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.

Target Enrichment and Extensive Population Sampling Help Untangle the Recent, Rapid Radiation of Oenothera Sect. Calylophus.

Oenothera sect. Calylophus is a North American group of 13 recognized taxa in the evening primrose family (Onagraceae) with an evolutionary history that may include independent origins of bee pollination, edaphic endemism, and permanent translocation heterozygosity. Like other groups that radiated relatively recently and rapidly, taxon boundaries within Oenothera sect. Calylophus have remained challenging to circumscribe. In this study, we used target enrichment, flanking noncoding regions, gene tree/species tree methods, tests for gene flow modified for target-enrichment data, and morphometric analysis to reconstruct phylogenetic hypotheses, evaluate current taxon circumscriptions, and examine character evolution in Oenothera sect. Calylophus. Because sect. Calylophus comprises a clade with a relatively restricted geographic range, we were able to extensively sample across the range of geographic, edaphic, and morphological diversity in the group. We found that the combination of exons and flanking noncoding regions led to improved support for species relationships. We reconstructed potential hybrid origins of some accessions and note that if processes such as hybridization are not taken into account, the number of inferred evolutionary transitions may be artificially inflated. We recovered strong evidence for multiple evolutionary origins of bee pollination from ancestral hawkmoth pollination, edaphic specialization on gypsum, and permanent translocation heterozygosity. This study applies newly emerging techniques alongside dense infraspecific sampling and morphological analyses to effectively reconstruct the recalcitrant history of a rapid radiation. [Gypsum endemism; Oenothera sect. Calylophus; Onagraceae; phylogenomics; pollinator shift; recent radiation; target enrichment.].

A machine learning approach towards the differentiation between interoceptive and exteroceptive attention.

Interoception, the representation of the body's internal state, plays a central role in emotion, motivation and wellbeing. Interoceptive sensibility, the ability to engage in sustained interoceptive awareness, is particularly relevant for mental health but is exclusively measured via self-report, without methods for objective measurement. We used machine learning to classify interoceptive sensibility by contrasting using data from a randomized control trial of interoceptive training, with functional magnetic resonance imaging assessment before and after an 8-week intervention (N = 44 scans). The neuroimaging paradigm manipulated attention targets (breath vs. visual stimuli) and reporting demands (active reporting vs. passive monitoring). Machine learning achieved high accuracy in distinguishing between interoceptive and exteroceptive attention, both for within-session classification (~80% accuracy) and out-of-sample classification (~70% accuracy), revealing the reliability of the predictions. We then explored the classifier potential for 'reading out' mental states in a 3-min sustained interoceptive attention task. Participants were classified as actively engaged about half of the time, during which interoceptive training enhanced their ability to sustain interoceptive attention. These findings demonstrate that interoceptive and exteroceptive attention is distinguishable at the neural level; these classifiers may help to demarcate periods of interoceptive focus, with implications for developing an objective marker for interoceptive sensibility in mental health research.

Fabrication of Specimens for Atom Probe Tomography Using a Combined Gallium and Neon Focused Ion Beam Milling Approach.

We demonstrate a new focused ion beam sample preparation method for atom probe tomography. The key aspect of the new method is that we use a neon ion beam for the final tip-shaping after conventional annulus milling using gallium ions. This dual-ion approach combines the benefits of the faster milling capability of the higher current gallium ion beam with the chemically inert and higher precision milling capability of the noble gas neon ion beam. Using a titanium-aluminum alloy and a layered aluminum/aluminum-oxide tunnel junction sample as test cases, we show that atom probe tips prepared using the combined gallium and neon ion approach are free from the gallium contamination that typically frustrates composition analysis of these materials due to implantation, diffusion, and embrittlement effects. We propose that by using a focused ion beam from a noble gas species, such as the neon ions demonstrated here, atom probe tomography can be more reliably performed on a larger range of materials than is currently possible using conventional techniques.

Development of a quantitative semi-mechanistic model of Alzheimer's disease based on the amyloid/tau/neurodegeneration framework (the Q-ATN model).

