Ongoing changes in disturbance regimes are predicted to cause acute changes in ecosystem structure and function in the coming decades, but many aspects of these predictions are uncertain. A key ...challenge is to improve the predictability of postdisturbance biogeochemical trajectories at the ecosystem level. Ecosystem ecologists and paleoecologists have generated complementary data sets about disturbance (type, severity, frequency) and ecosystem response (net primary productivity, nutrient cycling) spanning decadal to millennial timescales. Here, we take the first steps toward a full integration of these data sets by reviewing how disturbances are reconstructed using dendrochronological and sedimentary archives and by summarizing the conceptual frameworks for carbon, nitrogen, and hydrologic responses to disturbances. Key research priorities include further development of paleoecological techniques that reconstruct both disturbances and terrestrial ecosystem dynamics. In addition, mechanistic detail from disturbance experiments, long-term observations, and chronosequences can help increase the understanding of ecosystem resilience.
We synthesize existing sedimentary charcoal records to reconstruct Holocene fire history at regional, continental and global scales. The reconstructions are compared with the two potential controls ...of burning at these broad scales – changes in climate and human activities – to assess their relative importance on trends in biomass burning. Here we consider several hypotheses that have been advanced to explain the Holocene record of fire, including climate, human activities and synergies between the two. Our results suggest that 1) episodes of high fire activity were relatively common in the early Holocene and were consistent with climate changes despite low global temperatures and low levels of biomass burning globally; 2) there is little evidence from the paleofire record to support the Early Anthropocene Hypothesis of human modification of the global carbon cycle; 3) there was a nearly-global increase in fire activity from 3 to 2 ka that is difficult to explain with either climate or humans, but the widespread and synchronous nature of the increase suggests at least a partial climate forcing; and 4) burning during the past century generally decreased but was spatially variable; it declined sharply in many areas, but there were also large increases (e.g., Australia and parts of Europe). Our analysis does not exclude an important role for human activities on global biomass burning during the Holocene, but instead provides evidence for a pervasive influence of climate across multiple spatial and temporal scales.
The aim of this study was to test the efficacy of brief physician advice in reducing alcohol use and related harm in college students.
The College Health Intervention Projects (CHIPs) is a ...randomized, controlled clinical trial with 12-month follow-up conducted in five college health clinics in Wisconsin; Washington state; and Vancouver, Canada. Of the 12,900 students screened for high-risk drinking, 484 men and 502 women met inclusion criteria and were randomized into a control (n = 493) or intervention (n = 493) group. Ninety-six percent of students participated in the follow-up procedures. The intervention consisted of two 15-minute counseling visits and two follow-up phone calls, and used motivational interviewing, contracting, diary cards, and take-home exercises.
No significant differences were found between groups at baseline on alcohol use, age, socioeconomic or smoking status, rates of depression, or measures of alcohol-related harm. At 12 months, the experimental subjects reduced their 28-day drinking totals by 27.2%, and the control group reduced their totals by 21%. A mixed effects repeated measures model found a statistical difference in favor of the brief-intervention group (beta = 4.7, SE = 2.0, p = .018) in 28-day drinking totals. The total Rutgers Alcohol Problem Index score was also significantly different during the 12-month follow-up period (beta = 0.8, SE = 0.4, p = .033). There was no difference on the other outcome measures of interest, such as frequency of excessive heavy drinking, health care utilization, injuries, drunk driving, depression, or tobacco use.
The study supports resource allocation and implementation of alcohol screening and brief physician advice in primary care-based college health clinics.
Wildfire plays an important role in ecosystems of the Pacific Northwest, but past relationships among fire, climate, and human actions remain unclear. A multiscale analysis of thirty-four macroscopic ...charcoal records from a variety of biophysical settings was conducted to reconstruct fire activity for the Pacific Northwest (PNW) during the past 12,000 years. Trends in biomass burning and fire frequency are compared to paleoenvironmental and population data at a variety of temporal and spatial scales to better understand fire regime variability on centennial- to millennial-length time scales. PNW fire activity in the early Holocene is linked to climatic and vegetation changes; however, increased fire activity in the middle to late Holocene is inconsistent with long-term trends in temperature and precipitation. Two hypotheses are explored to explain the rise in fire activity after ca. 5,500 calendar years before present, including greater climate variability and increased human use of fire. Climatic changes such as increased El Niño/Southern Oscillation event frequency during the past approximately 6,000 years could have led to hydrologic shifts conducive to more frequent fire events, despite overall trends toward cooler and moister conditions. Alternatively, increasing human populations and their associated uses of fire might have increased biomass burning. Centennial-scale changes in fire activity, such as during the Medieval Climate Anomaly and the Little Ice Age, closely match widespread shifts in both climate and population, suggesting that one or both influenced the late-Holocene fire history of the PNW.
Altered coagulation is a striking feature of COVID-19. Adult patients with congenital heart disease (ACHD) are prone to thromboembolic (TE) and bleeding complications.
The purpose of this study was ...to investigate the prevalence and risk factors for COVID-19 TE/bleeding complications in ACHD patients.
COVID-19-positive ACHD patients were included between May 2020 and November 2021. TE events included ischemic cerebrovascular accident, systemic and pulmonary embolism, deep venous thrombosis, myocardial infarction, and intracardiac thrombosis. Major bleeding included cases with hemoglobin drop >2 g/dl, involvement of critical sites, or fatal bleeding. Severe infection was defined as need for intensive care unit, endotracheal intubation, renal replacement therapy, extracorporeal membrane oxygenation, or death. Patients with TE/bleeding were compared to those without events. Factors associated with TE/bleeding were determined using logistic regression.
Of 1,988 patients (age 32 IQR: 25-42 years, 47% male, 59 ACHD centers), 30 (1.5%) had significant TE/bleeding: 12 TE events, 12 major bleeds, and 6 with both TE and bleeding. Patients with TE/bleeding had higher in-hospital mortality compared to the remainder cohort (33% vs 1.7%; P < 0.0001) and were in more advanced physiological stage (P = 0.032) and NYHA functional class (P = 0.01), had lower baseline oxygen saturation (P = 0.0001), and more frequently had a history of atrial arrhythmia (P < 0.0001), previous hospitalization for heart failure (P < 0.0007), and were more likely hospitalized for COVID-19 (P < 0.0001). By multivariable logistic regression, prior anticoagulation (OR: 4.92; 95% CI: 2-11.76; P = 0.0003), cardiac injury (OR: 5.34; 95% CI: 1.98-14.76; P = 0.0009), and severe COVID-19 (OR: 17.39; 95% CI: 6.67-45.32; P < 0.0001) were independently associated with increased risk of TE/bleeding complications.
ACHD patients with TE/bleeding during COVID-19 infection have a higher in-hospital mortality from the illness. Risk of coagulation disorders is related to severe COVID-19, cardiac injury during infection, and use of anticoagulants.
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