478 research outputs found
Study of Genotype X Environment Interaction in Alfalfa Forage Yield
The response of alfalfa (Medicago sativa L.) forage yield to eight Alberta test sites was studied for the 1990 and 1991 production years. Cluster analysis was used to group locations and cultivars. Analyses of variances indicated genotype x environment (location) interaction for the first cut yield, the total yield and the difference between first and second cut yields. The Brooks, Bow Island (irrigation), Bow Island (dryland) and Provost locations always clustered together indicating that three of these four test sites may be eliminated without sacrificing reliability
Numeric and symbolic evaluation of the pfaffian of general skew-symmetric matrices
Evaluation of pfaffians arises in a number of physics applications, and for
some of them a direct method is preferable to using the determinantal formula.
We discuss two methods for the numerical evaluation of pfaffians. The first is
tridiagonalization based on Householder transformations. The main advantage of
this method is its numerical stability that makes unnecessary the
implementation of a pivoting strategy. The second method considered is based on
Aitken's block diagonalization formula. It yields to a kind of LU (similar to
Cholesky's factorization) decomposition (under congruence) of arbitrary
skew-symmetric matrices that is well suited both for the numeric and symbolic
evaluations of the pfaffian. Fortran subroutines (FORTRAN 77 and 90)
implementing both methods are given. We also provide simple implementations in
Python and Mathematica for purpose of testing, or for exploratory studies of
methods that make use of pfaffians.Comment: 13 pages, Download links:
http://gamma.ft.uam.es/robledo/Downloads.html and
http://www.phys.washington.edu/users/bertsch/computer.htm
Neuropsychological parameters indexing executive processes are associated with independent components of ERPs
AbstractLesion studies have indicated that at least the three executive processes can be differentiated in the frontal lobe: Energization, monitoring and task setting. Event related potentials (ERPs) in Go/NoGo tasks have been widely used in studying executive processes. In this study, ERPs were obtained from EEG recorded during performance of a cued Go/NoGo task. The Contingent Negative Variation (CNV) and P3NoGo waves were decomposed into four independent components (ICs), by applying Independent Component Analysis (ICA) to a collection of ERPs from 193 healthy individuals. The components were named IC CNVearly, IC CNVlate, IC P3NoGoearly and IC P3NoGolate according to the conditions and time interval in which they occurred. A sub-group of 28 individuals was also assessed with neuropsychological tests. The test parameters were selected on the basis of studies demonstrating their sensitivity to executive processes as defined in the ROtman-Baycrest Battery for Investigating Attention (ROBBIA) model. The test scores were categorized into the domain scores of energization, monitoring and task setting and correlated with the amplitudes of the individual ICs from the sub-group of 28 individuals. The energization domain correlated with the IC CNVlate and IC P3NoGoearly. The monitoring domain correlated with the IC P3NoGolate, while the task setting domain correlated with the IC CNVlate. The IC CNVearly was not correlated with any of the neuropsychological domain scores. The correlations between the domains and ICs remained largely unchanged when controlling for full-scale IQ. This is the first study to demonstrate that executive processes, as indexed by neuropsychological test parameters, are associated with particular event-related potentials in a cued Go/NoGo paradigm
Shape from Sound: Toward New Tools for Quantum Gravity
To unify general relativity and quantum theory is hard in part because they are formulated in two very different mathematical languages, differential geometry and functional analysis. A natural candidate for bridging this language gap, at least in the case of the Euclidean signature, is the discipline of spectral geometry. It aims at describing curved manifolds in terms of the spectra of their canonical differential operators. As an immediate benefit, this would offer a clean gauge-independent identification of the metricâs degrees of freedom in terms of invariants that should be ready to quantize. However, spectral geometry is itself hard and has been plagued by ambiguities. Here, we regularize and break up spectral geometry into small, finite-dimensional and therefore manageable steps. We constructively demonstrate that this strategy works at least in two dimensions. We can now calculate the shapes of two-dimensional objects from their vibrational spectra
Global Wheat Head Detection (GWHD) dataset: a large and diverse dataset of high resolution RGB labelled images to develop and benchmark wheat head detection methods
Detection of wheat heads is an important task allowing to estimate pertinent
traits including head population density and head characteristics such as
sanitary state, size, maturity stage and the presence of awns. Several studies
developed methods for wheat head detection from high-resolution RGB imagery.