INTRODUCTION: A quantitative model of Alzheimer's disease (AD) based on the amyloid/tau/neurodegeneration biomarker framework (Q-ATN model) was developed to sequentially link amyloid positron emission tomography (PET), tau PET, medial temporal cortical thickness, and clinical outcome (Clinical Dementia Rating - Sum of Boxes; CDR-SB). METHODS: Published data and biologically plausible mechanisms were used to construct, calibrate, and validate the model. Clinical trial simulations were performed for different anti-amyloid antibodies, including a 5-year simulation of subcutaneous gantenerumab treatment. RESULTS: The simulated time-course of biomarkers and CDR-SB was consistent with natural history studies and described the effects of several anti-amyloid antibodies observed in trials with positive and negative (or non-significant) outcomes. The 5-year simulation predicts that the beneficial effects of continued anti-amyloid treatment should increase markedly over time. DISCUSSION: The Q-ATN model offers a novel approach for linking amyloid PET to CDR-SB, and provides theoretical support for the potential clinical benefit of anti-amyloid therapy. HIGHLIGHTS: A semi-mechanistic model was developed to link amyloid/tau/neurodegeneration biomarkers to clinical outcome (Q-ATN model). The Q-ATN model describes the disease progression seen in natural history studies. Model simulations agree well with mean data from the aducanumab EMERGE study. A 5-year simulation of gantenerumab predicts greater benefit with longer treatment.

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.

The effect of participation in accountable care organization on electronic health information exchange practices in U.S. hospitals.

BACKGROUND: Accountable care organizations (ACOs) are a recent incentive program that are designed to address inefficiencies in the U.S. health care sector. To meet their design objectives, ACO participants must engage in greater electronic health information exchange (HIE) practices both internally and externally with care participants, such as patients and other providers. PURPOSE: The aim of this study was to examine the relationship between hospital participation in ACOs and electronic HIE practices with different participants of care and how these practices vary differentially across market types. APPROACH: Grounding our work in the reward-motivational view of organizational action, we proposed hypotheses that linked hospital participation in ACOs to three dimensions of HIE practices (intraorganizational, interorganizational, and provider-patient HIE practices). We tested our hypotheses by analyzing a sample of 1,926 hospitals. RESULTS: Hospital participation in ACOs is associated with greater intraorganizational and provider-patient HIE practices, but not interorganizational HIE practices. We also found that whereas the relationship between ACO participation and intra- and interorganizational HIE practices remains unchanged irrespective of the degree of competition in the health care market, the relationship between ACO participation and provider-patient HIE practices holds true only for hospitals operating in noncompetitive markets. PRACTICE IMPLICATIONS: Our results showed that hospitals participating in ACOs vary in their HIE practices, and attributes of the local market in which ACO participants operate in contribute to this variation. These insights should provide guidance to researchers, policymakers, and hospital administrators who aim to improve the effectiveness of ACOs.

Molecular Biology and Evolution of Cancer: From Discovery to Action.

Cancer progression is an evolutionary process. During this process, evolving cancer cell populations encounter restrictive ecological niches within the body, such as the primary tumor, circulatory system, and diverse metastatic sites. Efforts to prevent or delay cancer evolution-and progression-require a deep understanding of the underlying molecular evolutionary processes. Herein we discuss a suite of concepts and tools from evolutionary and ecological theory that can inform cancer biology in new and meaningful ways. We also highlight current challenges to applying these concepts, and propose ways in which incorporating these concepts could identify new therapeutic modes and vulnerabilities in cancer.

Tree height and leaf drought tolerance traits shape growth responses across droughts in a temperate broadleaf forest.

As climate change drives increased drought in many forested regions, mechanistic understanding of the factors conferring drought tolerance in trees is increasingly important. The dendrochronological record provides a window through which we can understand how tree size and traits shape growth responses to droughts. We analyzed tree-ring records for 12 species in a broadleaf deciduous forest in Virginia (USA) to test hypotheses for how tree height, microenvironment characteristics, and species' traits shaped drought responses across the three strongest regional droughts over a 60-yr period. Drought tolerance (resistance, recovery, and resilience) decreased with tree height, which was strongly correlated with exposure to higher solar radiation and evaporative demand. The potentially greater rooting volume of larger trees did not confer a resistance advantage, but marginally increased recovery and resilience, in sites with low topographic wetness index. Drought tolerance was greater among species whose leaves lost turgor (wilted) at more negative water potentials and experienced less shrinkage upon desiccation. The tree-ring record reveals that tree height and leaf drought tolerance traits influenced growth responses during and after significant droughts in the meteorological record. As climate change-induced droughts intensify, tall trees with drought-sensitive leaves will be most vulnerable to immediate and longer-term growth reductions.

Electrocardiographic predictors of successful resynchronization of left bundle branch block by His bundle pacing.

