Consistent patterns of common species across tropical tree communities

Trees structure the Earth’s most biodiverse ecosystem, tropical forests. The vast number of tree species presents a formidable challenge to understanding these forests, including their response to environmental change, as very little is known about most tropical tree species. A focus on the common species may circumvent this challenge. Here we investigate abundance patterns of common tree species using inventory data on 1,003,805 trees with trunk diameters of at least 10 cm across 1,568 locations1,2,3,4,5,6 in closed-canopy, structurally intact old-growth tropical forests in Africa, Amazonia and Southeast Asia. We estimate that 2.2%, 2.2% and 2.3% of species comprise 50% of the tropical trees in these regions, respectively. Extrapolating across all closed-canopy tropical forests, we estimate that just 1,053 species comprise half of Earth’s 800 billion tropical trees with trunk diameters of at least 10 cm. Despite differing biogeographic, climatic and anthropogenic histories7, we find notably consistent patterns of common species and species abundance distributions across the continents. This suggests that fundamental mechanisms of tree community assembly may apply to all tropical forests. Resampling analyses show that the most common species are likely to belong to a manageable list of known species, enabling targeted efforts to understand their ecology. Although they do not detract from the importance of rare species, our results open new opportunities to understand the world’s most diverse forests, including modelling their response to environmental change, by focusing on the common species that constitute the majority of their trees

Response of finger circulation to energy equivalent combinations of magnitude and duration of vibration

OBJECTIVES - To investigate the acute response of finger circulation to vibration with different combinations of magnitude and duration but with the same "energy equivalent" acceleration magnitude according to current standards for hand transmitted vibration.METHODS - Finger skin temperature (FST) and finger blood flow (FBF) were measured in the middle fingers of both hands of 10 healthy men who had not used hand held vibrating tools regularly. With a static load of 10 N, the right hand was exposed to 125 Hz vibration with the following unweighted root mean square (rms) acceleration magnitudes and durations of exposure: 44 m/s2 for 30 minutes; 62 m/s2 for 15 minutes; 88 m/s2 for 7.5 minutes; 125 m/s2 for 3.75 minutes; and 176 m/s2 for 1.88 minutes. These vibration exposures produce the same 8 hour energy equivalent frequency weighted acceleration magnitude (~1.4 m/s2 rms) according to international standard ISO 5349 (1986). Finger circulation was measured in both the right (vibrated) and the left (non-vibrated) middle fingers before application of the vibration, and at fixed intervals during exposure to vibration and during a 45 minute recovery period.RESULTS - The FST did not change during exposure to vibration, whereas vibration with any combination of acceleration magnitude and duration produced significant percentage reductions in the FBF of the vibrated finger compared with the FBF before exposure (from 40.1% (95% confidence interval (95% CI) 24.3% to 57.2%) to 61.4% (95% CI 45.0% to 77.8%). The reduction in FBF during vibration was stronger in the vibrated finger than in the non-vibrated finger. Across the five experimental conditions, the various vibration stimuli caused a similar degree of vasoconstriction in the vibrated finger during exposure to vibration. There was a progressive decrease in the FBF of both fingers after the end of exposure to vibration with acceleration magnitudes of 44 m/s2 for 30 minutes and 62 m/s2 for 15 minutes. Significant vasoconstrictor after effects were not found in either finger after exposure to any of the other vibration stimuli with greater acceleration magnitudes for shorter durations.CONCLUSIONS - For the range of vibration magnitudes investigated (44 to 176 m/s2 rms unweighted; 5.5 to 22 m/s2 rms when frequency weighted according to ISO 5349), the vasoconstriction during exposure to 125 Hz vibration was independent of vibration magnitude. The after effect of vibration was different for stimuli with the same energy equivalent acceleration, with greater effects after longer durations of exposure. The energy equivalent acceleration therefore failed to predict the acute effects of vibration both during and after exposure to vibration. Both central and local vasoregulatory mechanisms are likely to be involved in the response of finger circulation to acute exposures to 125 Hz vibration