They are based on computer vision and machine learning and are generally
calibrated and validated on limited datasets. However, variability in
observational conditions, genotypic differences, development stages, head
orientation represents a challenge in computer vision. Further, possible
blurring due to motion or wind and overlap between heads for dense populations
make this task even more complex. Through a joint international collaborative
effort, we have built a large, diverse and well-labelled dataset, the Global
Wheat Head detection (GWHD) dataset. It contains 4,700 high-resolution RGB
images and 190,000 labelled wheat heads collected from several countries around
the world at different growth stages with a wide range of genotypes. Guidelines
for image acquisition, associating minimum metadata to respect FAIR principles
and consistent head labelling methods are proposed when developing new head
detection datasets. The GWHD is publicly available at
http://www.global-wheat.com/ and aimed at developing and benchmarking methods
for wheat head detection.Comment: 16 pages, 7 figures, Dataset pape
Data-driven Development of ROTEM and TEG Algorithms for the Management of Trauma Hemorrhage A Prospective Observational Multicenter Study
Viscoelastic haemostatic assay augmented protocols for major trauma haemorrhage (ITACTIC): a randomized, controlled trial
Purpose: Contemporary trauma resuscitation prioritizes control of bleeding and uses major haemorrhage protocols
(MHPs) to prevent and treat coagulopathy. We aimed to determine whether augmenting MHPs with Viscoelastic Haemostatic
Assays (VHA) would improve outcomes compared to Conventional Coagulation Tests (CCTs).
Methods: This was a multi-centre, randomized controlled trial comparing outcomes in trauma patients who received
empiric MHPs, augmented by either VHA or CCT-guided interventions. Primary outcome was the proportion of subjects
who, at 24 h after injury, were alive and free of massive transfusion (10 or more red cell transfusions). Secondary
outcomes included 28-day mortality. Pre-specified subgroups included patients with severe traumatic brain injury
(TBI).
Results: Of 396 patients in the intention to treat analysis, 201 were allocated to VHA and 195 to CCT-guided therapy.
At 24 h, there was no difference in the proportion of patients who were alive and free of massive transfusion (VHA:
67%, CCT: 64%, OR 1.15, 95% CI 0.76â1.73). 28-day mortality was not different overall (VHA: 25%, CCT: 28%, OR 0.84,
95% CI 0.54â1.31), nor were there differences in other secondary outcomes or serious adverse events. In pre-specified
subgroups, there were no differences in primary outcomes. In the pre-specified subgroup of 74 patients with TBI, 64%
were alive and free of massive transfusion at 24 h compared to 46% in the CCT arm (OR 2.12, 95% CI 0.84â5.34).
Conclusion: There was no difference in overall outcomes between VHA- and CCT-augmented-major haemorrhage
protocols
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Production of Gratings for High-Energy Petawatt-Class Lasers
At the time of this writing, we have manufactured and delivered more than 25 multilayer dielectric diffraction gratings from 470-800 mm in long aperture for pulse compression on Petawatt-class,1-micron laser systems being built at government and university facilities in the U.S and elsewhere. We present statistics of diffraction efficiency and its spatial uniformity, diffracted wavefront, and laser damage results on witness gratings. We also discuss yield, failure modes, and manufacturing improvements necessary to improve upon the current state of the art
When assessment defines the contentâunderstanding goals in between teachers and policy
© 2020 The Authors. The Curriculum Journal published by John Wiley & Sons Ltd on behalf of British Educational Research Association.Education policy development internationally reflect a widespread expansion of learning outcome orientation in policy, curricula and assessment. In this paper, teachersâ perceptions about their work are explored, as goals and assessment play a more prominent role driven by the introduction of a learning outcomesâoriented system. This is investigated through interviews of Norwegian teachers and extensive policy analysis of Norwegian policy documents. The findings indicate that the teachers are finding ways to negotiate and adjust to the language in the policies investigated in this study. Furthermore, the findings show that the teachers have developed their professional language according to the policies. The teachers referred to their selfâmade criteria and goal sheets as central tools in explicating what is to be learned. In many ways, the tools for assessment, thus determine the content of education as well as what is valued in the educational system.publishedVersio
Cascade oxime formation, cyclization to a nitrone, and intermolecular dipolar cycloaddition.
Simple haloaldehydes, including enolisable aldehydes, were found to be suitable for the formation of cyclic products by cascade (domino) condensation, cyclisation, dipolar cycloaddition chemistry. This multi-component reaction approach to heterocyclic compounds was explored by using hydroxylamine, a selection of aldehydes, and a selection of activated dipolarophiles. Initial condensation gives intermediate oximes that undergo cyclisation with displacement of halide to give intermediate nitrones; these nitrones undergo in situ intermolecular dipolar cycloaddition reactions to give isoxazolidines. The cycloadducts from using dimethyl fumarate were treated with zinc/acetic acid to give lactam products and this provides an easy way to prepare pyrrolizinones, indolizinones, and pyrrolo[2,1-a]isoquinolinones. The chemistry is illustrated with a very short synthesis of the pyrrolizidine alkaloid macronecine and a formal synthesis of petasinecine
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