Neighborhood Analyses Of Canopy Tree Competition Along Environmental Gradients In New England Forests

We use permanent-plot data from the USDA Forest Service's Forest Inventory and Analysis (FIA) program for an analysis of the effects of competition on tree growth along environmental gradients for the 14 most abundant tree species in forests of northern New England, USA. Our analysis estimates actual growth for each individual tree of a given species as a function of average potential diameter growth modified by three sets of scalars that quantify the effects on growth of (1) initial target tree size (dbh), (2) local environmental conditions, and (3) crowding by neighboring trees. Potential growth of seven of the 14 species varied along at least one of the two environmental axes identified by an ordination of relative abundance of species in plots. The relative abundances of a number of species were significantly displaced from sites where they showed maximum potential growth. In all of these cases, abundance was displaced to the more resource-poor end of the environmental gradient (either low fertility or low moisture). The pattern was most pronounced among early successional species, whereas late-successional species reached their greatest abundance on sites where they also showed the highest growth in the absence of competition. The analysis also provides empirical estimates of the strength of intraspecific and interspecific competitive effects of neighbors. For all but one of the species, our results led us to reject the hypothesis that all species of competitors have equivalent effects on a target species. Most of the individual pairwise interactions were strongly asymmetric. There was a clear competitive hierarchy among the four most shade-tolerant species, and a separate competitive hierarchy among the shade-intolerant species. Our results suggest that timber yield following selective logging will vary dramatically depending on the configuration of the residual canopy, because of interspecific variation in the magnitude of both the competitive effects of different species of neighbors and the competitive responses of different species of target trees to neighbors. The matrix of competition coefficients suggests that there may be clear benefits in managing for specific mixtures of species within local neighborhoods within stands

Measuring Transit Signal Recovery in the Kepler Pipeline II: Detection Efficiency as Calculated in One Year of Data

The Kepler planet sample can only be used to reconstruct the underlying planet occurrence rate if the detection efficiency of the Kepler pipeline is known, here we present the results of a second experiment aimed at characterising this detection efficiency. We inject simulated transiting planet signals into the pixel data of ~10,000 targets, spanning one year of observations, and process the pixels as normal. We compare the set of detections made by the pipeline with the expectation from the set of simulated planets, and construct a sensitivity curve of signal recovery as a function of the signal-to-noise of the simulated transit signal train. The sensitivity curve does not meet the hypothetical maximum detection efficiency, however it is not as pessimistic as some of the published estimates of the detection efficiency. For the FGK stars in our sample, the sensitivity curve is well fit by a gamma function with the coefficients a = 4.35 and b = 1.05. We also find that the pipeline algorithms recover the depths and periods of the injected signals with very high fidelity, especially for periods longer than 10 days. We perform a simplified occurrence rate calculation using the measured detection efficiency compared to previous assumptions of the detection efficiency found in the literature to demonstrate the systematic error introduced into the resulting occurrence rates. The discrepancies in the calculated occurrence rates may go some way towards reconciling some of the inconsistencies found in the literature.Comment: 13 pages, 7 figures, 1 electronic table, accepted by Ap

Can verbal instruction enhance the recall of an everyday task and promote error-monitoring in people with dementia of the Alzheimer-type?

People with dementia of the Alzheimer-type (DAT) have difficulties with performing everyday tasks and error awareness is poor. Here we investigated whether recall of actions and error monitoring in everyday task performance improved when they instructed another person on how to make tea. In this situation, both visual and motor cues are present, and attention sustained by the requirement to keep instructing. The data were drawn from a longitudinal study recording performance in four participants with DAT, filmed regularly for five years in their own homes, completing three tea-making conditions: performed-recall (they made tea themselves); instructed-recall (they instructed the experimenter on how to make tea); and verbal-recall (they described how to make tea). Accomplishment scores (percentage of task they correctly recalled), errors and error-monitoring were coded. Task accomplishment was comparable in the performed-recall and instructed-recall conditions, but both were significantly better than task accomplishment in the verbal-recall condition. Third person instruction did not improve error-monitoring. This study has implications for everyday task rehabilitation for people with DAT

Comparing air-sea flux measurements from a new unmanned surface vehicle and proven platforms during the SPURS-2 field campaign.

