Latitudinal patterns in stabilizing density dependence of forest communities.

Numerous studies have shown reduced performance in plants that are surrounded by neighbours of the same species1,2, a phenomenon known as conspecific negative density dependence (CNDD)3. A long-held ecological hypothesis posits that CNDD is more pronounced in tropical than in temperate forests4,5, which increases community stabilization, species coexistence and the diversity of local tree species6,7. Previous analyses supporting such a latitudinal gradient in CNDD8,9 have suffered from methodological limitations related to the use of static data10-12. Here we present a comprehensive assessment of latitudinal CNDD patterns using dynamic mortality data to estimate species-site-specific CNDD across 23 sites. Averaged across species, we found that stabilizing CNDD was present at all except one site, but that average stabilizing CNDD was not stronger toward the tropics. However, in tropical tree communities, rare and intermediate abundant species experienced stronger stabilizing CNDD than did common species. This pattern was absent in temperate forests, which suggests that CNDD influences species abundances more strongly in tropical forests than it does in temperate ones13. We also found that interspecific variation in CNDD, which might attenuate its stabilizing effect on species diversity14,15, was high but not significantly different across latitudes. Although the consequences of these patterns for latitudinal diversity gradients are difficult to evaluate, we speculate that a more effective regulation of population abundances could translate into greater stabilization of tropical tree communities and thus contribute to the high local diversity of tropical forests.

The unexpected influence of legacy conspecific density dependence.

When plants die, neighbours escape competition. Living conspecifics could disproportionately benefit because they are freed from negative intraspecific processes; however, if the negative effects of past conspecific neighbours persist, other species might be advantaged, and diversity might be maintained through legacy effects. We examined legacy effects in a mapped forest by modelling the survival of 37,212 trees of 23 species using four neighbourhood properties: living conspecific, living heterospecific, legacy conspecific (dead conspecifics) and legacy heterospecific densities. Legacy conspecific effects proved nearly four times stronger than living conspecific effects; changes in annual survival associated with legacy conspecific density were 1.5% greater than living conspecific effects. Over 90% of species were negatively impacted by legacy conspecific density, compared to 47% by living conspecific density. Our results emphasize that legacies of trees alter community dynamics, revealing that prior research may have underestimated the strength of density dependent interactions by not considering legacy effects.

Biogeographic context is related to local scale tree demography, co-occurrence and functional differentiation.

Identifying the drivers of community structure and dynamics is a major pursuit in ecology. Emphasis is typically placed on the importance of local scale interactions when attempting to explain these fundamental ecological patterns. However, regional scale phenomena are also important predictors. The importance of regional scale context should be more evident in assemblages where multiple species are close to their range margins. Here, we test the importance of regional scale context using data from a temperate forest plot that contains two species groups - one near its northern range limit and one near its southern range limit. We show the proximity of species to their southern or northern range margins is linked to local scale co-occurrence, similarity in gene expression responses to a key environmental driver, demographic performance and inter-specific variation in conspecific negative density dependence. In sum, many of the key local scale patterns and processes of interest to community ecologists are linked to biogeographic context that is frequently ignored.

The Billirud Mill Blastomycosis Outbreak: Comparison to Historical Controls.

A large outbreak of blastomycosis among paper mill workers in Escanaba, Michigan began with the first cases reported on February 28, 2023 and expanded to 120 cases. Analysis of baseline regional data and the data collected during this unprecedented outbreak provide insight on the outbreak's unique characteristics. The Michigan Disease Surveillance System provided descriptive and outcome data on blastomycosis cases in the Upper Peninsula from 2007 through 2022 and the 2023 outbreak. Baseline incidence for the region was estimated and outbreak cases were compared to historic controls using quantitative methods such as t-tests, chi-square, and Poisson and logistic regression. The Billirud blastomycosis outbreak has resulted in 28 confirmed and 92 probable cases. Blastomycosis incidence for the Upper Peninsula was 2.13 (95%CI: 1.75, 2.59) per 100,000 person-years with counties bordering Wisconsin having a higher incidence more than other counties (4.56, 95%CI: 3.48, 5.97; RR=3.46, 95%CI: 2.35, 5.11). Outbreak cases were significantly younger, more likely to be male, reported more respiratory symptoms, and had a shorter time from onset of illness to diagnosis. The Billirud paper mill blastomycosis outbreak is the largest reported to date, the first in an industrial facility, and the first to specifically involve Blastomyces gilchristii. Blastomyces species are endemic in regional forests, so other facilities handling forestry products may be at risk.

