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Nitrogen-fixing trees are a major potential source of nitrogen in terrestrial ecosystems. The degree to which they persist in older forests has considerable implications for forest nitrogen budgets. We characterized nitrogen-fixing tree abundance across stand age in the contiguous United States and analyzed a theoretical model to help understand competitive outcomes and successional trajectories of nitrogen-fixing and nonfixing trees. Nitrogen-fixing tree abundance is bimodal in all regions except the northeastern United States, even in older forests, suggesting that competitive exclusion (including priority effects) is more common than coexistence at the spatial scale of our analysis. Our model analysis suggests conditions under which alternative competitive outcomes are possible and when they are transient (lasting decades or centuries) versus persistent (millennia). Critically, the timescale of the feedbacks between nitrogen fixation and soil nitrogen supply, which is thought to drive the exclusion of nitrogen-fixing trees through succession, can be long. Therefore, the long transient outcomes of competition are more relevant for real forests than the long-term equilibrium. Within these long-term transients, the background soil nitrogen supply is a major determinant of competitive outcomes. Consistent with the expectations of resource ratio theory, competitive exclusion is more likely at high and low nitrogen supply, while intermediate nitrogen supply makes coexistence or priority effects possible. However, these outcomes are modified by the nitrogen fixation strategy: obligate nitrogen fixation makes coexistence more likely than priority effects, compared with perfectly facultative fixation. These results advance our understanding of the successional trajectories of nitrogen-fixing trees and their effects on ecosystem development in secondary succession. [ABSTRACT FROM AUTHOR]

Background: Recognition of rates and causes of hard, patient-centered outcomes of death and cerebrovascular events (CVEs) after heart rhythm disorder management (HRDM) procedures is an essential step for the development of quality improvement programs in electrophysiology laboratories. Our primary aim was to assess and characterize death and CVEs (stroke or transient ischemic attack) after HRDM procedures over a 17-year period.Methods: We performed a retrospective cohort study of all patients undergoing HRDM procedures between January 2000 and November 2016 at the Mayo Clinic. Patients from all 3 tertiary academic centers (Rochester, Phoenix, and Jacksonville) were included in the study. All in-hospital deaths and CVEs after HRDM procedures were identified and were further characterized as directly or indirectly related to the HRDM procedure. Subgroup analysis of death and CVE rates was performed for ablation, device implantation, electrophysiology study, lead extraction, and defibrillation threshold testing procedures.Results: A total of 48 913 patients (age, 65.7±6.6 years; 64% male) who underwent a total of 62 065 HRDM procedures were included in the study. The overall mortality and CVE rates in the cohort were 0.36% (95% confidence interval [CI], 0.31-0.42) and 0.12% (95% CI, 0.09-0.16), respectively. Patients undergoing lead extraction had the highest overall mortality rate at 1.9% (95% CI, 1.34-2.61) and CVE rate at 0.62% (95% CI, 0.32-1.07). Among patients undergoing HRDM procedures, 48% of deaths directly related to the HDRM procedure were among patients undergoing device implantation procedures. Overall, cardiac tamponade was the most frequent direct cause of death (40%), and infection was the most common indirect cause of death (29%). The overall 30-day mortality rate was 0.76%, with the highest being in lead extraction procedures (3.08%), followed by device implantation procedures (0.94%).Conclusions: Half of the deaths directly related to an HRDM procedure were among the patients undergoing device implantation procedures, with cardiac tamponade being the most common cause of death. This highlights the importance of the development of protocols for the quick identification and management of cardiac tamponade even in procedures typically believed to be lower risk such as device implantation. [ABSTRACT FROM AUTHOR]

Abstract: Continuous reservoir fluid pressure monitoring is a technique being deployed and evaluated for monitoring CO2 sequestration projects for storage integrity. Pressure data are known to reveal information about bulk reservoir properties and performance, and the pressure magnitude trajectory through time is commonly used as a metric for demonstrating numerical flow model conformance with observed injection history (i.e. pressure history match). Identification of well leakage using a pressure history approach can be difficult due to the subtle effects such leaks can have on the characteristic pressure magnitude evolution. Using a combination of theory, an analytically-derived synthetic reservoir pressure history example, and analysis of field pressure data, we develop a broadly applicable technique for analyzing reservoir pressure transients in continuous time series and illustrate how that technique can be used to quantify sensitivity to wellbore leakage in the field. Analysis presented here focuses on information provided by second derivative of the continuous pressure time series (d 2 P/dt 2 ). We show that d 2 P/dt 2 transients reveal consistent relationships with known (theoretical case) or induced (field case) pressure perturbations that are independent of prior pressure history, making them a very useful diagnostic tool for identifying and evaluating any observed transients of unknown origin (i.e. sudden well leakage events unrelated to injection schedule). To the degree that the onset of well leakage is expressed as a pressure transient similar to decreases in injection rates, we are able to identify the source functions (changes in flow rates from variable distances) that our gauges are (and are not) sensitive to. Observational data indicate that sensitivities in the field can be much lower than theoretical expectations, mostly a result of noisy and heterogeneous natural systems. Our analysis can be applied to other field scenarios with different reservoir properties for refining observation well placement design with predictable and quantifiable sensitivity. [Copyright &y& Elsevier]

