Search

Numerous laboratory experiments have been performed in an attempt to mimic atmospheric secondary organic aerosol (SOA) formation. However, it is still unclear how close the aerosol particles generated in laboratory experiments resemble atmospheric SOA with respect to their detailed chemical composition. In this study, we generated SOA in a simulation chamber from the ozonolysis of α-pinene and a biogenic volatile organic compound (BVOC) mixture containing α- and β-pinene, Δ3-carene, and isoprene. The detailed molecular composition of laboratory-generated SOA was compared with that of background ambient aerosol collected at a boreal forest site (Hyytiälä, Finland) and an urban location (Cork, Ireland) using direct infusion nanoelectrospray ultrahigh-resolution mass spectrometry. Kendrick mass defect and van Krevelen approaches were used to identify and compare compound classes and distributions of the detected species. The laboratory-generated SOA contained a distinguishable group of dimers that was not observed in the ambient samples. The presence of dimers was found to be less pronounced in the SOA from the BVOC mixtures when compared to the one component precursor system. The molecular composition of SOA from both the BVOC mixture and α-pinene represented the overall composition of the ambient sample from the boreal forest site reasonably well, with 72.3 ± 2.5% (n = 3) and 69.1 ± 3.0% (n = 3) common ions, respectively. In contrast, large differences were found between the laboratory-generated BVOC samples and the ambient urban sample. To our knowledge this is the first direct comparison of molecular composition of laboratory-generated SOA from BVOC mixtures and ambient samples. more...

Abstract A global decline in seagrass populations has led to renewed calls for their conservation as important providers of biogenic and foraging habitat, shoreline stabilization and carbon storage. Eelgrass (Zostera marina) occupies the largest geographic range among seagrass species spanning a commensurately broad spectrum of environmental conditions. In Canada, eelgrass is managed as a single phylogroup despite occurring across three oceans and a range of ocean temperatures and salinity gradients. Previous research has focused on applying relatively few markers to reveal population structure of eelgrass, whereas a whole‐genome approach is warranted to investigate cryptic structure among populations inhabiting different ocean basins and localized environmental conditions. We used a pooled whole‐genome re‐sequencing approach to characterize population structure, gene flow and environmental associations of 23 eelgrass populations ranging from the Northeast United States to Atlantic, subarctic and Pacific Canada. We identified over 500,000 SNPs, which when mapped to a chromosome‐level genome assembly revealed six broad clades of eelgrass across the study area, with pairwise FST ranging from 0 among neighbouring populations to 0.54 between Pacific and Atlantic coasts. Genetic diversity was highest in the Pacific and lowest in the subarctic, consistent with colonization of the Arctic and Atlantic oceans from the Pacific less than 300 kya. Using redundancy analyses and two climate change projection scenarios, we found that subarctic populations are predicted to be potentially more vulnerable to climate change through genomic offset predictions. Conservation planning in Canada should thus ensure that representative populations from each identified clade are included within a national network so that latent genetic diversity is protected, and gene flow is maintained. Northern populations, in particular, may require additional mitigation measures given their potential susceptibility to a rapidly changing climate. more...

We suggest rethinking ecology as a set of continuous, interconnected dynamics and spatial networks that would represent an alternative framework to the traditional organizational levels—cell, organism, population, community, and ecosystem. We draw on unifying biological theories—information theory, cell theory, and metabolic theories—to propose a continuous space for living systems that avoids epistemological constraints imposed by a priori assumptions of discrete levels of biological organization. The discrete levels of organization that ecologists have traditionally envisioned can be viewed instead as coarse-grained, localized groupings within continuous dimensions of information (I), cell number (C), and energy flux (E). Moving from levels of organization to emergent properties of information, cells, and energy flux allows us to illustrate how diverse ecological and evolutionary phenomena—such as allometric and diversity-related scaling patterns, predator-prey dynamics, evolutionary trajectories, and alternative stable states—can be represented within the same continuum. We suggest that there may be structure within this information-cells-energetic flux (ICE) framework that unifies ecology from the beginning of life to the present and provides a useful lens through which patterns and processes in nature can be viewed. more...

