2,265 research outputs found
The Evolutionary and Biogeographic Origin and Diversification of the Tropical Monocot Order Zingiberales
Zingiberales are a primarily tropical lineage of monocots. The current pantropical distribution of the order suggests an historical Gondwanan distribution, however the evolutionary history of the group has never been analyzed in a temporal context to test if the order is old enough to attribute its current distribution to vicariance mediated by the break-up of the supercontinent. Based on a phylogeny derived from morphological and molecular characters, we develop a hypothesis for the spatial and temporal evolution of Zingiberales using Dispersal-Vicariance Analysis (DIVA) combined with a local molecular clock technique that enables the simultaneous analysis of multiple gene loci with multiple calibration points. We employ a pairwise relative rates test to assign four rate classes to 24 ingroup and 12 outgroup taxa using evidence from three gene regions (rbcL, atpB, 18S). Five nodes of in group and outgroup taxa were calibrated using fossils and previous monocot-wide age estimates. The results are compared with non-parametric rate smoothing and penalized likelihood estimates of temporal diversification. The divergence of Zingiberales from the remaining commelinid monocots is found to have occurred around 124 million years ago, with major family-level lineages becoming established in the late Cretaceous (80-110 mya) and crown lineages within each family beginning to diversify during the early to mid-Tertiary (29-64 mya). Ancestral Gondwanan vicariance combined with a potential Laurasian distribution and multiple secondary dispersal events within families during the Tertiary can explain the main biogeographic events leading to the current pantropical distribution of this tropical order
Prince Farming Takes a Wife: Exploring the Use of Agricultural Imagery and Stereotypes on ABC\u27s The Bachelor
The 19th season of ABC’s The Bachelor stars Chris Soules, an Iowa farmer who is pursuing a wife. Soules appears to exhibit all the qualities of a gentleman farmer desired by the contestants: good looks, kindness, strong family values, and courteous manners. However, research of previous reality television programs has concluded negative views of agricultural lifestyles typically are present. The Bachelor aired during prime-time television hours and exposed millions of viewers to agricultural imagery, which is why an analysis of this season is important to agricultural communicators. This qualitative discourse analysis examines the representation of agriculture and rural communities through selected videos and episodes of The Bachelor that show Soules and the bachelorettes in agriculture-related settings. Previous research indicates entertainment media have impacted audience’s perceptions of agriculture and reality television programming is adept at perpetuating stereotypes. Repeated exposure to stereotypes through media representation causes viewers to absorb those images into their social reality and, in turn, impacts their beliefs, attitudes, and behaviors toward the subject of those stereotypes. The Bachelor Season 19 contains both positive and negative agricultural stereotypes, including isolated small-town life, hard-working farmers, and “country” as a personality type. Farm-centric content is used to elicit laughs and to build romantic tension with the effect of minimizing the importance of agriculture. The researchers plan further investigation of the perceptual effects of the program’s televised content and the related social-media conversation surrounding “Prince Farming.
Calculating the Fine Structure of a Fabry-Perot Resonator using Spheroidal Wave Functions
A new set of vector solutions to Maxwell's equations based on solutions to
the wave equation in spheroidal coordinates allows laser beams to be described
beyond the paraxial approximation. Using these solutions allows us to calculate
the complete first-order corrections in the short-wavelength limit to
eigenmodes and eigenfrequencies in a Fabry-Perot resonator with perfectly
conducting mirrors. Experimentally relevant effects are predicted. Modes which
are degenerate according to the paraxial approximation are split according to
their total angular momentum. This includes a splitting due to coupling between
orbital angular momentum and spin angular momentum
Benchmarking Treatment Response in Tourette’s Disorder: A Psychometric Evaluation and Signal Detection Analysis of the Parent Tic Questionnaire
This study assessed the psychometric properties of a parent-reported tic severity measure, the Parent Tic Questionnaire (PTQ), and used the scale to establish guidelines for delineating clinically significant tic treatment response. Participants were 126 children ages 9 to 17 who participated in a randomized controlled trial of Comprehensive Behavioral Intervention for Tics (CBIT). Tic severity was assessed using the Yale Global Tic Severity Scale (YGTSS), Hopkins Motor/Vocal Tic Scale (HMVTS) and PTQ; positive treatment response was defined by a score of 1 (very much improved) or 2 (much improved) on the Clinical Global Impressions – Improvement (CGI-I) scale. Cronbach’s alpha and intraclass correlations (ICC) assessed internal consistency and test-retest reliability, with correlations evaluating validity. Receiver- and Quality-Receiver Operating Characteristic analyses assessed the efficiency of percent and raw-reduction cutoffs associated with positive treatment response. The PTQ demonstrated good internal consistency (α = 0.80 to 0.86), excellent test-retest reliability (ICC = .84 to .89), good convergent validity with the YGTSS and HM/VTS, and good discriminant validity from hyperactive, obsessive-compulsive, and externalizing (i.e., aggression and rule-breaking) symptoms. A 55% reduction and 10-point decrease in PTQ Total score were optimal for defining positive treatment response. Findings help standardize tic assessment and provide clinicians with greater clarity in determining clinically meaningful tic symptom change during treatment
Personalised learning: a familiar concept to secondary teachers? And which teachers?