BACKGROUND: His bundle pacing (HBP) is an alternative to biventricular pacing (BVP) for delivering cardiac resynchronization therapy (CRT) in patients with heart failure and left bundle branch block (LBBB). It is not known whether ventricular activation times and patterns achieved by HBP are equivalent to intact conduction systems and not all patients with LBBB are resynchronized by HBP. OBJECTIVE: To compare activation times and patterns of His-CRT with BVP-CRT, LBBB and intact conduction systems. METHODS: In patients with LBBB, noninvasive epicardial mapping (ECG imaging) was performed during BVP and temporary HBP. Intrinsic activation was mapped in all subjects. Left ventricular activation times (LVAT) were measured and epicardial propagation mapping (EPM) was performed, to visualize epicardial wavefronts. Normal activation pattern and a normal LVAT range were determined from normal subjects. RESULTS: Forty-five patients were included, 24 with LBBB and LV impairment, and 21 with normal 12-lead ECG and LV function. In 87.5% of patients with LBBB, His-CRT successfully shortened LVAT by ≥10 ms. In 33.3%, His-CRT resulted in complete ventricular resynchronization, with activation times and patterns indistinguishable from normal subjects. EPM identified propagation discontinuity artifacts in 83% of patients with LBBB. This was the best predictor of whether successful resynchronization was achieved by HBP (logarithmic odds ratio, 2.19; 95% confidence interval, 0.07-4.31; p = .04). CONCLUSION: Noninvasive electrocardiographic mapping appears to identify patients whose LBBB can be resynchronized by HBP. In contrast to BVP, His-CRT may deliver the maximum potential ventricular resynchronization, returning activation times, and patterns to those seen in normal hearts.

Critical Elements of Community Engagement to Address Disparities and Related Social Determinants of Health: The Centers of Disease Control and Prevention Community Approaches to Reducing Sexually Transmitted Disease Initiative.

BACKGROUND: Community Approaches to Reducing Sexually Transmitted Disease (CARS), a unique initiative of the US Centers for Disease Control and Prevention, promotes the use of community engagement to increase sexually transmitted disease (STD) prevention, screening, and treatment and to address locally prioritized STD-related social determinants of health within communities experiencing STD disparities, including youth, persons of color, and sexual and gender minorities. We sought to identify elements of community engagement as applied within CARS. METHODS AND MATERIALS: Between 2011 and 2018, we collected and analyzed archival and in-depth interview data to identify and explore community engagement across 8 CARS sites. Five to 13 interview participants (mean, 7) at each site were interviewed annually. Participants included project staff and leadership, community members, and representatives from local community organizations (e.g., health departments; lesbian, gay, bisexual, transgender, and queer-serving organizations; faith organizations; businesses; and HIV-service organizations) and universities. Data were analyzed using constant comparison, an approach to grounded theory development. RESULTS: Twelve critical elements of community engagement emerged, including commitment to engagement, partner flexibility, talented and trusted leadership, participation of diverse sectors, establishment of vision and mission, open communication, reducing power differentials, working through conflict, identifying and leveraging resources, and building a shared history. CONCLUSIONS: This study expands the community engagement literature within STD prevention, screening, and treatment by elucidating some of the critical elements of the approach and provides guidance for practitioners, researchers, and their partners as they develop, implement, and evaluate strategies to reduce STD disparities.

Comparison of electric hand dryers and paper towels for hand hygiene: a critical review of the literature.

Numerous studies are published on the benefits of electric hand dryers vs paper towels (PT) for drying hands after washing. Data are conflicting and lacking key variables needed to assess infection risks. We provide a rapid scoping review on hand-drying methods relative to hygiene and health risks. Controlled vocabulary terms and keywords were used to search PubMed (1946-2018) and Embase (1947-2018). Multiple researchers independently screened abstracts for relevance using predetermined criteria and created a quality assessment scoring system for relative study comparisons. Of 293 papers, 23 were included in the final analysis. Five studies did not compare multiple methods; however, 2 generally favoured electric dryers (ED); 7 preferred PT; and 9 had mixed or statistically insignificant results (among these, 3 contained scenarios favourable to ED, 4 had results supporting PT, and the remaining studies had broadly conflicting results). Results were mixed among and within studies and many lacked consistent design or statistical analysis. The breadth of data does not favour one method as being more hygienic. However, some authors extended generalizable recommendations without sufficient scientific evidence. The use of tools in quantitative microbial risk assessment is suggested to evaluate health exposure potentials and risks relative to hand-drying methods. We found no data to support any human health claims associated with hand-drying methods. Inconclusive and conflicting results represent data gaps preventing the advancement of hand-drying policy or practice recommendations.

The Laborist trend: its implications.