Acute vascular responses to the frequency of vibration transmitted to the hand

OBJECTIVES - To investigate the acute effects of the frequency of hand transmitted vibration on finger circulation. A further aim was to investigate whether the frequency weighting assumed in current standards for hand transmitted vibration reflects the haemodynamic changes which occur in the fingers exposed to vibration with different frequencies but with the same frequency weighted acceleration magnitude. METHODS - Finger skin temperature (FST) and finger blood flow (FBF) were measured in the middle fingers of both hands of 10 healthy men. With a static load of 10 N, the right hand was exposed for 15 minutes to the following root mean square (rms) acceleration magnitudes and frequencies of vertical vibration: 5.5 m/s2 at 16 Hz; 11 m/s2 at 31.5 Hz; 22 m/s2 at 63 Hz; 44 m/s2 at 125 Hz; and 88 m/s2 at 250 Hz. These exposures to vibration produce the same frequency weighted acceleration magnitude (5.5 m/s2 rms) according to the frequency weighting included in the international standard ISO 5349. A control condition consisted of exposure to the static load only. Finger circulation was measured before application of the vibration and static load and at fixed intervals during exposure to vibration and a 45 minute recovery period. RESULTS - No significant changes in finger circulation were found with only the static load. The FST did not change significantly during or after acute exposure to vibration. In the vibrated right finger, exposures to vibration with frequencies of 31.5-250 Hz provoked a greater reduction in FBF than did vibration of 16 Hz or the static load only. In the non-vibrated left finger, the FBF measured with vibration at each frequency of 63-250 Hz was significantly lower than that measured with static load only. The reduction in FBF during exposure to vibration with any frequency was stronger in the vibrated finger than in the non-vibrated finger. In both fingers, there was a progressive decrease in FBF after the end of exposure to vibration with frequencies of 31.5-250 Hz. The higher the frequency of vibration, the stronger the decrease in FBF in both fingers during recovery. CONCLUSIONS - Acute exposures to vibration with equal frequency weighted magnitude reduce the FBF in both vibrated and non-vibrated fingers for frequencies between 31.5 and 250 Hz. The extent of digital vasoconstriction after exposure to vibration increases with increasing frequency. The frequency weighting given in current standards tends to overestimate the vasoconstriction associated with acute exposures to vibration frequencies around 16 Hz

Standardised diagnostic methods for assessing components of the hand-arm vibration syndrome

SIGLEAvailable from British Library Document Supply Centre-DSC:4335.321(197) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Biomarkers for Traumatic Brain Injury: Data Standards and Statistical Considerations

Recent biomarker innovations hold potential for transforming diagnosis, prognostic modeling, and precision therapeutic targeting of traumatic brain injury (TBI). However, many biomarkers, including brain imaging, genomics, and proteomics, involve vast quantities of high-throughput and high-content data. Management, curation, analysis, and evidence synthesis of these data are not trivial tasks. In this review, we discuss data management concepts and statistical and data sharing strategies when dealing with biomarker data in the context of TBI research. We propose that application of biomarkers involves three distinct steps-discovery, evaluation, and evidence synthesis. First, complex/big data has to be reduced to useful data elements at the stage of biomarker discovery. Second, inferential statistical approaches must be applied to these biomarker data elements for assessment of biomarker clinical utility and validity. Last, synthesis of relevant research is required to support practice guidelines and enable health decisions informed by the highest quality, up-to-date evidence available. We focus our discussion around recent experiences from the International Traumatic Brain Injury Research (InTBIR) initiative, with a specific focus on four major clinical projects (Transforming Research and Clinical Knowledge in TBI, Collaborative European NeuroTrauma Effectiveness Research in TBI, Collaborative Research on Acute Traumatic Brain Injury in Intensive Care Medicine in Europe, and Approaches and Decisions in Acute Pediatric TBI Trial), which are currently enrolling subjects in North America and Europe. We discuss common data elements, data collection efforts, data-sharing opportunities, and challenges, as well as examine the statistical techniques required to realize successful adoption and use of biomarkers in the clinic as a foundation for precision medicine in TBI

Global Differences in Characteristics, Precipitants, and Initial Management of Patients Presenting with Acute Heart Failure

