1,151 research outputs found
Long-term Success of Stump Sprouts in High-graded Baldcypress-water Tupelo Swamps in the Mississippi Delta
Regeneration of baldcypress (Taxodium distichum (L.) Rich.) and water tupelo (Nyssa aquatica L.) in swamps of the deltaic plain of the Mississippi River are of major importance for ecosystem sustainability and forest management in the context of regional hydrological changes. Water tupelo often forms prolific sprouts from cut stumps, and baldcypress is one of few conifers to produce stump sprouts capable of becoming full-grown trees. Previous studies have addressed early survival of baldcypress stump sprouts, but have not addressed the likelihood of sprouts becoming an important component of mature stands. We surveyed stands in southeastern Louisiana that were partially logged 10–41 years ago to determine if stump sprouts are an important mechanism of regeneration. At each site we inventoried stumps and measured stump height and diameter, presence and number of sprouts, sprout height, and water depth.We determined age and diameter growth rate for the largest sprout fromeach stump from increment cores. The majority of stumps did not have surviving sprouts. Baldcypress sprout survival was about the same (median 10%) as previously found for stumps up to 7 years old, so it appears that, although mortality is high soon after sprouting, it is low after age 10.Water tupelo sprouting was rare at our sites but it was not clear whether this may have been because trees were not cut at our sample locations. Baldcypress stump sprouts were more likely to survive on shorter, smaller-diameter stumps, and baldcypress sprout growth was greatest on drier sites with less competition from overstory trees. Surviving baldcypress stump sprouts had high growth rates, but were not regularly spatially distributed within stands and many had advancing decay from stumps into sprouts
Randomised, single-masked non-inferiority trial of femtosecond laser-assisted versus manual phacoemulsification cataract surgery for adults with visually significant cataract : the FACT trial protocol
The study is supported by a grant from the National Institute for Health (NIHR) Health and Technologies Assessment (HTA) programme (reference 13/04/46). The corneal endothelial cell counter used at the Moorfields St Ann's Hospital site was purchased by a grant from the Special Trustees of Moorfields Eye Hospital (reference ST1503D).Introduction Cataract is one of the leading causes of low vision in the westernised world, and cataract surgery is one of the most commonly performed operations. Laser platforms for cataract surgery are now available, the anticipated advantages of which are broad and may include better visual outcomes through greater precision and reproducibility, and improved safety. FACT is a randomised single masked non-inferiority trial to establish whether laser-assisted cataract surgery is as good as or better than standard manual phacoemulsification. Methods and analysis 808 patients aged 18 years and over with visually significant cataract will be randomised to manual phacoemulsification cataract surgery (standard care) or laser-assisted cataract surgery (intervention arm). Outcomes will be measured at 3 and 12 months after surgery. The primary clinical outcome is uncorrected distance visual acuity (UDVA, logMAR) at 3 months in the study eye recorded by an observer masked to the trial group. Secondary outcomes include UDVA at 12 months, corrected distance visual acuity at 3 and 12 months, complications, endothelial cell loss, patient-reported outcome measures and a health economic analysis conforming to National Institute for Health and Care Excellence standards. Ethics and dissemination Research Ethics Committee Approval was obtained on 6 February 2015, ref: 14/LO/1937. Current protocol: v2.0 (08/04/2015). Study findings will be published in peer-reviewed journals. Trial registration number: ISRCTN: 77602616.Publisher PDFPeer reviewe
Framing research on school principals' identities
This paper provides a basis for a tentative framework for guiding future research into principals’ identity construction and development. It is situated in the context of persisting emphases placed by government policies on the need for technocratic competencies in principals as a means of demonstrating success defined largely as compliance with demands for the improvement in student test scores. Often this emphasis is at the expense of forwarding a broader view of the need, alongside these, for clear educational values, beliefs and practices that are associated with these. The framework is informed by the theoretical work of Wenger and Bourdieu as well as recent empirical research on the part played by professional identity and emotions in school leadership. In the paper, we highlight different lines of inquiry and the issues they raise for researchers. We argue that the constructions of school leadership identities are located in time, space and place, and emotions reflect complex leadership identities situated within social hierarchies which are part of wider structures and social relations of power and control
Validity of Recall of Tobacco Use in Two Prospective Cohorts
This project studied the convergent validity of current recall of tobacco-related health behaviors, compared with prospective self-report collected earlier at two sites. Cohorts were from the Oregon Research Institute at Eugene (N = 346, collected 19.5 years earlier) and the University of Pittsburgh, Pennsylvania (N = 294, collected 3.9 years earlier). Current recall was examined through computer-assisted interviews with the Lifetime Tobacco Use Questionnaire from 2005 through 2008. Convergent validity estimates demonstrated variability. Validity estimates of some tobacco use measures were significant for Oregon subjects (age at first cigarette, number of cigarettes/day, quit attempts yes/no and number of attempts, and abstinence symptoms at quitting; all P < 0.03). Validity estimates of Pittsburgh subjects’ self-reports of tobacco use and abstinence symptoms were significant (P < 0.001) for all tobacco use and abstinence symptoms and for responses to initial use of tobacco. These findings support the utility of collecting recalled self-report information for reconstructing salient lifetime health behaviors and underscore the need for careful interpretation
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BioTIME: A database of biodiversity time series for the Anthropocene.
MotivationThe BioTIME database contains raw data on species identities and abundances in ecological assemblages through time. These data enable users to calculate temporal trends in biodiversity within and amongst assemblages using a broad range of metrics. BioTIME is being developed as a community-led open-source database of biodiversity time series. Our goal is to accelerate and facilitate quantitative analysis of temporal patterns of biodiversity in the Anthropocene.Main types of variables includedThe database contains 8,777,413 species abundance records, from assemblages consistently sampled for a minimum of 2 years, which need not necessarily be consecutive. In addition, the database contains metadata relating to sampling methodology and contextual information about each record.Spatial location and grainBioTIME is a global database of 547,161 unique sampling locations spanning the marine, freshwater and terrestrial realms. Grain size varies across datasets from 0.0000000158 km2 (158 cm2) to 100 km2 (1,000,000,000,000 cm2).Time period and grainBioTIME records span from 1874 to 2016. The minimal temporal grain across all datasets in BioTIME is a year.Major taxa and level of measurementBioTIME includes data from 44,440 species across the plant and animal kingdoms, ranging from plants, plankton and terrestrial invertebrates to small and large vertebrates.Software format.csv and .SQL
Study of e+e- --> pi+ pi- pi0 process using initial state radiation with BABAR
The process e+e- --> pi+ pi- pi0 gamma has been studied at a center-of-mass
energy near the Y(4S) resonance using a 89.3 fb-1 data sample collected with
the BaBar detector at the PEP-II collider. From the measured 3pi mass spectrum
we have obtained the products of branching fractions for the omega and phi
mesons, B(omega --> e+e-)B(omega --> 3pi)=(6.70 +/- 0.06 +/- 0.27)10-5 and
B(phi --> e+e-)B(phi --> 3pi)=(4.30 +/- 0.08 +/- 0.21)10-5, and evaluated the
e+e- --> pi+ pi- pi0 cross section for the e+e- center-of-mass energy range
1.05 to 3.00 GeV. About 900 e+e- --> J/psi gamma --> pi+ pi- pi0 gamma events
have been selected and the branching fraction B(J/psi --> pi+ pi- pi0)=(2.18
+/- 0.19)% has been measured.Comment: 21 pages, 37 postscript figues, submitted to Phys. Rev.
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