong, weak, or none. Multivariate regression analyses were conducted to evaluate the relationship between provider alignment and MRI leakage, while adjusting for selected covariates. RESULTS: Among 8,215 patients meeting inclusion criteria, there were 13,272 MRI encounters. The overall proportion of leaked MRI studies was 12.7%. MRI studies ordered by providers with weak AMC alignment (odds ratio, 3.16; 95% confidence interval, 2.49-4.02) or no AMC alignment (odds ratio, 3.68; 95% confidence interval, 3.12-4.33) were more likely to leak than MRI studies ordered by providers with strong AMC alignment. CONCLUSIONS: An ordering provider with no alignment with an AMC's commercial risk-shared insurance contract was the strongest predictor of MRI leakage. Population health management initiatives aimed at reducing leakage should consider the impact of provider networks and clinical referral patterns that drive imaging utilization.

Residential household yard care practices along urban-exurban gradients in six climatically-diverse U.S. metropolitan areas.

Residential land is expanding in the United States, and lawn now covers more area than the country's leading irrigated crop by area. Given that lawns are widespread across diverse climatic regions and there is rising concern about the environmental impacts associated with their management, there is a clear need to understand the geographic variation, drivers, and outcomes of common yard care practices. We hypothesized that 1) income, age, and the number of neighbors known by name will be positively associated with the odds of having irrigated, fertilized, or applied pesticides in the last year, 2) irrigation, fertilization, and pesticide application will vary quadratically with population density, with the highest odds in suburban areas, and 3) the odds of irrigating will vary by climate, but fertilization and pesticide application will not. We used multi-level models to systematically address nested spatial scales within and across six U.S. metropolitan areas-Boston, Baltimore, Miami, Minneapolis-St. Paul, Phoenix, and Los Angeles. We found significant variation in yard care practices at the household (the relationship with income was positive), urban-exurban gradient (the relationship with population density was an inverted U), and regional scales (city-to-city variation). A multi-level modeling framework was useful for discerning these scale-dependent outcomes because this approach controls for autocorrelation at multiple spatial scales. Our findings may guide policies or programs seeking to mitigate the potentially deleterious outcomes associated with water use and chemical application, by identifying the subpopulations most likely to irrigate, fertilize, and/or apply pesticides.

Stoichiometry and daily rhythms: experimental evidence shows nutrient limitation decouples N uptake from photosynthesis.

Diel variability in nutrient concentrations is common but not universal in aquatic ecosystems. Theoretical models of photoautotrophic systems attribute the absence of diel uptake variation to nutrient scarcity, such that diel variability in nutrient uptake disappears as nutrients become limiting. We tested this prediction in a mesocosm experiment, by exposing benthic algal communities to a range of nitrogen (N) and phosphorus concentrations and recording the rates of uptake during both day and night. We found that higher concentrations of N produced diel variability in uptake and that the difference between the day and night total mass uptakes approximately equaled N demand for observed primary production as seen in other studies. At lower concentrations of N, uptake rates during the day and night were indistinguishable. These results are the first empirical evidence to imply that diel nitrate patterns in streams and rivers indicate a release from N limitation and offer a new way to assess nutrient limitation.

Climate and lawn management interact to control C4 plant distribution in residential lawns across seven U.S. cities.

In natural grasslands, C4 plant dominance increases with growing season temperatures and reflects distinct differences in plant growth rates and water use efficiencies of C3 vs. C4 photosynthetic pathways. However, in lawns, management decisions influence interactions between planted turfgrass and weed species, leading to some uncertainty about the degree of human vs. climatic controls on lawn species distributions. We measured herbaceous plant carbon isotope ratios (δ13 C, index of C3 /C4 relative abundance) and C4 cover in residential lawns across seven U.S. cities to determine how climate, lawn plant management, or interactions between climate and plant management influenced C4 lawn cover. We also calculated theoretical C4 carbon gain predicted by a plant physiological model as an index of expected C4 cover due to growing season climatic conditions in each city. Contrary to theoretical predictions, plant δ13 C and C4 cover in urban lawns were more strongly related to mean annual temperature than to growing season temperature. Wintertime temperatures influenced the distribution of C4 lawn turf plants, contrary to natural ecosystems where growing season temperatures primarily drive C4 distributions. C4 cover in lawns was greatest in the three warmest cities, due to an interaction between climate and homeowner plant management (e.g., planting C4 turf species) in these cities. The proportion of C4 lawn species was similar to the proportion of C4 species in the regional grass flora. However, the majority of C4 species were nonnative turf grasses, and not of regional origin. While temperature was a strong control on lawn species composition across the United States, cities differed as to whether these patterns were driven by cultivated lawn grasses vs. weedy species. In some cities, biotic interactions with weedy plants appeared to dominate, while in other cities, C4 plants were predominantly imported and cultivated. Elevated CO2 and temperature in cities can influence C3 /C4 competitive outcomes; however, this study provides evidence that climate and plant management dynamics influence biogeography and ecology of C3 /C4 plants in lawns. Their differing water and nutrient use efficiency may have substantial impacts on carbon, water, energy, and nutrient budgets across cities.

Trends and Factors Associated With Physician Burnout at a Multispecialty Academic Faculty Practice Organization.

Importance: Physician burnout is common, and prevalence may differ throughout a clinician's career. Burnout has negative consequences for physician wellness, patient care, and the health care system. Identifying factors associated with burnout is critical in designing and implementing initiatives to reduce burnout. Objective: To measure trends and identify factors associated with physician burnout. Design, Setting, and Participants: Survey study conducted from May 16 to June 15, 2014, and again from May 16 to June 15, 2017, measuring rates of physician burnout in a large academic medical practice. Factors associated with burnout out were evaluated. In 2014, 1774 of 1850 eligible physicians (95.9%) completed the survey. In 2017, 1882 of 2031 (92.7%) completed the survey. Exposures: Medical specialty, demographic characteristics, years in practice, and reported rates of burnout. Main Outcomes and Measures: Burnout rates measured at 2 points and risk factors associated with burnout. Results: Respondents included 1027 men (57.9%) and 747 women (42.1%) in 2014 and 962 men (51.1%) and 759 women (40.3%) in 2017. The mean (SD) number of years since training completion was 15.3 (11.3) in the 2014 survey data and 15.1 (11.3) in the 2017 data. Burnout increased from 40.6% to 45.6% between the 2 points. The increased rate was associated with an increase in exhaustion (from 52.9% in 2014 to 57.7% in 2017; difference, 4.8%; 95% CI, 1.6%-8.0%; P = .004) and cynicism (from 44.8% in 2014 to 51.1% in 2017; difference, 6.3%; 95% CI, 3.1%-9.6%; P < .001). Compared with midcareer physicians (11-20 years since training), early-career physicians (≤10 years since training) were more susceptible to burnout (odds ratio, 1.36; 95% CI, 1.05-1.77), while physicians in their late career (>30 years since training) were less vulnerable (odds ratio, 0.59; 95% CI, 0.40-0.88). Conclusions and Relevance: Efforts to alleviate physician burnout and administrative burden require a combination of a shared commitment from physicians and organizations and central and locally implemented programs. Continued research is necessary to establish the most effective initiatives to decrease physician burnout at the individual and organizational level.