Obesity, defined as a body mass index (BMI) >30, is associated with an increased likelihood of osteoarthritis and need for total joint arthroplasty (TJA). Unfortunately, the morbidly obese population has a higher risk of postoperative complications. For some surgeons, patient selection criteria for TJA includes BMI40 to minimize risks, including tailored preoperative, intraoperative, and postoperative considerations. more...

Background: Obese and African American populations suffer from higher incidence of hip and knee osteoarthritis, yet African Americans are less likely to undergo total hip and knee arthroplasty (TJA). Patient interest in TJA is a necessary first step for surgery. Medical device company direct-to-consumer advertising for TJA represents 1 potential factor driving disparities in utilization. Here we analyze demographics of models represented in medical device company direct-to-consumer TJA advertisements to understand whether advertisement content correlates with the population in need. Methods: We analyzed medical device company pamphlets, websites, and banner and video advertisements of the top 4 medical device companies in US arthroplasty sales, collected via ad-specific search engine and direct correspondence. Variables include model race, sex, age, and weight. Pearson likelihood ratio tests were used to compare categorical variables. Results: Of the 116 advertisements collected, the model featured in the advertisement was white in 69.8%. The proportion of white models differed across medical device companies (company C, 75%) (P < .001) and advertisement type (video, 81.8%) (P < .001). Only 2.6% of advertisements featured obese models. Neither company C nor D, nor pamphlet or website advertisements used obese models. Conclusions: Direct-to-consumer advertising from the top 4 orthopedic US medical device companies does not represent the population in need: While TJA remains underutilized by African American/Hispanic patients, models were overwhelmingly white. While obese patients are known to need TJA, patients in the advertisements were overwhelmingly not obese. We advocate for medical device companies to refocus their advertising strategies to target diverse patients in need of TJA. Level of evidence: III (retrospective cohort study). more...

Background: Patients with chronic knee pain are often unaware of treatment options and likely outcomes—information that is critical to decision-making. A consistent framework for communicating patient-personalized information enables clinicians to provide consistent, targeted, and relevant information. Our objective was to user-test a shared decision-making (SDM) tool for chronic knee pain. Methods: A cross-functional team developed a Markov-based health economics model and tested the model outputs with patient panels, patient and clinician focus groups, and clinical specialists. The resulting SDM tool was user-tested in a parallel-designed, randomized controlled study with 52 African American and 52 Latina women from geographically representative areas of the US. Participants were randomized to counseling with or without the SDM tool. Feedback was collected at intervention and at 1 month after intervention and analyzed with Student's t-tests and Chi-squared analyses (alpha = 0.05). Results: Qualitative results indicated patients understood the material, rated the overall experience highly, and were likely to recommend the physician. The SDM group reported high satisfaction with the tool. A greater proportion of the SDM group (56%) reported increased physical activity over baseline at 1 month compared with the control group (33%) (P = 0.0005). New use of medications for knee pain (58% SDM; 49% control) did not differ significantly between groups (P = 0.15). Conclusion: Use of this innovative SDM tool was associated with high satisfaction and a significant increase in self-reported physical activity level at 1 month. The SDM tool may elicit behavioral changes to promote musculoskeletal health. more...

Recent research has revealed the diversity and biomass of life across ecosystems, but how that biomass is distributed across body sizes of all living things remains unclear. We compile the present-day global body size-biomass spectra for the terrestrial, marine, and subterranean realms. To achieve this compilation, we pair existing and updated biomass estimates with previously uncatalogued body size ranges across all free-living biological groups. These data show that many biological groups share similar ranges of body sizes, and no single group dominates size ranges where cumulative biomass is highest. We then propagate biomass and size uncertainties and provide statistical descriptions of body size-biomass spectra across and within major habitat realms. Power laws show exponentially decreasing abundance (exponent -0.9±0.02 S.D., R2 = 0.97) and nearly equal biomass (exponent 0.09±0.01, R2 = 0.56) across log size bins, which resemble previous aquatic size spectra results but with greater organismal inclusivity and global coverage. In contrast, a bimodal Gaussian mixture model describes the biomass pattern better (R2 = 0.86) and suggests small (~10-15 g) and large (~107 g) organisms outweigh other sizes by one order magnitude (15 and 65 Gt versus ~1 Gt per log size). The results suggest that the global body size-biomass relationships is bimodal, but substantial one-to-two orders-of-magnitude uncertainty mean that additional data will be needed to clarify whether global-scale universal constraints or local forces shape these patterns. more...