The characteristics of the cases from the largest outbreak of blastomycosis in North America are compared to sporadic cases from the same region over the previous 16 years. The outbreak cases were younger, more likely to be male, and reported more respiratory difficulties.

Age-Related Reliability of B-Mode Analysis for Tailored Exosuit Assistance.

In the field of wearable robotics, assistance needs to be individualized for the user to maximize benefit. Information from muscle fascicles automatically recorded from brightness mode (B-mode) ultrasound has been used to design assistance profiles that are proportional to the estimated muscle force of young individuals. There is also a desire to develop similar strategies for older adults who may have age-altered physiology. This study introduces and validates a ResNet + 2x-LSTM model for extracting fascicle lengths in young and older adults. The labeling was generated in a semimanual manner for young (40,696 frames) and older adults (34,262 frames) depicting B-mode imaging of the medial gastrocnemius. First, the model was trained on young and tested on both young (R2 = 0.85, RMSE = 2.36 ± 1.51 mm, MAPE = 3.6%, aaDF = 0.48 ± 1.1 mm) and older adults (R2 = 0.53, RMSE = 4.7 ± 2.51 mm, MAPE = 5.19%, aaDF = 1.9 ± 1.39 mm). Then, the performances were trained across all ages (R2 = 0.79, RMSE = 3.95 ± 2.51 mm, MAPE = 4.5%, aaDF = 0.67 ± 1.8 mm). Although age-related muscle loss affects the error of the tracking methodology compared to the young population, the absolute percentage error for individual fascicles leads to a small variation of 3-5%, suggesting that the error may be acceptable in the generation of assistive force profiles.

Distribution of biomass dynamics in relation to tree size in forests across the world.

Tree size shapes forest carbon dynamics and determines how trees interact with their environment, including a changing climate. Here, we conduct the first global analysis of among-site differences in how aboveground biomass stocks and fluxes are distributed with tree size. We analyzed repeat tree censuses from 25 large-scale (4-52 ha) forest plots spanning a broad climatic range over five continents to characterize how aboveground biomass, woody productivity, and woody mortality vary with tree diameter. We examined how the median, dispersion, and skewness of these size-related distributions vary with mean annual temperature and precipitation. In warmer forests, aboveground biomass, woody productivity, and woody mortality were more broadly distributed with respect to tree size. In warmer and wetter forests, aboveground biomass and woody productivity were more right skewed, with a long tail towards large trees. Small trees (1-10 cm diameter) contributed more to productivity and mortality than to biomass, highlighting the importance of including these trees in analyses of forest dynamics. Our findings provide an improved characterization of climate-driven forest differences in the size structure of aboveground biomass and dynamics of that biomass, as well as refined benchmarks for capturing climate influences in vegetation demographic models.

Temporal population variability in local forest communities has mixed effects on tree species richness across a latitudinal gradient.

Among the local processes that determine species diversity in ecological communities, fluctuation-dependent mechanisms that are mediated by temporal variability in the abundances of species populations have received significant attention. Higher temporal variability in the abundances of species populations can increase the strength of temporal niche partitioning but can also increase the risk of species extinctions, such that the net effect on species coexistence is not clear. We quantified this temporal population variability for tree species in 21 large forest plots and found much greater variability for higher latitude plots with fewer tree species. A fitted mechanistic model showed that among the forest plots, the net effect of temporal population variability on tree species coexistence was usually negative, but sometimes positive or negligible. Therefore, our results suggest that temporal variability in the abundances of species populations has no clear negative or positive contribution to the latitudinal gradient in tree species richness.

