1,888 research outputs found
Evolution Of Myrmecophytism In Western Malesian Macaranga (Euphorbiaceae)
Plants inhabited by ants (myrmecophytes) have evolved in a diversity of tropical plant lineages. Macaranga
includes approximately 300 paleotropical tree species; in western Malesia there are 26 myrmecophytic species that
vary in morphological specializations for ant association. The origin and diversification of myrmecophytism in Macaranga
was investigated using phylogenetic analyses of morphological and nuclear ITS DNA characters and studies
of character evolution. Despite low ITS variation, the combined analysis resulted in a well-supported hypothesis of
relationships. Mapping myrmecophytism on all most parsimonious trees resulting from the combined analysis indicated
that the trait evolved independently between two and four times and was lost between one and three times (five
changes). This hypothesis was robust when tested against trees constrained to have three or fewer evolutionary
transformations, although increased taxon sampling for the ITS analysis is required to confirm this. Mapping morphological
traits on the phylogeny indicated that myrmecophytism was not homologous among lineages; each independent
origin involved a suite of different specializations for ant-plant association. There was no evidence that
myrmecophytic traits underwent sequential change through evolution; self-hollowing domatia evolved independently
from ant-excavated domatia, and different food-body production types evolved in different lineages. The multiple
origins of myrmecophytism in Macaranga were restricted to one small, exclusively western Malesian lineage of an
otherwise large and nonmyrmecophytic genus. Although the evolution of aggregated food-body production and the
formation of domatia coincided with the evolution of myrmecophytism in all cases, several morphological, ecological,
and biogeographic factors appear to have facilitated and constrained this radiation of ant-plants
Hydraulic architecture explains species moisture dependency but not mortality rates across a tropical rainfall gradient
Intensified droughts are affecting tropical forests across the globe. However, the underlying mechanisms of tree drought response and mortality are poorly understood. Hydraulic traits and especially hydraulic safety margins (HSMs), that is, the extent to which plants buffer themselves from thresholds of water stress, provide insights into species-specific drought vulnerability. We investigated hydraulic traits during an intense drought triggered by the 2015–2016 El Niño on 27 canopy tree species across three tropical forest sites with differing precipitation. We capitalized on the drought event as a time when plant water status might approach or exceed thresholds of water stress. We investigated the degree to which these traits varied across the rainfall gradient, as well as relationships among hydraulic traits and species-specific optimal moisture and mortality rates. There were no differences among sites for any measured trait. There was strong coordination among traits, with a network analysis revealing two major groups of coordinated traits. In one group, there were water potentials, turgor loss point, sapwood capacitance and density, HSMs, and mortality rate. In the second group, there was leaf mass per area, leaf dry matter content, hydraulic architecture (leaf area to sapwood area ratio), and species-specific optimal moisture. These results demonstrated that while species with greater safety from turgor loss had lower mortality rates, hydraulic architecture was the only trait that explained species’ moisture dependency. Species with a greater leaf area to sapwood area ratio were associated with drier sites and reduced their transpirational demand during the dry season via deciduousness
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
Genome Sequence Conservation of Hendra Virus Isolates during Spillover to Horses, Australia
Bat-to-horse transmission of Hendra virus has occurred at least 14 times. Although clinical signs in horses have differed, genome sequencing has demonstrated little variation among the isolates. Our sequencing of 5 isolates from recent Hendra virus outbreaks in horses found no correlation between sequences and time or geographic location of outbreaks
Appendectomy versus non-operative treatment for acute uncomplicated appendicitis in children: Study protocol for a multicentre, open-label, non-inferiority, randomised controlled trial
Background Appendectomy is considered the gold standard treatment for acute appendicitis. Recently the need for surgery has been challenged in both adults and children. In children there is growing clinician, patient and parental interest in non-operative treatment of acute appendicitis with antibiotics as opposed to surgery. To date no multicentre randomised controlled trials that are appropriately powered to determine efficacy of nonoperative treatment (antibiotics) for acute appendicitis in children compared with surgery (appendectomy) have been performed. Methods Multicentre, international, randomised controlled trial with a non-inferiority design. Children (age 5–16 years) with a clinical and/or radiological diagnosis of acute uncomplicated appendicitis will be randomised (1:1 ratio) to receive either laparoscopic appendectomy or treatment with intravenous (minimum 12 hours) followed by oral antibiotics (total course 10 days). Allocation to