This paper presents the main results of a questionnaire survey that sought to evaluate secondary school teachers’ familiarity with the notion of personalised learning and to relate it to personal, sociological and professional characteristics. The outcomes of this work are both an exploratory study aimed at defining more focused questions about the theme of personalisation, and the first tryout of the questionnaire designed to gather data. Although this was thus a preliminary study which did not lay claim to any more general scope, it still enables some hypotheses to be framed and examined in the light of the answers of 43 practitioners. The appendix provides the full questionnaire on personalisation, as distributed to participants.Peer reviewe
Photocycloaddition Of 4,5\u27,8-trimethylpsoralen And Oleic-acid Methyl-ester - Product Structures And Reaction-mechanism
The stereochemical structures of the four adducts formed between oleic acid methyl ester (OAME) and 4,5\u27,8-trimethylpsoralen (tmPso) have been determined. Assignment of the tmPso \u27H NMR spectrum was accomplished by analogy to two coumarin model compounds and with the use of homonuclear decoupling and resonance enhancement. Assignment of the lH NMR spectra for the OAME-tmPso adducts was made by analogy to the spectra of OAME and tmPso and using 2D &resolved and COSY analyses. The configurations of the cyclobutyl rings in these adducts was determined by The stereochemical structures of the four adducts formed between oleic acid methyl ester (OAME) and 4,5\u27,8-trimethylpsoralen (tmPso) have been determined. Assignment of the tmPso \u27H NMR spectrum was accomplished by analogy to two coumarin model compounds and with the use of homonuclear decoupling and resonance enhancement. Assignment of the lH NMR spectra for the OAME-tmPso adducts was made by analogy to the spectra of OAME and tmPso and using 2D &resolved; and COSY analyses. The configurations of the cyclobutyl rings in these adducts was determined by MM2 energy minimization calculations, homonuclear \u27H NOE analysis, and comparison of products obtained with cis-OAME and trans-EAME (elaidic acid methyl ester). Only four of the eight possible disastereomeric adducts are detected. These adducts have the cis-cis- , cis-cis-HT, trans-cis- , and trans-cis-HT configurations. The lack of formation of the other isomers may be due to the geometric requirements of exciplex formation. The mechanism of the reaction was established to involve initial bond formation at the 4 position of tmPso, most likely to form a diradical intermediate. The rate of dissociation of the trans diradical is much faster than ring closure, in contrast to the cis diradical whose rate of ring closure is at least as fast as dissociation. The rate of cis-trans isomerization of the 9,lO-bond of the fatty ester portion of the diradical is faster than ring closure for the cis diradical and slower than ring closure for the trans diradical
Frictional Drag Between Coupled 2D Hole Gases in GaAs/AlGaAs Heterostructures
We report on the first measurements of the drag effect between coupled
2D-hole gases. We investigate the coupling by changing the carrier densities in
the quantum wells, the widths of the barriers between the gases and the
perpendicular magnetic field. From the data we are able to attribute the
frictional drag to phonon coupling, because the non-parabolicity allows to tune
the Fermi wavevector and the Fermi velocity separately and, thereby, to
distinguish between phonon- and plasmon-dominated coupling.Comment: 10 pages, 5 figure
MathE - improve mathematical skills in higher education
Higher education students of scientific subjects often lack the basic mathematical skills to follow lectures and make the most of the lecturer’s teachings. It is necessary to identify the gaps in each students’ understanding of the concepts and offer teachers adequate resources to motivate and provide their students the skills and competences they miss. The main goal of MathE - Improve Maths Skills in Higher Education is to encourage training and exchange in order to enhance and strengthen the quality of teaching and to support the use of digital and online technologies to improve pedagogies and assessment methods. MathE also aims to set up transnational teacher training courses and strengthen cooperation between universities that already offer such courses.info:eu-repo/semantics/publishedVersio
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