An estimated 8.2 million occupational injuries occur annually to women in the United States. This case-crossover study of 1166 subjects compares transient risk factors for occupational traumatic hand injury to women and men. Study subjects were recruited over a 3-year period (1997 to 2000) from 23 occupational health clinics in five New England states. The case-crossover design was used to estimate the short-term risk of an acute hand injury while controlling between-person potential confounders. Subjects reported on the occurrence of seven transient exposures within a 90-min period and provided control exposure information during the month before an acute hand injury. A total of 275 women and 891 men were interviewed a median of 1.3 days after injury. Lacerations were the most common injury type in both women (58%) and men (64%). Relative risks for women were higher for being distracted, doing unusual tasks, and working with malfunctioning equipment or materials, and were lower than men for being rushed. Gloves provided significant protection for males and females. Results suggest the importance of considering both the prevalence of various exposures and gender in modifying risk factors to reduce the incidence of acute hand injury in the workplace. Thus, greater emphasis should be placed on the planning of safer working environments for all workers. [ABSTRACT FROM AUTHOR]

Survival and cause-specific mortality estimates are needed to develop effective conservation strategies for the endangered ocelot (Leopardus pardalis) in the United States. We radiomonitored 80 ocelots (36 F, 44 M) from 1983 to 2002 and analyzed survival and cause-specific mortality rates. Pooled estimates of annual survival rates differed between resident (S = 0.87) and transient (S = 0.57) ocelots (P = 0.02); therefore, survival and cause-specific mortality analyses were partitioned for resident and transient ocelots. Sex-specific annual survival was similar between resident ocelots (M = 0.92, F = 0.83, P = 0.16) and transient ocelots (M = 0.53, F = 0.63, P = 0.75). Most mortalities were from human (e.g., ocelot-vehicle collisions; M = 45%) and natural (e.g., animal attack, disease; M = 35%) sources. Transient ocelots had higher natural mortality rates (disease, intraspecific mortality; M = 0.26) than resident ocelots (M = 0.04, P = 0.03). Other sources of mortality did not differ (P ≥ 0.10) between resident or transient ocelots or male and female resident or transient ocelots (P ≥ 0.08). Human population expansion within the Lower Rio Grande Valley of southern Texas, USA, will increase transportation-related problems and decrease the quantity of ocelot habitat, leading to increased ocelot-vehicle collisions and possibly cause more transient behavior, thus significantly lowering ocelot survival. Research and development of ocelot road underpasses should be conducted to mitigate ocelot-vehicle collisions. [ABSTRACT FROM AUTHOR]

This study formulates a model for the investigation of international migration and tests the model with data on emigration from Greece to the United States. The model uses a Bernoulli-type differential equation and is based upon the existence of a pool of potential emigrants at the sending country created by the push-pull forces operating between a country of origin and a country of destination. Information flows from the receiving to the sending country also influence the migratory current. Applying the model to emigration from Greece to the U.S. from 1820 to 1980 reveals several interesting findings. The intensity of migration was greatly affected by events in Greece and was conditioned by the constraints introduced by changes in American immigration law. Economic reasons, for the most part, forced Greeks to emigrate, but political upheavals also played an important role. At the destination, the U.S. immigration quota system of 1924 (restrictive) and the immigration act of 1965 (facilitative) were particularly critical factors affecting emigration from Greece. [ABSTRACT FROM AUTHOR]