PURPOSE: To offer obstetrical practitioners a current perspective about an important contemporary practice model which has implications that may not have been adequately recognized. METHODS: A description of individual past professional experience. RESULTS: A resultant perspective from decades of professional obstetric practice. CONCLUSION: A description of potential clinical impact on patients and practitioners alike.

Comparative Apex Electrostatics of Atom Probe Tomography Specimens.

Rigorous electrostatic modeling of the specimen-electrode environment is required to better understand the fundamental processes of atom probe tomography (APT) and guide the analysis of APT data. We have developed a simulation tool that self-consistently solves the nonlinear electrostatic Poisson equation along with the mobile charge carrier concentrations and provides a detailed picture of the electrostatic environment of APT specimen tips. We consider cases of metals, semiconductors, and dielectrics. Traditionally in APT, and regardless of specimen composition, the apex electric field Eapex has been approximated by the relation Eapex=SV/(kr), which was originally derived for sharp, metallic conductors; we refer to this equation as the "k-factor approximation". Here, SV is tip-electrode bias, r is the radius of curvature of the tip apex, and k is a dimensionless fitting parameter with 1.5

Ocular Half-Life of Intravitreal Biologics in Humans and Other Species: Meta-Analysis and Model-Based Prediction.

Therapeutic antibodies administered intravitreally are the current standard of care to treat retinal diseases. The ocular half-life (t1/2) is a key determinant of the duration of target suppression. To support the development of novel, longer-acting drugs, a reliable determination of t1/2 is needed together with an improved understanding of the factors that influence it. A model-based meta-analysis was conducted in humans and nonclinical species (rat, rabbit, monkey, and pig) to determine consensus values for the ocular t1/2 of IgG antibodies and Fab fragments. Results from multiple literature and in-house pharmacokinetic studies are presented within a mechanistic framework that assumes diffusion-controlled drug elimination from the vitreous. Our analysis shows, both theoretically and experimentally, that the ocular t1/2 increases in direct proportion to the product of the hydrodynamic radius of the macromolecule (3.0 nm for Fab and 5.0 nm for IgG) and the square of the radius of the vitreous globe, which varies approximately 24-fold from the rat to the human. Interspecies differences in the proportionality factors are observed and discussed in mechanistic terms. In addition, mathematical formulae are presented that allow prediction of the ocular t1/2 for molecules of interest. The utility of these formulae is successfully demonstrated in case studies of aflibercept, brolucizumab, and PEGylated Fabs, where the predicted ocular t1/2 values are found to be in reasonable agreement with the experimental data available for these molecules.

Diversity, distribution, development, and evolution of medullary bundles in Nyctaginaceae.

PREMISE: Medullary bundles, i.e., vascular units in the pith, have evolved multiple times in vascular plants. However, no study has ever explored their anatomical diversity and evolution within a phylogenetic framework. Here, we investigated the development of the primary vascular system within Nyctaginaceae showing how medullary bundles diversified within the family. METHODS: Development of 62 species from 25 of the 31 genera of Nyctaginaceae in stem samples was thoroughly studied with light microscopy and micro-computed tomography. Ancestral states were reconstructed using a maximum likelihood approach. RESULTS: Two subtypes of eusteles were found, the regular eustele, lacking medullary bundles, observed exclusively in representatives of Leucastereae, and the polycyclic eustele, containing medullary bundles, found in all the remaining taxa. Medullary bundles had the same origin and development, but the organization was variable and independent of phyllotaxy. Within the polycyclic eustele, medullary bundles developed first, followed by the formation of a continuous concentric procambium, which forms a ring of vascular bundles enclosing the initially formed medullary bundles. The regular eustele emerged as a synapomorphy of Leucastereae, while the medullary bundles were shown to be a symplesiomorphy for Nyctaginaceae. CONCLUSIONS: Medullary bundles in Nyctaginaceae developed by a single shared pathway, that involved the departure of vascular traces from lateral organs toward the pith. These medullary bundles were encircled by a continuous concentric procambium that also constituted the polycyclic eustele, which was likely a symplesiomorphy for Nyctaginaceae with one single reversion to the regular eustele.

Eye Movements and White Matter are Associated with Emotional Control in Children Treated for Brain Tumors.