Ultrasound Imaging Characterization of Soft Tissue Dynamics of the Seated Human Body.

To characterize the dynamics of internal soft organs and external anatomical structures, this paper presents a system that combines medical ultrasound imaging with an optical tracker and a vertical exciter that imparts whole-body vibrations on seated subjects. The spatial and temporal accuracy of the system was validated using a phantom with calibrated internal structures, resulting in 0.224 mm maximum root-mean-square (r.m.s.) position error and 13 ms maximum synchronization error between sensors. In addition to the dynamics of the head and sternum, stomach dynamics were characterized by extracting the centroid of the stomach from the ultrasound images. The system was used to characterize the subject-specific body dynamics as well as the intrasubject variabilities caused by excitation pattern (frequency up-sweep, down-sweep, and white noise, 1-10 Hz), excitation amplitude (1 and 2 m/s2 r.m.s.), seat compliance (rigid and soft), and stomach filling (empty and 500 mL water). Human subjects experiments (n = 3) yielded preliminary results for the frequency response of the head, sternum, and stomach. The method presented here provides the first detailed in vivo characterization of internal and external human body dynamics. Tissue dynamics characterized by the system can inform design of vehicle structures and adaptive control of seat and suspension systems, as well as validate finite element models for predicting passenger comfort in the early stages of vehicle design.

Automatically steering cardiac catheters in vivo with respiratory motion compensation.

A robotic system for automatically navigating ultrasound (US) imaging catheters can provide real-time intra-cardiac imaging for diagnosis and treatment while reducing the need for clinicians to perform manual catheter steering. Clinical deployment of such a system requires accurate navigation despite the presence of disturbances including cyclical physiological motions (e.g., respiration). In this work, we report results from in vivo trials of automatic target tracking using our system, which is the first to navigate cardiac catheters with respiratory motion compensation. The effects of respiratory disturbances on the US catheter are modeled and then applied to four-degree-of-freedom steering kinematics with predictive filtering. This enables the system to accurately steer the US catheter and aim the US imager at a target despite respiratory motion disturbance. In vivo animal respiratory motion compensation results demonstrate automatic US catheter steering to image a target ablation catheter with 1.05 mm and 1.33° mean absolute error. Robotic US catheter steering with motion compensation can improve cardiac catheterization techniques while reducing clinician effort and X-ray exposure.

Circumcision registry promotes precise research and fosters informed parental decisions.

BACKGROUND: In 2017 Ploug and Holm argued that anonymizing individuals in the Danish circumcision registry was insufficient to protect these individuals from what they regard as the potential harms of being in the registry (overreaching social pressure, stigmatization, medicalization of a religious practice, discrimination and promoting polarized research). DISCUSSION: We argue that Ploug and Holm's fears in each of the areas are misguided, not supported by the evidence, and could interfere with the gathering of accurate data. The extent of the risks and harms associated with ritual circumcision is not well known. The anonymized personal health data supplemented with the circumcision registry will enable more precise research into the medical consequences of ritual circumcision, and allow parents to make more fully informed decisions about circumcision with minimal, if any, adverse consequences.

Transition from Hemochron Response to Hemochron Signature Elite Activated Clotting Time Devices in a Congenital Cardiac Surgery Practice.