Background and Objectives: The relative efficacy and safety of apixaban compared with no anticoagulation have not been studied in patients on maintenance dialysis with atrial fibrillation. We aimed to determine whether apixaban is associated with better clinical outcomes compared with no anticoagulation in this population., Design, Setting, Participants, & Measurements: This retrospective cohort study used 2012-2015 US Renal Data System data. Patients on maintenance dialysis with incident, nonvalvular atrial fibrillation treated with apixaban (521 patients) were matched for relevant baseline characteristics with patients not treated with any anticoagulant agent (1561 patients) using a propensity score. The primary outcome was hospital admission for a new stroke (ischemic or hemorrhagic), transient ischemic attack, or systemic thromboembolism. The secondary outcome was fatal or intracranial bleeding. Competing risk survival models were used., Results: Compared with no anticoagulation, apixaban was not associated with lower incidence of the primary outcome: hazard ratio, 1.24; 95% confidence interval, 0.69 to 2.23; P =0.47. A significantly higher incidence of fatal or intracranial bleeding was observed with apixaban compared with no treatment: hazard ratio, 2.74; 95% confidence interval, 1.37 to 5.47; P =0.004. A trend toward fewer ischemic but more hemorrhagic strokes was seen with apixaban compared with no treatment. No significant difference in the composite outcome of myocardial infarction or ischemic stroke was seen with apixaban compared with no treatment. Compared with no anticoagulation, a significantly higher rate of the primary outcome and a significantly higher incidence of fatal or intracranial bleeding and of hemorrhagic stroke were seen in the subgroup of patients treated with the standard apixaban dose (5 mg twice daily) but not in patients who received the reduced apixaban dose (2.5 mg twice daily)., Conclusions: In patients with kidney failure and nonvalvular atrial fibrillation, treatment with apixaban was not associated with a lower incidence of new stroke, transient ischemic attack, or systemic thromboembolism but was associated with a higher incidence of fatal or intracranial bleeding., Podcast: This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2020_05_29_CJN11650919.mp3., (Copyright © 2020 by the American Society of Nephrology.)

Purpose: Our objective was to determine significant predictors of spinal cord ischemia (SCI) following Thoracic Endovascular Aortic Repair (TEVAR) and to further develop a simple and clinically orientated risk score model., Methods: A retrospective review of data from the Society of Vascular Surgery/Vascular Quality Initiative national data set was performed for all patients undergoing TEVAR from January, 2014 to June 2018. Preoperative demographics, procedure-related variables, and clinical details related to SCI were examined. A SCI risk score was developed utilizing a multivariable logistic regression model., Results: For the 7889 patients in the final analysis who underwent TEVAR during the study period, the mean age was 67.6 ± 13.9, range 18 to 90 years, and the majority was male (65%). Postoperative outcomes included stroke (3.0%), myocardial infarction (2.9%), inhospital mortality (5.4%), transient SCI (1.5%), and permanent SCI (2.1%). Nearly half of the overall cases were performed in high volume centers. Predictors of increased risk for SCI included age by decade (odds ratio [OR]: 1.2), celiac coverage (OR: 1.5), current smoker (OR: 1.6), dialysis (OR: 1.9), 3 or more aortic implanted devices (OR: 1.7), emergent or urgent surgery (OR: 1.5), adjunct aorta-related procedure (OR: 2.5), adjunct not related (OR: 2.6), total estimated length of aortic device (19-31 cm, OR: 1.9 and ≥32 cm, OR: 3.0), ASA class 4 or 5 (OR: 1.6), and procedure time ≥154 minutes (OR: 1.8). Two predictors decreased the risk of SCI, cases from high-volume centers (OR: 0.6) and eGFR ≥ 60 (OR: 0.6). To evaluate the risk score model, probabilities of SCI from the original regression, raw score, and raw score categories resulted in area under the curve statistics of 0.792, 0.786, and 0.738, respectively., Conclusions: Spinal cord ischemia remains one of the most feared complications of TEVAR. Incidence of SCI in this large series of patients with TEVAR was 3.6% with nearly 60% being permanent. The proposed model provides an assessment tool to guide clinical decisions, patient consent process, risk-assessment, and procedural strategy.

Background: Novel oral anticoagulants (NOACs) have been shown to be at least as good as warfarin for preventing stroke or transient ischemic attack in patients with atrial fibrillation, yet diffusion of these therapies and patterns of use among atrial fibrillation patients with ischemic stroke and transient ischemic attack have not been well characterized., Methods and Results: Using data from Get With The Guidelines-Stroke, we identified a cohort of 61 655 atrial fibrillation patients with ischemic stroke or transient ischemic attack hospitalized between October 2010 and September 2012 and discharged on warfarin or NOAC (either dabigatran or rivaroxaban). Multivariable logistic regression was used to identify factors associated with NOAC versus warfarin therapy. In our study population, warfarin was prescribed to 88.9%, dabigatran to 9.6%, and rivaroxaban to 1.5%. NOAC use increased from 0.04% to a 16% to 17% plateau during the study period, although anticoagulation rates among eligible patients did not change appreciably (93.7% versus 94.1% from first quarter 2011 to second quarter 2012), suggesting a trend of switching from warfarin to NOACs rather than increased rates of anticoagulation among eligible patients. Several bleeding risk factors and CHA2DS2-VASc scores were lower among those discharged on NOAC versus warfarin therapy (47.9% versus 40.9% with CHA2DS2-VASc ≤5, P<0.001 for difference in CHA2DS2-VASc)., Conclusions: NOACs have had modest but growing uptake over time among atrial fibrillation patients hospitalized with stroke or transient ischemic attack and are prescribed to patients with lower stroke risk compared with warfarin., (© 2015 American Heart Association, Inc.)