© The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Zhang, D., Cronin, M. F., Meinig, C., Farrar, J. T., Jenkins, R., Peacock, D., Keene, J., Sutton, A., & Yang, Q. Comparing air-sea flux measurements from a new unmanned surface vehicle and proven platforms during the SPURS-2 field campaign. Oceanography, 32(2), (2019): 122-133, doi:10.5670/oceanog.2019.220.Two saildrones participated in the Salinity Processes in the Upper-ocean Regional Study 2 (SPURS-2) field campaign at 10°N, 125°W, as part of their more than six-month Tropical Pacific Observing System (TPOS)-2020 pilot study in the eastern tropical Pacific. The two saildrones were launched from San Francisco, California, on September 1, 2017, and arrived at the SPURS-2 region on October 15, one week before R/V Revelle. Upon arrival at the SPURS-2 site, they each began a two-week repeat pattern, sailing around the program’s central moored surface buoy. The heavily instrumented Woods Hole Oceanographic Institution (WHOI) SPURS-2 buoy serves as a benchmark for validating the saildrone measurements for air-sea fluxes. The data collected by the WHOI buoy and the saildrones were found to be in reasonably good agreement. Although of short duration, these ship-saildrone-buoy comparisons are encouraging as they provide enhanced understanding of measurements by various platforms in a rapidly changing subsynoptic weather system. The saildrones were generally able to navigate the challenging Intertropical Convergence Zone, where winds are low and currents can be strong, demonstrating that the saildrone is an effective platform for observing a wide range of oceanographic variables important to air-sea interaction studies.The TPOS-2020 saildrone pilot study was funded by the NOAA Ocean Observations and Monitoring Division of the Climate Programs Office. The WHOI flux mooring was funded by NASA as part of the SPURS-2 program. This work is partially funded by the Joint Institute for the Study of the Atmosphere and Ocean (JISAO) under NOAA Cooperative Agreement NA15OAR4320063. We thank SPURS-2 cruise Chief Scientist Kyla Drushka of APL/University of Washington, Fred Bingham of the University of North Carolina, and Dave Rivera of PMEL onboard R/V Revelle for close coordination between ship operation and saildrone piloting. High-quality shipboard air-sea flux measurements by Carol Anne Clayson and James Edson of WHOI are greatly appreciated. We also thank the editors and two anonymous reviewers for their thoughtful suggestions that helped to improve this manuscript. This is PMEL contribution #4899

Measuring Transit Signal Recovery in the Kepler Pipeline. III. Completeness of the Q1-Q17 DR24 Planet Candidate Catalogue, with Important Caveats for Occurrence Rate Calculations

With each new version of the Kepler pipeline and resulting planet candidate catalogue, an updated measurement of the underlying planet population can only be recovered with an corresponding measurement of the Kepler pipeline detection efficiency. Here, we present measurements of the sensitivity of the pipeline (version 9.2) used to generate the Q1-Q17 DR24 planet candidate catalog (Coughlin et al. 2016). We measure this by injecting simulated transiting planets into the pixel-level data of 159,013 targets across the entire Kepler focal plane, and examining the recovery rate. Unlike previous versions of the Kepler pipeline, we find a strong period dependence in the measured detection efficiency, with longer (>40 day) periods having a significantly lower detectability than shorter periods, introduced in part by an incorrectly implemented veto. Consequently, the sensitivity of the 9.2 pipeline cannot be cast as a simple one-dimensional function of the signal strength of the candidate planet signal as was possible for previous versions of the pipeline. We report on the implications for occurrence rate calculations based on the Q1-Q17 DR24 planet candidate catalog and offer important caveats and recommendations for performing such calculations. As before, we make available the entire table of injected planet parameters and whether they were recovered by the pipeline, enabling readers to derive the pipeline detection sensitivity in the planet and/or stellar parameter space of their choice.Comment: 8 pages, 5 figures, full electronic version of Table 1 available at the NASA Exoplanet Archive; accepted by ApJ May 2nd, 201