Heparin is the primary anticoagulant used during cardiac surgery to prevent thrombosis due to cardiopulmonary bypass (CPB)-related activation of the hemostatic system. The efficacy of heparin in the operating room is generally determined by activated clotting time (ACT) point-of-care tests performed throughout the procedure. In an effort to transition to the Hemochron Elite which requires approximately 1/10th the sampling volume of blood, we conducted a prospective study in 260 pediatric patients undergoing CPB. ACT tests were performed during CPB with a total of 260 pre-bypass and 1,117 on-bypass ACT values recorded. All samples were run simultaneously on both ACT devices. Several therapeutic cut-off possibilities ranging from >380 to >480 seconds were evaluated to ascertain the ACT level on the Elite device which best correlated with results from the Response device. Linear regression was used to determine correlation. The correlation between the two methods was moderate with a Pearson r of .6 and .4 for pre-bypass bolus ACT values and on-bypass ACT values, respectively. As the therapeutic ACT cut-off values were lowered from 480 to 380 seconds on the Elite device relative to the Response device (>480 seconds) for the on-bypass heparin samples, more patients would be under-dosed (incidence rising from 1 to 2%) and fewer patients would be overdosed (incidence decreasing from 32 to 5%) and the percent correlation between devices increased from 67 to 93%. A similar trend was observed with the pre-bypass heparin bolus samples. There was no significant effect of temperature on the ACT values comparing both devices. A therapeutic ACT value of >400 seconds for CPB with the Hemochron Elite device reasonably approximates a therapeutic ACT value of >480 seconds on the Hemochron Response device in our congenital cardiac surgery practice. Transitioning to the Elite device significantly reduces the overall sampling volume required for ACT monitoring during cardiac surgery.

Leveraging a Landscape-Level Monitoring and Assessment Program for Developing Resilient Shorelines throughout the Laurentian Great Lakes.

Traditionally, ecosystem monitoring, conservation, and restoration have been conducted in a piecemeal manner at the local scale without regional landscape context. However, scientifically driven conservation and restoration decisions benefit greatly when they are based on regionally determined benchmarks and goals. Unfortunately, required data sets rarely exist for regionally important ecosystems. Because of early recognition of the extreme ecological importance of Laurentian Great Lakes coastal wetlands, and the extensive degradation that had already occurred, significant investments in coastal wetland research, protection, and restoration have been made in recent decades and continue today. Continued and refined assessment of wetland condition and trends, and the evaluation of restoration practices are all essential to ensuring the success of these investments. To provide wetland managers and decision makers throughout the Laurentian Great Lakes basin with the optimal tools and data needed to make scientifically-based decisions, our regional team of Great Lakes wetland scientists developed standardized methods and indicators used for assessing wetland condition. From a landscape perspective, at the Laurentian Great Lakes ecosystem scale, we established a stratified random-site-selection process to monitor birds, anurans, fish, macroinvertebrates, vegetation, and physicochemical conditions of coastal wetlands in the US and Canada. Monitoring of approximately 200 wetlands per year began in 2011 as the Great Lakes Coastal Wetland Monitoring Program. In this paper, we describe the development, delivery, and expected results of this ongoing international, multi-disciplinary, multi-stakeholder, landscape-scale monitoring program as a case example of successful application of landscape conservation design.

Response to Vogelstein: How the 2012 AAP Task Force on circumcision went wrong.

Vogelstein cautions medical organizations against jumping into the fray of controversial issues, yet proffers the 2012 American Academy of Pediatrics' Task Force policy position on infant male circumcision as 'an appropriate use of position-statements.' Only a scratch below the surface of this policy statement uncovers the Task Force's failure to consider Vogelstein's many caveats. The Task Force supported the cultural practice by putting undeserved emphasis on questionable scientific data, while ignoring or underplaying the importance of valid contrary scientific data. Without any effort to quantitatively assess the risk/benefit balance, the Task Force concluded the benefits of circumcision outweighed the risks, while acknowledging that the incidence of risks was unknown. This Task Force differed from other Academy policy-forming panels by ignoring the Academy's standard quality measures and by not appointing members with extensive research experience, extensive publications, or recognized expertise directly related to this topic. Despite nearly 100 publications available at the time addressing the substantial ethical issues associated with infant male circumcision, the Task Force chose to ignore the ethical controversy. They merely stated, with minimal justification, the opinion of one of the Task Force members that the practice of infant male circumcision is morally permissible. The release of the report has fostered an explosion of academic discussion on the ethics of infant male circumcision with a number of national medical organizations now decrying the practice as a human rights violation.