Introduction The timing of tranexamic acid (TXA) administration in fragility hip fracture patients is controversial. Prior studies have demonstrated reduction in transfusion requirements using the two-dose arthroplasty model. However, unlike arthroplasty patients whose bleeding starts at the time of surgical incision, hip fractures have an onset of bleeding at the time of the injury. The primary goal of this study was to evaluate the optimal timing of TXA administration and to determine its effect on red blood cell transfusions in fragility hip fracture patients. Methods All patients admitted to the fragility hip fracture service from April 1, 2019 to September 30, 2019 were prospectively screened for inclusion in the study. Eligible patients received 4 intravenous doses of TXA: Ineligible patients received no TXA. Patients with medical conditions precluding the use of TXA were deemed ineligible: allergy to TXA; creatinine clearance 48 hours prior to presentation. A subset of patients received only admission TXA dosing and a separate subset of patients received only incision and post op TXA dosing. Red blood cell transfusions, major adverse vascular events, and minor drug and infusion-related adverse events were recorded for all subgroups of patients. Results A total of 508 patients were eligible for analysis. In total, 180 patients received no TXA, 32 patients only received the admission doses of TXA, 112 patients received only the arthroplasty based (incision and post op) doses of TXA, and 183 patients received all 4 doses of TXA. The transfusion rate was significantly lower in patients who received all 4 doses of TXA (8.7%) and in those who only received one dose of TXA at admission (9.4%) compared to patients who received TXA at incision and recovery room (25.7%) or those patients who did not receive TXA prophylaxis (29.4%) (P = 0.001). Additionally, the transfusion rate for intramedullary nailing was higher compared to patients undergoing any other procedure (27% vs 13.8%, P < 0.001). Conclusions Patients with fragility hip fractures who received IV TXA at hospital admission have significantly lower transfusion rates compared to those who received no tranexamic acid or those who received two dose-TXA (at the operative incision and in the post-operative recovery room). These findings suggest that isolated dosing of TXA at hospital admission may be more effective at reducing post-operative bleeding than the traditional arthroplasty dosing (incision and post-op doses) and is equally as effective as the 4-dose TXA protocol in hip fracture patients undergoing surgery. more...

Introduction: Shorter length of stays (LOS) at a Skilled Nursing Facility (SNF) after hip fracture surgery would be expected to lead to costs savings for the healthcare system. Evidence also suggests that shorter SNF stays also leads to improved 30-day outcomes, thus compounding this value proposition. Our Integrated Fragility Hip Fracture Program created a simple algorithm at discharge to provide each post-operative hip fracture patient with an expected SNF LOS. We studied whether this intervention produced a shorter SNF LOS and other observable short-term outcomes. Methods: We retrospectively reviewed all original Medicare hip fracture patients treated with operative fixation who were admitted to our hospital in 2015, 2017 and 2018. We selected patients who were discharged to a single SNF following hospitalization, and excluded patients with incomplete records. The algorithm for the expected LOS recommendation was based on the degree of assistance the patient needed for ambulation: 7 days (“0-person assist”), 14 days (“1-person assist”), or 21 days (“2-person assist”). We compare the SNF LOS of our hip fracture patient population between those discharged to a program participant, those SNF that agreed to this algorithm, and those discharged to a non-program participant SNF. Results: We identified 246 patients meeting our selection criteria. 69 were discharged to a program participant SNF. Patients discharged to a participant SNF had similar baseline demographics and ASA distributions to those discharged to a non-participant provider. There was a statistically significant difference in length of stay between the groups, with program participant patients spending an average of 23 days at the SNF while the control group spent an average of 31 days. (p < 0.001). Program participant discharges were also associated with additional cost savings. There was no significant difference in ED visits within 90 days of discharge. Discussion: SNF LOS for geriatric hip fractures can be decreased with implementation of a simple physical therapy driven algorithm based on the patient’s ambulatory independence at hospital discharge. Conclusion : This is a simple, yet completely unique program that seems to have increased the value of healthcare provided. more...