Advanced EFL learners' beliefs about language learning and teaching: a comparison between grammar, pronunciation, and vocabulary

This paper reports on the results of a study exploring learners’ beliefs on the learning and teaching of English grammar, pronunciation and vocabulary at tertiary level. While the importance of learners’ beliefs on the acquisition process is generally recognized, few studies have focussed on and compared learners’ views on different components of the language system. A questionnaire containing semantic scale and Likert scale items probing learners’ views on grammar, pronunciation and vocabulary was designed and completed by 117 native speakers of Dutch in Flanders, who were studying English at university. The analysis of the responses revealed that (i) vocabulary was considered to be different from grammar and pronunciation, both in the extent to which an incorrect use could lead to communication breakdown and with respect to the learners’ language learning strategies, (ii) learners believed in the feasibility of achieving a native-like proficiency in all three components, and (iii) in-class grammar, pronunciation and vocabulary exercises were considered to be useful, even at tertiary level. The results are discussed in light of pedagogical approaches to language teaching

Structure and tethering mechanism of dynein-2 intermediate chains in intraflagellar transport

Dynein-2 is a large multiprotein complex that powers retrograde intraflagellar transport (IFT) of cargoes within cilia/flagella, but the molecular mechanism underlying this function is still emerging. Distinctively, dynein-2 contains two identical force-generating heavy chains that interact with two different intermediate chains (WDR34 and WDR60). Here, we dissect regulation of dynein-2 function by WDR34 and WDR60 using an integrative approach including cryo-electron microscopy and CRISPR/Cas9-enabled cell biology. A 3.9 Å resolution structure shows how WDR34 and WDR60 use surprisingly different interactions to engage equivalent sites of the two heavy chains. We show that cilia can assemble in the absence of either WDR34 or WDR60 individually, but not both subunits. Dynein-2-dependent distribution of cargoes depends more strongly on WDR60, because the unique N-terminal extension of WDR60 facilitates dynein-2 targeting to cilia. Strikingly, this N-terminal extension can be transplanted onto WDR34 and retain function, suggesting it acts as a flexible tether to the IFT "trains" that assemble at the ciliary base. We discuss how use of unstructured tethers represents an emerging theme in IFT train interactions

Asteroseismology of the open clusters NGC 6791, NGC 6811, and NGC 6819 from nineteen months of Kepler photometry

We studied solar-like oscillations in 115 red giants in the three open clusters NGC 6791, NGC 6811, and NGC 6819, based on photometric data covering more than 19 months with NASA's Kepler space telescope. We present the asteroseismic diagrams of the asymptotic parameters \delta\nu_02, \delta\nu_01 and \epsilon, which show clear correlation with fundamental stellar parameters such as mass and radius. When the stellar populations from the clusters are compared, we see evidence for a difference in mass of the red giant branch stars, and possibly a difference in structure of the red clump stars, from our measurements of the small separations \delta\nu_02 and \delta\nu_01. Ensemble \'{e}chelle diagrams and upper limits to the linewidths of l = 0 modes as a function of \Delta\nu of the clusters NGC 6791 and NGC 6819 are also shown, together with the correlation between the l = 0 ridge width and the T_eff of the stars. Lastly, we distinguish between red giant branch and red clump stars through the measurement of the period spacing of mixed dipole modes in 53 stars among all the three clusters to verify the stellar classification from the color-magnitude diagram. These seismic results also allow us to identify a number of special cases, including evolved blue stragglers and binaries, as well as stars in late He-core burning phases, which can be potentially interesting targets for detailed theoretical modeling.Comment: 30 pages, 15 figures, 1 table, accepted to Ap