A red cell preservation strategy reduces postoperative transfusions in pediatric heart surgery patients.

BACKGROUND: Blood transfusion has well-documented adverse effects. As part of a blood conservation initiative at our center, we began routine use of cell saver for all congenital heart surgery performed on cardiopulmonary bypass since 2014. AIMS: This study aimed to compare transfusion rates prior to, and in the first and second year after this initiative. We hypothesized that cell saver use would decrease transfusion requirements in second year after use of the cell saver compared to the pre cell saver group. METHODS: Consecutive patients under 18 years undergoing congenital heart surgery on cardiopulmonary bypass were retrospectively analyzed as 3 one-year cohorts defined above. We excluded patients who required mechanical support or reoperation at index admission. Baseline characteristics, and use of blood intraoperatively and postoperatively were compared between groups. RESULTS: The 3 groups had similar baseline characteristics. Blood use was significantly lower in year 2 after cell saver initiation as compared to the pre cell saver group both intra- and postoperatively. The median difference in volume of intraoperative blood transfusion was lower by 138 mL/m2 (-266, -10 mL/m2 ) in year 2 when compared to the pre cell saver group. Similarly, the proportion of subjects requiring red blood cell transfusion postoperatively on day of surgery was lower by 10% (-15%, -6%). CONCLUSION: Standardized use of cell saver significantly decreased perioperative blood use in children undergoing cardiac surgery at our center. A risk-adjusted transfusion threshold for children undergoing heart surgery needs to be developed to further decrease exposure to blood products and associated costs.

A Deployable Transseptal Brace for Stabilizing Cardiac Catheters.

A bracing device for stabilizing cardiac catheters inside the heart was developed to provide surgical-level dexterity to minimally invasive catheter-based procedures for cardiac valve disease. The brace was designed to have a folding structure, which lies flat along a catheter during navigation through vasculature and then unfolds into a rigid bracing configuration after deployment across the interatrial septum. The brace was designed to be easily deployable, provide bracing support for a transseptal catheter, and also be compliant enough to be delivered to the heart via tortuous vasculature. This aims to improve dexterity in catheter-based mitral valve repair and enable other complex surgical procedures to be done with minimally invasive instruments.

Algorithms for Automatically Pointing Ultrasound Imaging Catheters.

A system for automatically pointing ultrasound (US) imaging catheters will enable clinicians to monitor anatomical structures and track instruments during interventional procedures. Off-the-shelf US catheters provide high quality US images from within the patient. While this method of imaging has been proven to be effective for guiding many interventional treatments, significant training is required to overcome the difficulty in manually steering the imager to point at desired structures. Our system uses closed-form four degree of freedom (DOF) kinematic solutions to automatically position the US catheter and point the imager. Algorithms for steering and imager pointing were developed for a range of useful diagnostic and interventional motions. The system was validated on a robotic test bed by steering the catheter within a water environment containing phantom objects. While the system described here was designed for pointing ultrasound catheters, these algorithms are applicable to accurate 4-DOF steering and orientation control of any long thin tendon-driven tool with single or bi-directional bending.

Stochastic dilution effects weaken deterministic effects of niche-based processes in species rich forests.