The seagrass Zostera marina is a widespread foundational species in temperate coastal ecosystems that supports diverse communities of epiphytes and grazers. Bacteria link the production of seagrass to higher trophic levels and are thought to influence seagrass biology and health. Yet, we lack a clear understanding of the factors that structure the seagrass microbiome, or whether there is a consistent microbial community associated with seagrass that underpins functional roles. We sampled surface microbiome (epibiota) from new and old growth seagrass leaves and the surrounding seawater in eight meadows among four regions along the Central Coast of British Columbia, Canada to assess microbiome variability across space and as leaves age. We found that the seagrass leaf microbiome differs strongly from seawater. Microbial communities in new and old growth leaves are different from each other and from artificial seagrass leaves we deployed in one meadow. The microbiome on new leaves is less diverse and there is a small suite of core OTUs (operational taxonomic units) consistently present across regions. The overall microbial community for new leaves is more dispersed but with little regional differentiation, while the epiphytes on old leaves are regionally distinct. Many core OTUs on old leaves are commonly associated with marine biofilms. Together these observations suggest a stronger role for host filtering in new compared to old leaves, and a stronger influence of the environment and environmental colonization in old leaves. We found 11 core microbial taxa consistently present on old and new leaves and at very low relative abundance on artificial leaves and in the water column. These 11 taxa appear to be strongly associated with Z. marina. These core taxa may perform key functions important for the host such as detoxifying seagrass waste products, enhancing plant growth, and controlling epiphyte cover. more...

Aquatic ecosystems worldwide continue to experience unprecedented warming and ecological change. Warming increases metabolic rates of animals, plants, and microbes, accelerating their use of energy and materials, their population growth, and interaction rates. At a much larger biological scale, warming accelerates ecosystem-level processes, elevating fluxes of carbon and oxygen between biota and the atmosphere. Although these general effects of temperature at finer and broader biological scales are widely observed, they can lead to contradictory predictions for how warming affects the structure and function of ecological communities at the intermediate scale of biological organization. We experimentally tested the hypothesis that the presence of predators and their associated species interactions modify the temperature dependence of net ecosystem oxygen production and respiration. We tracked a series of independent freshwater ecosystems (370 L) over 9 weeks, and we found that at higher temperatures, cascading effects of predators on zooplankton prey and algae were stronger than at lower temperatures. When grazing was weak or absent, standing phytoplankton biomass declined by 85%-95% ( more...

The persistence of ecological systems in changing environments requires energy, materials, and information. Although the importance of information to ecological function has been widely recognized, the fundamental principles of ecological science as commonly expressed do not reflect this central role of information processing. We articulate five fundamental principles of ecology that integrate information with energy and material constraints across scales of organization in living systems. We show how these principles outline new theoretical and empirical research challenges, and offer one novel attempt to incorporate them in a theoretical model. To provide adequate background for the principles, we review major concepts and identify common themes and key differences in information theories spanning physics, biology and semiotics. We structured our review around a series of questions about the role information may play in ecological systems: (i) what is information? (ii) how is information related to uncertainty? (iii) what is information processing? (iv) does information processing link ecological systems across scales? We highlight two aspects of information that capture its dual roles: syntactic information defining the processes that encode, filter and process information stored in biological structure and semiotic information associated with structures and their context. We argue that the principles of information in living systems promote a unified approach to understanding living systems in terms of first principles of biology and physics, and promote much needed theoretical and empirical advances in ecological research to unify understanding across disciplines and scales. more...