Importance: Acute heart failure (AHF) precipitates millions of hospital admissions worldwide, but previous registries have been country or region specific. Objective: To conduct a prospective contemporaneous comparison of AHF presentations, etiologic factors and precipitants, treatments, and in-hospital outcomes among global regions through the International Registry to Assess Medical Practice with Longitudinal Observation for Treatment of Heart Failure (REPORT-HF). Design, Setting, and Participants: A total of 18553 adults were enrolled during a hospitalization for AHF. Patients were recruited from the acute setting in Western Europe (WE), Eastern Europe (EE), Eastern Mediterranean and Africa (EMA), Southeast Asia (SEA), Western Pacific (WP), North America (NA), and Central and South America (CSA). Patients with AHF were approached for consent and excluded only if there was recent participation in a clinical trial. Patients were enrolled from July 23, 2014, to March 24, 2017. Statistical analysis was conducted from April 18 to June 29, 2018; revised analyses occurred between August 6 and 29, 2019. Main Outcomes and Measures: Heart failure etiologic factors and precipitants, treatments, and in-hospital outcomes among global regions. Results: A total of 18553 patients were enrolled at 358 sites in 44 countries. The median age was 67.0 years (interquartile range [IQR], 57-77), 11372 were men (61.3%), 9656 were white (52.0%), 5738 were Asian (30.9%), and 867 were black (4.7%). A history of HF was present in more than 50% of the patients and 40% were known to have a prior left-ventricular ejection fraction lower than 40%. Ischemia was a common AHF precipitant in SEA (596 of 2329 [25.6%]), WP (572 of 3354 [17.1%]), and EMA (364 of 2241 [16.2%]), whereas nonadherence to diet and medications was most common in NA (306 of 1592 [19.2%]). Median time to the first intravenous therapy was 3.0 (IQR, 1.4-5.6) hours in NA; no other region had a median time above 1.2 hours (P <.001). This treatment delay remained after adjusting for severity of illness (P <.001). Intravenous loop diuretics were the most common medication administered in the first 6 hours of AHF management across all regions (65.4%-89.9%). Despite similar initial blood pressure across all regions, inotropic agents were used approximately 3 times more often in SEA, WP, and EE (11.3%-13.5%) compared with NA and WE (3.1%-4.3%) (P <.001). Older age (odds ratio [OR], 1.0; 95% CI, 1.00-1.02), HF etiology (ischemia: OR, 1.65; 95% CI, 1.11-2.44; valvular: OR, 2.10; 95% CI, 1.36-3.25), creatinine level greater than 2.75 mg/dL (OR, 1.85; 95% CI, 0.71-2.40), and chest radiograph signs of congestion (OR, 2.03; 95% CI, 1.39-2.97) were all associated with increased in-hospital mortality. Similarly, younger age (OR, -0.04; 95% CI, -0.05 to -0.02), HF etiology (ischemia: OR, 0.77; 95% CI, 0.26-1.29; valvular: OR, 2.01; 95% CI, 1.38-2.65), creatinine level greater than 2.75 mg/dL (OR, 1.16; 95% CI, 0.31-2.00), and chest radiograph signs of congestion (OR, 1.02; 95% CI, 0.57-1.47) were all associated with increased in-hospital LOS. Conclusions and Relevance: Data from REPORT-HF suggest that patients are similar across regions in many respects, but important differences in timing and type of treatment exist, identifying region-specific gaps in medical management that may be associated with patient outcomes. © 2020 American Medical Association. All rights reserved

A proposal to standardize dyspnoea measurement in clinical trials of acute heart failure syndromes: The need for a uniform approach

Dyspnoea is the most common presenting symptom amongst patients with acute heart failure syndromes (AHFS). It is distressing to patients and therefore an important target for treatment in clinical practice, clinical trials, and for regulatory approval of novel agents. Despite its importance as a treatment target, no consensus exists on how to assess dyspnoea in this setting. There is a considerable uncertainty about the reproducibility of the various instruments used to measure dyspnoea, their ability to reflect changes in symptoms and whether they accurately reflect the patient's experience. Little attempt has been made to ensure consistent implementation with respect to patients' posture during assessment or timing in relationship to therapy. There is also limited understanding of how rapidly and completely dyspnoea responds to standard therapy. A standardized method with which to assess dyspnoea is required for clinical trials of AHFS in order to ensure uniform collection of data on a key endpoint. We propose the Provocative Dyspnoea Assessment, a method of measurement that combines sequential dyspnoea provocation by positioning and walking with a dyspnoea self assessment using a five-point Likert scale, to yield a final Dyspnoea Severity Score. This proposed tool requires detailed validation but has face validity for the uniform assessment of dyspnoea. © The Author 2008