Recent theory predicts that stochastic dilution effects may result in species-rich communities with statistically independent species spatial distributions, even if the underlying ecological processes structuring the community are driven by deterministic niche differences. Stochastic dilution is a consequence of the stochastic geometry of biodiversity where the identities of the nearest neighbors of individuals of a given species are largely unpredictable. Under such circumstances, the outcome of deterministic species interactions may vary greatly among individuals of a given species. Consequently, nonrandom patterns in the biotic neighborhoods of species, which might be expected from coexistence or community assembly theory (e.g., individuals of a given species are neighbored by phylogenetically similar species), are weakened or do not emerge, resulting in statistical independence of species spatial distributions. We used data on phylogenetic and functional similarity of tree species in five large forest dynamics plots located across a gradient of species richness to test predictions of the stochastic dilution hypothesis. To quantify the biotic neighborhood of a focal species we used the mean phylogenetic (or functional) dissimilarity of the individuals of the focal species to all species within a local neighborhood. We then compared the biotic neighborhood of species to predictions from stochastic null models to test if a focal species was surrounded by more or less similar species than expected by chance. The proportions of focal species that showed spatial independence with respect to their biotic neighborhoods increased with total species richness. Locally dominant, high-abundance species were more likely to be surrounded by species that were statistically more similar or more dissimilar than expected by chance. Our results suggest that stochasticity may play a stronger role in shaping the spatial structure of species rich tropical forest communities than it does in species poorer forests. These findings represent an important step towards understanding the factors that govern the spatial configuration of local biotic communities. The stochastic dilution effect is a simple geometric mechanism that can explain why species' spatial distributions in species-rich communities approximate independence from their biotic neighborhood, even if deterministic niche processes are in effect.

Tree-mycorrhizal associations detected remotely from canopy spectral properties.

A central challenge in global ecology is the identification of key functional processes in ecosystems that scale, but do not require, data for individual species across landscapes. Given that nearly all tree species form symbiotic relationships with one of two types of mycorrhizal fungi - arbuscular mycorrhizal (AM) and ectomycorrhizal (ECM) fungi - and that AM- and ECM-dominated forests often have distinct nutrient economies, the detection and mapping of mycorrhizae over large areas could provide valuable insights about fundamental ecosystem processes such as nutrient cycling, species interactions, and overall forest productivity. We explored remotely sensed tree canopy spectral properties to detect underlying mycorrhizal association across a gradient of AM- and ECM-dominated forest plots. Statistical mining of reflectance and reflectance derivatives across moderate/high-resolution Landsat data revealed distinctly unique phenological signals that differentiated AM and ECM associations. This approach was trained and validated against measurements of tree species and mycorrhizal association across ~130 000 trees throughout the temperate United States. We were able to predict 77% of the variation in mycorrhizal association distribution within the forest plots (P < 0.001). The implications for this work move us toward mapping mycorrhizal association globally and advancing our understanding of biogeochemical cycling and other ecosystem processes.

Mechanisms underlying local functional and phylogenetic beta diversity in two temperate forests.

Although trait information has been widely used to explore underlying mechanisms of forest community structure, most studies have focused on local patterns of phylogenetic or functional alpha diversity. Investigations of functional beta diversity, on the other hand, have not been conducted at local scales in a spatially explicit way. In this study, we provide a powerful methodology based on recent advances in spatial point pattern analysis using fully mapped data of large and small trees in two large temperate forest plots. This approach allowed us to assess the relative importance of different ecological processes and mechanisms for explaining patterns of local phylogenetic and functional beta diversity. For both forests and size classes, we found a clear hierarchy of scales: habitat filtering accounted for patterns of phylogenetic and functional beta diversity at larger distances (150-250 m), dispersal limitation accounted for the observed decline in beta diversity at distances below 150 m, and species interactions explained small departures from functional and phylogenetic beta diversity at the immediate plant-neighborhood scale (below 20 m). Thus, both habitat filtering and dispersal limitation influenced the observed patterns in phylogenetic and functional beta diversity at local scales. This result contrasts with a previous study from the same forests, where dispersal limitation alone approximated the observed species beta diversity for distances up to 250 m. In addition, species interactions were relatively unimportant for predicting phylogenetic and functional beta diversity. Our analysis suggests that phylogenetic and functional beta diversity can provide insights into the mechanisms of local community assembly that are missed by studies focusing exclusively on species beta diversity.