OBJECTIVE: Children treated for brain tumors often experience social and emotional difficulties, including challenges with emotion regulation; our goal was to investigate the attention-related component processes of emotion regulation, using a novel eye-tracking measure, and to evaluate its relations with emotional functioning and white matter (WM) organization. METHOD: Fifty-four children participated in this study; 36 children treated for posterior fossa tumors, and 18 typically developing children. Participants completed two versions of an emotion regulation eye-tracking task, designed to differentiate between implicit (i.e., automatic) and explicit (i.e., voluntary) subprocesses. The Emotional Control scale from the Behavior Rating Inventory of Executive Function was used to evaluate emotional control in daily life, and WM organization was assessed with diffusion tensor imaging. RESULTS: We found that emotional faces captured attention across all groups (F(1,51) = 32.18, p < .001, η2p = .39). However, unlike typically developing children, patients were unable to override the attentional capture of emotional faces when instructed to (emotional face-by-group interaction: F(2,51) = 5.58, p = .006, η2p = .18). Across all children, our eye-tracking measure of emotion regulation was modestly associated with the parent-report emotional control score (r = .29, p = .045), and in patients it was associated with WM microstructure in the body and splenium of the corpus callosum (all t > 3.03, all p < .05). CONCLUSIONS: Our findings suggest that an attention-related component process of emotion regulation is disrupted in children treated for brain tumors, and that it may relate to their emotional difficulties and WM organization. This work provides a foundation for future theoretical and mechanistic investigations of emotional difficulties in brain tumor survivors.

Crystallographic polarity measurements in two-terminal GaN nanowire devices by lateral piezoresponse force microscopy.

Lateral piezoresponse force microscopy (L-PFM) is demonstrated as a reliable method for determining the crystallographic polarity of individual, dispersed GaN nanowires that were functional components in electrical test structures. In contrast to PFM measurements of vertically oriented (as-grown) nanowires, where a biased probe tip couples to out-of-plane deformations through the d33 piezoelectic coefficient, the L-PFM measurements in this study were implemented on horizontally oriented nanowires that coupled to shear deformations through the d15 coefficient. L-PFM phase-polarity relationships were determined experimentally using a bulk m-plane GaN sample with a known [0001] direction and further indicated that the sign of the d15 piezoelectric coefficient was negative. L-PFM phase images successfully revealed the in-plane [0001] orientation of self-assembed GaN nanowires as part of a growth polarity study and results were validated against scanning transmission electron microscopy lattice images. Combined characterization of electrical properties and crystallographic polarity was also implemented for two-terminal GaN/Al0.1Ga0.9N/GaN nanowires devices, demonstrating L-PFM measurements as a viable tool for assessing correlations between device rectification and polarization-induced band bending.

Field Ion Emission in an Atom Probe Microscope Triggered by Femtosecond-Pulsed Coherent Extreme Ultraviolet Light.

This paper describes initial experimental results from an extreme ultraviolet (EUV) radiation-pulsed atom probe microscope. Femtosecond-pulsed coherent EUV radiation of 29.6 nm wavelength (41.85 eV photon energy), obtained through high harmonic generation in an Ar-filled hollow capillary waveguide, successfully triggered controlled field ion emission from the apex of amorphous SiO2 specimens. The calculated composition is stoichiometric within the error of the measurement and effectively invariant of the specimen base temperature in the range of 25 K to 150 K. Photon energies available in the EUV band are significantly higher than those currently used in the state-of-the-art near-ultraviolet laser-pulsed atom probe, which enables the possibility of additional ionization and desorption pathways. Pulsed coherent EUV light is a new and potential alternative to near-ultraviolet radiation for atom probe tomography.

The Metronome Counting Task for measuring meta-awareness.

How can we measure the absence of awareness? Attention research has developed tools for measuring self-caught meta-awareness restoration and behavioral mind-wandering, but we lack a way to dynamically track the loss of meta-awareness. The present pre-registered study sought to bring together three extant paradigms into one tool designed to dynamically measure meta-awareness: the Metronome Counting Task (MCT). The MCT is a continuous performance task wherein participants tap along to a steady beat while counting to 20, indicating the final count by a special button press. This sample (N = 74) provides evidence that participants could self-catch their failures in the task, that a response variability metric measuring mind-wandering depth was successfully recreated in this new tool, and that dynamic performance changes may be useful for detecting meta-awareness loss before participants become internally aware of the loss or are caught by external errors. The MCT was conceived as a tool that will support neuroimaging models of dynamic fluctuations during sustained attention, providing a link between the phenomenology of meta-awareness, the behavior measured by a replicable index of task engagement, and a continuous performance task on time-scales relevant for MRI. We discuss the possibility that meta-awareness may exist on a continuum and that conceptions of mind-wandering as attention failures may plausibly be reconceived as changes in goal priority manifesting as shifting task engagement.