groups will be stratified by gender, duration of symptoms (≫ or \u3c48 hours) and centre. Children in both treatment groups will follow a standardised treatment pathway. Primary outcome is treatment failure defined as additional intervention related to appendicitis requiring general anaesthesia within 1 year of randomisation (including recurrent appendicitis) or negative appendectomy. Important secondary outcomes will be reported and a cost-effectiveness analysis will be performed. The primary outcome will be analysed on a non-inferiority basis using a 20% non-inferiority margin. Planned sample size is 978 children. Discussion The APPY trial will be the first multicentre randomised trial comparing non-operative treatment with appendectomy for acute uncomplicated appendicitis in children. The results of this trial have the potential to revolutionise the treatment of this common gastrointestinal emergency. The randomised design will limit the effect of bias on outcomes seen in other studies. Trial registration number clinicaltrials.gov:NCT02687464. Registered on Jan 13th 2016
Micro-Symposium on Orin Kerr\u27s \u27A Theory of Law\u27
For more than a century, careful readers of the Green Bag have known that “[t]here is nothing sacred in a theory of law...which has outlived its usefulness or which was radically wrong from the beginning...The question is What is the law and what is the true public policy?” Professor Orin Kerr bravely, creatively, and eloquently answered that question in his article, “A Theory of Law,” in the Autumn 2012 issue of the Green Bag. Uniquely among all theories of law that I know of, Kerr’s answer to the fundamental question of law and true public policy enables all scholars to answer that same question in their own ways. The Green Bag is pleased to be featuring his “A Theory of Law” in its first micro-symposium, and just as pleased with the quality, quantity, and diversity of the responses to the call for papers. Blessed with an abundance of good work but cursed by a shortage of space, we were compelled to select a small set – representative and excellent – of those essays to publish in the Green Bag or its sibling publication, the Journal of Law. We regret that we cannot do full justice to the outpouring of first-rate legal-theoretical commentary we received
Would contact with extraterrestrials benefit or harm humanity? A scenario analysis
While humanity has not yet observed any extraterrestrial intelligence (ETI),
contact with ETI remains possible. Contact could occur through a broad range of
scenarios that have varying consequences for humanity. However, many
discussions of this question assume that contact will follow a particular
scenario that derives from the hopes and fears of the author. In this paper, we
analyze a broad range of contact scenarios in terms of whether contact with ETI
would benefit or harm humanity. This type of broad analysis can help us prepare
for actual contact with ETI even if the details of contact do not fully
resemble any specific scenario.Comment: 33 Pages, 1 Figure, PDF Fil
The Long-Baseline Neutrino Experiment: Exploring Fundamental Symmetries of the Universe
The preponderance of matter over antimatter in the early Universe, the
dynamics of the supernova bursts that produced the heavy elements necessary for
life and whether protons eventually decay --- these mysteries at the forefront
of particle physics and astrophysics are key to understanding the early
evolution of our Universe, its current state and its eventual fate. The
Long-Baseline Neutrino Experiment (LBNE) represents an extensively developed
plan for a world-class experiment dedicated to addressing these questions. LBNE
is conceived around three central components: (1) a new, high-intensity
neutrino source generated from a megawatt-class proton accelerator at Fermi
National Accelerator Laboratory, (2) a near neutrino detector just downstream
of the source, and (3) a massive liquid argon time-projection chamber deployed
as a far detector deep underground at the Sanford Underground Research
Facility. This facility, located at the site of the former Homestake Mine in
Lead, South Dakota, is approximately 1,300 km from the neutrino source at
Fermilab -- a distance (baseline) that delivers optimal sensitivity to neutrino
charge-parity symmetry violation and mass ordering effects. This ambitious yet
cost-effective design incorporates scalability and flexibility and can
accommodate a variety of upgrades and contributions. With its exceptional
combination of experimental configuration, technical capabilities, and
potential for transformative discoveries, LBNE promises to be a vital facility
for the field of particle physics worldwide, providing physicists from around
the globe with opportunities to collaborate in a twenty to thirty year program
of exciting science. In this document we provide a comprehensive overview of
LBNE's scientific objectives, its place in the landscape of neutrino physics
worldwide, the technologies it will incorporate and the capabilities it will
possess.Comment: Major update of previous version. This is the reference document for
LBNE science program and current status. Chapters 1, 3, and 9 provide a
comprehensive overview of LBNE's scientific objectives, its place in the
landscape of neutrino physics worldwide, the technologies it will incorporate
and the capabilities it will possess. 288 pages, 116 figure
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